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dear osmosis,

good to hear you have polished your skills in smd soldering .post some tips and photos.
 
tony1 said:
post some tips and photos.
Click to expand...

I'll have to work on the photos, not sure I have anything capable of taking a good enough shot of small objects.

As for reflowing, you will need something along the lines of a mylar stencil, available from Polulu.com. You send them your gerber file with the paste layer, they laser cut the stencil and mail it to you.

Position the stencil over the board, wipe some solder paste across with a putty knife, then lift the stencil off, leaving a perfect solder paste pattern on the board. Amount of solder is controlled by thickness of stencil. Verify the paste job: it needs to be close, but not 100% exact.

Now carefully populate the board. I use bent tweezers. Take static precautions if called for, which is almost always. Don't drink eight cups of coffee shortly before attempting, you'll need a steady hand.

Preheat your $20 walmart skillet to 200F. Place your board in the center of the skillet, put on the lid and crank the temp knob to 400F. On my skillet, this is max temp. Now watch through the clear plastic lid as the reflow occurs.

As soon as liquidus is reached and the components have aligned from the surface tension, turn the heat OFF. Remove the lid, but don't touch the board yet. If the board cools too quickly, thermal fracture can occur. Wait at least 5 minutes, until the board is cool enough to handle.

Inspect and rework as necessary. Tiny air bubbles in your solder paste can pop under heat, blowing tiny passives clean off the board. And sometimes the alignment doesn't happen properly (4mil stencil can help this. a little more paste can make the alignment smoother) but you shouldn't have any bridges to deal with.

Watch all the reflow methods on youtube, I did. While some prefer to use a toaster oven, and it probably is better if you find the right one, I find a cheap skillet does the job just fine.
 
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Hi, Osmosis,
Thank you for all the advice and tips.Is the Skillet the same size as a ordinary Oven?.
For Photo works , a camera with good Zoom lens or additional close up lens can help you there. Close up lens are just one thin peace which you screw on to your main lens like a filter lens and they are cheap.
 
Is the Skillet the same size as a ordinary Oven?

It was on sale for $20 when I got it.
GE Portable Electric Skillet ? Walmart.com

tony1 said:
For Photo works , a camera with good Zoom lens or additional close up lens can help you there. Close up lens are just one thin peace which you screw on to your main lens like a filter lens and they are cheap.
Click to expand...

Thx for the tip. Should be a able to get some pics uploaded in a month or so, ask again if you're still interested.
 
I use a skillet to make bacon an eggs.
If you plan to sell your PCBs then I would suggest
a Toaster Oven with a PID controller to precisely
control the PCB Reflow Heat/Cool curves.

If you are just experimenting and not selling your
PCBs to paying customers then the skillet method
would be fine.


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
 
lasersbee said:
If you plan to sell your PCBs then I would suggest
a Toaster Oven with a PID controller to precisely
control the PCB Reflow Heat/Cool curves.
Click to expand...

Agreed, toaster oven should be better. Even better still, an infrared toaster oven. A company called Silicon Horizon (thesiliconhorizon.com) makes just such a temperature controller. I have one but I've not yet tried it. It's somewhat comical, I'm surrounded by thousands of dollars worth of tools and equipment and I'll go out of my way to reflow with a cheap skillet.

lasersbee said:
If you are just experimenting and not selling your
PCBs to paying customers then the skillet method would be fine.
Click to expand...

If you just give it the minimum necessary amount of heat to reflow the solder, it works like a charm. I haven't had ANY problems with the skillet method, and boards can be tested. Any reason I shouldn't be content with this, even for saleable units? Are working boards liable to stop working with this method?
 
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I've used my plastic welder a couple of times now. Aside from it being pretty big, and the loud and annoying noise of my compressor kicking on, it works quite well. You just have to regulate the air flow so you don't blow the smd parts off.
 
Mohrenberg said:
but why use that method when a new GE toaster oven is about the same price at wal-mart?
Click to expand...

no reason at all. for me, it was the allure of getting a $40 skillet for $20. I'd ordered the toaster oven controller and planned on getting an IR oven for it, but the skillet is so simple and, frankly, IT WORKS. I never bothered to spend the money on a toaster oven. If I ever go into production mode though, I'll probably get a toaster oven.

You say you use a plastic welder. If that works, more power to you. I've a $1000 Weller hot-air pencil specifically made for such tasks, and it's one of the last things I ever use.
 
osmosis321 said:
no reason at all. for me, it was the allure of getting a $40 skillet for $20. I'd ordered the toaster oven controller and planned on getting an IR oven for it, but the skillet is so simple and, frankly, IT WORKS. I never bothered to spend the money on a toaster oven. If I ever go into production mode though, I'll probably get a toaster oven.

You say you use a plastic welder. If that works, more power to you. I've a $1000 Weller hot-air pencil specifically made for such tasks, and it's one of the last things I ever use.
Click to expand...

Yeah, I want one of those but cannot justify the $1000 purchase, nor afford it.
The plastic welder is something i wanted to have anything, cause i'm always melting shit.
 
Mohrenberg said:
Yeah, I want one of those but cannot justify the $1000 purchase, nor afford it.
Click to expand...

Forget affording it or justifying the cost. Take it from someone who paid the $1k, it's not worth it. You can get something just as good if not better for half the cost. Having said that, it's imperative to have SOMETHING capable of blasting hot air.

Mohrenberg said:
The plastic welder is something i wanted to have anything, cause i'm always melting shit.
Click to expand...

If it works, use it. Having spent thousands on gear and consumables, the best advice is I can give you is don't spend thousands on gear and consumables. The best tools have more than one use and vary from person to person, and often price is no indication of usefulness.

In short, SHOP AROUND.
 
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osmosis321 said:
Agreed, toaster oven should be better. Even better still, an infrared toaster oven. A company called Silicon Horizon (thesiliconhorizon.com) makes just such a temperature controller. I have one but I've not yet tried it. It's somewhat comical, I'm surrounded by thousands of dollars worth of tools and equipment and I'll go out of my way to reflow with a cheap skillet.
Click to expand...

I suppose you could reflow a PCB and parts on a tin can and
a propane torch but I would not sell a PCB assembled like
that to a paying customer. I guess that's just me...

If you just give it the minimum necessary amount of heat to reflow the solder, it works like a charm. I haven't had ANY problems with the skillet method, and boards can be tested. Any reason I shouldn't be content with this, even for saleable units? Are working boards liable to stop working with this method?
Click to expand...

There is no way you can guarantee that your PCBs were
re-flowed using the correct Heat/Cool curves and proper
temperatures using just a skillet and without any possible
stress on the components or solder joints. Just because
the parts don't fall of the PCB does not indicate proper
assembly.

I have a toaster oven with PID controller and I still feel
more comfortable with the products we sell when we let a
professional PCB manufacturing facility mount our SMD
parts with the proper equipment that precisely controls
the Heat/Cool curves does not stress any solder joints or
electronic parts.

I'll need to watch out for any precision electronics that
you will be selling assembled in a skillet in the future...;)

Sorry... It's just not my way of doing business when it
concerns a customer's hard earned $$$. Like I said...
I guess it's just me...


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
 
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lasersbee said:
I suppose you could reflow a PCB and parts on a tin can and a propane torch but I would not sell a PCB assembled like
that to a paying customer. I guess that's just me...
Click to expand...

Tin can and propane torch... hmm.. I have a propane torch and a coffee can.. maybe I should try that..http://laserpointerforums.com/images/smilies/biggrin.gif

Just kidding, it's not just you.

lasersbee said:
There is no way you can guarantee that your PCBs were
re-flowed using the correct Heat/Cool curves and proper
temperatures using just a skillet
Click to expand...

True. I'd only do it on small boards with very few IC's, and only on prototypes or hobby stuff.

lasersbee said:
I'll need to watch out for any precision electronics that you will be selling assembled in a skillet in the future...;)
Click to expand...

I doubt I'd sell them, for the very reasons you've mentioned. It's mostly for personal projects. This is for people who DIY, not for business.
 
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