Ultimate Guide to PC Board Thickness

Printed circuit boards are vital parts of electronic technology and you have to focus on various factors to design or buy them. PCB thickness is the most important factor in this case. However, the weight, profile, and components of PCB also matter a lot.
PCB thickness can influence its function, affecting resistance and conductivity. The application of a circuit board determines its thickness and there are different levels of thickness in this regard.

A-Thickness Of A Standard PCB

A standard printed circuit board has different types, like one-sided having one layer of copper or double-sided boar with two layers of copper. Whereas multiple layers are also in practice. The double-sided PCB has a substrate layer between two layers.
Generally, a standard circuit board is 1.57mm or 0.0065 inches as it used to be the thickness of the plywood in old circuit boards. Later, multilayered PCBs emerged and the designer had to make their thickness according to the connectors. So, the designers need a standard thickness of 1.57mm.
The board thickness also ranges from 0.008 inches to 0.240 inches, and you can select any thickness between these figures to match the PCB application. You can give your requirements to the manufacturer or can hire an engineer to evaluate PCB thickness for a specific application.

Copper Thickness Of A Standard PCB

You also have to consider the copper thickness as it helps get the desired PC Board thickness and influences its function. Like, one square foot area of the circuit board needs an ounce of copper which becomes 1.37 mils. But, it can vary, depending on your needs according to the current that passes through the board.
Most circuits come up with 1oz copper i.e. equal to one ounce. However, it can be 2oz if the circuit board needs high currents. Designers often increase the track’s thickness which results in higher current points. Moreover, they don’t add anti-welding masks because they want to reinforce the track during assembly, like with tin.
Sometimes laminate manufacturers use an intermediate thickness of copper just to lower the price, like 0.75 oz. But, such a practice is technically not so good. Experts don’t recommend this because the PCB thickness also reduces during mechanical or chemical cleaning. The popular copper thickness is 0.5oz, like in the case of two-sided laminates.

Trace Thickness In PCB

You have to specify the trace thickness while making the Gerber files to avoid overheating. Trace thickness is the trace width that can tolerate the temperature difference ranging from the standard to maximum operating temperatures. In other words, the trace width should be enough to bear increased temperatures. Besides, PCB width calculators are available to find the trace width.

B-FR4 Thickness Of A Standard PCB

FR4 is the flame retardant material which is a fiberglass sheet with epoxy lamination. FR4 shows the quality of the laminate in PCB. Generally, it’s the base material for Printed Circuit board Fabrication.
The rigidity occurs due to epoxy that resists fire, and engineers prefer it for its low cost. The dielectric strength of FR4 is high, moreover, it is lightweight and also resists heat and water. So, they are compatible with different environments.
The FR4 thickness lies between 3 and 10 inches, and it can cause an increase in PCB thickness. You have to evaluate the FR4 thickness by considering the board components and space.
Design Parameters of an FR4 Board Thickness
Generally, the designers prefer thick boards because thin FR4 boards get damaged faster, especially when they are large, besides, the grooves are missing. Whereas thicker boards provide more flexibility and also include grooves.
Should Be Flexible
Thin circuit boards are more flexible than heavy or thick boards, especially in the medical field’s control unit. But, thinner circuit boards cause lots of issues during soldering that results in bending. Eventually, several other components also get curved, damaging a board’s connections.
Compatible Impedance
PCB thickness is crucial while constructing multilayer boards became you have to match the impedance. Besides, you also have to consider each layer’s capacitance. The board won’t function if its impedance is not compatible.
Edge Connectors
The edge connectors also directly influence the PCB thickness, especially when there is FR4. An incompatible mating part of the connectors can result in PCB damage. So, you must be clear about materials before PCB manufacturing.
PCB Weight
More thickness means more weight and increased shipping costs. So, you have to keep in mind the weight of the circuit board that determines the weight of the final product. Experts find thinner layers better than the others, however, one should go for a standard PCB thickness.
C- Core Thickness of Standard PCB
The core is a PCB layer having FR4 between copper layers or foils. The core of a standard PCB involves certain items of which copper should be precise. It’s a fiber mesh layer having resin, moreover, it has incurred FR4 as well.
The core thickness of the standard PCB becomes hard to select during a multilayer PCB design. However, sometimes PCB remains effective even if the core thickness is not compatible. But, the end product should perform high for which PCB should have accurate thickness. The designer must consider this factor and share the right details with the manufacturer.
The weight of the core thickness goes from 1 to 3 ounces depending on the requirements. The weight also includes copper layers that can be on both sides. However, if both sides’ weight differs, it would cause additional expenses and poor results. The core thickness with the desired copper weight is also possible through pre-preg sheets.
D-Two-Layered PCB Thickness
Printed circuit boards with multiple layers are getting popular these days. They include glass fabric based on epoxy having copper coils. A multi-layered PCB can bear high loads, however, its thickness remains only 63mm.
Complex PCBs need wiring, resulting in more layers, so PCB thickness becomes up to 93mm. The thickness of a standard PCB also gets influenced by foil lamination, if the lamination consists of 4 layers, 0.031 would be the PCB thickness. The thickness would become 0.062 if the foil lamination includes 6 layers.
Likewise, the thickness becomes 0.062 to 0.125 for 8 to 10-layer PCB. Your requirements can also demand half, one, or two-ounce copper foil.
PCB Thickness Allowance
Also known as PCB thickness allowance, it is the tolerance for PCB manufacturing substances. It can be more or less than the average amount of material. Designers consider certain parameters for it, such as the IPC guidelines. Such design parameters help manufacturers have the flexibility to develop a circuit board that performs well.

FAQs

What Is The Importance Of Knowing PCB Thickness?
You have to focus on the circuit board thickness because both electronic devices and boards have a tendency to shrink. So the board has to be thin and lightweight to help manufacturers place it into the device. The weight of the final product also matters as thicker circuit boards can increase the weight of the device, resulting in increased shipping costs.
How Many Layers Are There In A Standard PCB fabrication?
There are various types of standard printed circuit boards, including one-sided having one layer of copper or double-sided board with two layers of copper. There is also PCB with more than two layers called a multi-layered PCB.
What Is FR4 In A Standard PCB?
FR4 is the flame retardant material which is a fiberglass sheet with epoxy lamination. FR4 shows the quality of the laminate in PCB. Generally, it’s the base material of a rigid circuit board.
What Is Core Thickness In A Standard PCB?
PCB layer with FR4 between copper layers or foils is known as the core. The core of a standard PCB consists of various elements, including copper that has to be accurate. PCB core is a fiber mesh layer having resin, moreover, it has incurred FR4 as well.
What To Consider While Designing A Standard PCB?
Designers have to focus on various factors to design or buy a printed circuit board. PCB thickness is the most important factor, but the weight, profile, and components of PCB also matter a lot.
What is Trace Thickness In PCB?
Trace thickness is the trace width that can tolerate the temperature difference ranging from the standard to maximum operating temperatures. You have to specify the trace thickness while making the Gerber files to avoid overheating.

Wrap Up

Now, you know how important it is to consider PCB thickness in different ways. PCB thickness can influence its function, affecting resistance and conductivity. The application of a circuit board determines its thickness and there are different levels of thickness in this regard. You can have a good circuit board by choosing the board thickness wisely, depending on its application.
Would like to know more about printed circuit board assembly? Email us at sales@pnconline.com

Written by Sam Sangani

Sam Sangani is the President & CEO of PNC Inc., a Nutley, NJ based Printed Circuit Board manufacturer. Sam graduated from L. D. Engineering College with a BS Degree in Mechanical Engineering. He also continued his education and graduated from Steven’s Institute of Technology where he acquired a Master’s degree in Computer Science.

After completion of his BS, Sam worked as a QC Manager, for Xerox, Romania and London. He was responsible for the Quality Control of Cable and Wire Harness imports from Romania. After completing his Master’s Degree, he worked as a Senior Programmer with IBM, Tucson, Arizona. Sam was responsible for leading the Mainframe System Programming Team.

In 1997, Sam acquired PNC INC., a Nutley, NJ based PC Board fabrication Shop. From 1997-2013, Sam has made tremendous improvements and changes within PNC INC., as he added many new Products and Technologies in PNC’s portfolio. With his proven track record and leadership, PNC has never had an unprofitable year and has continued its growth yearly since 1997.

His current responsibilities are Strategic Planning, Corporate Management, New Business Ventures, Sales & Marketing, Trade Shows, Professional Services and leading productive teams to achieve peak potential. He has also utilized Lean Management techniques which have built a foundation for PNC’s high-paced growth. Sam also enjoys real-estate investing, web design & SEO, trading stocks, options, futures and Forex markets.