Louis, Here is my 2 cents. Popconing is caused by the evaporation of moisture inside the Plastic mold compound, die attach paste (and BT substrate for BGA package). By baking the PEMs (at 100-125C, 8-24 hrs) to dry out the moisture from the plastic material, there wouldn't be any popconning. For the internal delamination, die top delamination parts should be rejected. If the delamination is between the die and the Leadframe (Substrate in the case of BGAs), 10% should be tolerable. Pls note that the delamination between die and the Leadframe/substrate will reduce the thermal dissipation capability on the PEMs. Hope this help. TL -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Louis, Edwin @ CSE Sent: Thursday, July 12, 2001 6:30 AM To: [log in to unmask] Subject: [TN] PEMs If one receives PEMs from the manufacturer which are supposedly dry and handled correctly but are found to have internal delamination by acoustic spectroscopy, whether this is an automatic sentence of popcorning when the devices are put through convection reflow. Is there air inside the part that can cause popcorning of a dry part when no outward signs of delamination or popcorning is visible.Also, ---------------------------------------------------------------------------- ----- 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 To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL 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 ---------------------------------------------------------------------------- ----- --------------------------------------------------------------------------------- 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 To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL 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 ---------------------------------------------------------------------------------