Smonson's poorly-thought-out toaster oven reflow experiments

[Smonson]

My plan for the weekend was to apply solder paste directly to the IC leads before placement. But it turns out it wasn't as simple as I was hoping. I had a lot of trouble getting the right amount of paste applied to the IC leads.

toaster-reflow11.jpg (240.32 KiB) Viewed 4084 times

This was done using a set of dentist's tools which are actually perfect for the job, but with the tiny sizes involved, it just wasn't possible to put a small enough quantity of paste on the "feet".

After I soldered this one there were still far too many bridged leads. I'll have to wait for a stencil on my next run of boards.

[rubber_jonnie]

I have been thinking of a similar plan for my Mac Classic. CPU seemed to be dead based on the fact that it was too hot to touch, but all the voltages were good. So I removed it and have a socket to put in it's place, but seriously worried about the amount of solder paste I need to use, so was thinking of applying it to the socket rather than the PCB, then I can run the flux pen across the contacts on the PCB before attempting to line up. Too much will cause bridges that will be pretty hard to deal with.

I suppose at least I have a x1000 magnifier so I can inspect it.

[Smonson]

I have been thinking of a similar plan for my Mac Classic. CPU seemed to be dead based on the fact that it was too hot to touch, but all the voltages were good. So I removed it and have a socket to put in it's place, but seriously worried about the amount of solder paste I need to use, so was thinking of applying it to the socket rather than the PCB, then I can run the flux pen across the contacts on the PCB before attempting to line up. Too much will cause bridges that will be pretty hard to deal with.

I suppose at least I have a x1000 magnifier so I can inspect it.

You can't squeeze in there with the braid afterwards? Maybe you could do some practice runs beforehand on another board. The package I've used for my test is 0.65mm pitch, but for bigger stuff like 0.8 I think it would work a lot better. I think the pitch on most PLCC sockets is 1.27mm so you might be on the road to an easy success!

[DrF]

What about getting one of those controller kits?
They were quite the fashion a few years ago, I suspect they have come down loads now with the masses of cheap micro controllers all over the place.

[Smonson]

What about getting one of those controller kits?
They were quite the fashion a few years ago, I suspect they have come down loads now with the masses of cheap micro controllers all over the place.

To control the oven? I'm expecting it to be a lot quicker and cheaper to scratch-build it. Plus, I don't know what kind of display I need to mount on the front yet. It depends on what will fit into the space.

[rubber_jonnie]

You can't squeeze in there with the braid afterwards? Maybe you could do some practice runs beforehand on another board. The package I've used for my test is 0.65mm pitch, but for bigger stuff like 0.8 I think it would work a lot better. I think the pitch on most PLCC sockets is 1.27mm so you might be on the road to an easy success!

The socket doesn't make for easy access with an iron and braid after the fact due to the way it's made, and I don't have another board I can practise on sadly. The connectors to the PCB are inside the socket in order for it to be large enough for the 68K to plug in. One thing I won't do here is rush it as I only have one chance for success!

[Smonson]

Hmmm you could get some boards made, I think it would be worth it.

[rubber_jonnie]

Hmmm you could get some boards made, I think it would be worth it.

Actually, as it happens a chap from Germany I've been talking to on 68kMLA has just told me he's sent me over some dead boards for spares, so looks like I will have some for practice runs plus hopefully some of the Apple chips as spares

[Tomswork]

@rubber_jonnie

How many plcc smd sockets did you order. Are they the type you can cut the center plastic out of for working inside with a iron

Tom

[rubber_jonnie]

@rubber_jonnie

How many plcc smd sockets did you order. Are they the type you can cut the center plastic out of for working inside with a iron

Tom

Stupidly, I ordered one

I will order some more from the same supplier since they do have a center plastic piece that I could remove.

EDIT: More sockets on the way!!