Have you ever been in a physics laboratory where you were instructed to solder some components on a “board” to build amazing projects? Projects such as an emergency alarm, amplifier and so on. Of course, it must have been a difficult thing to do like a lot of teenagers in college back in the days detested attemanding physics classes.
Never mind if you weren’t a science student however the so-called “board” is actually called a printed circuit board. This printed circuit board or PCB for short has a lot of great benefits in the electronics world which cannot be trivialized.
What is The Essence of Printed Circuit Boards (PCB)?
PCB designing is the process of aiming to get the required layout of the connection networks. This is desired for both electrical devices and circuit components without altering the required levels of electrical parameters. Examples of such parameters are mechanical parameters such as getting enough rigidity for the given material thickness.
Likewise, we also have thermal parameters which have to do with the adequate dissipation of heat from power components, and finally impedance. There are actually other parameters that are considered in the designing and which play a significant role in pricing.
It’s discovered that most times the final design released for production is not price-optimized. The prices are majorly borne out of design production complexity.
What are the Important PCB Design Parameters that are available?
The PCB parameters are the determining factor in the performance of PCB. It also determines the scope of its application. However, various products have different requirements and conditions on the PCB base material. The development of the electronics industry would have not been made possible without putting these designs and parameters into consideration.
The first parameter that has to be present is thickness lamination. This was made possible through the development of copper clad laminate (CCL) and aluminum board. This CCL has good heat dissipation and it comes in three layers namely: insulating layer, circuit layer (copper foil) and the metal base.
The standard values for production of the laminate and copper foils are 1.6 mm and 35 µm, respectively. Price of the board can be minimized through the standard ones however it is the thick ones that make the prices inflated.
The value of the thick laminate circuits ranges from 2.4 to 3.2 mm and 70 to 140 µm for the copper foils. It is possible to increase the path thickness by removing the resists and tin plate and it ends up increasing from 20 to 40 µm.
Examples of the laminates are as follows:
1) The most popular and cheapest laminate available is FR4. It has all-round electrical parameters such as thermal conductivity of ca. 0.4W/mK and the standard dielectric constant of 4.5. It is encouraged that circuits with moderate power losses use the FR4 laminate.
2) Another one is the laminate from Rogers called Teflon-based laminates. This one exhibits low loss and they are made for HF circuits.
3) A popular laminate choice for high-power SMD circuits is the Aluminum core laminate. Why is it so popular? This is none other than the fact that they oscillate at several W/mK making them attain higher thermal conductivity. They are mostly utilized in the LED lighting industry. It is actually recommended to use the single layer Aluminum board based on the fact that it is available as against the Multilayer Aluminum board which is rarely seen and expensive.
The next parameter worthy of mention is the number of layers. It is advisable to build a 6-layer printed circuit board network across 4 layers. This is the best path to take since cutting two layers doesn’t make any financial sense. Furthermore, in order to meet the permitted DRC parameters, the higher density interconnections necessitate redesigning the mosaic.
Another PCB design parameter for consideration is flammability characteristics. An important factor when designing and choosing PCB is the ability to be resistant to burning. The board is meant to be soft when exposed to heat rather than get burnt. The temperature at which the circuit board becomes soft is referred to as “vitrification temperature” or “glass transition temperature”. This temperature is denoted as Tg. It’s also treated as the melting point of the board.
What is the purpose of a printed circuit board having a High Tg?
The following are the advantages of having a high vitrification temperature for PCB:
- Moisture resistance
- Chemical resistance
- Heat resistance
- It has a wider application than free processing materials although the price of the former is higher.
The above-mentioned parameters are the ones that are mostly required when determining the right PCB designs.