Yes, the known problems with any potting compound are the different coefficient of expansion with temperature, and the thermal conductivity. The expensive ones have high thermal but low electrical conductivity, and a thermal expansion coefficient similar to the electrical components. They have to balance stiffness, which is generally desirable, against failure due to thermal cycling.

 

Even as a kid I had poor small muscle control but I was soldering to octal and 9 pin sockets, so it did't matter much. Now, in my old age I have even worse small muscle control--I have to clear up short circuits between two adjacent pins of a perf board almost as often as I don't. The other day I bought a "mystery board" for 50 cents and noticed a white, hard caulk-like substance holding many parts in place. It is NOT used as a heatsink though it might be heatsink compound. It is around two ferrite beads not near each other, a wire wound inductor, five various electrolytics and a couple of small black rectangles. I has, obviously, been squirted one fairly casually, but not wastefully.
This leads me to think I could just confirm that my breadboard is working and smear glue over everything to make a permanent unit.
I'm going to try it, but if anyone has a suggestion for the type of glue or caulk or ??? I would be glad to know it.

I would imagine hot glue would hold most components in place nicely, and has little measurable effect except for perhaps some high voltage circuits. I've even used it to hold RF coils in place with no noticeable change of inductance.

 

Your mystery circuit has many more components that you think - all those SMD resistors add up quickly. Also, the chips are not all available in PDIP (0.1" pin spacing) - they may have to be mounted on adapter boards. All those resistors will not be so nicely positioned on a protonoard vs a purpose-designed multilayer PCB with vias that allow traces to cross-over each other. Limiting yourself to a protoboard / breadboard is going to get very complicated and messy. In fact, you could google an old and famous project referred to as, "Big Mess o Wires" if you want to see what your project will look like once all the jumpers are installed.

Also, why don't you want to want to do PCB? Some vendors in china are doing 10 boards sized 4x4" for less than $30. Way cheaper and easier than protoboards.


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Big mess o wires computer. Granted, it is wire wrapping, not solderless breadboard but not much different once all of your parts are placed.

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I've breadboarded quite a few circuits incorporating kadaptor boards, since some op amps are only available in surface mount. It depends on the type of circuitry. I've used breadboard methods up into the low HF range with no problems.

 

I used Loctite Instant. It comes in a double barreled hypodermic-like tube and requires no mixing. I used it because I had bought it for another project and then did not need it. I would bet that any hardware store epoxy would work. The next time I need to pot a circuit I'm going to try GOOP which is not an epoxy and does not need mixing. It is cheaper than epoxy and a lot cheaper than the no-mix unit I used.

 

One other thing you might consider, instead of a liquid epoxy or other fluid compound, is an epoxy putty. It would secure your components and wires in place without much danger of leaking down into the innards of the breadboard and messing up the electrical contacts.

 

I've breadboarded quite a few circuits incorporating kadaptor boards, since some op amps are only available in surface mount. It depends on the type of circuitry. I've used breadboard methods up into the low HF range with no problems.

I have too - for breadboarding. By the time to OP buys 6 or 8 adapter boards, they may find that they equal the price of a PCB.

 

For the sake of anyone wanting to follow in your shoes, what epoxy did you use? There are thousands of products out there called 'epoxy'.

I thought I had posted this a couple of hours ago but I don't see it. I used Loctite no mix--the double barreled hypodermic-like device. I had bought it for another project and did not use it. My guess is that any hardware store epoxy would work though I'd avoid JBWeld with its powdered iron base. I'm pretty sure it does not conduct electricity but it sure would add capacitance.
The next time I need to do this I intend to use GOOP which is cheaper and doesn't require mixing.

 

I thought I had posted this a couple of hours ago but I don't see it. I used Loctite no mix--the double barreled hypodermic-like device. I had bought it for another project and did not use it. My guess is that any hardware store epoxy would work though I'd avoid JBWeld with its powdered iron base. I'm pretty sure it does not conduct electricity but it sure would add capacitance.
The next time I need to do this I intend to use GOOP which is cheaper and doesn't require mixing.

The toluene in goop may "melt" (swell/dissolve) some of the plastic on capacitors and cause issues with your board. The whole board may swell to 2x in some places as the toluene attacks (depending on the type of board you have). Goop is a high solvent product, like rubber cement.

Safety Information

Contains toluene and petrolatum distillate. Vapor harmful. May cause dizziness, headache or nausea. Causes eye, skin, nose and throat irritation. Intentional misuse by deliberately concentrating and inhaling contents may be harmful. This product contains a chemical known to the state of California to cause birth defects or other reproductive harm. Keep away from heat, spark and flame. Extinguish all sources of ignition during use and until all vapors are gone. Prevent build-up of vapors by opening all windows and doors to achieve cross ventilation. Use only with adequate ventilation. To avoid breathing vapors, open windows and doors or use other means to ensure fresh air entry during application and drying. Close container after use. Avoid contact with eyes and skin. Wash thoroughly after handling. First Aid: If you experience difficulty in breathing, leave the area to obtain fresh air. If continued difficulty is experienced, get medical assistance immediately. In case of eye contact, flush immediately with plenty of water and get medical attention; for skin, wash thoroughly with soap and water. If swallowed, do not induce vomiting; get medical attention. Keep out of the reach of children.

 

As a side note, I ordered an 8 watt soldering iron which, I hope, will be small enough to help me solder 0.1 inch spaced pins. There is no way I'll ever be able to use a SMD.

I use a temperature controlled 40W iron. If your iron is too small, you will not be able to get good joints. One misconception is to use a tiny tip for small parts and it is actual harder to do. Not enough heat is transferred to flow the solder correctly.

I very rarely use the thin one.
As for working on SMT parts, the 1206 sizes are pretty easy. Just pre-tin one PCB pad, place the 1206 part on it with tweezers, solder it on then when it is set, do the other end.
I got a Video Presenter, similar to this... http://www.ebay.com.au/itm/Lumens-P...997040?hash=item2380b1e330:g:G9IAAOSwMpBZa9Fc

It make it really easy!
I'm over 65 now and with the correct tools have soldered 0.4mm spaced PICs onto boards quite well. 1206 and 0805 parts are ok, and 0603 is a little harder. 0402 is my limit by hand. And I use a decent sized soldering iron tip, not a thin one.
Flux is your friend!
For SMT work, a heat gun is a must. To pull a processor off the board just heat it up until it drops off.

 

I use a temperature controlled 40W iron. If your iron is too small, you will not be able to get good joints. One misconception is to use a tiny tip for small parts and it is actual harder to do. Not enough heat is transferred to flow the solder correctly.
.

I'd like to add a corollary to this warning. Many folks use an undersized soldering iron on SMD under the impression that you're less likely to burn out the part. Not so; if you have insufficient heat, you have to leave the soldering iron in contact LONGER, giving more time for heat to transfer to the delicate innards. It's far safer to get the job done VERY Quickly, so there is no time for the heat to transfer far from the actual solder connection.

 

I'd like to add a corollary to this warning. Many folks use an undersized soldering iron on SMD under the impression that you're less likely to burn out the part. Not so; if you have insufficient heat, you have to leave the soldering iron in contact LONGER, giving more time for heat to transfer to the delicate innards. It's far safer to get the job done VERY Quickly, so there is no time for the heat to transfer far from the actual solder connection.

Just like in cooking - "the higher the heat, the rarer the meat." (or, for a constant heat source, like broiling, "the closer the heat, the rarer the meat"

A low heat iron can result in a "well done" SMD.

 

Just like in cooking - "the higher the heat, the rarer the meat." (or, for a constant heat source, like broiling, "the closer the heat, the rarer the meat"

A low heat iron can result in a "well done" SMD.

I have no idea how this thread got switched to SMDs. It started as a way for me to avoid 0.1 inch DIPs. I would no more try to solder SIPs than I would enter a NASCAR race. I'm satisfied that the breadboard and glue system will work and that is the end of it for me. Bye and thanks to all those who helped.

 

I have no idea how this thread got switched to SMDs.

It's called "thread drift." We're good at it.

 

I'm satisfied that the breadboard and glue system will work and that is the end of it for me.

Let us know how it turns out the first time you need to troubleshoot and make a repair.

 

For pcbs I use a iron technology if there are dips and separate components AND there will be a larger amount, probably 10 or 100 pieces (because it is very cheap technology). For smd - it is not impossible, however MUCH better results will come with Positiv-20 bottle. Just puff it, dry in the controlled T, and put under UV diodes matrix. After 10 seconds You are ready for bath and etching. Results: the 50 micrometer width with high accuracy is not the limit at all. Actually the resolution is set by type of used printer on the film. But as the printer must be here coloured, let the black would composed from 3 colours with aim to be darker, and film costs, and aerosol costs makes the material costs about dollar or two per A4 sheet.
But while prototyping, everything MUST be large enough, then SMD I mount on the smaller pads what has `normal` size for wires, and all other details on the reused pcb from what by flexmachine is eliminated all copper. That always has a plenty of drilling and places for copper may be made of wires.

 

Let us know how it turns out the first time you need to troubleshoot and make a repair.

Or just a simple change.