How do multiple layer PCBs avoid mechanical damage due to "shearing" forces?

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How do multiple layer PCBs avoid mechanical damage due to "shearing" forces?

Hello,


Multiple layer (>4) PCBs consist of multiple layers glued together........how do they ensure that the layers always stay "true" with each other ....that is , how do they make sure that the layers don't slide in relation to each other......such sliding , or "shearing" could cause vias to break and tracks to short together.

..are their limits to how close internal tracks should be to internal restrings of through vias so as to avoid shorting?
 

Re: How do multiple layer PCBs avoid mechanical damage due to "shearing" forces?

Hello,

you know Prepreg will be used ase the gluing material between two layers except the laminate, during heat pressing, factory will use Pins to fasten the Prepreg and laminate, so the layers will not slide . also, since the prepreg exist between two layers as the dielectric material , it will not cause short between tracks from different layers.

if more questions, please let me know.

Koen
Regards
 
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Re: How do multiple layer PCBs avoid mechanical damage due to "shearing" forces?

Tooling holes, and line up pins during the lamination process, not a concern these days.
As to limits consult the relevent manufacturers cababily itvaries from one to the other, but 0.1/0.1mm track/gap is pretty standard these days.
 
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Re: How do multiple layer PCBs avoid mechanical damage due to "shearing" forces?

Yes, 0.1/0.1mm track/gap is becoming the standard for most of factories in China, i am also a PCB supplier which can fabricated 0.075/0.075mm for fine line boards, if you would like to know more about the manufacturers capability, you can contact me freely.
 
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Re: How do multiple layer PCBs avoid mechanical damage due to "shearing" forces?

Hi,

as i mentioned that the Prepreg was used during pressing, this kind of material consist of glue and glass fiber, during pressing, the resin will become glue, but the glass fiber will keep the structures and seperate the circuits in different layers, and also, the preprege and laminate will be fasten by Pin during pressing, it will prevent the movement during pressing . it is impossible to cause short between different layer.
 
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