Rudy,
Thanks for your reply. Any thoughts on solderability after multiple heat
cycles. Our current involve 2 reflow cycles as well as some postwave
handsoldering. We encounter problems with the handsoldering operations,
particularly when boards have been sitting in storage 4+ months.
Wendy Worth
Harris Corporation
585-242-4543
-----Original Message-----
From: Rudy Sedlak [mailto:[log in to unmask]]
Sent: Thursday, July 18, 2002 11:20 AM
To: [log in to unmask]
Subject: Re: [TN] Immersion Tin Plating
Wendy:
The chemical that is the real "cause", or engine, of immersion Tin is:
Stannous Chloride (Thiourea Complex) and this item is not real soluble, (read
that as rinseable). You want thick Tin plate (for shelf life reasons), and in
order to have thick Tin, your fabricator needs a lot of this chemical in
solution, usually held in solution by it being heated. When this stuff hits
cold rinse water, it can set up like a gooey gel, and be difficult to rinse.
Back in the days when we used to use immersion Tin to cover dewetting on
reflowed boards...this is really the stone age, most readers will be too young
to remember, we used to use hot water first rinse, to assure getting good
rinsing.
I do not recommend HOT rinsing, but I do think WARM rinsing is not a bad idea.
Rudy Sedlak
RD Chemical Company
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