Hot Plate for Soldering

Under the "I'm open to any and all ideas" category...a $30 hotplate from Target!

Cheers, James Arthur

On 2 May 2006 07:51:38 -0700, snipped-for-privacy@yahoo.com Gave us:

Surface mount repair using a hot plate for the reflow segment of the process is very bad if the PCB assembly has parts on both sides of the board.

Also, the board should be pre-heated in a chamber (read toaster oven) before placing it on the "reflow bench" (read hot plate) for the repair.

Reflow benches, as they are called are old school and can be very bad for many parts. Ceramic capacitors, in particular, can lose the layer connections to the end "caps" (platings actually).

This is why a modern reflow oven ramps up the temp, reflows the assembly, and gets the product out the other end in a very timely fashion, and is also why hand soldering is detrimental, because a would be assembler or repair "technician" invariably turns up their irons far far too high for such tasks.

It reminds me of the argument I had with the girl that insisted on attaching resistors and caps to the board with two irons, even going so far as to pick the part up with the two irons.

Me? Tweezers, and one side at a time, and that is Solder it fast (less than 2 seconds), and NO big blobs on the pad. Just a tiny drop of solder on the tip of the iron, and lots of flux present is all that is required for hand operations. Less IS more!

The word for today is "FILLET".

When I assemble, it looks like it came from a machine. In fact, one cannot tell the difference.

The crap I see others build is so blobby that a rocket launch would rip the pads and parts right off the board, they are so big.

Sad that we cannot educate our kids so well these days.

Anyway, hand assembly of short runs by skilled soldering personnel is far far better for the life of your product than a hot plate or toaster oven reflow process could ever be. I mean you aren't talking about 12" x 18" digital HDTV processing CCAs (I have done them).

If you are stenciling paste onto the PCB, you have six hours to get the parts placed and get it reflowed, before the paste begins to express major performance issues like tombstoning and flux popping parts clean off the board.

I am Solder Man (Black Sabbath inflection).

NASA certification is the best, most comprehensive soldering cert. followed by mil 2000, then IPC 610-A.

DON'T OVERHEAT YOUR PARTS AND ASSEMBLIES! MTBF goes right out the window.

For lead free ?

Graham

On Wed, 03 May 2006 06:41:31 +0100, Pooh Bear Gave us:

No. It would be a higher temperature. Sad, that.

The whole RoHS thing is utter crap.

Metallic form lead does not pose an environmental threat.

It was certain European nations' way of boosting the eurodollar and that's about it.

Now an entire industry in the US has to switch gears. The flux makers, and the PCB makers, etc. etc. all get screwed to play into some lame pissy country's baby bullshit directives.

I am only glad that military product makers got an exemption.

If it were such a big problem, lead would have been showing up in the water tables near dumps decades ago, and it never did. Nor was there an increase in cancer rates near such water tables.

I totally agree. Furthermore, WEEE is supposed to stop electronics being dumped anyway.

Graham

Solderman, Thou art forsooth Solderman, and all thy points hard and true, and I acknowledge all except perhaps the bit about hand-soldering caps one side at a time seems inconsistent with your earlier admonitions.

Although this is exactly how I solder caps, doesn't it throw all that careful ramping / thermal profile stuff right out the window and apply maximum thermal and mechanical shock to an brittle, inflexible part? And yet, carefully done, these connections seem very secure and reliable.

Of course I'm just doing small stuff for fun this way, not launching anything into space, but perhaps there's a little more lattitude in the soldering process than is otherwise acknowledged, yes?

For single-sided soldering, I'd think one could do a really good job on a skillet, as you can ramp the temperature up to suit, and ramp it back down the instant you see the solder flow. That should be very gentle on the components, exposing them to the minimum temperature needed, and for the shortest time.

Soldering double-sided boards on an electric skillet would of course be a good way to roast the parts riding on the skillet surface, as well as preventing proper heat flow through the printed circuit board substrate. Ergo, double-sided needs a double-sided, controlled heat source...a toaster !

From SED's own Robert Lacoste, a toaster oven controller:

The Seattle Robotics Society has a manually operated scheme:

If you're too busy, here's a pre-built toaster oven controller for sale:

And the Sparkfun guys are at it too:

If you read through their discussion of the merits,

All in good fun! James Arthur

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James,

Here are a few possibly-related discussions that I found interesting (mainly was looking for through-hole whole-board-at-once soldering ideas, at the time):

Regards,

Tom Gootee

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FYI the matcal talon recommends picking up tiny parts with the tips

That sounds kind to the parts (but the thermal cycling will be rough on that lovely Metcal).

There was a rather contentious thread discussing this topic on s.e.d. a few eons ago... ah, here we go: Soldering surface mount components,

Therein Clarence reported reliably hand-soldering caps in hi-rel (space) hardware, while others gave a dimmer view. All in the technique, perhaps?

Best, James Arthur

On 3 May 2006 08:25:27 -0700, snipped-for-privacy@yahoo.com Gave us:

Hold on pads with tweezers, solder one pad, then the other in succession. Both together is where to part is held by two irons in tweezer like fashion, soaking far too much heat into them for far too long. Very, very bad. Quite consistent.

On 3 May 2006 08:25:27 -0700, snipped-for-privacy@yahoo.com Gave us:

The single iron ramps it up faster, and it doesn't ramp back down between the two sub second operations. Absolutely proper. Iron temp should only be a few tens of degrees over the 495F 63/37 typical melt point. Minimal attack on the part. Circuit boards are a lot hardier these days, but the parts are susceptible. It becomes very apparent when working with high voltage ceramic SMDs. If done right, everything works fine. DOne wrong, and the thing won't make voltage, and sinks a lot of power. Testing the cap doesn't show anything as the problem only exhibits itself at working voltages.

It is cheaper at that point to replace all six caps in a three stage multiplier with fresh, than it is too attempt to determine which cap is leaking. Ceramic terminations are actually contacting a huge number of "plate ends". Such attachments are weak at best. Far weaker than say a plated through hole's integrity is. Heat damage is one of the only ways to damage a ceramic that has never been overvoltaged.

Back to the heat issue...

The two iron approach, however has the full iron temp on the part, on both terminations with nowhere for the heat to go until you lace it on the board. Very, very bad.

On 3 May 2006 08:25:27 -0700, snipped-for-privacy@yahoo.com Gave us:

There has to be a lot of flux present, a fume hood, and unless you are using a paste, you may as well hand solder the entire assembly. Also, one should remove the board immediately after reflow, not even attempt waiting for a huge thermal mass like an iron skillet face to cool down. Bad move. It will hold its temp a while. It also sports a very high emissivity, which is a factor in this case. A teflon coated griddle would be best as even the REAL reflow benches are teflon coated. They also pass the PCB OFF the plate area. There is a ramp up heat plate, and a reflow plate, and the boards are slid across in continuous fashion. With skillets or griddles, one would be about

Gentle? The solder process is by far the most damaging event in the life of an assembly. That discounts circuit/part failures and shorts etc.. I am talking about proper operation.

The water or solvent wash after soldering should be followed by a

On 03 May 2006 13:12:16 -0400, DJ Delorie Gave us:

Metcals are famous for coming up to temp in 5 seconds flat.

On 3 May 2006 12:51:46 -0700, snipped-for-privacy@yahoo.com Gave us:

They are meant to be turned of after each and every use. The life of your $45 plus tip depends on only using it when needed. The supply they hit it with is designed to handle it, and meant to be used just that way.

Nice units, those Metcals.

Cheers, James Arthur

I don't have any data to judge the thermal time constant of an electric skillet. It seems to me a very lossy device, but if it cools too slowly, one might simply add a cooling fan blowing underneath, or a

Certainly being awash in molten metal isn't gentle in the ordinary sense. I meant 'gentle' in that the skillet produces less thermal shock (dT/dt) to the components than being suddenly contacted by a blob of molten solder sitting on a soldering iron.

Such a thermal shock--and more particularly, the resulting thermal gradient across the part, and resultant mechanical strain--could shatter a component with sufficient thermal mass, such as a large ceramic capacitor.

Cheers, James Arthur

On 4 May 2006 00:26:30 -0700, snipped-for-privacy@yahoo.com Gave us:

Still, simply removing the PCB to another surface IS what you WANT to do.

Actually time at reflow stage should be minimal required to perform full reflow. After that, the ramp down has traditionally always been faster than the ramp up. The ramp up passes through four or more step in a big reflow oven, then the last stage IS reflow temp area, then it passes out the end into a room temp environment, seconds after it actually got soldered.

Id say it matters.

I'd also still say that hand soldering the first article, if not the entire run, by a skilled soldering personage is the best route. Especially for short runs.

Thank you one and all for all of your input. It was a bit more than I originally asked but its all good.

Cheers,

James.