Hello, The acceptance criteria would very much depend on respective company. Usually, I would not accept any lead that overhang its solder pad by more than 25% of its width. Just my contribution. Regards, Wee Mei ----- Original Message ----- From: "Steve Kelly" <[log in to unmask]> To: <[log in to unmask]> Sent: Wednesday, October 31, 2007 5:54 AM Subject: Re: [TN] Samtec SMT Connector Woe's...(again) > Hi Steve, > We build with these connectors daily. 1) Richard's remarks are correct - the > post hole is better to be loose than tight because the positional tolerance > stack of this connector is OK at best- we have learned from experience to > make the hole bigger or spec the connector without this feature 2) we do > from time to time get in connectors with the leads at an angle - we reject > them 3) the question you need to ask is whether the solder joint can handle > mating and unmating - it takes a lot of force to unmate these connectors and > how often will it be done. Good luck. Steve Kelly > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. > Sent: October-30-07 5:03 PM > To: [log in to unmask] > Subject: Re: [TN] Samtec SMT Connector Woe's...(again) > > Steve, I think your problem probably lies in two different print notes, > both of which state the same thing, "2 deg. maximum sway". One of these > is for the pins themselves, the other is for the positioning posts. If > the posts allow a small amount of "whole-connector-body" mispositioning, > and the pins themselves can move 2 degrees, you can end up with a > cumulative worst-case scenario that looks like what I am seeing in the > previous pictures, the result of the stackup tolerance after soldering. > One cannot help but believe that this is due in part to having to place > these manually and push them firmly down to the board. > > The question that is in the back of my mind is whether there is enough > mounting hole slop to allow the connectors (as well as the connector > pins) to pull themselves into alignment during solder reflow. If they > are pressed down such that the loose pins are firmly being held down > (out of alignment with the pads) by the tension of the small mounting > holes on each end of the connector, there is no way they can float > freely into alignment somewhere near the centers of the pads during > reflow. > > I also note that every other pin is off the pad and off in the same > direction. Is this always the case? > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory > Sent: Tuesday, October 30, 2007 2:52 PM > To: [log in to unmask] > Subject: [TN] Samtec SMT Connector Woe's...(again) > > Hi All, > > I'm running into a problem with some Samtec connectors again, and maybe > you all can guide me on how I should handle this... > > First here's a picture of the connector: > > http://stevezeva.homestead.com/files/Samtec_Connector.jpg > > Next, here's a picture of the problem: > > http://stevezeva.homestead.com/files/Samtec_Solder_Joints.jpg > > QA is calling these solder joints as rejectable. These leads aren't > gull-wing leads. I view them as some sort of mutated butt joint leads > (sort of). I don't know what you would call them really, so I'm not > quite sure what inspection criteria you would use. As you can see, the > toe of every other lead doesn't sit 100% over the pad, and it continues > like that through-out the length of the connector. I see that as a > connector manufacturing issue, not something we have any control over. > > Here's a picture of the bottomside of the connector so that you can see > what the bottom construction of the connector looks like: > > http://stevezeva.homestead.com/files/Samtec_Bottom.jpg > > In the top of the picture you see what Samtec calls a locking tab, one > at each end of the connector. It has barbs that dig into the PCB and you > have to force them into the holes. Obviously, we're hand placing them. > What's funny is that they come in tape and reel and the have a pick and > place pad on them! I don't know of any pick and place machine that has > enough force to place these connectors and push the locking tabs into > the holes so that the leads sit flush on the pads. I've also posted > Samtec's drawing of the connector: > > http://stevezeva.homestead.com/files/SAMTEC_ROLC.pdf > > My gut feel is that the solder joints are acceptable. If the toe of > these leads are tweeked a little, there's still a good percentage of the > lead over top of the pads in which to form a decent solder joint because > of the way the connector and leads are constructed. > > What say you all? > > Thanks! > > Steve Gregory > > P.S. I HATE Samtec connectors!!!!! > > > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 To > unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or > (re-start) delivery of Technet send e-mail to [log in to unmask]: SET > Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the > posts: send e-mail to [log in to unmask]: SET Technet Digest Search the > archives of previous posts at: http://listserv.ipc.org/archives Please > visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for > additional information, or contact Keach Sasamori at [log in to unmask] or > 847-615-7100 ext.2815 > ----------------------------------------------------- > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt or (re-start) delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 > for additional information, or contact Keach Sasamori at [log in to unmask] or > 847-615-7100 ext.2815 > ----------------------------------------------------- > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 > ----------------------------------------------------- > --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------