Solder Paste

[Trampas Stern]

Does someone have a recommendation on which solder paste to use.  

I was thinking I might should go with water soluble paste as I normally clean boards with dish soap and tooth brush, but would like to improve my process.

Thanks

Trampas 

[you...@ciciora.com]

My understanding is that water soluble flux doesn't mean you 'can' clean it with water, but you 'have to' clean it with water.  And it needs to be at an elevated temperature.  I'm sure the manufactures have better guidelines as to what's required.
- Steve

[Peter Betz]

Loctite GC 10, changed my life. Only slightly exaggerating. I think there is a replacement for this now but this one has been amazing (no refrigeration etc.) .

http://www.henkel-adhesives.com/loctite-g10-solder-47933.htm

Peter.

[PK]

Agree. It's good.. But not as good as lead solder. If you can use leaded solder then save yourself the hassle.
We use no clean paste for everything.
PK

[Trampas Stern]

Do you guys use flux for touch up and rework? Does the flux require cleaning?

[Peter Betz]

I do not do any clean up.

Peter Betz
BETZtechnik.ca

> On Jun 20, 2017, at 2:49 PM, Trampas Stern <tra...@gmail.com> wrote:
>
> Do you guys use flux for touch up and rework? Does the flux require cleaning?
>

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[Marek T.]

As I have been informed by some paste manufacturer, "no clean" paste doesn't mean that board will be clean after soldering. But that the remains of flux are passive (neutral) for electronics. And the "no clean" paste which we tested was really not looking clean.
After many experiments we use Koki - leaded if only may use leaded. Koki is expensive a bit but idiot proof, no matter what the profile of will oven you set the effect is perfect :-). Even after double passing through oven... Agree with Paul - leaded if possible to be used, unleaded soldering it's tragedy (like all eko-logic solutions) - looks shity and quality is shity.

[Eagle Media]

I'm also using Loctite GC 10 and cleaning the boards after reflow.

Regards,
Rick

[Michael Anton]

I use Kester EP256 leaded, and alway clean using perchloroethylene in an ultrasonic cleaner.  Most solder residues are inert, as long as there is no further contamination to the board.  If there is ever the presence of high humidity levels, that remaining residue can become conductive, so it is important to remove it.  Every contract manufacturer I've ever used, cleaned the PCBs after soldering.  This is especially important if the boards will be conformal coated.

On Tuesday, June 20, 2017 at 10:16:27 AM UTC-6, Trampas Stern wrote:

[Lamont Cranston]

GC10 is great as long as you can use 0.10mm-thick stencils. Anything thicker with BGAs and it cruds up the stencil, eventually leading to misprints. And it is really really hard to clean off of fine-print stencils. The stuff is just too damn sticky for anything but passives on low volume-deposit-per-area artwork.

For LGAs where we need a high volume-deposited-per-area ratio, and some BGAs too, we use EP256 -- nothing comes close for high-aspect-ratio stencil printability... NOTHING. And of course leaded solder has a lot of advantages, not least the reduced thermal stress on components.

Amtech 4300 is the real "Game Changer" flux. It is "can wash" flux -- the only flux I know of that is both water washable and not washing-mandatory. I have now thrown all of our tacky flux except 4300 in the trash can -- it is the only tacky flux I use. The solderpaste version is pretty good but not quite a cure-all (and expensive). Having a "can-wash" flux is a pretty big deal; putting "no-clean" (aka "can't clean") through the ultrasonics means ugly white residues that block any rework or test probing (and look hideous too). 4300 is like blood type "o negative", the universal donor.

For wave soldering we use Kester Zestron (ZX series). That stuff is the shizz-bizz except that it is more caustic than your mother-in-law until washed properly. Still it has its place and the boards come out looking beautiful.

[Trampas Stern]

I got some GC10 and I must say it is nice! 

Thanks

Trampas

www.misfittech.net

[Andrew Frazer]

>GC10 is great as long as you can use 0.10mm-thick stencils.  Anything thicker with BGAs and it cruds up the stencil, eventually leading to misprints.  And it is really really hard to clean off of fine-print stencils.  The stuff is just ?>too damn sticky for anything but passives on low volume-deposit-per-area artwork.

I've been usign .12mm stencils on fine pitch, (0.4mm pitch QFP, 0.5mm QFN,  0402 ) and not had this issue. I've found that it does need to be in the range 20-25 degrees C for it to work well, or it does feel 'thick'.    

I don't have a problem with flux, because i'm using vapour phase soldering, and all the flux ends up washed off the board and in the bottom of the tank. . Actually i do have a problem with it. but not on the boards.  Peridically i need to filter the vapour phase fludi as the flux ends up in solution with it..     A paper coffee filter works wonders. 

[Michael Anton]

I would think that if the flux is washed away that might make it difficult for it to do its job, unless it is only washed away after reflow.

[Lamont Cranston]

On Aug 10, 2017, at 11:02 PM, Andrew Frazer <andrew...@stellascapes.com> wrote:
>
> >GC10 is great as long as you can use 0.10mm-thick stencils.
>

> I've been usign .12mm stencils on fine pitch, (0.4mm pitch QFP, 0.5mm QFN, 0402 ) and not had this issue.

Yeah, you have to be using a thin 0.10mm (+/-20um) stencil like that to make GC10 work.

We do LGAs that call for a 0.2mm stencil in order to deposit enough paste and GC10 can't handle it. Even the 0.15mm stencils are troublesome with it.

I haven't tried the washable GC10 yet, but I get nervous about using washing-required fluxes on LGA+BGA parts.

Also when I first bought GC10 it only came in Type4; the Type3 that is available now has larger particles which release more easily from the stencil sidewalls.

[Trampas Stern]

I am new to stenciling board and have been using GC10, I have found too much paste gets on the pads for the QFN parts.  I am not sure if this is my my poor stenciling work or other yet.  I figure I might go with thinner stencil and/or decrease the solder paste hole size for QFN parts.  

I also have cheap Chinese reflow (T-962A) which I also need to modify to have better temperature control on the reflow.  

My production volumes are low so rework is not terrible at the moment, hence a good time to learn, which of course a is a mixed blessing. 

[SMdude]

Trampas, mod that oven!
I did mine and it is much better now.

[Matt Brocklehurst]

I've just scrapped a T962A - horrible things that are a waste of time - even with a different controller you can't fix the poor mechanics - components directly under the tubes get scorched compared to the ones in between the tubes that barely get touched.

Buy a decent oven when you can, esp. if your doing BGAs etc... I got a JEM-310 batch oven pretty cheap second hand, heats via convection.

On Fri, Aug 11, 2017 at 1:17 PM, SMdude <spiteri...@gmail.com> wrote:

Trampas, mod that oven!
I did mine and it is much better now.

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[Trampas Stern]

Yes I was suppose to get a decent oven with the PnP machine, but they could not find it, must have grown legs and walked off. 

Trampas

On Friday, August 11, 2017 at 9:07:02 AM UTC-4, Matt Brocklehurst wrote:

I've just scrapped a T962A - horrible things that are a waste of time - even with a different controller you can't fix the poor mechanics - components directly under the tubes get scorched compared to the ones in between the tubes that barely get touched.

Buy a decent oven when you can, esp. if your doing BGAs etc... I got a JEM-310 batch oven pretty cheap second hand, heats via convection.

On Fri, Aug 11, 2017 at 1:17 PM, SMdude <spiteri...@gmail.com> wrote:

Trampas, mod that oven!
I did mine and it is much better now.

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[Andrew Frazer]

The flux has done its job well before the paste has hit melt point..   95% of what i do is onto ENIG and without flux it woudl struggle, but the GC10 in the vapour phase works awesomely. boards come out absolutely clean with no flux hanging around.

[Andrew Frazer]

I've not used a .2mm stencil, for a long time.  But .1, .12, .15 dont' appear to have any trouble.    This is with both hand stenciled and semi-automatic printing.    I'm doing some very fine pitched pads and i'm just not havintg the issue? 

If they are clogging..

(a) you use using electropolished stencils?
(b) what kind of squeegee are you using

(c) are you ensuring that the stencil is flat against the work?  

(d) are you working / stiring the paste before you use it..  This is pretty important it seems. as well as being in that 20-25C range.

It does seem different folks have different results with it,  Assuming that the material is consistent, it has to be a process thing?