Good Day Ya'll! We just got a new customer here last week and built two 10-board proto kits for them. Those boards are a type of power supply, and we're going to be doing another board that they call a 4-port RS-232 + 48 digital I/O PC/104 Module. All 3 assemblies are roughly 3.5" square and are mixed technology. There's another thing common between all three assemblies besides their size, what they call dual-mount headers. Each board has two of these, one is a 64-pin (2X32 pins), and the other is a 40-pin (2X20 pins). These are basically real long gold plated headers with plastic female type receptacles at one end. They're installed with the header pins going THROUGH the board and soldered. The header pins stick out the backside of the board 10mm, and you have your female sockets on the topside, so now what you have is a stackable type of board connection system. Cool connection system, BUT, there's a big problem with soldering these dad- blamed things! You can't wave solder them because: 1.) They're gold plated, no solder on the contact area (solder fillet must stay below .100" as measured up the pin from the surface of the PCB). 2.) Even if the gold plating wasn't an issue, they stick out 10mm on the bottom...you'd need a wave that shoots up and looks like "Old Faithful" to reach the bottom of the board! "So hand solder em' ya big weenie!" some of you may be muttering under your breath now. Well there's a problem there too. The way these two connectors are laid-out on the boards couldn't be any worse, they're parallel right next to each other, spaced .100" apart. We've got 4-rows of 10mm long gold plated pins, .100" apart, that we've got to solder and not get any solder on the gold plating...just peachy huh? My senior rework lady Trang, got us through the two proto kits of 20-boards. She somehow was able to thread her soldering iron down thru the pins and solder the connectors in without so much as a pimple of solder on the pins (She simply amazes me sometimes! Goes to show what clean livin' and no caffeine can do for ya!) But we simply can't do that in production, it'll take forever, and I don't wanna burn Trang out, she's the only one steady enough to do it. So I called around to get quotes on some preforms. I've seen daisy-chained donut preforms that you can use for headers and what have you that has the same kind of footprint. I've used preforms before, but the kind for edge clips for little SIP modules, not for PTH. So I called Indium, AlphaMetals, Bow Solders, and Kester...they all make preforms. Everybody has quoted me, but Kester told me that they think I may still may have a problem. They said that from their experience, I'm going to have difficulty obtaining consistent solder joints using preforms. They said that unless I can ensure very consistent heating between all the pins, that I'll probably wind-up with some joints being insufficient because the solder will tend to wick to the hottest pin. I was planning on using a heat gun to provide the heat, and maybe even going so far as to make a nozzle that will enclose all the pins. But I can't put it in a reflow oven unless I want to hand solder eight 10-pin SIP RPACKS, and a 2-pin metal canned crystal afterwards...I still need to look and see if the plastic on the headers can take the heat anyway. So after reading this journal, my question is (boy, I sure take the scenic route sometimes don't I?); have any of you had any experience with the kind of preforms I'm thinking of using? Is what Kester saying true? 'Preciate any info at all!! -Steve Gregory- ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################