Ryan, Solder paste vendors has a rule that says: At least 5 balls must fit inside stencil apertures to have a good solder paste release. ( good "brick" ) <<...>> Based on that rule they recomend type 4 for ultra fine pitch, very probably they conducted a laboratory experiments to achieve this conclusion. Thanks Jorge Dourado de Santana Maintenance / Process Engr Microtec - Brazil > -----Original Message----- > From: Ryan Jennens [SMTP:[log in to unmask]] > Sent: 14 de Maio de 1999 18:21 > To: [log in to unmask] > Subject: [TN] FW: [TN] FW: Fine Powder Solder Paste > > -----Original Message----- > From: Ryan Jennens [mailto:[log in to unmask]] > Sent: Friday, May 14, 1999 5:21 PM > To: [log in to unmask] > Subject: RE: [TN] FW: Fine Powder Solder Paste > > > Thanks, all, for the responses. I was wondering if the type 4 paste would > have value at pitches below 20 mil, say around 12 or 16. If all I will > get > is more oxidation and worse release, does it offer any other advantages > besides sharper corners and straighter sides on its deposits? > > -Ryan Jennens > TelGen Corporation > > -----Original Message----- > From: [log in to unmask] [mailto:[log in to unmask]] > Sent: Friday, May 14, 1999 4:15 PM > To: [log in to unmask]; [log in to unmask] > Subject: RE: [TN] FW: Fine Powder Solder Paste > > > Hey Ryan, > > As far as 20 mil printing is concerned I would say type 3 i.e (-325/+500) > should be ok. If you go for type 4 ( i.e -400/+500 ) it has some issues > like > the particle size getting smaller will increase the surface area exposed > to > oxidation affecting the soldering quality. Also it would be expensive than > type 3. > If you are laready printing 20 mils with type 3, why you want to switch to > trype 4? > As far as more mass is concerned the volume of the paste will remain same > irrespective of particle size. > > Thanks.. > Ashok > SMT Engineer > Solectron Corp. > Milpitas > > > ---------- > > From: Ryan Jennens[SMTP:[log in to unmask]] > > Reply To: TechNet E-Mail Forum.;Ryan Jennens > > Sent: Friday, May 14, 1999 11:11 AM > > To: [log in to unmask] > > Subject: [TN] FW: Fine Powder Solder Paste > > > > > > > > -----Original Message----- > > From: Ryan Jennens [mailto:[log in to unmask]] > > Sent: Thursday, May 13, 1999 11:51 AM > > To: TechNet > > Subject: Fine Powder Solder Paste > > > > > > What stencil design guidelines differ when one decides to go with > > > > a -400/+500 particle size solder paste? The paste companies tout > > that the > > > > finer particle paste offers print improvements below 20 mil pitch. > > But I > > > > believe one would have to reduce the aperture sizes all around > > because more > > > > metal would be deposited in each one. Is this accurate? How much > > reduction > > > > is needed. Is home-plating the apertures even more important? I > > could not > > > > find this topic in the archives. We are considering switching for > > our > > > > finer-pitch boards, as their pitch decreases, if it really offers > an > > > > advantage. However, we have been printing 20-mil for a long time > > > > with -325/+500 paste for quite a while. > > > > -Ryan Jennens > > > > TelGen Corporation > > > > > > ################################################################ > TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c > ################################################################ > To subscribe/unsubscribe, send a message to [log in to unmask] with > following text in the body: > To subscribe: SUBSCRIBE TechNet <your full name> > To unsubscribe: SIGNOFF TechNet > ################################################################ > Please visit IPC's web site (http://www.ipc.org) "On-Line Services" > section for additional information. > For technical support contact Hugo Scaramuzza at [log in to unmask] or > 847-509-9700 ext.312 > ################################################################ ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################