SMD to Thru-hole Converters

Jim McCorison

I think I've found the op amps I'm looking for, but they're only available in an SMD package. Prototyping with that would be a bear. While poking around the web I stumbled across these www.bitscope.net/store/?p=view&i=item+6 which allows you to use an smd op amp for breadboarding. The downside is that they're in Australia and I'll have to spend at least twice as much as the product costs in shipping plus wait a minimum of 2-4 weeks.

Has anybody encountered anything like this in the US?

Thanks,
Jim

Paul Baker

digikey has adapters, whats the package for the op-amp? I am confused about your link, which contains digital oscilloscope logic analyzers on them, how is this pertainent to prototyping surface mount devices?

Jim McCorison

Their web store is a bit bonkers I think. It seems to keep a cookie of what you viewed, so when I click on the link I get it, but if I close everything, reopen, click on the link, I get the top page... but not every time. Sometimes I get what the link is supposed to point to. Oh well.

From www.bitscope.net/store/ look down to "PICuP Modules, PODs and PCBs" and click the link, then at the bottom you'll find "OP-AMP CONVERTOR PCB (6 PACK)"

I guess I need to get a paper catalog from Digikey and just read it through. So much has change since I last was looking at this kind of stuff.

The op amp is the Linear LT1990 and is an S8 package.

Jim

Jim McCorison

Ok, to answer my own post... With Paul's pointer to Digikey (why didn't I think of that?) I came upon Capital Advanced Technologies www.capitaladvanced.com/ which makes just what I'm looking for.

Now all I have to do is learn how to solder smd devices.

Jim

Paul Baker

what soldering iron are you using? Doing SMT you should have a temperature controlled iron with a very small tip (smt devices are more sensitive to temperature, and a smaller tip for obvious reasons)

Jim McCorison

I'm going to have to buy a new one for this. I know my weller soldering gun won't be appropriate! My fine work iron is a Weller WM120 (12w), and while it's great for the detailed stuff I used to do, it isn't temp controlled or a fine enough tip. I gather from a prior post that you use a Xytronic. Would the Auto-temp 379 be adequate as a starting unit, or would you recommend something different?

Jim

Paul Baker

yes it would be a good iron, the major difference between that and mine is there is no temp display, also I cannot determine if the temperature setting is measured in temperature tip or wattage, most smt parts list max temp at pin, I don't know how difficult it would be to convert between the two.

I suggest emailing them to answer which it is, they have a very helpful staff and have always promptly resonded to any inquiries I make. You can use the online contact form or you can email directly to the guy who answers most of my questions, Shane Eustice (s\h/a\n/e@/h\o/w\a/r\d/e\l/e\c/t\r/o\n/i\c/s.c/o\m, remove all "/" and "\" from the addresses, I did this to keep any email sniffers from snagging his address and spamming him) If you email him, mention I sent you, Im very happy using them and would like to drum up additional business for them.

I use the 1.6mm mini-wave soldering tip as I mentioned in the post you refered to. It is compatable with the 379 as well. The XYB03, 04, or 23 tips should work for smt as well.

When I solder, I put a touch of no-clean flux (Kester, I can't remember the part #) on the joint, melt a bead of low-temperature solder so that 1/2 to 2/3 of the flat surface of the tip is covered, slowly lower the tip to the joint without touching to melt/burn the flux, touch the ball to the pin then slide it to the pad. Depending on the surface, sometimes the sliding motion needs to be repeated, and sometimes pad to pin works better. The key is to not keep the iron touching the pin for more than a second or two though some smt parts require heating a bit longer, the doc for the part will give you guidance on what the maximum temp and time at that temp should be, if you dont get the bond your looking for let the part cool for a few seconds then repeat the heating up motion.

If you use low temperature solder, you may notice the joint frost, especially if you have more solder on the joint. This caused considerable consternation for me when I first started using the low temperature solder, because I was always taught that a frosted joint = a bad joint. But after some considerable testing via a multimeter and experimentation with varying temperatures (which didn't effect the frosting), I detemined this is a natural characteristic of the solder. And after a little research I determined this frosting is not the same as the frosting warned about in soldering technique booklets.

Paul

PS. When dealing with smt the part can slip when soldering the first one or two joints, I have a set of wax carving picks that I use to gently hold the part in place while soldering, I got them from allelectronics for under $10, but any thin metal object will do. Also when doing a chip its best to start with one corner then solder the opposite corner, this will freeze the part in place and prevent slipping for the remainder of the joints.

Post Edited (Paul Baker) : 1/14/2005 6:17:36 PM GMT

Paul Baker

I just noticed they have a used version of my soldering iron at http://www.howardelectronics.com/used.html·for $70, it was used a a trade show and in like-new condition, they have a 136ESD for $45 also used at a tradeshow, you have to order these over the phone.

Jim McCorison

Well, they don't have it any more. I just bought it. Thanks for the hot tip. (couldn't resist that)

When I called, Shane answered the phone. He thanks you for the added business. I also ordered the wave soldering tip and the flux, so aside from the solder I should be good to go.

Thanks for your advice on this.

Jim

Paul Baker

which one did you get the 136 or 137?

Jim McCorison

I got the 137. I figured the turn the dial and read the temp feature was worth it. And with a $30 savings it made the decision easy.