Mr.Hammond

   A 1:1 aspect ratio of blind via is limit.
   Vibration through electroless,electro plating process and lower current
   density in electro plating are very important.
   Regards
Motoyo Wajima
General Purpose Computer Division,Hitachi,Ltd.(JAPAN)


[log in to unmask] ,3,ñ,I_`,«,Ü,µ,½_F
>     I've heard that the general rule limiting blind vias is a 1:1 aspect 
>     ratio.  You are at it with the 16 mil holes & 16 mil depth.  It seems 
>     like you are doing the right things (i.e. vibration, etc.) so I'm not 
>     sure what else to suggest.
>     
>     
>     MB
>_____________________________ Reply Separator 
_________________________________
>Subject: Blind vias & fine lines
>Author:  [log in to unmask] at SMTPLINK-HADCO
>Date:    2/12/97 10:07 PM
>
>
>Techneters,
>  Can anyone help? I am having two problem areas:
>     
> 1) Blind via holes 16 mil diameter 16 mil deep contacting with 4 
>inner layers. I cannot always plate copper into all holes. If I do copper 
>plate them I cannot tin plate all the holes. I have vibrators on the 
>cathode movement frame and a giant to clout the fight bars with a 2 pound 
>hammer. Is there anything else I can do?!?
>     
> 2) Circuits with 2 mil track and gaps. The finish required is 
>electroless nickel/immersion gold. How can this be done without causing 
>the tracks to short with nickel spikes?
>     
>  Thanks in advance,
>   Roger Hammond
>     
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