I am curious, why are the ceramic BGA solder balls not eutectic and made with the 90/10 Pb/Sn solder? [log in to unmask] on 09/14/98 11:30:26 AM Please respond to [log in to unmask]; Please respond to [log in to unmask] To: [log in to unmask] cc: (bcc: Ed Holton/Hella North America Inc.) Subject: Re: [TN] X-ray for open joints on BGA's ? Hi Daan, Two comments come to mind: 1) Remember that not all BGA solder balls are eutectic (and therefore collapse during reflow). CBGA devices typically use 90/10 Pb/Sn solder which don't melt during reflow. Opens are much more common with these. 2) I've had some experiences with some large PBGA devices having opens around the periphery during rework, but generally with packages which showed a marked tendency to "potato chip". This was much more noticeable when solder paste wasn't used (some folks just use a tacky flux). Personally, I never found much use for X-ray on BGA devices in a production mode. Develop the process (which may or may not entail the use of X-ray) and control the critical parameters, and you'll find the instances of BGA solder joint defects is extremely low. Best regards, Greg Bartlett Teledyne Electronic Technologies Hudson, NH [log in to unmask] ------------------------- Hello Technet, I remember a discussion a couple of weeks ago about X-ray inspection. It was stated that the nr.1 defect that one wishes to see with a X-ray machine is open joints, but unluckily this type of defect can only be seen with the most expensive X-ray machines on the market. I was thinking : if the BGA (the balls) collapses during soldering and is soldered perfectly parallel to the board surface, all the balls must have reflowed ! If only one of the balls didn't melt, the component can not be soldered parallel to the board surface ! Since the chance that a collapsed ball forms a joint with the pad is almost 100 % , it can be concluded that X-ray inspection for "opens" does not make much sense. Just looking at the parallellity should tell you enough !! What do you think, is this a reasonable thought or am I overlooking some things ?? Regards, Daan Terstegge Signaal Communications * Unclassified * ################################################################ 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 ################################################################