SMD -- keeping it simple

If you hand solder, the cylindrical parts have a tendency to roll away...

MELFs are a nuisance. SOD323 is convenient, small but not too small, but won't dissipate much power. The SMB size is good for diodes that will get warm; add some copper pours to improve heat transfer.

SOT23 opamps and mosfets are nice. Use SO8 amps if you have tons of room; they run cooler and are easier to probe than smaller stuff.

Why are you using the digikey catalog? (do they still make those?) Their website has a nice search engine.

George H.

I meant search but not much help on this size thing.

So John -- use SO for the IC's ? Yes, I do have plenty of room.

-- thanks this makes it easy.

My usual advice for SMD parts: If you're hand-soldering them, change the footprints to have the pads extend a few mm away from the part. This gives you an easy way to "drag" excess solder away from the pins, so you can fix bridges.

That would be easy to assemble and probe.

We have a mixed stock of resistors, 1206 and 0805 and 0603 and a few oddballs. When I design a board and need, say, a 3.24K resistor, I might have to pick an 0603, because it's in stock, even though the board is mostly 0805. We should have planned better, I guess.

Yeah and it gives you a landing spot for the iron tip and solder... (I use the thinnest grade rosin core solder for smd parts.) The bigger the part the better IMO. Sometimes there is no room.

George H.

I just pick the part I want and even the manufacturer (most are in there). They're all stocked. I personally keep (sometimes short) reels of Panasonic (ERJ2RKF) 1% 0402 resistors for my prototypes. They're what Digikey carries. ;-)

I've tended to standardise on 0603, being of sufficient size to be handled, and was the cheaper[1] style for most Rs and Cs.

f, mini melf, sod 80,110,123 and 323 in my software.

e ones I should go with but which?

fancy.

The 30 mil width of the 0603s line up better with the 50 mil pitch of SOICs than the 0805s. You just offset the end ones a little to fit in the slight ly wider pads and the spacing for 8mil traces and spaces. The 0603s end up on about a 60 mil pitch compared to the 50 mil pitch of the SOIC pins.

My experience is that the lowest priced package depends on the part. Because of the density of my boards, I tend to use the smallest possible packages without crossing over to BGAs and the like. TSSOP seem to be priced well as well as VSSOP. But it depends on the device. In some cases DIPs are the low priced option, others they are hugely expensive. Supply and demand.

I love Digikey. You can sort on price and easily see what is cheaper in a given category. Mouser has a much better search capability these days too and offers different product lines.

I love Mouser because I live near to them and I can place a ground delivery online order as late as 6PM (I think) and I will get it the next day. Very convenient.

I live half a continent away from Digikey and can get two day delivery for the cost of Priority mail (usually the cheapest option available). Priority mail is pretty amazing.

You are correct. I have received packages in about two days as well from those distances. Works a treat.

I concur, except my issue is they use UPS. UK variant of UPS is the pits.

??? Priority mail is USPS here. No guarantee of delivery time, but I've gotten shipments from the other coast in 2 days and they are *very* economical. I don't think USPS ships Priority to the UK, but I could be wrong.

The last issue was it was delivered to a UPS "shop" that no one else but me could retrieve. Digi-Key wouldn't help at the time either. UPS-UK were saying they had their rules.

DigiKey does that, half-way across the country. The only problem is to get purchasing off their ass. If I walk over and say "pretty please", sometimes they'll get the order out in three days. I have $3K in orders for a prototype board, on its way to DigiKey and Mouser (~6:1 ratio - we gel a much better deal from DK). It'll be interesting to see which one gets here faster.

Yeah, I've given up on UPS. They won't deliver to the house/office unless someone is there to sign. Then they send it back *immediately* after the third delivery attempt. Like you I have to show my ID to pick it up although I think someone else can do that for me if they have my ID. But yeah, it's pretty onerous. That's another reason why I like the USPS and Priority mail.