TECHNET Archives

December 2001

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Charles McMahon <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 7 Dec 2001 13:36:13 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (161 lines)
Hello Mr. Hillman:

Thank you very much for your input. Your time is most appreciated.

As a board supplier I do prefer ENIG when process control is superior
(black pad notwithstanding). However, it is the customer
who is King and our goal is to surpass their requirements for quality
and reliablity. As CM's are now a driving force as to vendor choice,
their needs
have become a primary influencer in choosing  friendly surface finishes
beneficial to their process.

What comments might you have relative to solderability problems found
specific to silver/gold/tin coatings.
When the design calls for fine pitch what do you choose for your
facility? And why?
Regarding silver again; would corrosion of the surface upon exposure to
flux be an issue at rework?
Secondly, when reflow issues arise, have you found them to be traced
back to the thickness of the silver itself (or lack of thickness)?

One view is that as lead is taken out of the PCB fab process, one of
these alternative finishes will dominate. The driver will be
rework/touch-up flexibility as to which one wins. Would you agree?

Your insights are thanked for in advance.

Charlie McMahon
McMahon Sales Company

David Hillman wrote:

>Hi Charlie! I hadn't seen an assembler's response so I'll deposit mine for
>TechNet dissection. We have qualified immersion gold, immersion tin, and
>immersion silver as alternative pwb surface finishes for our manufacturing
>processes as HASL replacements. I don't foresee any one of the three
>alternatives as becoming "dominate" because each has both pro's and con's:
>
>Immersion gold: wonderfully flat, good long term solderability, good
>industry availability, BUT black pad issues, its a nasty chemistry on
>soldermask, and soldering to nickel is not soldering to copper
>
>Immersion tin: wonderfully flat, metallurgical compatibility, reworkable,
>BUT long term solderability issues, compatibility with soldermasks, and
>supply sources
>
>Immersion silver: wonderfully flat, reworkable, great RF design
>characteristics, BUT supply source issues, metallurgical questions, and
>long term solderability questions
>
>I think that the selection of an alternative surface finishes will become a
>question of materials organization within a particular manufacturing
>environment - HASL made our choices simpler but was definitely robustness
>limiting for certain manufacturing flows (like SMT fine pitch).
>
>Dave Hillman
>Rockwell Collins
>[log in to unmask]
>
>
>
>
>
>Charles McMahon <[log in to unmask]>@ipc.org> on 12/05/2001 11:33:26 AM
>
>Please respond to "TechNet E-Mail Forum." <[log in to unmask]>
>
>Sent by:  TechNet <[log in to unmask]>
>
>
>To:   [log in to unmask]
>cc:
>
>Subject:  Re: [TN] SURFACE FINISHES
>
>
>EARL:
>
>Does your view hold the same from an assemblers point of view.
>
>More specifically, in your history, would the assembler prefer ENIG over
>SILVER and/or TIN?
>THe assemblers I speak with just do not have the background/experience to
>decide. However, they
>are quick to reject the bare board vendor for what they THINK is a
>solderability problem.
>(That's when I move with failure review etc. I hope to reduce this
>incidence
>dramatically by proposing user friendly finishes based on board design.)
>
>Charlie
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]]On Behalf Of Earl Moon
>Sent: Wednesday, December 05, 2001 12:14 PM
>To: [log in to unmask]
>Subject: Re: [TN] SURFACE FINISHES
>
>
>As a cost factor to you it's nickle and dime stuff. To most board shops I
>work with, it is as well. It's a matter of choice so much that it's almost
>subjective (whatever looks best though black pad isn't too pretty) -
>excluding HASL, or course. I hope you are right about its final demise.
>
>MoonMann
>
>----------------------------------------------------------------------------
>
>-----
>Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
>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 delivery of Technet send the following message: SET
>Technet NOMAIL
>Search previous postings at: www.ipc.org > On-Line Resources & Databases >
>E-mail Archives
>Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
>additional
>information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
>ext.5315
>----------------------------------------------------------------------------
>
>-----
>
>---------------------------------------------------------------------------------
>
>Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
>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 delivery of Technet send the following message: SET
>Technet NOMAIL
>Search previous postings at: www.ipc.org > On-Line Resources & Databases >
>E-mail Archives
>Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
>additional
>information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
>ext.5315
>---------------------------------------------------------------------------------
>
>---------------------------------------------------------------------------------
>Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
>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 delivery of Technet send the following message: SET Technet NOMAIL
>Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
>Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
>information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
>---------------------------------------------------------------------------------
>
>

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
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 delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------

ATOM RSS1 RSS2