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Title: Question: Why are IC pins always splayed - need bending? Post by: K1JJ on January 13, 2009, 09:57:49 PM One of those things that makes me say, "hmmmmm."
I just built up a PC board for a telescope project. As usual, all the 14 pin dip IC pins needed to be bent inwards to fit into the sockets. Most needed quite a bit of bending to fit. I've seen this go on for decades across most all chip lines. Why is this so? Is it the way manufacturers can tell if a chip has been used? But why put technicians through such a hassle - what's the deal? I'll bet there are pin straighteners, but I still use my fingers... sigh. I did a Google and see no answers. Tom, K1JJ Title: Re: Question: Why are IC pins always splayed - need bending? Post by: WB2YGF on January 13, 2009, 10:29:04 PM I have an insertion tool that came in one of those computer tool kits (similar to the one in the link but mine is metal) so its a "known issue".
http://cableorganizer.com/outlet/NQP-TMS-1110.html?section=5&catname=Installation+Tools+%5D+Miscellaneous+Tools&src=froogle&CAWELAID=261925642 Perhaps its to help the auto insertion machine. The spring loaded pressure might help to stabilize the positioning of the IC in whatever does the inserting. Title: Re: Question: Why are IC pins always splayed - need bending? Post by: KF1Z on January 13, 2009, 10:52:16 PM Yup,
Not just for auto-insertion, but hand tools as well.... It ensures the pins are aligned properly, due to the tool's straight edge when it sqeezes them together.. Easier to push them together, rather than to pull them apart. Title: Re: Question: Why are IC pins always splayed - need bending? Post by: K1JJ on January 13, 2009, 10:54:44 PM That makes a lot of sense, guys. And the price is right for the tool...
Yes, I can see now that an automated (or hand) machine would want to compress the pins inward to maintain pin placement tolerance. Now if I worked in industry, I would know that... :-) TNX. T Title: Re: Question: Why are IC pins always splayed - need bending? Post by: w1vtp on January 14, 2009, 10:24:30 AM I just lay those chips sideways on the static mat and grabbing the plastic body bend them in all at the same time. I then flip the IC and repeat the process. Been doing that for decades. I think I have an insertion / straightener tool somewhere but never used it
Al Title: Re: Question: Why are IC pins always splayed - need bending? Post by: KE6DF on January 14, 2009, 10:33:28 AM Yes, I can see now that an automated (or hand) machine would want to compress the pins inward to maintain pin placement tolerance. Now if I worked in industry, I would know that... :-) TNX. T Well I did work in that industry, and you are right. By starting with them splayed out a little the automatic insertion machines can adjust them to the right spacing by pressiing inward -- in only one direction. Title: Re: Question: Why are IC pins always splayed - need bending? Post by: Todd, KA1KAQ on January 14, 2009, 10:35:02 AM That's probably the best way to do it for onesies-twosies, would become a pita fast with any number of pieces. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Back in the early 90s I worked for a small company called Certified Software/Spuren Systems as a technician building the prototype and later production models of a D/A converter to be used between a PC and paper recorders for seismology work. We also built the first digital throttle for model railroads but never got it to production. The biggest issue with the chips is that the legs come from the factory with a less-than-90 degree straight bend, which means they're trying to reach out and away from the body. I think this is meant to keep some spring tension on them for contact purposes, not sure. Anyway, most sockets allow for this but placement is important. Can't remember how many I bent in haste. Tubes are so much easier.... ;) |