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October 2005

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Subject:
From:
Lee Parker <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Lee Parker <[log in to unmask]>
Date:
Tue, 11 Oct 2005 22:45:01 -0400
Content-Type:
text/plain
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text/plain (256 lines)
Joel



I am glad to here that you are successfully using ENIG boards;
unfortunately this has not been the case with some other OEMs and CMs.
Almost every week in this forum, I see a report of a problem with ENIG. I
myself spent this spring moving several clients from ENIG to other
solderability coatings. It has been my experience that if the gold
thickness is <2 microinches there is a serious risk of poor solderability.
If the gold thickness is> 4 microinches black pad may become a problem.
The issue can also be elevated or diminished by the particular plating
chemistry and the ability of the fabricator to control the process.



Consequently, I often work with clients to evaluate and migrate too other
hard metal finishes such as immersion silver and flash gold. The
attributes of immersion silver have been discussed here at length many
times and I am an advocate. I installed the first immersion silver line in
North America at the AT&T plant in Richmond. I then worked with most of
the AT&T assembly locations to verify the process.



Flash gold is more recent and is found mostly in Chinese PCB shops where
it has been resurrected and improved upon. In fact, we used a similar
process at the AT&T facility in Richmond many years ago for “other” OEM
boards. Most Chinese shops have installed the process and have made
substantial improvements. The price is competitive. I along with others
will be giving a paper on this process at the IPC February meeting.



As an aside, this is probably the first novel technology innovation to
originate in the Chinese PCB industry and we should all take notice. I
believe we are seeing the same ingenuity in the Chinese PCB shops that
Marco Polo found on his first visit to China when he returned to Venice
with firecrackers and gun power.



Best regards



Lee



J. L. Parker Ph.D.

JLP Consultants LLC

(804) 779 3389





-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joel Mearig
Sent: Tuesday, October 11, 2005 3:54 PM
To: [log in to unmask]
Subject: Re: [TN] Hasl



Lee,

Good input that I agree with. However, I was wondering if you could
further

discuss the "flash" vs. "ENIG" issue. I have been using ENIG on my Pb-free

assemblies for about 7 years with very little problems. If I am missing

something further education would be extremely helpful. Thanks



Joel Mearig

Delta Tau Data Systems, Inc.



-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Lee parker

Sent: Tuesday, October 11, 2005 10:03 AM

To: [log in to unmask]

Subject: Re: [TN] Hasl



Ramon



After reflowing a soldered surface, you will form a meniscus which will

interfere with SMT component placement. To avoid the problem I suggest a

flat metal finish such as immersion silver or flash gold (not ENIG)



Best regards

Lee



J. Lee Parker, Ph.D.

JLP Consultants LLC

804 779 3389

  ----- Original Message -----

  From: Dehoyos, Ramon<mailto:[log in to unmask]>

  To: [log in to unmask]<mailto:[log in to unmask]>

  Sent: Tuesday, October 11, 2005 12:52 PM

  Subject: [TN] Hasl







              Hi technetters:

             Is there a fine pitch limit  to the use of HASL board plating

  finish due to its variation in thickness?  Does selective solder strip

  and reflow plating, SSSR, have a significant advantage over HASL? Any

  comments relating to platting finish would be greatly appreciated. I

  thank you for your comments.

          Ramon

          ME

          410.552.2210



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