Any reccomendation for Solder paste and dispenser?

[Watcher]

Whats is the best type of solder paste for SMD soldering?

What kind of dispenser do you use?


Some come in containers like this .

Others in syringes like this


How do you best apply small quantities in TQFP64 IC for example?

[MarkT]

Firstly the container you refer to is plumbers solder paste (acid flux) and will destroy electronics.

The syringe stuff you refer to is lead-based so large toxic hazard (paste is extremely easy to ingest by
accident compared to solid solder since it gets everywhere).

Just get a small amount of no-clean unleaded paste in a synringe - remember it doesn't
keep indefinitely and you don't need much.  I've used the ChipQuik stuff and it lives up to
its no-clean claims.

[xl97]

I buy/use this stuff all the time (I order from DX or ebay).

(this was just the first link I found)
http://www.ebay.co.uk/itm/Useful-Solder-Soldering-Paste-Flux-25-45um-63-37-Upgrade-From-MCN-300-XG-500-New-/331246577777?hash=item4d1fd5a871:g:MqAAAOxyoVZTHyXw


I use this and not paste in a syringe because I use solder paste stencils/masks..  and I do not apply it by hand to each pad.. but 'smear' (squeegee) my paste over the top..and remove the stencil leave solder paste on all pads.

like so:




its really amazing on how LITTLE paste you need to secure a part.

after that I bake my boards in a $17 toaster oven I picked up my local wal-mart.

[Watcher]

xl97: Very nice !

However you also need to make the stencil, which the last I checked, is quite expensive to order for every PCB design.

Unless you can get a sort of generic stencil  for each part...

[DrAzzy]

Generic stencils won't work - they'd smear the solder paste from adjacent parts.

You can get laser cut stencils from OSHStencils at sane prices.

[MorganS]

The stencils cost less than the boards and the boards are astoundingly cheap from my point of view. I can solder 20 SMD components onto a board faster than I can put 10 through-hole components on and the result is so much better.


This was soldered in a frypan on the stove. The neat placement of the little components is controlled by the stencil and the soldermask on the board.

[xl97]

xl97: Very nice !

However you also need to make the stencil, which the last I checked, is quite expensive to order for every PCB design.

Unless you can get a sort of generic stencil  for each part...

no.. I dont use generic stencils..  nor do I pay for them anymore.

I own a laser cutter  (but I dont use that either as I find the 'melted' edges grab solder and make the squugee'ing of the paste not as smooth as it could be... but dont get me wrong.. they are quite acceptable to use)

I also own a Cameo Silhouette vinyl cutter.. in which I use to make my stencils out of overhead transparencies.

(plus I get to make stickers and stencils.. and other stuff with it as an added bonus)

you can install some additional software.. and basically use the gerber files to cut out the stencil for you using your/a vinyl plotter.  I found and also posted a lot on this on the Dangerous Prototypes forums)

so roughly $150 investment.. I have unlimited solder stencils.    (plus whatever else I want to use it for)

I do 0603 parts all day with it.. (havent tried anything smaller)

[dannable]

I also own a Cameo Silhouette vinyl cutter..

you can install some additional software.. and basically use the gerber files to cut out the stencil for you using your/a vinyl plotter.

This sounds interesting. May I ask what is the 'additional software' required?

[GilchristT]

I also use a Cameo cutter and acetate sheets (try to get 0.1mm thickness or thereabouts).

I'd guess the software xl97 was talking about was this https://github.com/pmonta/gerber2graphtec

It takes a bit of tinkering to get working but there is plenty of help included and on the net and it's really worth the effort, if I'm feeling particularly lazy I'll bin stencils after use as it's easier and quicker to cut a new one than clean the old one :-)

[dannable]

Thank you, it's certainly food for thought.

[CrossRoads]

How is it on pads for say a Atmega328P, 1284P, FTDI FT232,  2560? (roughly decreasing in pitch I think).


I've been buying stencils from pololu.com, 5 day turnaround, $6 shipping via USPS
3 mil or 4mil thick, I've done up 20 card batches on a weekend.

Solder paste  - Kester EP256., 35 gram syringe from CMLSupply.com last a long time. I also have a 500gram tub that I use to fill empty syringe. Squeeze paste out along the top of the stencil stiff plastic putty knife to smear it across.
http://www.kester.com/products/product/EP256-Solder-Paste
http://www.cmlsupply.com/kester-ep256-lead-solder-paste-63-37-syringe-dispenser/
I think they have a winter promotion going on now also.

[xl97]

I do pads for ATMEGA328P-AU (TQFP) no problem as well as ADX335 accelerometer chips (16-LQFN Exposed Pad, CSP)..

and as mentioned above, mostly 0603 stuff.

here is a post on the differences between using the software that comes with the cameo (Silhouette Studio... which is good for vinyl/paper..etc...but not so much for solder stencils)


http://www.dmstudios.net/?p=311

also shows the difference between using a .dxf file.. and the gerber (using the above mentioned: gerber2graphtec approach)

^ it involves installing a few things. python, gerbv.....etc......has a little 'GUI' you can use to make it somewhat more user friendly.


for me.. it was a great investment, any little pcb I have I can make a stencil for it in 10 minutes or so.. depending on how big I guess...  (not the fastest)

plus I use it for other stuff (making vinyl stencils for etching on glasses, cutting card stock (my wifes sister always wants to use it for crafty stuff)...stickers for cars/whatever)

[CrossRoads]

Can you try cutting a 2560?

[xl97]

ahh.. like the mega 2560..

I need to get a board file and grab the part.

I can try to get to it tonight/tomorrow..

things like the material used for the mask a difference too...

I like the overhead transparencies, because they are rigid enough.. but still have some give. (maybe a mm too thick.. as it really takes little solder to make the part adhesion/connection.)

you might be able to get finer with something like paper..etc..  but then your re-uability is like 'that use for how many boards you can swipe in a few minutes.. if that'  haha

[xl97]

I ran the test for you Robert.

It came out.... IMHO... flawless.  (much better than I expected at that size)..

I swelled (shrunk) the pads in Eagle (tCream layer) by 2mil both min and max.

(ie: shrinking pads:  first couple lines)
http://dorkbotpdx.org/blog/travis_s/making_kapton_stencils_at_adx_portland_using_eagle_pcb)

is this was a serious cut.. I would have done more tests.

I probably should have turned up my blade size to make more penetrating cuts..as I have to blown/poke some of the hole out due to them being so small..etc.

outside of the two pads I manually fubar'd with my exacto knife  (I was being fast and careless to be clear..just trying to get the test done)

every pad/side came out great!..


the width is seriously no bigger than the width (thickness) of my exacto knife blade..  


ok I tried to take a pic.. but its extremely hard.. not only because I stink at taking pics.. but the clear transparency makes it that much more difficult.

along the right side of the pads.. you can see where I messed up two pads.. they were fine from the cutter. (I did that)

the pic is a bit 'shaky/blurry' as well.... my suggestion si to look at the left side/row of pads.. that seems to be the most focus.

in person. they look great.