In IPC website there is a search tab. It might help you Ramon -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson Sent: Thursday, October 12, 2006 4:03 PM To: [log in to unmask] Subject: Re: [TN] Compression Limit on FR4? I don't know. That's why I wondered if there was any kind of industry consensus on the subject. Jack On 10/12/06, Ian Hanna <[log in to unmask]> wrote: > > 'damage' occurs as soon as you assemble the board... > > how much 'damage' is acceptable to your application? > > > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson > Sent: Thursday, October 12, 2006 3:53 PM > To: [log in to unmask] > Subject: Re: [TN] Compression Limit on FR4? > > Thank you for responding. > > The problem is, someone is asking me about the MAXIMUM before damage > occurs, so I am quite interested in your statement that it "tends to > deform the fiberglass over time". > > Where can I learn more about that? > Does any IPC document even mention it? > I wish there was such a thing as an "IPC index"... any IPC people > listening? > > thanks again, though > Jack > > > On 10/12/06, Stadem, Richard D. <[log in to unmask]> wrote: > > > > Hi, Jack > > I can tell you that typically the torque setting used for hardware > > on pwb assemblies is between 1 to 6 in/lbs. More than that tends to > deform > > the fiberglass over time. Of course, it all depends on the type of > board > > material, layer count, etc. > > It also depends on the application. > > Realize that a lot of relaxation occurs during any type of thermal > > excursion, and the hardware will loosen up. It is always a good idea > to > > use a Bellville washer in conjunction with a serrated or star washer > to > > continue to hold the torque. It is also a good idea to use Glyptol > > or some other threadlocker. > > > > -----Original Message----- > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson > > Sent: Thursday, October 12, 2006 1:54 PM > > To: [log in to unmask] > > Subject: [TN] Compression Limit on FR4? > > > > Does anyone know of any guidelines or recommendations that suggest a > > maximum limit on compressing board material? > > > > Can any damage occur by over-torque'n screws, for example? > > > > I've never heard anyone discuss that... > > > > Jack > --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 1.8e 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 -----------------------------------------------------