Hi Linda,

As a board manufacturer we see fine pitch devices in all finishes. however, feedback we get is that  the hot air level process process does not provide a consistent finish and a coplanarity issue can become problematic. 

I have heard a lot of rumblings about a electroless or immersion tin process that has come about lately. I have one customer that have been getting it from another supplier and loves it. They have asked us to look into the process but I really dont have any information on it yet. You might want to find out more about this. From what I hear the surface coplanarity is as good as the gold finish and it solders better... Just what I've heard.

Ed Cosper

----------
From:   (No Name Available)
Sent:   Thursday, October 22, 1998 3:00 PM
To:     [log in to unmask]
Subject:        [TN] PCB for fine pitch

Hi Technetters,
It is time to ask advice from the experts so here I am.  I need some help, as
usual.  I think I need you guys and gals about once a month.  Thanks for being
here.

Here is the problem.  If you have a board that has 15 mil pitch should the
board be tin/lead plated or should it have a flash of gold?  I have heard that
gold flashing is a must for 15 mil boards.  So tell me, what is the answer.
Also if you had any problems and solutions you would like to share with this
pitch of component.

Thanks in advance,

Linda Zellars
[log in to unmask]

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