First time surface mount soldering (SPI serial FRAM)

RDL2004

I got this strange urge to play with one of those FRAM chips, but they're only available in surface mount. So, I soldered my first surface mount chip the other day and it didn't turn out too bad [noparse]:)[/noparse]



I used the "blob of solder, followed by flux and Solder Wick" method (Solder Wick is amazing). I used a spring clamp to hold the chip in place. Next time I'm going to try gluing it first, because this one is a little mis-aligned.

I got the test code working last night and it seems the chip survived okay.



Here is the basic schematic I used for the testing circuit. The code is attached.



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- Rick

Post Edited (RDL2004) : 11/2/2008 5:04:29 PM GMT

Peter Verkaik

I would change the Serial I/O connection to SI,
because now, when Serial I/O is driven high(low) while SO is driven low(high),
there is a very low resistance path (eg. short circuit) between Serial I/O and SO.

regards peter

peterz

I have used myself these FRAM chips.

In first place I used a socket to use it as an 'adapter'. I soldered each chip pin to a socket pin with a thin piece of wire. It did not work! Despite my tester shown all connections were Ok.

Then I soldered another FRAM chip to a breakuout board (like the one in your pictures). I used only flux and an ordinary iron. This time the FRAM did work!

RDL2004

My biggest mistake was using too small of a soldering iron tip. I tried using one with a very sharp, tiny tip, but had trouble getting the solder across the pins. After I switched to a larger "chisel" type tip it worked much better.

Also, I thought R1 was to prevent any possibility of a short between SI and SO, I don't see how connecting to SI would be any better. Should I use a larger resistor? I have run the chip through my test program over a dozen times with no problems.

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- Rick

Peter Verkaik

Then your program is correct and makes Serial I/O an input at the right moments.
But suppose you were to make a program error where Serial I/O would be high
while SO was low, that generates a short. By connecting Serial I/O to SI
resistor R1 serves as current limiter between Serial I/O and SO.

regards peter

BillDer

I am very new. Can you tell me where to get the pcb boards for surface mounting?
I am clueless.
Thanks,
Bill

Oldbitcollector (Jeff)

There are a little different design, but can be had here.

www.sparkfun.com/commerce/product_info.php?products_id=494

OBC

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RDL2004

If all you need is the soic-8 like in the first photo, I can send you all you want for $1 each and less than a dollar S&H (I'll have to check how much envelopes cost). That's assuming you wouldn't mind it being sent in an envelope by regular mail. Otherwise, Sparkfun or eBay is the best place to look.

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- Rick