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Why should high TG boards be used for PCB circuit boards? Because the high Tg sheet is high heat resistance.
At present, with the development of the electronics industry, the current electronic products represented by computers are developing towards high-functionality and high-multilayer development, which requires the guarantee of high heat resistance of PCB substrate materials.
The emergence and development of high-density mounting technologies represented by SMT and CMT have made PCBs more and more inseparable from the support of high heat resistance of substrates in terms of small apertures, fine lines, and thinning.
PCB substrate materials will not only soften and deform at high temperatures, but also exhibit reduced mechanical and electrical properties.
The difference between general FR-4 and high-Tg FR-4: when heated after moisture absorption, the material's mechanical strength, dimensional stability, adhesiveness, water absorption, thermal decomposition, thermal expansion and other various conditions The difference is that high Tg products are obviously better than ordinary PCB substrate materials.
2. With the increasing integration of ICs, the more IC pins become denser. The vertical spray tin process is difficult to flatten the thin pads, which will bring difficulty to the SMT placement; in addition, the stand-by life of the tin spray board is very short.
The gold-plated board just solves these problems:
1. For the surface mount process, especially for 0603 and 0402 ultra-small surface mounts, because the flatness of the pad is directly related to the quality of the solder paste printing process, it has a decisive influence on the quality of the subsequent reflow soldering, so the whole board Gold plating is common in high-density and ultra-small surface mount processes.
2. Affected by factors such as component procurement, it is often not that the board is soldered as soon as it comes, but it is often used after a week or two or even a month. The standby life of the gold-plated board is many times longer than that of the lead-tin alloy, so Many customers use gold plating
As the wiring becomes denser, the line width and spacing have reached 3MIL.
Therefore, the problem of gold wire short circuit is brought about: as the frequency of the signal becomes higher and higher, the skin effect causes the signal to be transmitted in the multi-plated layer, which has a great influence on the signal quality.
