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January 1998

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Subject:
From:
Graham Naisbitt <[log in to unmask]>
Reply To:
TechNet Mail Forum.
Date:
Wed, 21 Jan 1998 22:01:12 -0000
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Mark,

Given that all fluxes leave residues, the issue is how will they inter-react
with the other process chemistries you have on your assembly.

In addition, we know that the higher the operating frequency, the more the
electrons migrate to the periphery of the conductor so, where they interface
with the board surface, you will have an area of high potential for
electro-chemical reactions.

Are you able to predict these and verify that they will not be harmful to
long term reliability? SIR testing developments will permit you to do this
by measuring the amount of leakage that is occurring. Use a voltage gradient
of 100v/mm that will better mimic your assembly operating conditions, apply
frequent monitoring so that you do not miss any dendrite formations
(electro-chemical migration) and use current limiting resistors to preserve
them for further analysis. Bear in mind that dendrites are known to form
within 20 minutes under the right conditions.

You should then be better placed to determine the reliability of your
assembly. I hope this helps - let me know if you would like more

Graham Naisbitt

__________________________________________________________________________

[log in to unmask]

Concoat Ltd
Alasan House, Albany Park
Camberley GU15 2PL UK                        http://www.concoat.co.uk

Application Engineers in Chemical Compounds to the Electronics Industry

-----Original Message-----
From: [log in to unmask] <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: 21 January 1998 14:22
Subject: [TN] RF Circuitry and Rosin Core Solder


>     Hello All,
>
>     Has anyone dealt with or have found any issues with using a Rosin Core
wire
>     solder on RF circuitry? Like Kester (no clean) "282" Rosin Core
(63/37)
>     We have heard of "theories" that the flux left behind after soldering
>     has some negative effect on the operation of the RF Circuit. Anyone?
>
>     Thanks,
>
>     Mark Pozorski
>     ADC Telecommunications
>
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