Grunde, Russ and Greg were weighing their boards so, yes, they do need to be using the 90% by weight figure not 50% volume figure. Bev RIM -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Grunde Gjertsen Sent: Tuesday, May 20, 2008 1:15 PM To: [log in to unmask] Subject: Re: [TN] Average paste volume estimate 90% is by weight so you can't use that figure, by volume it's approximately 50% for most solder pastes. You'll only need approxiations for this purpose anyway so to use the aperture area (including reduction) x stencil thickness divided by 2 will give you a useful figure for solder volume. Grunde "Nowland, Russell Howard (Russell)" <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 20.05.2008 18:40 Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to "Nowland, Russell Howard (Russell)" <[log in to unmask]> To [log in to unmask] cc Subject Re: [TN] Average paste volume estimate Well, We did a study many years ago and I need Greg Munie see if he remember the results. We actually did it on a PCA basis where we weight the bare PWB, PWB with paste and post reflow. We were trying to determine from that the volume of tin/lead. You can take the area times the stencil thickness plus one mil (if you are using metal squeegee blades). That will give you the average paste volume. Then you will have to look at the percent of metals in your paste. The % metals for the Indium SMQ92J is 90.25% but will vary from paste to paste. Then if you can identify the weight of Sn/Pb you can at least ballpark the number of grams per PCA. Perhaps Greg has more specific info. He is part of the TechNet but I sent it directly to him also. Good luck Russell Nowland Alcatel-Lucent Advanced Manufacturing Engineer Address: 14000 Quail Spring Parkway, Suite 300 Oklahoma City, OK 73134 email: [log in to unmask] Desk: 405-302-1660 Cell: 405-203-0034 Fax: 405-302-1622 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian Sent: Tuesday, May 20, 2008 11:23 AM To: [log in to unmask] Subject: Re: [TN] Average paste volume estimate It depends. The smaller the aperture, the less paste left on the board. The thicker the stencil the less paste left on the board. And then you have your aperture ratio that combines the two. And then there is which specific paste you are talking about. Etc., etc. I would say to be safe - between 0 and 100%. But I think we can say it is usually between 30 and 90%. I am a lab rat, so process engineers may be able to refine this a bit. Bev RIM -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Dan Mathews Sent: Tuesday, May 20, 2008 12:10 PM To: [log in to unmask] Subject: [TN] Average paste volume estimate Does anyone have an easy way to estimate how much paste is applied to a smt pcb? I understand it varies on squeegee pressure, stencil thickness, and pitch of the components but I was looking for an average. I would assume that somewhere out there someone can estimate that "2 grams of paste is used on a 2" x 2" smt pcb". I will then use this information to determine how much lead is used on non-RoHS products due to solder paste issues and not non-compliant components. Thank You in Advance, Dan Dan Mathews C.I.D.+ Engineering Support Supervisor B&B Electronics Ottawa, IL USA 61350 Phone: 815-433-5100 ext 217 Fax: 815-434-8831 (direct to my desk) URL: http://www.bb-elec.com <http://www.bb-elec.com/> --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------------------------- This transmission (including any attachments) may contain confidential information, privileged material (including material protected by the solicitor-client or other applicable privileges), or constitute non-public information. 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