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Imersion Tin - does anyone have experience ?

Roni H.

#22669

Imersion Tin - does anyone have experience ? | 12 December, 2002

I need to know basic details about Imersion Tin technology (what is the process, electroless? direct over Cu or over difusion barrier?....). More important is - Does anyone have experience with it? I'll be glad to hear some feedbacks from the "field".

Thanks Roni

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#22670

Imersion Tin - does anyone have experience ? | 12 December, 2002

Immersion plating appears like electroless, sorta, but is different chemically.

Plating is converting metal ions in solution to metal on the board. Those metal ions are "converted" by adding electrons to them. The source of these electrons defines the type of plating. * Electroplating: When the electrons come from a rectifier. * Electroless plating: When the electrons come from another, unrelated chemical in solution. * Immersion plating: When the electrons come from the substrate you are plating on to, as the substrate dissolves, goes into solution, and donates its electrons to the metal already in solution.

The big difference you see is that the immersion bath is one helluva lot more stable, and easier to run, AND, the plating thickness. * Electroless plating can, in theory, go on forever, so you can build up any thickness you want. * Immersion plating stops when the substrate gets fully covered (self limiting).

There are NO known tin electroless plating baths, only immersion tin.

In general, immersion plating gives VERY light finishes, from as low as 3 microinches to a maximum of 40 or so, with tin. While this is not an easy process to manipulate, generally increasing plating temperature tends to increase immersion plating thickness.

Get started by searching the fine SMTnet Archives. We've been talking about immersion tin for a couple of years. In conducting your search: * Immersion has two M * Sometimes 'immersion' is shortened to 'imm' and such.

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Randy Villeneuve

#22672

Imersion Tin - does anyone have experience ? | 12 December, 2002

We are using Immersion tin in production. We specify Omikron-plus tin which according to the information is much better in solderability and shelf life than standard immersion tin. I am not having any problems with the finish and we are running it though two reflows and wave.

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RDR

#22676

Imersion Tin - does anyone have experience ? | 12 December, 2002

I have had both success and failure with immersion tin. It seems to be very dependant upon the PCB suppliers process control. If its too thin, solderability is greatly diminished. I have never had it too thick (see Daves comments). We currently do not use it anymore with the exception of single sided no-clean assemblies. Just thought I would give another side of tin.

Russ

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MA/NY DDave

#22677

Imersion Tin - does anyone have experience ? | 12 December, 2002

Hi,

There are several good books and many technical articles written on Im Tin over the years. Get one of these if you are interested. They will take you through the entire process steps.

I have used it with 100% success for years, and then other finishes like OSP (Entek) for years with 100% success, and then still others. I even qualified Entek in it's first largest application with some great process guys. Don't ask the year of I will have to kill you.

DaveF described it's self limiting nature. Im Gold is another one of the common Immersion Processes.

Why do you want to know??

A>If you are thinking of putting one in place (I would say hire some people

B>If you are just working with it (Than other approaches would be good.

YiE, MA/NY DDave

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