Hi Leo,
No doubt , this is caused by the flux. We had faced the same
problem before .Our solution is to clean up the flux.
From: TGAsia
[mailto:[log in to unmask]] On Behalf Of Leo Yang
Sent: 26 September 2008 13:03
To: [log in to unmask]
Subject: [TGAsia] 转发:
The effect of Flux residue on PCB
Importance: High
FYI
B/R
Leo Yang
IPC WOFE
21-54973435-616
From: charles.lee
[mailto:[log in to unmask]]
Sent: Friday, September 26, 2008 11:51 AM
To: 'Asia Committe Task Group Forum'
Subject: The effect of Flux residue on PCB
Dear All,
Our customer complained us that flux residue
resulted in dielectric resistance reduction between two pads on PCB (From
10Mohm to 3Kohm), please refer to the attached picture.
The flux we have been using is No-clean type
supplied by Union Soltek.
We are now puzzled with below questions:
1) What is the chemical
substance around these two pads? Is it only flux residue?
2) Will the flux residue
be able to occur chemical reaction with solder mask after elapse of a long
time?
3) What is the root cause
which results in dielecric resistance variance?
We look forward to your expertised
explaination, thanks!
Best reagrds
Charles Lee