Overall the visual quality of soldered joints on thick film is not as
attractive as on PCB. Joints tend to be duller and have higher contact
angles. The opposite of what years of training and experience have
lead us to expect.
In that context the answer will depend on your no clean. If  your
man's experience of NC is with the higher residue types he may well
have seen lower contact angles and shinier looking joints than with a
washed water clean. This will come from the resin in the flux aiding
the spread and also simple cosmetics. On the lower solids types (to
oversimplify greatly) what you will be soldering with is a bland
organic acid mixture, compared to a relatively stronger organic acid
mix in the WS. Low solids [NC or WS] flux types will give good bonding
where deposited but tend to spread less than higher solids types.
Actual quality of the joint when  measured break force per area by say
shear or pull testing should be little different.


Mike Fenner


----- Original Message -----
From: "Rick Thompson" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, May 17, 2001 1:03 AM
Subject: [TN] No-clean vs Water-soluble wetting?


> I've been having an ongoing discussion with our QA Manager regarding
the
> wetting capabilities of No-clean versus Water-soluble solder pastes.
He
> believes that no-clean wets better, I think the opposite. This is in
an air
> reflow environment. I'm curious as to what some of you might have to
offer
> on the subject?
>
> Thanks in advance,
>
>
>
> Rick Thompson
> Ventura Electronics Assembly
> 2655 Park Center Dr.
> Simi Valley, CA 93065
>
> +1 (805) 584-9858   x-304  voice
> +1 (805) 584-1529 fax
> [log in to unmask]
>
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