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Plating Thickness at Via Hole

Haran

#29867

Plating Thickness at Via Hole | 5 August, 2004

What is the industry standard for Plating Thickness at via hole?What will be the problem if the thickness less than required spec.?

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#29883

Plating Thickness at Via Hole | 5 August, 2004

You need to have 1 thou of copper. If don't moisture absorbed by the board will out-gas through the plating.

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Haran

#29904

Plating Thickness at Via Hole | 5 August, 2004

Is 1 thou of copper refer to 1 mil or 1 mm.?In Asia,we do not really use this unit.Please advise.

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Andrew

#29905

Plating Thickness at Via Hole | 5 August, 2004

If the moisture does not has path to escape,what will happen to the entrapped moisture ,will there be a problem in the asssembly process?

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#29906

Plating Thickness at Via Hole | 5 August, 2004

A 'thou' is a 'mil'. It's intended use to to distinguish 'mil' from 'milli' [obviously with marginal success].

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#29907

Plating Thickness at Via Hole | 5 August, 2004

The entrapped moisture WILL escape. You just want to assure it is not through your PTH and via. Hopefully your board is constructed such that the alternate escape path for the moisture does not delaminate the board.

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ram

#29910

Plating Thickness at Via Hole | 6 August, 2004

What will be the impact on the plating if the moisture outgas thru the PTH?Can the plate get damaged?

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#29914

Plating Thickness at Via Hole | 6 August, 2004

When moisture outgasses through plating, it continues through the molten solder, causing a meak solder connection.

There's another issue with thin plating that we haven't focused on in this thread. If plating is thin, the stress on the barrel of a through hole or via caused by thermal expansion can crack the plating. We talked about this here: http://www.smtnet.com/forums/Index.cfm?CFApp=1&Message_ID=7762

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