cde 334 Posted October 15, 2010 Share Posted October 15, 2010 Numbers are misleading. What you may think is big (or small) enough in your head, might not be the right size. Visuals help. Edit: Update Below. Clockwise from top: DIP 8pin IC (100 mil Lead spacing) Sot-23 3pin Transistor (50 mil Lead Spacing, due to 3 pin configuration, pin 1 and 3 are 100 mils apart) 0805 Capacitor Soic(Wide) 28pin IC (50 mil Lead Spacing) 2pin 100x100 mil Header 1206 Capacitor On a 2010 Penny for the size reference. The 1206 and Sot23 cover the date exactly. The 0805 isn't big enough to do that. The 0805's solder pads fit on the Soic's 50 mil spaced leads exactly. If you don't want to dedicate a pad to a decoupling 0805, just solder it straight onto the pins (if you ever find an IC with V+ and Gnd right next to each other that is). Same goes for the 1206 and the DIP's 100 mil spaced leads. You can even use a 2pin header to make a smd to through-hole adapter if you don't have the needed through-hole version. Both the 1206 and the 0805 (barely) can be done. Even the Sot-23, if you use 3 inline header pins and a bit of wire. Sot-23 has the same spacing as a Soic package ic. With the 3-pin parts, the middle pin of one side is removed, while the outer two pins on the other side are removed as well, so it has a 100 mil spacing on the side with 2 pins. The 4-pin version has 3 pins on one side, with an extra big pin on the other side (heat dissipation purposes normally). The 5-pin version has all 3 pins on one side and the 2 outer pins on the other side. The 6-pin version has a full set of pins on both sides. Even though sot-23 and soic have the same pin spacing and sizes, Soic chips, having a bigger body, are easier to handle. Even sop/ssop/tssop parts, with 25 mil spaced pins, are easier to handle than sot-23 6 pin imho. Lesson is really, stick to through hole for prototyping till you are ready to beta. Sot23 is hella tiny, and I would have not gone with it for the transistors I bought if I had known (The standard to-92 versions were the same price, and have higher watt ratings to boot). Ha. --- It happened again. I was expecting a decent sized QFP chip. I got: A 3mm x 3mm package QFN with pin spacing smaller than tssop, in a reflow only package. Oh vey. jsolarski and bluehash 2 Quote Link to post Share on other sites
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