Surface mount components - anyone use 'em?

[Shea]

I once built a kit that used a surface mount microcontroller IC,and it wasn't as hard to solder it to the PCB as I expected it to be. With some practice, I think one could get their surface mount soldering technique down to where it would be worth doing to save the time of drilling out pads and clipping leads, at least for ICs and electrolytic capacitors. Surface mount resistors are too dang small, though.

The drawbacks I can foresee are that (1) for layout purposes, you have to picture your surface mount components in a reversed orientation from corresponding leaded components, and (2) the terminals on surface mount ICs are so close together that you'd be pushing the limits of toner transfer PCB fabrication for pad spacing and track width.

Are there any others?

Shea

[turbolx5oh]

I use photo transfer for my PCB layouts and it is way better than the toner transfer method. Its also easier as well.

I've got an idea to try a tube screamer using surface mount parts. As well as PCB mounted pots. That way the only wires you would have inside the box would be for power and switching and the PCB would be half the size of a normal one.

[Enzo]

I absolutely positively hate the damned things. The connections and such do tend to be reliable, but the parts are no more reliable than through hole parts. I only use them when repairing things made of them. On a through hole, when a resistor erupts into smoke, it is not very difficult to deal with the ruins. The middle resistor in a line of 6 in the space of half a centimeter is more liklely to erase traces that are difficult to renew.

I can hand solder the stuff, but what is the lead pitch on that LSI you soldered? The .1 stuff is OK, but the smaller stuff, the 0.5, .03 amd who knows how small they go now, are just too small. I need a lens just to check for solder bridges.

For the volume I do, I cannot justify the expense of hot air gear, so I rely on chip-quick. Seems to work.

[Steve Conner]

I hate SMT too, but I use them extensively at work.

We design on PCB layout software that works as if looking through from the top of the board, so the reversed layout isn't an issue.

We just send out to a prototyping service to have our boards etched, because we need real plated-through-hole stuff and sometimes 4 layers. That gets round the limits of the DIY transfer processes nicely

Having stuff made isn't as bad as you think, there are places in China that will do 100 square inches of double sided PTH board for about $160 including shipping. If your board is 5 square inches, they will make 20. If you do a board for a popular circuit, you can probably make the $160 back by selling off the extra boards you don't need.

I can solder those fine pitch SMTs by hand, the secret is just to have a few strong drinks to steady the nerves, tack the corner pins in place, then goop the solder on to all the other ones, and finally remove the inevitable solder bridges with de-soldering wick. Then have some more drinks to celebrate The biggest one I ever did had 128 pins on the 0.025" pitch It took a good half hour and I nearly destroyed the board, though.

[rockinrendell]

surface mount components are designed to work with SOLDER PASTE. i used to operate a surface mounting machine where i used to work last year. the pieces are very,very small. and to solder them properly you need hot air soldering equipment. the heat from an iron can kill the components. in mfg, the paste is flowed by traveling through an oven and then a cool down. they have to be inspected before the oven and after and sometimes repaired. i dont believe in my opinion they are good for home hobby use. they are for making boards small sized. unless you have real sharp eyesight and magnifying lens with light. you cant tell the marking on the pieces themselves, once removed from the spools they come on.