Dear Engelmaier, Thank for your help. I think perfect fillet shows good wetting, and our product is communication equipment, and I am not sure that which is inportant between wetting and fill ratio. Can you give any more advice? Best regards Liu Changkang ----- Original Message ----- From: "Werner Engelmaier" <[log in to unmask]> To: <[log in to unmask]> Sent: Wednesday, November 01, 2000 12:55 AM Subject: Re: [TN] Through-hole Solder Joint inspection and quality criteria > In a message dated 10/31/0 4:12:07, [log in to unmask] writes: > > One partly poor wetting component after wave soldering, through-hole > >solder joint shows good wetting near top side PCB, but show bad wetting > >on the bottom side and through-hole is about 70% filled. some suggest good > >wetting is key to evaluate a SJ reliability. IPC suggest 75% filled is > >OK, which one I choose? > >Same situation happen to paste in hole process, Which type SJ is ok? > >the key is the fill ratio or the good wetting? > >If half of through hole SJ is good wetting, half of which is bad, Is it ok? > > Hi Liu, > Good wetting is by far the more important physical aspect--however, an > incomplete fill may be a sign of wetting problems. Further, if you have > "partly poor wetting", how do you know the rest is "good wetting"? > If you have good wetting, a partial hole fill is only important in a severe > use environment, e.g. automotive, because of the stress concentration on the > PTH barrel at the solder/no-solder interface. > > Werner Engelmaier > Engelmaier Associates, L.C. > Electronic Packaging, Interconnection and Reliability Consulting > 7 Jasmine Run > Ormond Beach, FL 32174 USA > Phone: 904-437-8747, Fax: 904-437-8737 > E-mail: [log in to unmask], Website: www.engelmaier.com > > --------------------------------------------------------------------------------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 > ---------------------------------------------------------------------------------