The making of PCB involves different steps, technologies, and terms, and TG is one such term that refers to the Glass Transition Temperature. High TG PCB is the board made at a high temperature. We will discuss this topic in detail, including the TG value, features, applications, materials, parameters, and much more.
If a PCB’s temperature goes beyond a set TG value, its condition will change. Like, the solid board will turn rubbery, affecting a PCB’s function. Depending on where you use a PCB, the temperature of the application should be at least 10 to 20C less than the PCB temperature.
TG means Glass Transition Temperature like there is a certain limit of this temperature for PCB and that specific temperature is the TG value. TG value helps in understanding the PCB material, and you can find which temperature is required for its service.
Secondly, it helps you to find the condition of the PCB material, like if it’s solid, flexible, or solid-flex.
You have to choose a high TG Printed Circuit Board for your application carefully, because it involves multiple features, including thermal, electrical, mechanical, and chemical features.
Thermal Features: they include the TG or Glass Transition Temperature, thermal conductivity, thermal temperature’s coefficient, and decomposition temperature. TG is the temperature at which the state of the PCB material changes. But, when the board cools down, it gets back to its initial condition.
Electrical Features: they include the surface resistance, electrical power, volume relativity, and the dielectric constant and loss tangent.
Chemical Features: the chemical properties of a high TG PCB include the moisture absorption and the methylene chloride resistance of the PCB material. The TG PCB should be able to resist moisture if it’s near water.
Mechanical Features: the mechanical features are also important to know regarding the TG PCB. They include the flexural and peel strength, and the young’s module.
A PCB has two materials, including laminate and substrate. The substrate includes epoxy resin, glass, or paper weave. The substrate should be compatible with the TG. Some common substrates that we use for a high TG PCB are;
The last three materials are flexible.
The laminates should also be compatible with your TG PCB in terms of strength and temperature. Some common laminates are:
Printed circuit boards with a high TG value are based on certain criteria as described below:
Generally, manufacturers use bendability and strength to classify a TG PCB‘s physical properties.
You can use the high TG circuit boards in intense conditions, as the environments with high-vibration devices. They are also suitable for applications with shocks, chemical components, and high temperatures. Like, missiles and car parts often come up with chemicals. So, the suitable industries for high TG PCBs include aerospace, telecommunications, military and defense force, automobile, and down-hole drilling.
You must hire a professional PCB manufacturer for the right design, manufacturing, and assembly of these boards. The engineer must know the kind of environment that suits a TG PCB to function precisely. Below are a few examples to help you understand it.
Many telecommunication companies use the best materials for mobile devices to enable them to bear high shocks. Like, the phone should not get damaged easily when you drop it.
PCB has to be safe under a car’s hood as it’s mostly vibrating, so a shock or crash might happen. Hence, a rigid PCB is the best solution in this case.
The flying machinery always needs the high TG PCB because there is intense vibration, like in the jet engine, as there are thousands and millions of micro-vibrations in one minute. So, equipment related to aerospace should be able to tolerate extreme temperatures, like from -45°C to 85°C.
These boards are also ideal for solar power equipment, such as power inverters and cogeneration equipment. As these boards resist temperature, they work well in many industries. Like, one of its applications involves Lead technology, like the medical, computer, and telecommunication industries.
The TG PCB is also used in broadcasting, like booster stations. Besides, the fire detectors and burglar alarms also need such boards.
It is clear from the name that a flex PCB can adapt any design or shape to get compatible with certain products. Like, they can tolerate intense environments better than rigid PCBs. You can use the high TG flex PCB in defense and military, aerospace, medical equipment, consumer electronics, auto, wireless networks, as well as industrial equipment.
You must hire a professional PCB manufacturer for the right design, manufacturing, and assembly of flex PCB. The engineer must know the kind of environment that suits a TG PCB to function precisely. You should see if:
The design of a high TG PCB involves different steps, such as
The fabrication of a high TG PC Board Fabrication involves certain parameters and specs, depending on the application. Some standard parameters are described below.
Designers prefer the even number of layers while developing the high TG PCBs. But, the odd numbers of layers are also suitable in certain applications.
The PCB dimensions depend on its application. Like, you need a large circuit board for a broader application. Besides, there should be enough space on the board to place the electrical components.
The high TG PCB should be well-finished, and the material depends on where you want to use this board. Like, some common materials are;
HASL, or hot air leveling – It is ideal as it is cheap and can be stored for longer.
OSP, or organic protective surface
Immersion silver – It gives a smooth surface, and it is cost-effective. It has many storage limitations
Immersion tin – It suits the SMT
Immersion gold – It can be stored for longer with a few limitations.
ENEPIG, nickel palladium – It can be stored longer, but it involves a complex process.
Solder mask – It protects the PCB from environmental elements.
Weight of copper – You must also consider the weight of copper like it includes both initial and finishing copper. Generally, the weight is 1 oz. to 1.5 oz. or 5 oz. It also depends on the layer and board thickness.
Assembled PCB thickness – The TG PCB thickness depends on its material and type. Like, if it’s flexible, hard, or a hard-flex board.
Distance between layers – The distance or spacing of electrical components and layers should be equal for high-frequency signals. As it reduces the coupling effect.
Via sizes – The drill aspect ratio and the hole size should also be appropriate. Generally, the PG PCB can have either plated-through or non-plated through holes, depending on the placement and layout design.
Board quality – The board should have a high-grade material to ensure an effective function during application. Besides, you must check the quality of the TG PCB to evaluate its performance in terms of specs. Like, you should test its lamination, vias, copper plating, solderability, finishing, components, and cleanliness.