Dear all

 

I'd like to have your opinion about the interpretation of the IPC-6012.

A multilayer is sequentially built and has a (pre-drilled and plated)
core for layers 1 and 2. 

This core is not laser drillable and can be only mechanically drilled.

 

Table 3-3 applies to Through Holes, Blind and Buried Vias > 2 layers.

What about blind vias equal to 2 layers? (Such as layer 1-2 made of a
drilled and plated core). Table 3-5 applies to a 2 layers core, but is
defined as a buried core only.

 

Note 1 to table 3-3 : "Does not apply to microvias. Blind vias have
greater than 1:1 aspect ratio ."

Note 1 to table 3-4 :" Microvias are defined as less or equal to 1:1
aspect ratio ( excludes mechanical drill),  or mechanically drilled <_
0.15 mm."

 

Which standard shall apply to blind vias that have an aspect ratio less
or equal to 1:1 -  for example layer 1-2 made of  a drilled and plated
core : 

Case A : 0.25 mm thick core with 0.25 mm mechanically drilled holes .

Case B : 0.25 mm thick core with 0.20 mm mechanically drilled holes.

 

Just to compare: what is your opinion  for the copper needed for a
double sided PCB with filled vias

 

Regards,

Roberto Tulman, CTO

Eltek


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