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September 1998

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Subject:
From:
Graham Naisbitt <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Sat, 19 Sep 1998 17:26:26 +0100
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text/plain
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text/plain (91 lines)
Mary,

You have the right specs but you should bear the following in mind:

If your customer is driving this requirement - use these specs

If you are being driven by a warranty clause that could be onerous, then you
may well need to apply a far lower level of ionic extract cleanliness (ROSE
or SEC) test value.

If you are manufacturing Fine Line Fine Pitch, SMT with COB, BGA, high
impedences  and/or high operating frequencies, then values around 0.2
micrograms per centimetre squared, may need to be applied.

If the circuit is being used in a hostile operating environment, then a
Conformal coating may be required.

Please take a look at J-STD-001 Appendix D. This gives guidelines for
characterisation of your process involving SIR testing. Unlike ROSE/SEC,
Surface Insulation Resistance (SIR) testing, is used to determine the
reliability of your finished product rather than to define how clean is
clean.

If you would like more, please contact me directly.

Regards, Graham Naisbitt

[log in to unmask]

Concoat Ltd             Phone: +44 1276 691100
Alasan House          Fax:      +44 1276 691227
Albany Park
CAMBERLEY
GU15 2PL UK

Any opinions expressed are those of this employer.

-----Original Message-----
From: <Mary Smoot> <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: 18 September 1998 21:12
Subject: [TN] No-Clean Process - Cleanliness Specification


>I need to know what the appropriate cleanliness specification is for
no-clean
>processes for mixed technology printed circuit boards, fully assembled.
The
>IPC-A-610 paragraphs 5.0 reference the J-STD-001 and IPC-TM-650.  These
>reference the standard test parameters of 1.56 ug/cm2, or 10ug/in2.
>
>I am needing input on the correct test methods and standards for no-clean
>processes.
>
>Thank you very much for your information.
>
>Mary C. Smoot
>Lexmark Electronics
>740 New Circle Rd NW
>Lexington, KY 40550
>606-232-6687
>[log in to unmask]
>
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