Jeff,
sounds like the copper surface is not the problem but "between the trace" =
FR4 or what ever... it is absorb the plating solution, that is why it can
not obtain a good SIR value... something is porous and absorb the plating
solution..or for what ever the reason can not be clean away easily (may be I
read wrong...I will stay away any sponge like stuff.. may be low k or
cute..).
my 1.68 cents.
                            jk

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Jeffrey Bush
Sent: Tuesday, September 06, 2005 10:19 AM
To: [log in to unmask]
Subject: Re: [TN] Sand blasting pcb after copper etching


This is not a normal process. I would think that chemical etching is
more affective in removing metals and oxides from the resin surface.  We
see no issues with SIR/MIR using standard PCB processes.  I have done
this in the past of flex to promote stiffener bonding and mask adhesion.
Possible the PCB house has an issue with chemical etching or base
materials.

Jeffrey Bush
Director, Quality Assurance and Technical Support

VERMONT CIRCUITS INCORPORATED
  76 Technology Drive - POB 1890
    Brattleboro, Vermont 05302
      Voice: 802.257.4571.21 Fax: 802.257.0011
           http://www.vtcircuits.com


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ivanoe Pedruzzi
Sent: Tuesday, September 06, 2005 9:35 AM
To: [log in to unmask]
Subject: [TN] Sand blasting pcb after copper etching

Dear Technetters,

I'm not familiar with the process of making pcb and I would like to
have your comments on something I was told from a pcb maker
representative.

"...in order to ensure a well insulation between traces, we do
sandblasting (very little and tiny) pcb's after etching.
this is to remove the bonding material that remains on the board after
removing the copper. This is the only way to achieve a very good SIR
result."

Is this a normal procedure, was he correct in his claim?


Thanks,
Ivanoe Pedruzzi

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