Leland, forgot to tell you that not all resistor chips are for uwave applications. there ARE chips intended for mounting with resistor print against the board, e.g. http://www.caddock.com/Online_catalog/Mrktg_Lit/TypeCHR.pdf Inge ----- Original Message ----- From: "Inge" <[log in to unmask]> To: "TechNet E-Mail Forum" <[log in to unmask]>; "Leland Woodall" <[log in to unmask]> Sent: Thursday, July 31, 2008 3:28 PM Subject: Re: [TN] Repair Need for Inverted Chip Resistors > There are two or three reasons not to turn them up and down (if you are a > microwave guy >1 GHz ): > > 1. The L-cut laser trim groove may be filled by active substances from the > flux. (no glass or paint overprint) > 2. We have done simulations which show that your insertion and return loss > may be disadvantageous. > 3. None of our suppliers have demonstrated anything else than print side > up. > > E.g. Anaren, one of our good sources > > http://www.anaren.com/content/File/AnarenCeramicsDesignGuide.pdf > > Inge > > > ----- Original Message ----- > From: "Leland Woodall" <[log in to unmask]> > To: <[log in to unmask]> > Sent: Thursday, July 31, 2008 12:11 PM > Subject: Re: [TN] Repair Need for Inverted Chip Resistors > > > Dewey and others, > > I've been told the concern lies with the resistive element being on top > of the component. With it being mounted upside down, the hottest > portion of the part when under power is in direct contact with the > board. Would this lead to shortened life or cause any type of a > premature failure? > > Are we being over-cautious about this, or is there some truth to what > I'm being told? > > Leland > > -----Original Message----- > From: Whittaker, Dewey (EHCOE) [mailto:[log in to unmask]] > Sent: Thursday, July 31, 2008 2:00 PM > To: TechNet E-Mail Forum; Leland Woodall > Subject: RE: [TN] Repair Need for Inverted Chip Resistors > > I'll try to be discreet. If there is no functional impact, then a "let > the chips fall where they may" approach is acceptable. If the part > markings are not visible or the vision recognition algorithm of an AOI > machine is impaired, then they may be a problem. > Dewey > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Leland Woodall > Sent: Thursday, July 31, 2008 10:12 AM > To: [log in to unmask] > Subject: [TN] Repair Need for Inverted Chip Resistors > > TechPros, > > Can anyone tell me if there's a reliability concern with allowing chip > resistors to be mounted upside down? Our current policy requires that > we repair these, and I feel that to be unnecessary. > > IPC-A-610D shows this to be an acceptable condition on all classes of > product, and our customer has no specific contractual requirement. > > I'd like to try to change this policy at our facility, and welcome any > commentary you might have on the subject. > > Thanks in advance for your help, > > Leland Woodall > > --------------------------------------------------- > 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 -----------------------------------------------------