Tag Archives: SMT manufacturing

Printed Circuit Board

Printed Circuit Board Heat Sink Features/Functions

Heat management is essential for living on this earth as weather and devices affect buildings, vehicles, and equipment. Thermal management is also necessary for printed circuit boards, as they will get damaged if they can’t dissipate the heat their components generate. Besides, the board also gets hot due to soldering during manufacturing. Hence, heat dissipation methods become mandatory to increase the PCB speed.

Though FR4 is good at heat management, sometimes it is not enough when there is a high-speed circuit board. Likewise, the power supplies also generate heat and you have to install heat sinks and insulators. You must have experienced mechanical engineers to assess the heat flow to create a suitable heat dissipation system.

Printed circuit boards provide current to help devices function, but electronic devices get hot and heat sinks dissipate unnecessary heat. A PCB Manufacturer will use different heat sinks to prevent the overheating of PCB components and their damage, increasing the performance of the board.

Fourier’s law is an important law of heat that determines the heat sink function. When an element gets hot, heat travels from high-temperature areas to a low- temperature surface. The heat transfer occurs in three ways, such as:

  • Conduction
  • Radiation
  • Convention

When two components having different temperatures connect, it results in thermal conduction. In other words, fast molecules collide with slow molecules, resulting in heat transfer from hot components to cool components. PCB has high-temperature components like transistors, so you need to dissipate heat to cooling mediums, like water, air, or it can be oil, or some other element. This heat transfer occurs through conduction and convention.

Types of Heat Sinks

Heat sinks come up in different types as below:

Active Heat Sinks: There is a fan in an active heat sink to provide cooling. Such a heat sink provides great cooling, however, it needs regular maintenance as it is mostly running which affects its condition.

Passive Heat Sink: Passive heat sink is without a fan, so it remains still and needs less maintenance. You can consider it reliable and more effective than an active heat sink.

The shape and design also determine the type of heat sink, including swaged, stamped heat sinks, machining, folded and bonded fin, single fin sink, and forged heat sink.

Factors Affecting a Heat Sink

The main purpose of the heat sink is to exchange heat, so a large part of its surface area should be in contact with the cooling component like air. The quality of the heat sink depends on different factors, including its material, finishing, and certain physical features, like:

  • Air velocity
  • Attachment technique
  • Protrusion type

    Materials That Enhance Heat Sink Function

Manufacturers use specific materials to enhance the function of the heat sink in terms of heat transfer. These materials include:

  • Compounds
  • Conductive tape
  • Thermal paste

These materials are inserted between the surface of the heat sink and the surface of the component that generates heat. Metals having high thermal conductivity are ideal for heat sinks, including aluminum, copper, etc. But, aluminum is common as it is cheaper than others.

What To Consider Regarding Heat Sinks

Many factors affecting heat sink function include length, fin spacing and density, width, airflow, heat resistance, etc.

Which Devices Need Heat Sinks?

Electronic devices with components having poor heat dissipation ability need heat sinks. The devices in this case include multiple integrated circuits, diodes, transistors, switching devices, CPU and graphic processors, and LEDs.

Key Factors of Heat Sink Design

Heat sinks dissipate heat with the help of natural and forced convection, liquid, or radiation. The requirements of thermal management vary, depending upon the applications. Apart from a heat sink design, you have to consider several other factors while designing a thermal management system for a specific device. For like, you have to consider the standards of the component level, heat sink level standards, chassis levels, and requirements for a system level.

Let’s discuss essential factors that you have to consider during heat sink PCB design.

Heat Resistance: Thermal or heat resistance is the sum of multiple resistances occurring to heat flow between a cooling liquid and the die, thermal interference resistance, as well as the resistance between a moving fluid and a heat sink. Thermal resistance is bad for thermally unstable modeling systems.

The Value of Thermal Resistance: It is not precise, instead, it is approximate. It helps evaluate the thermal conductivity of the heat sinks and semiconductors. Heat dissipation depends on heat sink parameters that need proper analysis while designing the heat sink device. Heat sinks can be meshed through a 3D thermal resistance to have a complex system of thermal factors. Different platforms help design heat sink meshes.

Heat Sink Materials:  Generally, copper and aluminum are ideal heat sink materials as described above. These materials are good at conducting heat, especially copper as it also helps absorb heat, resists rust, and resist biofouling, moreover, it is also antimicrobial resistant. Though copper is better than aluminum, it is thick and costly compared to aluminum.

Another material is diamond and its thermal conductivity is also high due to the lattice vibrations it has. Some other materials for thermal applications include copper-tungsten pseudo-alloy, and AlSiCDymalloy.

Size and Shape of Heat Sink:  The shape and the size of the fins also help enhance heat dissipation. You can evaluate various fin shapes through modeling.

Fin Placement or Location: The arrangement of fins in a heat sink affects its cooling quality. Its configuration should be optimized to minimize the resistance of fluid movement, providing maximum air in the heat sink.

Cooling Quality: The cooling quality of the heat sinks has to be high. The aspect ratio of fins should be less to perform well. If the distance of the fin from the heat sink base is more, it will reduce the heat transfer to a cooling medium.

The function of the fins in a heat sink is to absorb heat from the electrical components of a device and sends it to the cooling medium. Besides, you should choose a cooling medium matching a PCB design and device requirements.

Heat Dissipation: Certain factors reduce the heat sink performance like a rough surface and gaps. They cause high resistance to thermal contact, thus affecting heat dissipation. You can reduce such thermal resistance by using thermal interface materials because most resistance-reduction techniques have limitations. You should consider specific things while selecting a thermal interface material, such as contact pressure, the material’s resistivity to current, and the dimensions of the surface gaps.

Attachment Methods: The attachment of the heat sink with PC Board components affects its thermal efficiency. So, you should choose the attachment technique carefully, considering the requirements of a thermal management system in terms of mechanical and thermal properties. Some popular attachment techniques include,

  • Thermal tape
  • Standoff spacers
  • Flat spring clamps

However, these attachment methods don’t end here as there are many others. You would also see m rein the future as engineers continuously update these methods according to new technologies.

By considering the above factors, engineers can design an effective heat dissipation system, including a heat sink.

Frequently Asked Questions

What Is Heat Sink?

The heat sink is a device and a way to manage heat in electronic products. Electronic components like transistors release heat, and you need heat sinks to dissipate heat to cooling mediums, like water, air, or it can be oil and other elements.

Do All Electronic Devices Need Heat Sinks?

Most devices need heat sinks to dissipate heat to cooling components. However, some electronic components have a built-in ability to dissipate heat. Generally, lasers or power transistors can’t transfer heat and need a solution to manage heat. MOSFETs and IGBTs are good examples in this case. So, here you need a heat sink device. 

Can PCB Survive Without Heat Sinks?

PCB components release heat which can damage them, making the electronic device slow. However, it also depends on the PCB materials as some have their heat dissipation property. Mostly you need a cooling system to enhance PCB performance. 

What Are The Types Of Heat Sinks?

The basic types in this case include the active heat sink system and the passive heat sink system. Some other types are also popular, like swaged heat sinks, stamped heat sinks, machining, folded and bonded fin, single-fin sinks, and forged heat sinks. 

Which Factors Influence The Heat Sink Design?

Many factors affect heat sink design, including its material, fin shape, and performance, fin size and location fin configuration, attachment technique of heat sink, and finally the thermal interface.

Final Thoughts

Devices having PCB also have heat sinks because they get hot due to high temperatures caused by different components. Heat sinks are either active or passive. You have to consider a few factors while designing the heat sinks, like its material, fin shape, and performance, fin size and location fin configuration, attachment technique of the heat sink, and finally the thermal interface. Various models help determine the heat sink parameters and geometry to provide a high-level heat transfer.

Would like to know more about the Heat Sink Features and Functions or pcb assembly services? Just Email us at sales@pnconline.com

Metal Core and Metal Black Printed Circuit Board

Printed Circuit Boards are a crucial component of any electronic device, but the materials used to manufacture them can significantly affect the performance and durability of the device. Metal core and metal black PCBs are two types of PCBs that offer numerous benefits over standard FR-4 PCBs. Here, we will explore the advantages of using metal core and metal black PCBs in electronic projects. We will discuss how they can improve their performance and reliability,   as well as their suitability for a variety of applications.

When it comes to a circuit board design, the metal core and metal black printed circuit boards offer a number of advantages over traditional PCBs. These benefits include improved heat dissipation, increased strength, electrical isolation, and reduced electromagnetic interference (EMI).

The use of the metal core and metal black printed circuit boards is a great way to improve the performance of your electronic devices. This type of PC Board provides excellent electrical and thermal conductivity, making them ideal for applications that require more power, speed, and accuracy. Metal core and metal black PCBs are also more resistant to environmental factors, such as temperature changes and corrosion, making them a better option than traditional PCBs.

What Are The Benefits Of Metal Core PCB?

Metal core PCBs are gaining popularity in the electronics industry due to their many advantages over traditional FR-4 and other standard PCBs. Metal core PCBs feature a dielectric layer, which is made from metal instead of a traditional fiberglass-epoxy material used in other PCBs. Such a metal core serves as a heat spreader and helps have better heat dissipation and improved thermal performance. This makes them ideal for applications that require high-level dissipation, and large temperature ranges.

The metal core also allows for a much thinner board than can be achieved with standard PCBs, reducing the overall weight of the assembly and making it easier to integrate into the design. As the metal core increases the rigidity of the board, it reduces the possibility of warping or cracking due to vibration and mechanical shock.

The copper layer used on the MCPCBs is often thicker than on standard boards, providing increased electrical performance as well. The additional copper layer also adds greater protection against EMI (electromagnetic interference), making them ideal for high-frequency and wireless applications.

Another benefit of metal-core PCBs is that they are more reliable than standard PCBs. As the metal core has better thermal conductivity than traditional fiberglass epoxy, it reduces the risk of solder joint failure due to overheating. This means that components are less likely to fail due to excessive heat, resulting in greater reliability.

Overall, the metal core PCBs offer many advantages over traditional PCBs, making them ideal for applications that require high power dissipation, thin boards, or robust performance in harsh environments. While they may cost more upfront than other types of PCBs, the benefits that come with using the MCPCBs often outweigh the costs in terms of improved performance and reliability.

For anyone looking to upgrade an existing project, or build one from scratch, there is never been a better time to consider switching to the metal core. If you’re looking to improve your product’s efficiency and reduce downtime, switching to a metal core PCB, maybe the right move for your next project.

Metal core PCBs are a special type of printed circuit board that uses metal instead of the traditional epoxy resin-based substrate. Metal core PCBs provide many advantages over their traditional counterparts, such as increased heat dissipation and better performance in higher-power applications. However, metal black PCBs offer a slightly different approach.

Metal black PCBs are constructed using metal cores that are plated with a black finish. This black finish helps reduce the emission of electromagnetic interference or EMI that can interfere with sensitive electronic components and impair their performance. Besides, the black finish helps absorb heat, which is beneficial in high-power applications.

The black finish also helps to prevent corrosion in the PCB itself, which can cause premature failure of the PCB over time. Moreover, the black finish increases the electrical resistance of the PCB, which can help protect against the short circuits caused by sudden changes in the voltage.

Finally, the metal black PCB offers an aesthetically pleasing look and a more rugged construction than a traditional printed circuit board. This makes the board ideal for a variety of applications that require superior durability, such as outdoor or industrial environments.

Overall, both metal core and metal black PCBs offer distinct advantages when compared to traditional printed circuit boards. While metal core PCBs provide greater heat dissipation and performance in higher-power applications, metal black PCBs offer superior protection against EMI and corrosion, as well as a more robust design for difficult environments. Ultimately, the choice of which type of PCB to use will depend on the specific requirements of the application.

For instance, if the application requires a higher level of heat dissipation and power output, then metal core PCBs may be preferable. On the other hand, if low levels of EMI emissions and protection against corrosion are desired, then metal black PCBs may be more appropriate. The final decision will ultimately depend on the specific needs of your project.
Which Type Of PCB Is Right For My Project?

When it comes to selecting the right type of PCB for your project, there are a number of factors to consider. One important factor is the type of material used for the PCB. Metal core and metal black PCBs are two popular options for many projects. Each one offers its own unique benefits, so let’s take a closer look at what each has to offer.

Metal core PCBs are constructed with an insulated metal substrate layer sandwiched between two layers of copper. This metal substrate layer helps conduct heat away from the board more efficiently than other PCB types, making it ideal for applications that generate high levels of heat. MCPCBs are also more resistant to temperature fluctuations, which makes them well-suited for automotive and avionics systems that need to perform reliably in changing environments.

Metal black PCBs are a specialized type of MCPCB that offer additional protection against an electrostatic discharge. Such boards contain an integrated layer of insulating polymer that is laminated over the metal core and then coated with a black solder mask. This makes metal core PCBs well-suited for electronic equipment where electromagnetic interference or electrostatic discharge (ESD) could damage the components.

When it comes to choosing the right type of PCB for your project, both MCPCBs and MBPCBs have their advantages and disadvantages. If you need a PCB that can handle high temperatures, then an MCPCB is the right choice. If you need a PCB that provides additional protection against EMI/ESD, then an MBPCB is the better option. Ultimately, it’s important to carefully evaluate your project’s requirements before deciding on which type of PCB is best for your needs.
FAQs
Why DO Manufacturers Us Metal Core And Metal Black PCBs?
When it comes to the design and manufacture of printed circuit boards, there are several advantages to choosing a metal core or metal black PCB. From improved thermal dissipation and electrical conductivity to better environmental protection and durability, these types of boards offer an array of benefits that cannot be achieved with conventional FR4 boards. Not only can metal core and metal black PCBs help reduce costs in the long run, but they can also enable more efficient product designs.

Overall, it’s clear that the benefits of using a metal core or metal black PCB greatly outweigh the costs.

What Is A Metal Core PCB?

Metal core PCB is a special type of printed circuit board that uses metal instead of the traditional epoxy resin-based substrate. Metal core PCBs provide many advantages over their traditional counterparts, such as increased heat dissipation and better performance in higher-power applications. However, metal black PCBs offer a slightly different approach.

What Includes In A Metal Core PCB?

The structure of a metal core PCB has multiple layers, including the circuit, copper, metallic, and dielectric layer, as well as the solder mask.

Wrap Up

In conclusion, metal core and metal black PCBs offer a range of advantages for designers and manufacturers. They provide superior heat dissipation, improved mechanical strength, longer product lifecycles, and improved EMI shielding properties. These advantages can help reduce costs and increase the longevity of the products, leading to improved customer satisfaction and increased profits.

Whether you are looking for increased performance, durability, or functionality, the metal core and metal black PCBs offer an ideal solution. The exceptional benefits these materials provide make them an ideal choice for engineers designing high-end applications.

With their ability to improve product performance while reducing production costs, the metal core and metal black PCBs should be seriously considered when designing a printed circuit board. With so many different varieties available, the sky’s the limit.

Would like to know more about the metal core and metal black PCB or printed circuit board assembly? Email us at sales@pnconline.com

Drill, Lamination, and Plating of PCB Design

Understanding Drilling

PC Board drilling involves different drilling machines which can make more than 30,000 holes in an hour. The machines have built-in systems for making precise holes and consist of spindles that can drill at a high speed of up to 110,000 RPM. An automated system and laser help manage drill bits to provide high-quality vias.

Drilling Of Through-Hole Vias

Standard PCBs have a through-hole where all PCB layers are drilled together under an NC machine. Then comes the plating of the holes’ inner and outer sides, and manufacturers use the same technique for all through holes, including the mounting holes.

Blind and Buried Via Drilling

The drilling of blind and buried vias occurs before lamination. The two-layered PCB goes through lamination after drilling. Whereas a multi-layer PCB is stacked and laminated after which it needs drilling and plating.

You can also make blind vias by drilling with a controlled depth where the drill machine works through the entire laminated board. Such a technique of making blind vias is cheaper than a sequential method, however, the hole size has some limitations. Besides, the routing of circuitry needs a specific technique.

Micro-vias Drilling

The drilling of micro-vias involves a laser machine because their size has to be small which is not easy to create through mechanical drilling. Micro-vias are ideal for thick PCBs, and you can connect them vertically by stacking them in layer pairs. Such as, in a traditional buried via, you can sequentially fabricate micro-vias whereas the buried vias need copper plating to connect the stacked vias.

When it comes to component holes, the through-hole technology works well. Such components are switches or standard connectors or mechanical components that need strong mounting that’s why the through hole suits them. Some common examples of devices having such holes include power regulators, resistors, op-amps, and capacitors, as they conduct heat and current.

How To Select A Drill

Though drilling is a basic function for a PCB Manufacturer, engineers use certain techniques to have precise drilling.

  • Sometimes a board needs lots of drills of the same size, which can cause changes in the bit during drilling. Such a change creates errors in terms of tolerance between hole diameters. So, engineers use drills of different sizes to avoid the quantity of the same-size drills.
  • Drilling diameter should be minimum, like in mechanical drilling, a six to eight mils drill is ideal for a 62-mils thick board. Whereas it is hard to use the small drill sizes in mechanical drilling, and its aspect ratio also makes plating difficult. So, engineers have to use laser drilling which is more expensive than normal drilling techniques. You have to use large drills for thick PCBs which are more than 62mils thick.
  • Use blind and buried vias when they are necessary otherwise avoid them. As their fabrication involves a sequential buildup method that increases the manufacturing cost of a raw board.

Different aspects affect the drilling methods and manufacturing cost of the PCB. Even the drill size affects the quality and cost of manufacturing. Too small holes highly increase a board’s cost, whereas too large holes can make assembly harder, increasing its cost. Engineers can avoid such issues by carefully designing a PCB, and having economical manufacturing.

PCB Plating or Metallization and Soldering

You need metal pads or lands to help components in mounting or soldering. You can’t solder the bare copper and have to plate it with an easy-to-solder material. In the past, lead-based tin was a common plating material. But, these days the environmental changes call for advanced materials like gold and nickel.

Unsoldered parts of the board need materials to resist soldering, such as polymer coating that prevents the bridging of traces. Moreover, it creates short circuits in the adjacent part leads.

Fabricating the External Layers

The above etching is ideal for circuits of external layers and the process includes drilling, metallization, and photoengraving. The final finishing happens after the external layers’ metallization. In general, the process includes soldering, silk screen application, testing, as well as packaging.

PCB Lamination

PCB lamination is crucial in terms of accuracy and creating a well-finished board. The process involves lots of stress, as you have to take care of the properties of PCB materials in terms of performance and production. PCB engineers and manufacturers have to work together to develop a functional product without sacrificing production.

Understanding the Lamination Process

The lamination of individual layers involves two main steps, such as:

Laying up:  It involves the stack-up of multiple layers. The manufacturer starts it from the bottom of the base substrate. Then comes the prepreg and internal etched layers. Then all layers are pinned together to make a final board without any disturbance. Laying up prepares the PCB before pressing.

Pressing of layers: Pressing involves heat and pressure that melts prepreg to finish the etched copper layer, making the insulation layers essential for electronic layers which can work closely. Prepreg bonds the layers, getting hard after curing, and makes a PCB mold.

You need to consider different factors during pressing. Like, many PCBs can be pressed together to save time and production costs. However, manufacturers have to place a separator between the individual layers to bear high pressure and heat without changing the PCB shape.

The laminating press also needs a vacuum to prevent the PCB voids to hinder the dielectric property, affecting its structural strength. The environment after pressing also needs consideration to prevent the STP quenching due to weather conditions. Manufacturers should store the pressed circuit boards in a press to cool them down. Cooling of the boards prevents the thermal contraction of the board.

Lamination Styles

Two styles are common in this case, such as:

  • Foil lamination
  • Cap lamination

PCB Lamination with A Foil: the foil lamination is simple and involves less hassle, as you have to foil the base and top layer. After lamination, the layers go through etching just like internal layers.  Foil lamination is more advanced than cap lamination, but you have to select the foil layer with care to remove them easily later on. The technician should work in alliance with the designer and material manufacturers to ensure precise production.

Copper Clad or Cap Lamination: It is an original method that PCB manufacturers have been using for years. There is a layer clad with copper between the base layer, top layer, and first and last inner layer. Such lamination is suitable for blind vias, however, you need a special laminate between the external and nearby layers to enhance a PCB function.

Purpose Of Sequential Lamination

You can use sequential lamination for advanced vias where drilling and plating come after lamination. However, vias other than through holes should be made before lamination, leading to sequential lamination. Such a technique involves many precautions in terms of materials and design to have a successful lamination. For like, you have to consider the z-axis CTE, Tg or glass transition temperature, and copper retention. A copper filling helps reduce copper accumulation to have a well-managed uniform CTE expansion.

The selection of the materials for PCB lamination involves great care. Besides, you should use the latest design software.

Testing a Final Product

Remember that PCB testing is very important to check damaged connectors and short circuits. Optical testing consists of layer scanning to find defects, whereas electrical tests involve a flying probe to verify different connections. It is easier to detect short circuits or breaks through electrical testing.  Whereas the optical inspection can better detect poor clearances between the conductors.

Final Thoughts

Drilling, plating, and lamination are important processes of PCB construction.  PCB drilling involves machines that can make more than 30,000 holes in an hour. The machines have built-in systems for making precise holes and consist of spindles that can drill at a high speed of up to 110,000 RPM.

An automated system and laser help manage drill bits to provide high-quality vias.  The two-layered PCB goes through lamination after drilling. Whereas a multi-layer PCB is stacked and laminated after which it needs drilling and plating.

The drilling of micro-vias involves a laser machine because their size has to be small which is not easy to create through mechanical drilling. Micro-vias are ideal for thick PCBs. Plating of the holes is also essential to provide electrical connections.

PCB laminating press needs a vacuum to prevent PCB voids to hinder the dielectric property, affecting its structural strength. The environment after pressing also needs to be considered to prevent any damage due to weather conditions.

Would like to know more about the Drilling, Lamination, & Plating or smt assembly? Email us at sales@pnconline.com

BGA SMT assembly process

BGA is an abbreviation for Balls Grid Arrays is a greater surface mounted packaging technique. The connections at the bottom of the packaging were circular and organized in a lattice-like structure, thus the term BGA. At the moment, motherboards controller chipsets employ such manufacturing materials and technologies, primarily earthenware. BGA technology, when combined with storage packaging, allows you to produce the same size storage while increasing SMT assembly processing capability by two to three times. BGA has a smaller frame and superior thermal conductivity qualities. BGA production process has substantially enhanced every square inch of memory; employing BGA manufacturing solutions, memory devices with the same capacity require just one-third the dimensions of a standard package; when contrasted with the conventional bundle.

It is a sort of surface-mount packaging (also known as a chip carrier) for interconnected circuitry. BGA modules have been used to install components like microcomputers securely. A BGA can accommodate more connectivity pins than a double inside or flat module. Instead of simply the boundary, the entire bottom area of the gadget may be employed. The connections were also smaller on aggregate than from an outer wall kind, resulting in improved effectiveness at incredible velocities. BGA gadget welding necessitates fine management and is often performed by computerized systems. Socket installation is not possible with BGA electronics.

Connectivity

The fundamental distinction between BGA Lead frame products and traditional SMT Lead frame products is the arrays structure of soldering sectors on the packaging, which suggests different interpretations for connecting communication, voltage, and ground connections on the PCBs.
In general, overall printable circuit boards design and implementation is a critical aspect in obtaining good solder connection durability. It is not suggested, for instance, to position BGA bundles in the very same contrary places here on the Printed Circuit Board (when double-edged mounting has been used), since this results in stiffness of the arrangement and earlier solder combined fatigue, particularly in comparison to a layout in which the element places have been started shifting against one another and.

Pattern for Soldering

Mass production is used to apply solder solution to the PCB metallic pads. The stencil apertures and thicknesses influence the amount of the generated soldering solution. In most circumstances, the thicknesses of a stencil must be adjusted to meet the requirements of all devices just on PCB. This is advised to use 100 – 150 m thickness overlays for BGA modules. The stencils perforations should be circular. The opening dimension must be the same as or slightly larger than the metallic pad thickness on the PCB.
To guarantee consistent and strong soldering paste application to the PCB, laser cut (mainly corrosion-resistant) or programs/projects (Nickel) stencils should be used.

Soldering

Solder paste is made up of soldering alloy and a fluxing system. Typically, the quantity is divided into 50 percent alloy and 50 percent flux. In terms of mass, this equates to around 90percentage alloys and 10percentage fluxes systems. During the resistance spot welding, the fluxes system removes environmental contamination from the soldering connections. The capacity to remove environmental contamination is controlled by the action potentials. The soldering solution metal alloy must be either lead-based austenite or near-eutectic (SnPb or SnPbAg) or lead-free (SnAgCu whereas Ag 3 – 4 percent, Cu 0.5 – 1 percent). Since washing underneath the connected BGA may be problematic, a “no-clean” solder solution was suggested. The solution should be adequate for producing the soldering stencils apertures measurements; Type 3 pasted is suggested for ball pitches of 0.80 mm and 0.65 mm, while Type 4 glue is suggested for ball pitches of 0.5 mm. Soldering paste has age, weather, and moisture dependent. Make sure to follow the pasted company’s treatment instructions.

Placement of Components

BGA packages must be precisely arranged according to their shape. Individually placing the packets is not advised. Sophisticated automated element placement devices with computer vision achieve element positioning levels of accuracy of 50 m. Both PCB, as well as the parts, were visually scanned in these systems, and the parts were put on the PC Board in their predetermined places. These fiducials on the PCB are now either positioned on the PCB’s edge for the whole PCB or particular mounting points (local fiducials). A visual interface detects them instantly before the installation procedure. A sophisticated vision algorithm identifies the packets, allowing for the exact alignment of the full program.

Due to the increased surface pressure of the soldering, packets with conductive spheres as the BGA have had the advantage of self-alignment during the reflow process if they have been significantly misaligned. As a rule of the thumb, the maximum allowable element movement equals 30% of the metallic pads thickness just on PCB (for non-solder mask defined pads). As a result, for BGA modules, the soldering contact to PCB pads mismatch must be higher than 150 m (higher than 100 m for spacing 0.5 mm) to provide a strong installation procedure. This is often possible with a broad variety of finding the most appropriate.

The subsequent statements stand necessary:

  • Particularly on big boards, localized fiducials near to the gadget might mitigate a substantial number of PCB limitations.
  • It is advised that you utilize the positioning system’s ball identification abilities rather than the outlining centered. This removes the program’s soldering ball to packaging edge limitations.
  • Effective illumination and the right selection of measurement modes are required to guarantee the visual state’s recognition of the items. The precise parameters may be obtained from the device instructions.
  • Excessive insertion force might result in pushed-up soldering paste and solder junction failures.

Solder joints

To a considerable degree, soldering influences the production and accuracy of component manufacturing. In principle, all typical reflow soldered procedures are applicable.

  • compelled circulation
  • during the gaseous stage
  • far-infrared (with restrictions)

The specified temperature patterns were suited for BGA board manufacturing. During the soldering procedure, each soldered joint must be subjected to temps beyond the soldering solubility limit for a good amount of time to get the best soldering joint integrity, while overheating the PCB and its elements must be prevented. For the highest product normal temperature, please see the barcode scanner labeling on the packaging.
Special attention may be required when utilizing ultraviolet ovens lacking ventilation to ensure suitably uniform temperatures profiles for all solder connections on the PCB, particularly on big, complicated boards with varied heating capacities of the elements, particularly with someone underneath the BGA. Forced convective routing protocol has been the most commonly suggested kind. Although a nitrous environment can increase solder connection quality generally, it is usually not required for solder tin-lead metal alloys.

Gathering on Both Sides

In principle, BGA packages are ideal for installation on double-sided PCBs. Be cautious that items with a high weight may fall off throughout the final soldering process procedure when facing down during the PC Board assembly. In such circumstances, the packages must be constructed during the final (= second) reflow procedure. A weight restriction of 0.2 g/mm2 soldering surface (NSMD pad) might be considered as a rule of thumb. Whether boxes are impacted is determined not just by mass, but also by vibration and air draught in the heating chamber.

Solder Alloys Interoperability

Because various solder alloys may be used for packaging spheres or bumping and soldering paste placed just on PCB, the interoperability of these compositions must be considered.

The benefits of BGA boards

Dense population

A BGA solves the difficulty of making a tiny packaging for a semiconductor technology with thousands of connections. Pin grids displays and dual-in-line surfaces mounted (SOIC) modules were being manufactured with an increasing number of connections and reducing distance amongst the connections, but this was producing problems with the soldered procedure. The risk of inadvertently crossing neighboring connections using soldering increased as packaging pins became closer apart. If the soldering is put to the packaging at the manufacturer, BGAs don’t have this issue.

Convection of heat

The decreased temperature difference across the container and the PCB is another benefit of BGA packaging over packaging with separate connections (i.e. boxes with legs). This permits heat produced by the semiconductor technology on the inside of the packages to transfer more freely to the PCB, reducing overheating of the chip.

Connections with low capacitance

The smaller the undesired capacitance of an electromagnetic wire, which causes signal distortions in high-speed electromechanical equipment, the smaller it is. Because of the slight distance between the packaging and the PCB, BGAs have consistently low inductors and so outperform pinning gadgets in terms of electromagnetic efficiency.

Problems with BGAs throughout PCB manufacturing

While research, soldering BGAs into place is impractical, therefore sockets are utilized instead, however, they are unstable. There seem to be two main types of sockets: the more dependable version features springtime pins that force up beneath the balls, but it doesn’t permit for the use of BGAs with both the balls detached since the springs pins might have been too shorter.

Interested to know more about BGAs or pcb assembly services? Email PNC at sales@pnconline.com

Smt Assembly Conformal Coating

SMT Assembly Conformal Coating

Definition

Conformal coating is a thin layer of protected polymeric coating applied to printed circuit boards (PCBs) and electronic components. Its goal is to provide environmental and mechanical protection for the components and circuits, allowing them to last longer and be more reliable. It maintains long-term surface insulation resistance values by being electrically insulating, ensuring the assembly’s operational integrity. It also prevents corrosion by acting as a barrier to airborne pollutants from the operational environment, like salt spray.

Conformal coatings are often applied in the 25-250 micron range. Parylene films, on the other hand, are applied significantly thinner and can be fractions of a micron thick. Conformal coatings are a flexible covering that will secure the printed circuit board assembly from the environment it is in by filtering out air pollutants and ensuring long-term interface resistance value while also allowing any moisture trapped in the circuit board to dissipate.

The notion of conformal electronics coating was first conceived and refined through research decades ago to suit the rigorous requirements of the military. HumiSeal was a pioneer and leader in that early research and the company has remained a pioneer and leader for over 60 years as the technology has spread to a variety of industries, including:

  • Industrial Controls
  • Automobiles like Hybrid and Electric Vehicles
  • Aerospace
  • Telecoms
  • Traditional and renewable energy
  • White thing

 Conformal coating types

While there are many other types of coatings, including a few specialist forms, five primary categories are depending on the chemical makeup of the substances.

  1. Urethane Resin (UR):

Single-part or two-part urethane resins are available. It is chemically resistant as well as humidity resistance. On the other side, it is simple to remove and rework with a soldering iron.

  1. Acrylic Resin (AR):

Preformed acrylic polymers that have been dissolved in a solvent are known as acrylic. Typically, they are one-part compounds. It is inexpensive and simple to apply and remove. During the curing method, there is no distortion.

  1. Epoxy Resin (ER):

Epoxy coatings are typically two-part compounds, but a one-part option is also available. It has moistures. It performs admirably in adverse conditions.

  1. Silicone Resin (SR):

Silicone resin coatings are one-component materials that are frequently used on devices that will be exposed to severe temperatures. Even at high temperatures, it performs excellently. It can stick to almost any PCB material.

  1. Parylene (XY)

Chemical vapor deposition is the method used to apply parylene coatings. When heated, parylene turns into a gas. It is then placed in a vacuum chamber to polymerize and form a film after cooling. After that, the film is applied over the circuitry. It is translucent and colorless. It is the ideal solvent for coating and can be done at room temperature.

Uses of conformal coating

When today’s dynamic electronics are faced with significant environments, additional protection is required to ensure proper operation. Moisture, salt sprays, strong chemicals and solvents, vapors, dust, abrasion, and even organic assault have all been proved to be resistant to conformal coatings. Furthermore, it has been demonstrated that the impact of mechanical stress and disturbances on the circuit and its functionality in severe temperature ranges can be reduced by using the right material. Conformal coatings protect the product while also improving its reliability. As a result, the negative impacts of early field failures are reduced, as is the potential cost. We use conformal coating for:

  • It works as a moisture and humidity-resistant barrier, resulting in lower leakage currents, converse, and electrical and chemical transfer throughout the board.
  • The coating has the potential to improve the strength of dielectric conductors.
  • The coating provides a high level of insulation safety, allowing conductor space to be reduced.
  • It prevents the board from chemical and corrosive attacks that can cause corrosion. It also protects against damage caused by hard handling, as well as thermal and mechanical load.
  • The coating prevents particle pollutants from reaching the board’s surface.

 Method of conformal coating

The following are types of common Printed Circuit Board conformal coatings:

  1. Brushing

Brushing a conformal coating is a popular method of application. Although this is a simple procedure, it needs the use of a trained operator to ensure the coating’s quality and finish. A brush, a container for storing the coating, and a specified area for application are all required. The coating material is dipped in the brush and applied to the board.

The type of brush, operator competence, coating viscosity, the environment, and the coating material all affect the brushing method’s quality. It has many benefits, including ease of use, simplicity, and reduced process control needs. This method is ideal for rework and low-volume production. In this process, we use hands and are thicker and less pleasing artistically. This is the ideal option for individuals who don’t have the tools to use other options or who are working on a few boards at once.

  1. Spraying:

This procedure produces a better surface polish and is more cost-effective, but it does not penetrate the board deeply. Spraying, which is also preferable for low-volume production, is time-consuming because all parts that do not require coating must be masked. Spraying with aerosols, batch spraying, and selective spraying are all part of this approach.

A spray gun is included with an aerosol. It’s a coating with a solvent basis. Aerosol spraying in a spray booth is a low-cost option. This procedure is superior to brushing because of the inexpensive setup costs, high process speed, simplicity, and final quality.

Batch spraying utilizes a compressed air spray cannon to provide a high-quality coating finish. For the setup, you’ll need a spray gun, a spray booth, and an air compressor. In this operation, it’s crucial to get the spray gun set up with the right atomization pressure and material supply. It’s also crucial to get the coating’s viscosity just correct. It has features such as inexpensive setup costs and flexibility.

Spraying selectively only coatings selected areas. The coating isn’t applied to regions that need to be masked, like connectors and other components. The coating is done with the use of a customized robot system that uses various spray patterns. Valve selection, board material, and board arrangement are all important considerations. The correct spray valve and coating viscosity must be selected.

All sorts of conformal coatings are supported by the spray approach, and designing for this procedure necessitates a high level of technical knowledge. As a result, spray application requires significant capital expenditure. In addition, the material’s performance over time and changes in the control environment must be monitored.

  1. Dipping:

Dipping is the process of immersing a board in a coating solution and then removing it. This process is ideal for high-volume assembly since it is quick, precise, and penetrates the board, coating the entire assembly. However, to eliminate leakage, masking must be flawless, rendering many boards unsuitable owing to design. This approach can only be used on boards that take coating on both sides.

This is a conventional procedure that involves dipping the pcb assembly into a tank of coating chemicals. The speed of immersion, coating dwell time, and board withdrawal speed are the variables that determine the process. Acrylics and urethanes, which are solvent-based conformal coatings, are recommended for dipping. It’s a high-speed process that can be used in batch or in-line processes.

The conformal coating manufacturing process

In the conformal coating production process, there are eight main steps:

Cleaning:

The cleaning eliminates a variety of residues that result from operator handling, soldering, machine use, and pollution from the environment.

Priming:

Priming is the process of applying a preliminary coating to a board before applying the conformal coating. It improves adherence and produces a binding layer to keep the coating in place. The amount of priming required varies depending on the type of resin.

Masking:

The function of masking is to prevent the conformal coating from being placed on the parts and selected board sections. Because of the insulating nature of the coating, certain regions of the circuit board must remain uncoated. Many materials are used in masking.

Cure and dry:

There is a difference between Cure and dry. That is:

Cure:

This means that the coating achieves the desired qualities (electrical and mechanical) and that the board is protected while in use.

Dry:

This assures that the PCB is laminated and suitable for the users to operate. It could take anywhere from a few minutes to several days.

Checking:

In the procedure, it is the most crucial stage. Manual inspection, UV lamp visibility, and automated optical inspection are all included.

Benefits of conformal coating

When it comes to choosing parylene coating that meets standards, there are several clear advantages and benefits. Because there is no liquid phase in this technique, there will be no pooling of coating in low regions. Furthermore, it will not bridge in substrate features. Furthermore, this sort of coating is extremely pure and is one of the best dielectric qualities available. It’s one of the purest polymer types. It also possesses the best mechanical and gas barriers, allowing it to suit a wide range of coating requirements, even when applied in thin layers.

It protects against impurities such as dust, filth, fungi, moisture, chemicals, thermomechanical stress, mechanical shock, and vibration, as well as environmental, mechanical, electrical, and chemical issues.

Finally, remember the project and the electronics’ user needs in mind when selecting a coating for your printed circuit board or other electronics. It’s necessary to preserve the board, but it’s even more critical to cover it with the right material. When choosing a coating type, keep the environment in mind as well as any rework or repair requirements.

Smt Assembly
Smt Assembly

At PNC, get your conformal coatings done at affordable rates. Contact us at sales@pnconline.com