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July 1997

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From:
peter dahlen <[log in to unmask]>
Date:
Thu, 10 Jul 1997 09:18:16 +0000
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Thanks for Your replay Vickie,

Which type of organic passivation are you using? We have started an
evaluation with Enthone ENTEK PLUS, which in the testing we have done so
far, has showed a good results (but not so good as nickel/gold surface). We
do not know about the shelf-life, how long board can be in store before
using them and also if there is a variation between lots of boards, due to
variation in the thickness of coating. Do you know a system to measure the
coating on each lot?

Peter Dahlen
Saab Ericsson Space


At 08:36 1997-07-09 -0700, you wrote:
>Peter --
>
>Our standard here for fine pitch (20 mil and below) is fast becoming organic 
>passivation. We have not had good luck with HAL; it's generally been nicknamed 
>"HAB" here instead (Bumpy instead of Level, and standard reflowed Sn/Pb
just is 
>not acceptable for fine pitch.
>
>For boards that don't contain any fine pitch parts, we are still using
reflowed 
>Sn/Pb. However, I believe that, at least through our (in-house) PCB shop, 
>organic passivation boards are actually cheaper than Sn/PB reflow, and I vote 
>for that becoming our standard. Organic passivation also allows for one less 
>heat cycle in the board manufacturing process, which should improve board 
>reliability.
>
>One downside is that reflow temperatures definitely do tend to break down the 
>coating. This does not seem to be a concern for reliability (it's OK if the 
>coating totally disappears after soldering) but it certainly has the potential 
>of making second and third soldering operations (2nd side reflow, or wave
solder 
>, or hand solder) more challenging if you leave the boards sit for very
long. We 
>have had some wave soldering problems that we think (not confirmed) are 
>attributable to having a 2 or 3 day delay after reflow before wave solder.
>
>
>Hope this helps!
>
>-- V. Chapman
>-------------------------------------------------------
> 
>Hello,
>
>I have some questions regarding PCB for data and microwave applications
>which I hope someone will give me some good inputs to.
>
>Questions:
>
>I would like to have some inputs abut solderability, shelf lifte etc. b=
>y
>using different surface treatment onto the cu-pattern on a PCB. Your
>experience by using:
>
>a.	HAL
>b.	Reflowed Sn/Pb
>c.	Unreflowed Sn/Pb
>d.	Electroless nickel/gold
>e.           Organic passivation
>f.	Other
>
>And above surface treatments in combination with:
>
>a.	Surface mounted chip components
>b.	Surface mounted fine-pitch IC
>c.	"Standard" hole mounted components=20
>
>
>Best Regards
>
>Peter Dahl=E9n
>
>Saab Ericsson Space
>[log in to unmask]
>fax. +46 31 359520
>
>
>
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