Homebrew PCBs

I'm looking for an adhesive for mounting SMT components, especially caps and resistors, on hobby circuit boards.

In the past I've used silicone caulking applied with a tooth pick. But some of my small components make it difficult to apply adhesive without compromising the cleanliness of the solder pads.

Are there other adhesive options?  

I remember one builder who would spray the board with lacquer and just mount components by soldering right through the finish. I suppose wet lacquer would make a good adhesive, though it dries quickly.  I don't know if lacquer would contaminate the solder joint.

I've also used the standard "tin one pad then solder component end" process.  I use a "Blu-Stick" type clay called "All Stick" on the tip of a tooth pick.  It works but my components don't always end up with precise alignment.

Generally speaking, SMD components only really need to be glued down
for wave soldering.

I recommend that you look into using solder paste and a reflow process
(hotplate, ofen, hot air), you will find it superior and faster than
manual soldering with an iron, and the components will usually align
very well.

If you still want to glue them down, maybe you can find professional
SMD glue, sometimes small quantities are sold in a syringe. I've seen
it on Ebay shipping worldwide from china if there is no local source.

Which leads to the next suggestion, buy or build a pneumatic
dispenser. With this (and a suitable blunt needle on the syringe) you
can make very nice consistent glue dots on your board, it is also very
fast. You can use the same system to dispense solder paste.

ST

On Thu, Jul 30, 2009 at 6:15 PM, bob_ledoux<bobledoux@...> wrote:
> I'm looking for an adhesive for mounting SMT components, especially caps and resistors, on hobby circuit boards.
>
> In the past I've used silicone caulking applied with a tooth pick. But some of my small components make it difficult to apply adhesive without compromising the cleanliness of the solder pads.
>
> Are there other adhesive options?
>
> I remember one builder who would spray the board with lacquer and just mount components by soldering right through the finish. I suppose wet lacquer would make a good adhesive, though it dries quickly.  I don't know if lacquer would contaminate the solder joint.
>
> I've also used the standard "tin one pad then solder component end" process.  I use a "Blu-Stick" type clay called "All Stick" on the tip of a tooth pick.  It works but my components don't always end up with precise alignment.
>

Most of the professional glue is heat cure and won't dry in the air.
So if you don't already have an oven set up to do SMT and a wave
solder machine with a chip wave, the glue won't do you any better.

In general, even if you are doing a 2 sided board, the cohesion of the
molten solder between the part and the board is enough to hold
virtually all parts on the bottom of the board from coming off during
re-flow.  Just don't knock the board while the solder is still molten!
Otherwise you'll be picking up parts for weeks.

If you are having problem with chips falling off on the bottom side of
your board when you re-flow the second side, I'd understand the need
for a small drop of glue.  But in general, only if you are wave
soldering the bottom side do you need to glue the parts on.

On Thu, Jul 30, 2009 at 9:30 AM, Stefan Trethan<stefan_trethan@...> wrote:
> Generally speaking, SMD components only really need to be glued down
> for wave soldering.
>
> I recommend that you look into using solder paste and a reflow process
> (hotplate, ofen, hot air), you will find it superior and faster than
> manual soldering with an iron, and the components will usually align
> very well.
>
> If you still want to glue them down, maybe you can find professional
> SMD glue, sometimes small quantities are sold in a syringe. I've seen
> it on Ebay shipping worldwide from china if there is no local source.
>
> Which leads to the next suggestion, buy or build a pneumatic
> dispenser. With this (and a suitable blunt needle on the syringe) you
> can make very nice consistent glue dots on your board, it is also very
> fast. You can use the same system to dispense solder paste.
>
> ST

-- 
Erik L. Knise
Pacific Shipping Company
Seattle, WA