Smorgasboard general conversation, SMD fun ... SRAMs and me:)

rjo__

Hi guys,

I ordered 3 of the smorgasboards... thanks to everyone who contributed. A fab fab.

http://gadgetgangster.com/find-a-project/56?projectnum=404

To prepare myself, I scoured the net for SMD soldering help, dusted off an old stereo microscope, and got some rosin flux from RadioShack. I practiced on some dead chips. Then I got myself set up at Mouser and DigiKey and waited.
My smorgasboards arrived a couple of days after release and I went to work. To my surprise, SMD soldering under a microscope is easypeasy and it is fun. Makes you feel like a regular rocket scientist. Only problem is... my first two attempts to make jazzed's SRAM board failed miserably, with chips on the board becoming hot.

Here's is my soldering technique. I tin my tip... slather flux on the target area and then touch my 15W tip to the pad just long enough for the solder to flow. I created a couple of bridges, which I removed with solder wick or by simply cleaning my tip and then using that to remove a microliter at a time.

Questions... could slathering be my problem? Invariably some of the flux gets on the chips and I disregard it... could this actually damage a chip? Do I need a temperature controlled soldering unit?

Can the failure of one SRAM chip cause the others to fail? The failures begin in the middle of the board... chips 3,4,5, but eventually others fail as well.

What is your Smorgasboard experience? Is it not the greatest thing since sliced bread or should I consider medication?


Rich

JLocke

rjo__ wrote: »

Is it not the greatest thing since sliced bread or should I consider medication?

Yes, and Yes.

jazzed

rjo__ wrote: »

my first two attempts to make jazzed's SRAM board failed miserably, with chips on the board becoming hot.

That can happen if the chips are reversed. How did you connect power? It takes a lot of soldering heat to destroy a TSSOP, still i never put the temperature over 750 unless it's silver solder.

My own technique for TSSOP is to tack one pin on one side, solder the other side all 4 pins at a time with a tiny blob of solder and flux, then repeat on the tacked side. Fast and simple.

rjo__

Thanks.

Reversing the power leads sounds like something I would do... and if I did it once, there is no reason why I wouldn't do it twice. I did this right before my cataract surgeries and I was using a non-standard power set-up.

The chips are seated correctly, and I don't think my little soldering iron ever got near 750:)
I'm going to try working up the last board and see what happens.

I would be interested in hearing from others about their experiences with the smorgasboard... what boards have you done? What is your favorite? Any problems?

Rich

Cluso99

I run my iron at 370-389C. You require a really fine tip. And just leave it on the pad just long enough to melt the solder.
With time you will improve - its really just practice. In no time you will be wondering what all the fuss is about even with 0.5mm spacing.
BTW I use a solder flux pen.

rjo__

Thanks,

I'm thinking temperature is the issue. I haven't had a problem getting the smd chips soldered on. After a little practice it is actually very easy. And I would strongly recommend the Smorgasboard. Beautiful designs. Fairly complete documentation... and if you mess up an individual board, you are out about $1. Im' considering whether I want to buy a temperature controlled soldering gun... or stick with my current $9 unit and build a thermometer for it:)

I have one of the SRAM boards left and I'm saving it til I figure out my setup.

Rich

Tubular

Hey Rich,

Thanks for the kind words re Smorgasboard. It has been a great experience and one that isn't over yet, I'm making up some 3d printed cases to fit all the boards.

Anything I can do to help you with the SRAM board? Perhaps I can make one up carefully and test as I go.

cheers
Lachlan

rjo__

Tubular,

Wonderful stuff... just what the doctor ordered.

How about doing an autopsy and publishing the results?

Rich