SparkFun Forums

[corvette123]

frying pans work too for single sided items...(i think the sparkfun guys were doing some BGA's on them??)

but yah make it a dedicated one and dont put the bacon on it hahaha..

for double sided SMD, you can get cheap 25 dollar stencils from www.pololu.com even for 3 or 4 mil stencil thickness for fine pitch parts (0.50).

the double sided requires a reflow oven!!

[ohararp]

Using a pan method or toaster oven is so easy! I bought a laser to make cases and stencils for myself and now offer this service to others as well.

We charge a flat rate for single or multiple designs that are 12"x12" or less. We just require the smt masks to be in one file, if you require more than one design to be cut.

[corvette123]

oh yah i forgot about you!

kapton ehh?? ill check it out...

pololu did mine in 1 day!! very fast service.

ill try you out

[corvette123]

yah i am happy with the pololu mylar stencil.... very fast service!

cant beat 25 bucks.

stencilsunlimited is the long lasting stencil out of metal for 99 bux.

[JimmyM]

The US is a split phase 240V system. So you have L1, L2, N, GND. Lx to N or GND is 120V, L1 to L2 is 240V. N is connected to the transformer, GND to a ground rod at the the service entrance.
.

L1 to L2 is 208V

Andy

Actually, L1 to L2 in residential wiring is 240V.
L1 to L2 is 208V in 120V 3 phase systems.

[JimmyM]

New here, but have been following the reflow oven thread.
I like the Reflow 2.0 controller. I found it before I found this thread.
I really like the Infrawave system, but I've been reading that convection relow is better. Actually, the best would be Convection and IR.

I'll be building a reflow oven based on the Reflow 2.0 controller. But I've seen that the convection ovens have sluggish response in the 1200-1300W range.
Since I have a 120/240V 20A circuit available to me. Would what I describe below work?

Use a convection oven like the Euro-Pro TO289 (I've read that it has a good fan) and add the elements from a second TO289 in series with the existing elements and run them on 240V. This would double the power of the oven. Ramping from the 150C soak to the 220C reflow plateau can happen per the recommended profile.
Or what about adding the quartz IR heaters from the Infrawave instead of those from another TO289? This would give IR and convection? They would have to be wired as a second 120V circuit instead of 240V. Thus neccessitating a second SSR.

I'm not worried about the heat too much, I have alumina ceramic blanket for insulation.

Thanks, all.

[funnynypd]

Get good solder paste is important to the refolw.
I don't remember SPF carry any solder paste. So probably you need get those from other suppliers.

[JimmyM]

I've ordered Shenmao 63/37 No-clean paste. We'll see how that does.

I've built the oven.
2600W convection on 220V.

[funnynypd]

So far, we only used the Kester Water-soluble solder paste. It works good on most PCB and components, it is a bit expensive, especially if you count the special shipping cost.

[funnynypd]

"Shenmao 63/37 No-clean paste. "

Where did you get those? It is hard to find solder paste alternatives these days.

We tried some Kester non-clean, and our evaluation found it is not as good as the Kester water-soluble type on manufacturing and end-product long-term durability.

It claimed non-clean, as the time goes, the residuals seem the root-cause on issues for some circuit mal-function. A normal fix is a wash (alcohol based solution and/or ultrasonic wash) of the board to make the issue disappear.

For the experience we accumulated in all these years, we always try to avoid the non-clean type solder wire and solder paste.

So far, the water-soluble type flux/solder paste make engineers sleep better in the night.

[JimmyM]

I got it at www.smtsolderpaste.com

Perhaps I should pick up a can of the water-soluble. Just in case.

What has your experience been with solder beading between the 2 types?

[funnynypd]

I didn't pay much attention to the solder beading between the 2 types, so I don't know the answer.

As far as I can tell from the manufacturing process, the water-soluble flux is more active during reflow.

Other than that, I cannot really tell the difference between the two boards using different pastes.(especially when the non-clean ones has been cleaned by Alcohol based solution in a ultrasonic washer.)

[JimmyM]

Well, I just ordered the Shenmao 63/37 Water Soluble paste.

I believe my beading problem (not much though) was caused by too much of the wrong paste and a slightly off profile.
I was testing by applying paste via syringe (87% solids). The second run with reduced paste came out better, but there was still a little beading. The stencil will lay down less paste. I also will be adjusting my profile for a slightly lower preheat temp (135C instead of 150C), then a shorter but slightly higher soak phase (150C-160C). Followed by the ramp to 220C for reflow. I had a rather lengthy soak period which I think was causing the flux to "go off" too soon then not be very active during reflow.
So the change in paste from 87% to 90%, the different flux, stenciled paste, and the altered profile should clean things up nicely.

[funnynypd]

Is your board made by PCB house? They normally have solder-resistance layer coated on PCB to avoid these kind of mess.

And once all solder is melt, the tension will pull them together on the pads nearby.

If you have excessive solder, it will just create bridge/short between pads, it is easy to fix with solder wicks.

The inspection and clean job are very important after the boards are reflowed.

[funnynypd]

also will be adjusting my profile for a slightly lower preheat temp (135C instead of 150C),

It is recommended to pre-heat at 85C for 5 minutes, it really depends on your board size, this will dry the solder paste and avoid "explosion" which may be the cause of the beading. Also it will make the board temperature even on all joints and components.