History of SurfaceMount
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2004-06-09 02:48:22 . . . . MembersPage/DanaScott [Add link]


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There are some very good tutorials on surface mount here:

http://www.arrl.org/tis/info/surface.html

especially "A Surface-Mount Technology Primer "- Parts 1 & 2 and the 4 part "Surface Mount Technology - You Can Work with It!" series.

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Other surface mount links, though not as good as the arrl link above:

http://www.geocities.com/vk3em/smtguide/websmt.html

http://www.psnw.com/~kd7s/smdhd.html

http://www.aade.com/tutorials.html

http://www.geocities.com/vk3em/smtguide/websmt.html

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SMT... It's scary until you get used to it. With the 0603 components (0.06" long by 0.03" wide) it's easy. Much faster than through-hole when you get used to it. The only components on the MS-AVR that were particularly pain in the rear were the SMT transistors for the LEDs andthe SMT LED. You'll want a good soldering iron (doesn't need to be $100! I use one that's about 30 years old but it has a nice sharp tip.) and tweezers to hold the SMT components in place. Put a bit of solder on each solder pad. Let it cool, then place the component on the board with the tweezers and heat up the component and the solder at the same time one pad at a time. Done.

Sometimes it is also advisable to only put a solderbump on one of the pads, then you can solder the component in position just by reheating that pad and moving the component into its position while this pad is molten. This prevents stress in the component. You then add tin to further pads fixating the component completely. Eventually all pads should look shiny and sexy (not too fat and not too lean).

For some, especially higher density components, more experienced solderers can also try the little solder wave technique (this requires tin with flux core and a PCB with solder mask) where one uses more than enough tin, and places the board in a appropriate angle - one then rolls a solderball that wets all the pads in its way down the fine line SMD side (this wont work if your tin gets dry = looses its shiny fluxyness => just add fresh tin). However CAREFULL a bad day can result in shorts which in the best case are easily removed with solder wick and in the worst case require searching under a microscope and use of an exacta knife. Anyhow it’s the impatient method and not necessarily as resource efficient as the take your time method!

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Q - The U1 LED. Any tips on soldering this little bugger. It is tiny!

A - Same as any other 0603 part. Melt a tiny bit of solder onto one pad. Hold the part with tweezers with one hand in the desired position. With the soldering iron in your other hand , re-heat the solder on the pad . When the part pushes thru the solder and sits flush to the board, remove the iron. Let the part cool down .Then solder the other side of the part. Be quick about it and try not to use too much solder. If you go too slow the solder on the first end will reflow and you'll have to start over. Be sure to observe polarity!

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