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soldering problem

Hi everyone,

I hope this counts as electronics as it's definitely a problem I'm having with an electronic circuit, but more with getting it put together on a PCB board (the circuit works fine). I'm pretty much a newbie with very little knowledge so I may be using terms wrong & such.

I'm making a project using several dozen of a touch-sensitive circuit which lights up an LED. Because of HIGH pricing on the DIP package, I'm using a SOIC version of the chip, and I found a PCB adaptor that I thought I could probably solder the chips onto easily enough.

Here's the adaptor (first item, 20 pin SOIC adaptor):

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I couldn't find a picture of the chip but it's an 8-pin SOIC package. I figured I would just ignore the extra pads and put the chip at one end and the 3 other components at the other end wherever they fit, and I wouldn't even need an additional board. This much is true, the 3 components fit fine and can be connected by the extra length of their leads.

Here's the problem. My SOIC chip is skinnier than the 20 pin chip the board was designed for. The legs don't bridge the gap. I can solder one side down onto the pads, but I'm left with about 2-3mm of space between the other side's legs and the other pads on the board.

I've tried a couple things, soldering tiny pieces of wire to the legs & soldering those to the pads, as well as attempting a kind of solder bridge on one or both sides (both is a bit easier b/c the bridge is much shorter). But none of these work very well and they all take a really long time.

Am I just screwed? Is there any kind of trick I might be able to use? Does anyone know of a part that might fit my chip better?

Any suggestions much appreciated!

Rachel

Reply to
mnrsiat
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This is going to sound real redneck and real nuts... but what have you got in the way of a hacksaw or bandsaw? Perhaps, if you cut that board right down the middle, it just might remove the right amount of material to make it about 2-3mm 'thinner'. It doesn't look like there are any traces that run across it laterally (that I can see), but you could jumper them if you had to.

This would at least move the problem from soldering the teensy SMT pins to the pins of the stuff on one of the edges. If the stuff you connect at the edges are through-hole components, you'll have longer leads to work with and more space to dink around with. You'll probably have a helluva time trying to glue it back together, so don't bother- just glue both halves down to the PCB you're working on.

Of course, you'll have to cut that tiny board REALLY straight, and it's going to be especially hard if you pound several cans of cheap malt liquor and put on your greasy-gas-station-food-stained Bubba Bibs. Note that this is the required uniform for doing modifications of this sort. Extra points if you perform it on the tailgate of a pickup truck.

Otherwise, buy the right chips or adapter. ;-)

Good luck, and don't judge me!

-phaeton

Reply to
phaeton

On 25 Aug 2006 12:24:18 -0700, in message , "mnrsiat" scribed:

I think the best solution is to find an SOIC adapter that fits the chip you wish to mount.

Reply to
Alan B

Looks to me you are stuck with tacking down 1 side and extending the other with small wires. Are you using 2 chips per board that way or trying to cut the adapter boards into 2?

Reply to
James Thompson

Hi, Rachel. It looks like you don't have an SOIC IC. Your part might be an SSOP, in which case the adapter on the web page directly underneath the one you bought might do the trick.

Here's the drill. Get a calipers and measure the part, then compare it with the package drawings on the IC data sheet, and see what you come up with.

Good luck Chris

Reply to
Chris

IIRC, SOIC packages come in two widths: wide and narrow. The 20SOIC (and 24 and 28) is available only in wide, and the 8SOIC in narrow. I think 14 &

16SOIC come in both widths.

Sounds like you're stuck soldering small wires (28 or 30 AWG) from the pin to the pad.

...jerry

Reply to
Jerry R

I was afraid of that. I will keep looking for an appropriate adaptor but it took me a while to find this one so I fear I might have to just Make It Work.

Phaeton, I like the idea of cutting the boards in half but since I'm not using a base board at all (the rest of the components fit right on the adaptor board) I think that would cause a worse problem.

Thanks for the advice, everyone.

Rachel

Reply to
mnrsiat

Stick the chip to the board and then solder wires on. Preferably find an old git like me who can solder anything to anything.

Reply to
Homer J Simpson

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