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December 1999

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Subject:
From:
"Kelly M. Schriver" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 16 Dec 1999 07:02:28 -0600
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Alain -

Is the defect area isolated to the solder side of the board or is it on both
sides?

The mask manufacturers can probably provide you information on the
compatibility of their masks with your process chemistries (flux and
whatever else).  This generally results in an appearance on the surface of
the board that the mask has been partially dissolved and partially peeled.
I would suggest a couple of quick phone calls to the mask suppliers tech
support people for this information.

When you use the words "peeling" and "blistering" I am more suspicious of
there being a surface contaminant present on the boards at the time of mask
application.  This is an item the board fab house will have to isolate and
deal with.  Some of the higher capability test labs may also be able to
assist in this area.

IPC-SM-840 contains a quick cure test, using a dab of methylene chloride, as
I recall.  This takes just a matter of minutes to perform and can be done
safely by any competent chemist.  (Methylene chloride is quite unfriendly.)

What it comes down to first is to isolate the cause.

Regards - Kelly

-----Original Message-----
From: Alain Mathieu <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Wednesday, December 15, 1999 3:52 PM
Subject: [TN] Soldermask peeling and blistering



Hi TechNetters.

We are a OEM that manufactures Hi-frequency products ( 5Mhz to 1Ghz range)
and therefore we use pcb (bare board) with big ground planes on both sides.

all our boards are FR-4 with solderMask over bare copper.

When we go thru the wave soldering process we experiment blistering and
peeling offon the ground plane.

We use Alpha No-Clean 26F flux , preheat top side at 230oF-240oF, bottom
side 300-320oF and a dwell time of 2.4-2.6 sec.
Solder Bath temp is 480oF.

In the past the pcb mfr was using a different Soldermask but now he uses 2
brands with approximately the same results : Epic #200 and Entone #3242.
The pcb Mfr was suspecting a problem with the curing, the thickness or a
contamination before soldermask application that could explain

Is there any one who had the same or similar problem? Any help on how to
resolve this would be greatly appreciated.

Alain Mathieu
Electroline Equipment Inc.
[log in to unmask]


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