Today I will tell you about the difficulties in multi-layer PCB prototyping and production?
There are four major difficulties in the production and processing of multi-layer circuit boards.
Multilayer PCB boards are used as the "core main force" in the fields of communications, medical care, industrial control, security, automobiles, electricity, aviation, military industry, computer peripherals, etc. The product functions are getting more and more, and the circuits are getting denser. So, relatively, the production The difficulty is also increasing.
At present, domestic PCB manufacturers that can mass-produce multi-layer circuit boards often come from foreign-funded enterprises, and only a few domestic-funded enterprises have the ability to mass-produce multi-layer circuit boards. The production of multi-layer circuit boards not only requires high investment in technology and equipment, but also requires experienced production technicians. At the same time, obtaining multi-layer board customer certification is strict and cumbersome. Therefore, the entry threshold for multi-layer circuit boards is very high. It is relatively high and has a long cycle to achieve industrialized production. Well, we at PCBAMake have our own PCB and SMT patch factories and have introduced a large number of advanced equipment to ensure customer quality and on-time delivery.
Specifically, the processing difficulties encountered in the production of multi-layer circuit boards mainly include the following four aspects.
Four major difficulties in the production and processing of multi-layer circuit boards
1. Difficulties in making inner circuits
Multilayer board circuits have various special requirements for high speed, thick copper, high frequency, and high Tg value. The requirements for inner layer wiring and pattern size control are getting higher and higher. For example, the ARM development board has a lot of impedance signal lines in the inner layer. Ensuring the integrity of the impedance increases the difficulty of producing the inner layer lines.
There are many signal lines in the inner layer, and the width and spacing of the lines are basically around 4 mil or less; the thin production of multi-core boards is easy to wrinkle, and these factors will increase the production cost of the inner layer.
2. Difficulties in alignment between inner layers
The number of layers in multi-layer boards is increasing, and the alignment requirements for the inner layers are getting higher and higher. The film will expand and contract due to the temperature and humidity of the workshop environment, and the core board will have the same expansion and contraction after production, which makes the alignment accuracy between inner layers more difficult to control.
3. Difficulties in the pressing process
The superimposition of multiple core boards and PP (pre-cured sheet) is prone to problems such as delamination, skateboard and steam drum residue during lamination. If there are many layers, the expansion and contraction control and size coefficient compensation cannot be consistent; if the interlayer insulation layer is thin, it will easily lead to the failure of interlayer reliability testing.
4. Difficulties in drilling production
Multilayer boards are made of high Tg or other special boards. The roughness of drilling holes in different materials is different, which increases the difficulty of removing glue residue in the holes. High-density multilayer boards have high hole density, low production efficiency, and are easy to break. Between different network vias, the edges of the holes are too close to each other, which will cause CAF effect problems.
Therefore, in order to ensure the high reliability of the final product, multilayer board manufacturers need to carry out corresponding controls during the production process.
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