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May 1998

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Subject:
From:
Mike Barmuta <[log in to unmask]>
Reply To:
Date:
Wed, 27 May 1998 08:13:45 -0700
Content-Type:
TEXT/PLAIN
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TEXT/PLAIN (72 lines)

        Sal: If I'm reading your post correctly this is showing up on a Sn/Pb
board not SMOBC. If that is the case and you are using mechanical screening such
as a DP10 which applies higher squeegee pressures than hand screening, then what
your seeing is not unusual.Take a close look at the residual soldermask and see
if it has a dot pattern and spacing the same as the mesh in your screen printer.
I have seen this on LPI's from many different suppliers. The mask forms a
"compression bond" to the surface of the Sn/Pb when screened and will not
release during development. We worked with our suppler in the formulation and
formulation processing steps to solve the problem.

                                                Regards
                                                        Michael Barmuta
                                                        Staff Engineer
                                                        Fluke Corp.
                                                        Everett Wa
                                                        425-356-6076

On Tue, 26 May 1998 11:33:56 -0700 Modular Components National, Inc. wrote:

> From: Modular Components National, Inc. <[log in to unmask]>
> Date: Tue, 26 May 1998 11:33:56 -0700
> Subject: [TN] Liquid Photo Image Soldermask
> To: [log in to unmask]
>
>    To All
>  We are using RONASCREEN OPSR 5600 HARDENER & RONASCREEN 5600
> OPSR 5600 CODE 2D-AU SOLDERMASK. The problem that we are having is after we
> screen the board and tack cure the board at 160 F for 30 min. We then
> expose the board then develop the board. Upon inspection of the board on
> the developed areas we have found small little areas of soldermask all over
> them if we try to develope them again they will not come off. Has anyone
> come across this before if so, how did you fix it?
> Last thing the the areas have Tin Lead on them.
>
>
>
> THANK FOR ANY IMPUT
>    SAL MITICHI
> Modular Components National, Inc.
> 2302 Industry Court
> Forest Hill, MD 2150
> PH (410) 879-6553
> Fax (410) 838-7629
>
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