Got Some Soldering Done

Posted 2012.08.14 8.20 in Computers/Internet/Technology by Stephanie

This past weekend I got the new version of the ISEB-6 mostly soldered out.

It all went together fairly easily, with two unfortunate exceptions. The BMP085 barometric pressure sensor, and the HMC6352 magnetometer/compass. Both components are surface mount ‘leadless chip carriers’ – and both proved harder to hand-solder than I expected.

The thing is, unlike the ATMega1284P which is a TQFP-44 or the few SOT23 parts — all of which have ‘pins’ sticking out (albeit tiny pins), the two aforementioned sensors are in LCC packages where the connections are all underneath the part. There’s nothing visible from ‘above’.

I had some tricks in mind to solder them, and the tricks failed. In the end, I unfortunately destroyed both parts. Boooooo. Fortunately I did have a spare BMP085 laying around, but the HMC6352 is kinda-expensive and I didn’t have a spare.

Also-fortunately, I had a backup plan for soldering these tricky parts – hot air. I have a Sparkfun Heaterizer XL-3000 which I hadn’t actually used before. It did the trick though, allowed me to remove the dead parts without destroying the rest of the ISEB6 board, and I was able to solder the new BMP085 with it.

When I get a replacement HMC6352, I’ll use the Heaterizer once again to get that in place.

After that, the next steps will be to assemble a new leather bracer, and then build it out, with all the peripherals.

4 Comments

  1. Ken Scharf says:

    That board looks nice. Did you use the ‘lite’ (‘free’) version of Eagle? I’ve been trying to learn Eagle, I want to try to get some circuit ideas onto PC. If nothing else I want to make some universal breakout boards for common TSOP and TQFP pacakges.

    BTW the atmega1284P used to look like such a bargain, but the price has almost doubled recently. Now some of the xmegas look real good. The atxmega128a3u and atxmega256a3u give real bang for the buck. Only drawback will be having to port Arduino stuff to it (which is already in progress someplace).

    1. Stephanie says:

      Hello Ken,

      Thanks for the comments!

      Yes, I used the free/lite Eagle. I found it had a very steep learning curve up front, but after the first couple hours it all sort of suddenly fell into place.

      I think I payed about $8.50 for the ATMega1284P. I wasn’t too concerned with the price since I’m only planning on doing this once (or maybe twice…) and the uC was cheap compared to the two most expensive components: the GPS module and the HMC6352 compass that I killed.

      Rather than component price, my main concern was compatibility. So I wanted to ensure I’d have a microcontroller that would be fairly easy to work with. The 1284p has proved to be a great choice for me, as it has worked perfectly.

      I’m using my own Arduino pinout / variant, and I customized an existing bootloader to work on the 1284p at 8MHz and 57,600 baud. Otherwise, I’m using the standard core Arduino files (ver. 1.0.1) and it’s all worked just fine.

      Once I have it finished I’m going to post up the sketch, the Arduino variant files, and the Eagle files. I’m planning to put them all on GitHub. I don’t want to do it before it’s ‘finished’ though as I am still making hardware changes. I probably won’t do another PCB but I’m tinkering with values on some of the components, and there’ll probably be some wire patches here and there as things get moved around.

      Cheers!

  2. Ken Scharf says:

    I bought three of the ‘1284p’s in DIP when they were about $5 each.

    One thing I’m wondering about with Eagle, can you put SMT parts on BOTH sides of the board? How? Also can you post the part lib’s you made for the Adafruit boards?

    1. Stephanie says:

      Hi Ken,

      For the SMD parts, you can put them on either side of the board. When in the board editor, use the ‘mirror’ function and that flips the part around and swaps it from the top to the bottom solder plane.

      I’ll make a separate post with my own Eagle library – it has the board footprints I made for the Adafruit boards, and a few other footprints I’ve made along the way.

      Cheers!

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