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Here are the mech specs for the part (it is a GSM module) -

enter image description here

Note that all dimension are in "mm".

If hand-solderable do I need to keep some specific precautions in mind (from soldering standpoint). The data-sheet, HW design docs do not specific any specific soldering type or temperature.

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2 Answers

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It is hand solderable, but fairly close. As the illustration shows, the contact pads extend up the edges with a plated groove, which makes it easier to heat them than on bottom-only QFNs. I suggest extending the PCB pads a bit outside the module edges to let you access both pads with your iron. You may want to practice working with 1mm pitch a bit beforehand. Also, I wouldn't want to make a larger production run by hand.

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Thanks @Yann. Honestly, I am bit jittery soldering 1mm. I am guessing that excess flux and drag-soldering technique is not going to work with this, right ? I do not have a professional PCB-work magnification setup, and will be using a 4x loupe, and a fixed temp. 40W iron. Is that suicidal or doable ? I can borrow a temp controlled iron, but then the datasheet doesn't mention any temp anyway. – icarus74 Jan 25 '12 at 12:29
I wouldn't want to do drag soldering, no. Personally I'd use a small tip and thin solder wire. Or solder paste and a gently applied heat gun. – Yann Vernier Jan 25 '12 at 13:27
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It is possible to do it if you have a small soldering iron and a steady hand (and a lot of flux).

Basically try not to heat the pins for a long time (so as not to overheat the chip) and use a lot of flux and little solder to avoid bridges between pins. I suggest you train yourself by desoldering (and resoldering) a chip with this pin density in some broken device (no no worries if you destroy the chip). If you have enough flux, you should be able to just tin the pads on the PCB, then solder corner pins (to keep the chip stable) and then just drag the soldering iron on the edge of the chip and all pins should be soldered.

I did this once with a chip that had the same pin density (wait, it was 0.6mm, so a bit smaller than yours) but had pins on only two edges (no comments about the PCB please - it was my 5th PCB): small chip

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I guess, we need the thick gel type flux, not the fairly thin fluid type flux, right ? – icarus74 Jan 25 '12 at 12:55
I wouldn't know. I had some solid flux (looks kinda like amber), so I dissolved some of it in ethanol. I also used solder with integrated flux. – Pentium100 Jan 25 '12 at 13:22
@icarus74, I actually suggest a water based flux in all cases, it can be thrown on anything and washes off with water. I have seen rosin flux really mess up RF circuits, you also really do not need a heavy duty flux unless something is very tarnished. – Kortuk♦ Jan 25 '12 at 18:31

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