In a message dated 4/10/99 5:39:43 PM Pacific Daylight Time, [log in to unmask] writes: > Hi Technetters, > > I would like to post the question to the members, is toothpick test to > check on the unsolder connection of QFP lead, cause reliability issue ? > > Poh Hi Poh! Well, I'd much rather see someone use a toothpick to check whether or not a lead is soldered than a stainless steel dental pick (which I've witnessed a time or two... I shudder to even think about it!) There's probes called "orange sticks" that are made from wood that are used for that purpose and if one realizes that it doesn't take much force at all to stress the joint enough to create a fracture, there shouldn't be much concern for a reliabilty issue. There have been times myself that by just looking at a joint it appears to be fine, but with just a little pressure it is apparent that (for whatever reason) the metalurgical bond isn't there...the foot moves. If you are seeing that problem you really need to go back into the process to find out why, because there definately IS a problem. I recall the times I've experienced the problem it has been during wave solder that it was happening. The joints were fine out of reflow during surface mount, but re-reflowed during wave because there were vias very close to the pads connected by a very short trace. Heat transfer during wave caused the joints to re-reflow at the interface between the bottom of the foot and the top of the pad, and the fillets would stay attached to the leads. It was very difficult to see that visually. You would easily notice the problem when a slight bit of pressure was applied to the lead and it moved. Have your ladies doing this instead of the guys, they tend to have more of a "delicate touch" that won't damage things when checking them....(GRIN) -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 ################################################################