As I'm waiting for the second revision of my Artix DDR3 board to arrive (I've botched up rev 1 due to some stupid mistakes - "curse of the first revision" hit me again :( ), I've decided to practice soldering 0201 capacitors as I've never used such small parts before. Also I've just bought a new "thermally stable" lead-free solder paste (this one), so I wanted to give it a try and see how it goes. Previously I tried regular LF paste (that needed to be refrigerated for storage) and in turned out to be a massive PITA - it dried up in like 1 hr, which was not long enough for me to place all components, and after it dried, soldering it created lots of bridges and "thumb stones" - to the point that I decided to use regular leaded paste instead as it was much easier to work with.
Anyway, after printing the paste I saw that some of the paste ended up between pads. Normally I'd clean in up using sharpened toothpick, but in case of 0201 pads were just 0.26 mm apart, so even sharpened toothpick was too thick, so after some tries I decided to just leave this alone and proceed to place components to see what happens if I don't clean it up first. As it turned out, such cleanup was absolutely NOT necessary because solder wicked out toward pads by it's surface tension, so previously I was just wasting my time cleaning it up!
I've placed a dozen or so of 0201 caps and some 0402 caps (I have full 10K reels of many 0402 parts and they are incredibly cheap, so I wasn't concerned about the waste at all). Here are some photos of what it looked like after reflow. There is a ruler with 1 mm divisions in the top part of photos to get idea of scale:
I'm very pleased with these results. My only worry is that if thumb stone will happen with 0201, I won't be able to fix this with an iron as these parts are so damn small!
I should receive rev 2 boards by the end of the next week. Can't wait to assemble it, or discover that I messed up something else :D
Anyway, after printing the paste I saw that some of the paste ended up between pads. Normally I'd clean in up using sharpened toothpick, but in case of 0201 pads were just 0.26 mm apart, so even sharpened toothpick was too thick, so after some tries I decided to just leave this alone and proceed to place components to see what happens if I don't clean it up first. As it turned out, such cleanup was absolutely NOT necessary because solder wicked out toward pads by it's surface tension, so previously I was just wasting my time cleaning it up!
I've placed a dozen or so of 0201 caps and some 0402 caps (I have full 10K reels of many 0402 parts and they are incredibly cheap, so I wasn't concerned about the waste at all). Here are some photos of what it looked like after reflow. There is a ruler with 1 mm divisions in the top part of photos to get idea of scale:
I'm very pleased with these results. My only worry is that if thumb stone will happen with 0201, I won't be able to fix this with an iron as these parts are so damn small!
I should receive rev 2 boards by the end of the next week. Can't wait to assemble it, or discover that I messed up something else :D
Thanks for sharing the information. Sorry my ignorance, how do you reflow the board? Do you have any domestic reflow oven? Cheers. Alex.
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