Hello All, I recommend to check the forces balance between the PCB side solder joint to the BGA/CGA side. Differences in the forces can cause cracks at the weak side. So, rectangular pad in one side and round pad at other side should be design carefully. Best Regards Reuven ROKAH e mail: [log in to unmask] John Burke <jburke@OPTICHRON .COM> To Sent by: TechNet [log in to unmask] <[log in to unmask]> cc Subject 24/04/2006 19:32 Re: [TN] BGA and CGA pad questions. Please respond to TechNet E-Mail Forum <[log in to unmask]> ; Please respond to John Burke <jburke@OPTICHRON .COM> Now Joe, if you really wanted me to think like a lawyer I would argue as follows: Example 1 Mask at pad periphery Not normal since boards need a clearance on the mask to avoid mask on the pads. Example 2 Mask opened up to give a tolerance to the pad Which is normal, and will give a smaller or larger "keyhole effect" depending on the clearance to the pad. The above example has been in existence for ever, and if they ever go get the Ark from up on mount Ararat, they will probably find this mask clearance in the boards on the GPS system............8-) So maybe we are not talking pad design at all here, maybe we are talking solder mask window opening. John John Burke Senior Manager - Operations , Optichron [log in to unmask] W: 510 249 5233 M: 408 515 4992 http://www.optichron.com Profile: https://www.linkedin.com/e/fps/2665502/ -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Fjelstad Sent: Monday, April 24, 2006 9:09 AM To: [log in to unmask] Subject: Re: [TN] BGA and CGA pad questions. In a message dated 4/24/2006 9:00:04 AM Pacific Daylight Time, [log in to unmask] writes: Very interesting. Does that mean that patent cover the solder mask open window and trace width?. If you simply change nothing on your design, but open up a slot in the solder mask on the trace side of the pad you will get a "keyhole" effect in the final soldered joint automatically. John John Burke Senior Manager - Operations , Optichron [log in to unmask] W: 510 249 5233 M: 408 515 4992 http://www.optichron.com Profile: https://www.linkedin.com/e/fps/2665502/ Hi John, Thinking like a lawyer are you?... RoHS is having that effect on a lot of good engineers lately... ;-) Actually I would argue that you are probably right but would need to make certain by reading the claims which could as a counter point might have a claim to equivalence, something which could possibly be construed from a well crafted claim. Therein lies the art... Best, Joe --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------