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May 1998

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Subject:
From:
Paul Klasek <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 14 May 1998 08:44:51 +1000
Content-Type:
text/plain
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text/plain (133 lines)
Scott
The PPT is formed with a mesh process ; leaving the checkered imprint on
the surface ; supposedly keeping the flux in place .
You still pay for the stencil ; only shift the process to bare board .
The polished rollers process sounds intriguing .
I've send a reply to this topic few moths back ; it'll be in files ,
incl. the contacts .
From cost , no clean , double sided application , ( you do need a reflow
with chiller of bottom side ), etc. , it is impractical for most of the
assy spectrum . Very limiting and complex on the mix TH & SMD as well .
There are better and cheaper ways how eliminate stencil process ,
pending the application .

See you                 paul ; ResMed

>----------
>From:  Lolmaugh, Scott (AZ15)[SMTP:[log in to unmask]]
>Sent:  Thursday, 14 May 1998 0:15
>To:    [log in to unmask]
>Subject:       Re: [TN] HASL alternatives
>
>All,
>There was an interesting article in the February issue of SMT Magazine
>(IHS Publishing Group) on page 56, entitled: "End Paste Defects with
>Solid Solder Deposits".  This is a technique where the PWB Manufacturer
>applies solder to the board, then runs the boards through polished
>rollers to flatten the solder coating into a flat surface roughly the
>same height as the soldermask.  Then a tacky flux is applied and finally
>an easy peel cover sheet.  They claim the boards retain solderability
>well and the paste stencil process is eliminated.
>
>There have been similar / identical techniques touted in the past, known
>as:
>"Sipad" (R) Siemens AG, (solderpaste application method)
>"Optipad" (R) Viele Circuits Inc. and Burkle USA, (liquid solder
>application method) and
>"Precision Pad Technology or PPT (R) Mask Technology Inc. (solderpaste
>application w/ textured finish)
>
>If anyone knows of domestic (USA) Manufacturers offering this technology,
>I'd like to hear who they are.
>Thanks
>Best Regards,
>Scott Lolmaugh
>SMT Production Engineering
>Honeywell IAC, Inc.
>602.313.3551 /FAX: 3402 (Please call first)
>
>
> -----Original Message-----
>From: [log in to unmask]
>Sent: Wednesday, May 13, 1998 8:39 AM
>To: [log in to unmask]
>Subject: [TN] HASL alternatives
>
>To All,
>We are now making a comparison between different alternatives to HASL.
>The
>chosen alternative will have to meet the following criterias criterias.
>
> - flat coating
> - compatible with No-clean process and mixed technology
> - resistant to 2-3 reflow (multiple heat cycle)
> -and MINIMUM 1 year shelf life (storage before assembly)
>
>These are the alternatives we think can meet our needs:
>
>* OSP
>        - Benzimidazole (?)
>
>* IMMERSION
>        - Silver
>        - Bismuth
>        - Au-Ni
>        - Palladium
>
>
>Q: Wich one do you think could be the best meet to our criterias ?
>
>Q: And what would be its advantage(s) compared to the others ?
>
>Q:  OTHERS  ? (is anyone using other coating alternative )
>
>
>Thanks for all for your help
>
>
>Nicolas van der Heyden
>
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