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Non-drilled PCB holes

Form vias in PCB's at the prepreg stage of the substrate.
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Category should be Business:Manufacturing.

The most common printed circuit board material, FR4, is a kind of prepreg (pre-impregnated) fiberglass. That material is made in a bulk roll process. Later, after delivery, the board is drilled for through holes. It's possible to form the holes while the prepreg is still wet, though.

The idea is to use a press drum with one pin for each via the board will later receive. The prepreg is cured on this form long enough for hole stability, then flattened without removing the holes. Copper cladding can happen normally, but assuming registration is not lost on the line (use a non-clad margin), the copper can then be pierced/punched in the same pattern.

Advantages: Eliminate drilling, a serial x-y positioning process, and substitute with a parallel forming one. Activate through-holes in the pierce/punch step and save a chemical activation process for through-hole plating.

eh9, Nov 22 2005

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       How much would the hole's position or shape adjust during the later steps (cooling/forming)? If they move out of spec enough to cause mounting problems or vibration sensitivity to mounts, then you may end up scrapping the whole board, as filling holes is usually cost prohibitive.
sophocles, Nov 22 2005
  

       I have no idea what you just said.
iamnafets, Nov 22 2005
  

       sophocles, - maybe under controlled conditions, it becomes entirely predictable.   

       eh9, - do you think this might also apply to multilayer?
Ian Tindale, Nov 22 2005
  

       Well, accuracy's not a massive concern, really - holes normally have plenty of play in them (the ones I've seen, anyway). Surely this is adding a process to get rid of a process, though?
moomintroll, Nov 22 2005
  

       <holds hearing trumpet to ear> excuse me? [iamnafets]
po, Nov 22 2005
  

       FR4, eh9. Eh9, FR4.
phoenix, Nov 24 2005
  

       [accuracy's not a massive concern, really - holes normally have plenty of play in them ]   

       Well, yes for some old school tech, but for fine pitch tech this won't work. But it get's my vote, for a hydraulic solution to a phonetic problem.
normzone, Nov 24 2005
  

       [eh9], are you referring to a process to manufacture pre-drilled PCB prototyping boards (like Vectorboard), or a process to make custom PCBs?
xrayTed, Nov 24 2005
  

       Many cheap consumer devices use punched phenolic.
supercat, Nov 24 2005
  

       It would cost more.   

       The substrate is economical only if made in large quantities. As soon as you make it "pre-punched" it is customised and good for only one job. There will be mountains of waste when the pcb design changes to accommodate the newer part with a different footprint, because the manufacturer stopped the old one because it was too cheap and margins too low.
neelandan, Nov 24 2005
  
      
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