I recieved from microchip 3 serial eeproms recently.

One is DIP, one is SMP, and one is ? ..canister?

Anyway..the SMP is so small it requires special soldering practices.

This is my question.....

How the hell do you solder a SMP without special equipment?

Comments from any appreciated.
Posted on 2003-03-23 02:18:30 by IwasTitan
Thats the rub with modern electronics. With SMD (Surface Mounted Devices) none of the traditional bread bording techniques work anymore.

It is a REAL problem for both the professional and the hobbiest.

One way around it is something called a Surf Board by Capital Advanced Technologies (and available at Digi-Key). These are small printed circuit boards with the proper footprint for SOIC and PLCC and such packages. Essentially, they reroute the leads to nice .1" center pins so you can use the old ways to do things.

However, they do add significant capacitance to your layout. I just had the problem of needing an op amp to amplify a 3MHz signal, and the best device ONLY came in an 8 lead SOT style package. Using a surf board just killed the high frequency responce.

I was forced to go to a custom printed circuit board for even the first breadboard. I got em pretty cheap from Express PCB. They provide free software to do a layout in their propriority format. If you keep your board size exactly 3.8 x 2.5 inches you can purchase 3 boards for just 62 bucks. They come in a few days. The big drawback is you don't get a solder mask (they do offer such, but at higher price).
Posted on 2003-03-23 12:18:01 by Ernie
Thanx for the tips ernie.
Posted on 2003-03-23 18:40:41 by IwasTitan
I personally dont have the patience, but there was others in my robotics group a school who would solder them by hand... (so it can be done with a fine tip soldering iron.. not too hard to find ~ 15$ CDN).

However, dont be mistaken, the guy im thinking of has been practicing this art for some time now ;)

:NaN:
Posted on 2003-03-24 00:02:52 by NaN
I have never done electronics before but it seemed interesting when i saw a bit of stuff at howstuffworks.com .

I just want to know can electronics devices be made at home like software?
Posted on 2003-03-24 07:17:36 by clippy
I've replaced many times smd devices. A way to replace a chip is for example cut every pin and de-soldering one by one. You just need a very thin solder tip. Nothing imppossible, just a steady hand, the right tip kind/right temperature (if temperature is too high or you stay too musch on a pad you can damage the board.).

B7
Posted on 2003-03-24 12:33:12 by Bit7

I have never done electronics before but it seemed interesting when i saw a bit of stuff at howstuffworks.com .

I just want to know can electronics devices be made at home like software?


You can build discrete circuits such as oscillators/ rectifier bridges etc using diodes, resistors, capacitors etc.

You can also program ICs such as serial eeproms or even micro-controllers. However this is not making a device..merely programming it to work in your curcuits.

You can even wind your own transformer cores for power supplies if you want to save money.

Nothing is impossible but i don't think you would make any ICs at home. Thats a huge investment.

Having said that..you can make software that mimics a digital device. In fact many devices are designed in software before they are actually made to function in the form of ICs etc.
Posted on 2003-03-24 13:49:57 by IwasTitan
I love SMD. I made an AM receiver with 11 transistors R24 and SMD capacitors and resistors in 3 square cm. The capacitors were hard to measure, and as I did not have a farad-meter, I made one myself. I was developing a digital faradmeter, too, but did not reach soldering things together. In fact, I love making the schematics, but soldering is tiring me always, if it's not SMD. And I did not use any special equipment. 80W IIRC soldering iron, a magnifying glass, and care.
Posted on 2003-03-24 14:54:35 by Ultrano
Unsoldering SMD's was never a problem for me.

I usually save the 'cut the leads' stuff for thru holes.

SMDs can be hit with solder wick which pretty much weakens the bond so a dental pick can lift each lead in turn. You can actually retrieve the device like this (most of the time).
Posted on 2003-03-24 15:56:39 by Ernie
Hello, IwasTitan,

I do this all the time where I work. It's not really that hard. Practice is the key.
You need a soldering iron with a fairly small tip, about 0.040" at the end. This will work well for 0.050" pitch SMD's. If your iron has temperature control, set it to about 700-750 deg F. If it's not adjustable, use a tip which will give you about the same temperature (for Weller, # 7 works well; this number is stamped on the end that goes into the soldering iron, so remove the cold tip and look at its end).

1. I place the PCB on a flat surface, over a mat, to increase friction. This will prevent it from skidding. (You can use a piece of cloth).
2. I add some flux to all the PCB pads for that device. This is a a little sticky and helps hold the device in place.
3. Next, I place the device on the pads and carefully align it. When satisfied, I use my pointed tweezers and push the device down. (I use pointed tweezers, but you can use anything else, such as a pin or nail. The important thing is that a sharp object will not slide).
4. I use a small amount of solder and solder one pin in the corner. This has to be done gently, else the device will slide. Now the device is fairly stable and you can remove the tweezers.
5. Then I solder the pin in the opposite corner. The device is now secure.
6. Next, I solder the resr of the pins, in order. I am right handed, so I solder from left to right. Thus, I avoid retouching the pins I just soldered. Do not worry about solder bridges now. You would overheat the pads.
7. If you have solder bridges, the best way to remove them is by using solder wick. The fluxed one works best for me. I take the end and make a loop about 2.5" long, by holding in my left hand the end and the wick that comes out of the container. I place the tip of the iron in the loop and stretch it with the iron, so I have good thermal contact. Now with the stretched end of the loop I touch the solder bridge, which disappears. If necessary (too little solder left), touch up the pins where the solder bridge was. (Always use a fresh piece of solder wick where it touches the iron; usually I move the iron about 0.5" after each use).
8. Clean up time. I generally use alcohol and an old toothbrush to remove the excess flux. Holding the board at an angle, brush off the excess flux.

That is how I do it. You can do it, too. Remember, flux really helps, so use it every time. Also, on home-made PCB's , pre-solder the pads first: flux them, add solder to each and then use the solder wick to remove the excess solder from each pad. This way the pads' surface is still flat, but tinned.

Good luck!
Posted on 2003-04-06 20:22:06 by VVV
For SMD's, I first solder opposite corners, then all corners, then work all around, alternating sides to help things not heat up so much. Go slow, over heat is your worst potential problem.

I just glob LOTS of solder, not caring if anyhting shorts. Let the whole thing cool for a few, then solder wick the leads clean. Enough solder will be left to keep things working.

Mind you, I'm an engineer, and I'd never ship my solder work. This is strictly for experimenting. If I'm actually working on shippable hardware, I identify all parts I've toutched and send it back to a real qualified rework tech.
Posted on 2003-04-06 21:21:44 by Ernie