It looks like delamination at an area below a ground plane. There may be area's that look "white" in the clearances. Dropping alcohol over area may make it easier to see in the clearance area. You can also try a sonoscan of the board and look for declamation. Rene -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Constantino J. Gonzalez Sent: Friday, October 28, 2005 2:50 PM To: [log in to unmask] Subject: [IPC-600-6012] Dent Hello does anybody has a clue what this can be if it is not a blister? Please read below and see attachments Attached is the best photo I can get. Fr top it sinking down, fr bottom it's budging up. We see this right after reflow on random location. It is not blister, the cross section photo does not show that. Only abnormalities is difference in Cu thickness ( slight thinner on dent area). Any clue?? Hello Constantino, How are you ?? I need your advise on recent issue I'm facing in our line. It pretty new for me .. I hv this PCA which produce "dent mark" during rework. This dent appeared after performing rework to remove the SRAM (the location that you see dent) with hot air blower, the temp is set to 350 deg C, blow time is around 15 seconds (dent will be created - in shape of circle about 10mils diameter ), effective temperature on the comp is 290 deg C. Every single board which we rework produce this condition. It's not d/c related as we see similar condition on other d/c as well. More then one d/c and more one location. We try to simulate the hot air rework on raw card and the dent appears too. Today line found 2 more boards with dent after going through IR reflow only ( no rework involved ). The PCB supplier perform cross section on the dent location, there is no abnormalities seen expect for a difference in the copper thickness before and after the dent. I hv attached the cross section photo.. I can not get a snap shot of the dent due to glossy appearance and light reflection. I can not figure out the root cause.. 1) What actually caused this dent ?? Mechanical or thermal 2) Thermal should expand not contract !! 3) Why the dent appear only after reflow / rework ?? Even the PCB suppliers cracking their head. This board is not failing ICT/ FVT however it not as simple as cosmetic defect !!! I really hope to hear fr you.