Solder resist on home made pcbs

[picclock]

Hi
I'm just making some pcb's for a project, photo resist board, uv exposed etc. Some of the tracks are very close to each other and also pass under components. Does anyone know of an easy or trick way to stop the solder bridging these close connections, basically the same as when you put soap or pencil lead on metal you are brazing to stop the flow of the molten metal.

Many thanks

picclock

[John Rudd]

Tippex?

[PekkaNF]

Flux. Flux pen or whatever PCB-stuff you have. Some modern ones do not need wash, but some you have to remove before use. Closely spaced componenets need flux or all soder runs together and takes way too long to heat up pads/pins without it.

Pekka

[John Rudd]

Flux. Flux pen or whatever PCB-stuff you have.
 Closely spaced componenets need flux or all soder runs together and takes way too long to heat up pads/pins without it.

Pekka

Which is what he's trying to avoid... I suggested Tippex but I've never tried it myself but have heard it works...

[picclock]

Hi

Will certainly check out tippex - if it works its exactly what I'm looking for. Will post the results. Problem with flux, apart from the mess is that if you have a bridge under a component, you can't get to it to apply it and if it does appear to fix it you can't be sure how well. When soldering  chips that have very small gaps between pins have soldered them in place by running the iron along the contacts and then used fine desolder wick to remove the bridging, which works by using capillary attraction to get rid of the excess solder, using the impregnated flux to make the solder flow. After cleaning with Isopropyl Alcohol it looks like a real reflow joint. So flux is a good solution, if you can get to the joint.

Off to try tippex now .. .

Best Regards

picclock

[picclock]

OK, I've tried the tippex and it seems to work really well. Got a scrap board with a 20 thou track running through a channel of 15 thou gap either side, the only way it would bridge was when I had built up about 2mm of solder height. Only slight issue is tippex application, which may need a thinner brush and possible Isoprop dilution.

Many thanks for the tip John - for me with my poorer eyesight and not such a steady hand this is a real gamechanger.

Best Regards

picclock

[awemawson]

The thinner for Tipex used to be rather exotic if I remember right - benzene or something similar. No doubt the health and safety polic have banned it by now and it's probably water based and useless.

[John Rudd]

OK, I've tried the tippex and it seems to work really well. Got a scrap board with a 20 thou track running through a channel of 15 thou gap either side, the only way it would bridge was when I had built up about 2mm of solder height.

Brill...... Good to hear it works..

Must be about the best advice I've had to offer on this forum

[Pete.]

OK, I've tried the tippex and it seems to work really well. Got a scrap board with a 20 thou track running through a channel of 15 thou gap either side, the only way it would bridge was when I had built up about 2mm of solder height. Only slight issue is tippex application, which may need a thinner brush and possible Isoprop dilution.

Many thanks for the tip John - for me with my poorer eyesight and not such a steady hand this is a real gamechanger.

Best Regards

picclock

Tip-ex pen?

[PekkaNF]

Flux. Flux pen or whatever PCB-stuff you have.
 Closely spaced componenets need flux or all soder runs together and takes way too long to heat up pads/pins without it.

Pekka

Which is what he's trying to avoid... I suggested Tippex but I've never tried it myself but have heard it works...

Good thing that the job got done.

I think you are confusing conventional terminology and processes with PCB/Electronics soldering.

To avoid the mess, flux made for electronics should be used. It doesn't only "wet" the solder, but does its part to prevent bridging. Less solder also helps. There are laquers to help soldering process and some kit/ready made PCBs may have it.

I use Multicore 6381:
http://krayden.com/tds/henk_multicore_6381_tds.pdf

But there are very many same kind of products that would work. Only trouble is that there are many different needs and process, so which one to choose.

This should be pretty much foolproof for fixing stuff and manual soldering of small components:
http://www.stannol.de/WS_Flux/TDB_HP_Fine_Fluxer_3000+_EN.pdf


Rest is YouTube tutorials, they are pretty long, but information packed:

Here is a right way to solder small component:

&NR=1

This is very good, many different techniques:

&feature=fvwrel

This is OLD:

But works very well on old stuff and leadbased solders.

I could not find the one video that had all wrong. The guy did not clean PCB (isopropyl alcohol), did not use flux, had too small iron and dwell over every leg too long.

Pekka

[John Rudd]

Pekka,

Dont misunderstand what I say, I'm not out to berate you...

Sometimes your 'English' is lost in tranlsation.

Great links you posted there....

[PekkaNF]

Pekka,

Dont misunderstand what I say, I'm not out to berate you...

Sometimes your 'English' is lost in tranlsation.

Great links you posted there....

Sorry, I didn't think you jumpped on a gun and I hope you didn't get that feeling about me either.  I was busy at the work when I wrote my first message and somewhat stressed. Really not my best shot.

I put some info and  the links to help, should anyone stumble on this thread later. Sometimes I have found seemingly usefull info. Just wished the tread would have been followed up a little further.

Pekka