[sdiy] More SMT

[Dave Manley]

On 4/14/2013 9:08 PM, dan snazelle wrote:
>
>
> On Apr 14, 2013, at 11:53 PM, Scott Gravenhorst wrote:
>
>>
>> This is regarding a video which depicted using a Schmartboard to solder a 64 pin 0.5 mm
>> pitch TQFP package.  The video showed a fine point soldering tip being used and the
>> process was to use the point of the tip to push solder already on the traces leading to
>> the IC pins.
>>
>> I do not have such a soldering tip, but I did have a good quality small chisel tip (I'm
>> guessing 3/16" wide).
>>
>> I first put paste flux on the Schmartboard with a toothpick.  Just a slime coating.  Then
>> I put the IC onto the board and after several attempts got it lined up.  It's tiny stuff
>> for me, so I had to use a magnifier (telescope eyepiece in my case) to make sure that the
>> IC leads lined up with the traces and that all were going to connect properly.
>>
>> I taped the board onto my desk with masking tape.  I then taped the IC to the board once
>> I had it registered correctly.
>>
>> I then cleaned my iron well and applied a very small amount of solder to the iron and
>> dragged it while heating both the board traces and the IC pins.
>>
>> Of course there was a small amount of "too much solder" which made bridges.
>>
>> I wiped and cleaned the soldering iron as much as I could and re-dragged the same places
>> on the board.  This caused solder to come out from the bridges and go onto the PCB
>> traces.  I used the magnifier to look at the solder job and it looks clean.  I will "ring
>> it out" tomorrow to see if I need to use solder wick.
>>
>> -- ScottG
>> ________________________________________________________________________
>> -- Scott Gravenhorst
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>>
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>
>
>
> informative post! can you explain how you taped the chip down? what kind of tape? and did you put it over the chip or behind it?
>

There's no need to tape down the part - just put some solder on one of the corner pads, and then under
the microscope/magnifier heat the pad and push the corner lead into place.  Then tack down the opposite
corner and then do the 'drag solder' thing for the rest.  Use a lot of liquid flux.

Gets very easy after you do a few of them.

-Dave