Subject: | |
From: | |
Reply To: | |
Date: | Tue, 6 Sep 2005 11:06:26 EDT |
Content-Type: | text/plain |
Parts/Attachments: |
|
|
In a message dated 9/6/2005 9:36:25 AM Eastern Daylight Time,
[log in to unmask] writes:
"...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."
For removal of traces of the adhesion promotion material (zinc, etc) that
are applied to copper foil, some companies have resorted to chemical treatments
such as alkaline permanganate. This is similar to "desmear" of the drilled
holes before metallization. I think alkaline etching of inner layers leaves
more of this "adhesion promotion" treatment in the rough epoxy between
traces, than say cupric chloride etching. However, the foil vendors should comment
whether any secondary treatment of etched layers is now needed to meet very
high (Telcordia?) SIR readings. I suspect that lower "tooth" foil does not
embed as much adhesion promotor as the older, rougher foils used ten years
ago. Certainly, drum side treatmented foil should embed little adhesion
promoter.
Also, there may be a patent to two concerning specific chemical cyles - it
has been like ten years since this high SIR need was recognized.
I have not heard of using sandblast to accomplish this same epoxy surface
treatment.
Dennis Fritz
MacDermid, Inc.
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
|
|