PCB Contamination ?

[Phil Allison]

Hi to all,


I just got through cleaning a large PCB from a modern 8 valve guitar amp
( Trace Elliot / Gibson ) where the PCB was covered in hard, *white*
coloured spots - looked a bit like an infected plant's leaves. Both sides
were affected, the component side less so. The board is fibre glass, double
sided with plated through holes and green resist over all but for the actual
solder pads.

The spots did not easily dissolve in metho and had to be scraped off in
same cases - a similar white deposit surrounded many of the larger solder
pads. I guess this was flux reside left over from manufacture - but why is
it white ??

Was it the modern water soluble flux that had not been washed off properly ?

The guitar amp suffered from annoying spitting/cracking noises during warm
up that would go after and hour or so - PCB leakage for sure.




............... Phil

 

[Jim]

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:2u92t7F235tm9U1@uni-berlin.de...

Hi to all,


I just got through cleaning a large PCB from a modern 8 valve guitar amp
( Trace Elliot / Gibson ) where the PCB was covered in hard, *white*
coloured spots - looked a bit like an infected plant's leaves. Both
sides
were affected, the component side less so. The board is fibre glass,
double
sided with plated through holes and green resist over all but for the
actual
solder pads.

The spots did not easily dissolve in metho and had to be scraped off in
same cases - a similar white deposit surrounded many of the larger solder
pads. I guess this was flux reside left over from manufacture - but why
is
it white ??

Was it the modern water soluble flux that had not been washed off properly
?

The guitar amp suffered from annoying spitting/cracking noises during warm
up that would go after and hour or so - PCB leakage for sure.




.............. Phil
Not the residue from some recreational drugzz ? )))

I once had to clean up an amp that had been in a bar for the last 1000
years....I've never had a beer since (

Cheers
Jim

 

[Mark Hathaway]

I'm not sure exactly what it is either, I don't get it on my own home etched
boards, but I see it on lots of professional pcb's made in the UK and USA
from well respected manufacturers, some who x ray every board and don't seem
to worry about the white goop.


Mark

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:2u92t7F235tm9U1@uni-berlin.de...

Hi to all,


I just got through cleaning a large PCB from a modern 8 valve guitar amp
( Trace Elliot / Gibson ) where the PCB was covered in hard, *white*
coloured spots - looked a bit like an infected plant's leaves. Both
sides were affected, the component side less so. The board is fibre glass,
double sided with plated through holes and green resist over all but for
the actual solder pads.

The spots did not easily dissolve in metho and had to be scraped off in
same cases - a similar white deposit surrounded many of the larger solder
pads. I guess this was flux reside left over from manufacture - but why
is it white ??

Was it the modern water soluble flux that had not been washed off properly
?

The guitar amp suffered from annoying spitting/cracking noises during warm
up that would go after and hour or so - PCB leakage for sure.




.............. Phil

 

[Adam Seidel]

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:2u92t7F235tm9U1@uni-berlin.de...

Hi to all,


I just got through cleaning a large PCB from a modern 8 valve guitar amp
( Trace Elliot / Gibson ) where the PCB was covered in hard, *white*
coloured spots - looked a bit like an infected plant's leaves. Both
sides
were affected, the component side less so. The board is fibre glass,
double
sided with plated through holes and green resist over all but for the
actual
solder pads.

The spots did not easily dissolve in metho and had to be scraped off in
same cases - a similar white deposit surrounded many of the larger solder
pads. I guess this was flux reside left over from manufacture - but why
is
it white ??

Was it the modern water soluble flux that had not been washed off properly
?

The guitar amp suffered from annoying spitting/cracking noises during warm
up that would go after and hour or so - PCB leakage for sure.




.............. Phil

No clean flux is just that, it doesn't require cleaning as the residue does

not cause any degradation to the PCB. Having been in the CM game for quite a
few years this is the biggest single complaint from customers (dirty
boards), when you try and explain the point of no-clean they quite often
don't understand..... board cleaning can be a very expensive and precise
process.

Adam