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Author Topic: First ebay Minimig sells for £214 (305 EUR / $428 US)  (Read 8713 times)

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Offline nBit7

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Re: First ebay Minimig sells for £214 (305 EUR / $428 US)
« on: October 30, 2007, 02:51:44 AM »
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Those 0805 Capacitor's and Resistors *REALLY* take time because of their size :)


0805 (2mm x 1.25mm) Rs and Cs, Yes they are small but it should not be taking too much too individually (unless you are tring to perfectly align thenm).  Ok, I will admit it does take a bit of practice to get quick at it.  But after a few minimigs you should be quite good at it.

0603 (1.6mm x 0.8mm) are not too bad.  
0402 (1mm x 0.5mm)  now thats getting a bit hard without magnification buts its the most common size now.  
0201 (0.6mm x 0.3mm) now thats small.  
01005 (0.4mm x 0.2mm) I don't think I would even bother attempting.

I don't know what method you are using.  But the quickest method is to use an ordinary soldering iron:

1. solder a small amount of solder too one pad only
2. place the part next to the pad (such that is is over the other pad) then hold by the sides with tweezers.
3. heat the pad with the iron on the outside edge of the pad.
4. slide the component into the pre-soldered pad
5. remove iron, wait a few sounds then remove tweezers
6. solder the oppersite side.
7. add a little more solder (or flux) to the first side if needed

 

Offline nBit7

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Re: First ebay Minimig sells for £214 (305 EUR / $428 US)
« Reply #1 on: October 30, 2007, 04:46:29 AM »
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rake the iron across the pads to build up a layer of solder

If you get the boards finished by HAL (Hot Air Leveling or HASL). Then you can skip this step.   HAL is where the pads are all pre tinned and the excess solder is blown off with hot air.  This is the best finish to get for soldering too.

Personally If I put solder on the pads first I use solderwick (braid) to remove the excess.  Untherwise the IC is harder to place and may sit too high above the pads.

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center the chip on the pads
tack down two corners
double check the centering
get a tiny solder ball on the tip of the iron, place down the iron at the start of the pad and trace it along the pad until it bumps the lead, you'll see surface tension on the solder work it way up the lead, etc.


It should be noted that you need a solder with a good flux for this to work well.  Or use liquid or gel flux.
Or anther way is too use lots of solder (and hence lots of flux from the solder).
 

Offline nBit7

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Re: First ebay Minimig sells for £214 (305 EUR / $428 US)
« Reply #2 on: October 30, 2007, 05:54:20 AM »
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One thing I have been wondering about is the method of tinning one pad, tacking it down, and then going to the other pad and applying solder. This method would appear to make sure the part is level with the board.


I just solder one corner pad.  Line the chip up.  and heat that one pad (I don't worry about height at this point).  

Then go to opposite corner and gently push down (if its not lining up at this point then heat the first pad and adjust)
Then tack one of the pins down.

Go back to the first joint and heat and push.  The chip should now be level.  You may wish to push and tack the other corners too.
 

Offline nBit7

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Re: First ebay Minimig sells for £214 (305 EUR / $428 US)
« Reply #3 on: October 31, 2007, 02:26:34 AM »
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This is the method I will be using:
http://warmcat.com/milksop/soldering.html


I would say it is good upto the point of using braid.
It is impossible to get nice looking joints using wick to remove excess solder.  Nice looking joints are normally reliable joins.

With the drag method koaftder and I use you get joints that look similar to production wave soldering.

Loading up the pins with solder like was shown on that site is a good substitute to using flux. Holding the board at an angle (or even upside at an angle) you can then drag the soldering iron across the pins and the solder will follow leaving just the right amount of solder behind.  This is a variation of what 'koaftder' does.

Don't worry about the heat issue.  Heat only couples into the chip slowly due to the thin wires.  The reflow solder process (ie. oven) puts more thermal strain on the IC than what you can do putting large blobs of solder on its pins.
 

Offline nBit7

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Re: First ebay Minimig sells for £214 (305 EUR / $428 US)
« Reply #4 on: October 31, 2007, 02:52:39 AM »
@freqmax
this video shows the drag solder method in action:

http://www.howardelectronics.com/xytronic/Images/Drag%20Soldering%20107.wmv