Wow,
        your being asked things that I have never even heard mentioned. Yes
I can hypothesize that the reflow temp could possibly be a bit higher
because the plating is not reflowed solder to start with. But, I have never
been asked these questions nor have I ever heard of this as a concern. In my
experience, we used immersion gold a lot (80 - 90% of our boards) at a
previous employer, I have never heard of this as an issue.

        My reasoning would tell me that you are correct, the gradual thermal
cycling should not impact the board much at all. How much temperature
increase are they talking about? 5 - 20 degrees Celsius? Also if they slow
the thermal inclines and declines slightly, this should also improve the
overall situation even more (just watch the overall characteristics on your
semis!). I don't see that you are talking about multi-layer boards so this
should be less of an issue then if you were talking multi-layers.

        Sorry, nothing in my experience or library can answer this question
definitively. I figured that you were looking for info on thickness and
types of gold with your initial enquiry.

Sincerely,

Brad Velander
Lead PCB Design
Norsat International Inc.
#100 - 4401 Still Creek Dr.,
Burnaby, B.C., Canada.
V5C6G9.
voice: (604) 292-9089 (direct line)
fax:    (604) 292-9010
email: [EMAIL PROTECTED]
www: www.norsat.com


> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, April 17, 2001 10:52 AM
> To: [EMAIL PROTECTED]
> Subject: Re: [PEDA] Gold Emersion
> 
> 
> Hi Brad,
> My understanding is that gold emersion is great for fine pitch, better
> conduction, excellent shelf life, and reduction in board warp due to
> inconsistent board cooling and thermal shock as it occurs with HASL.
> My Manufacturing people are worried because, the profile 
> temps in the oven
> need to be higher in order to get the solder to wick and 
> flow. How does this
> affect board warp? I would hypothesize that because the 
> profile is a gradual
> increase there is no thermal "shock" as in HASL but what are the other
> factors and effects.
> I checked out that website and it has some information but 
> not enough to do
> adequate research.
> Any comments?
> 
> 
> Lloyd Good
> Engineering Systems Co-ordinator
> GE Harris Energy Control Systems Canada Inc.
> 2728 Hopewell Place NE
> Calgary, AB, Canada T1Y 7J7
> * +1 (403) 214-4777
> * +1 (403) 287-7946


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