Pls help me to solve this issue

We use undefilll for two BGA in one product ,the epoxy is Loctite LPD 3513 and the curing condition is 115C , 15 minutes , the BGA' s package is below .

     U3 information :  Body size, 9*9mm ; height 1.7 ; bump diameter 0.3 ; pitch, 0.8*0.8 ;bump array 10*10
     U1 information :  Body size, 12*12 ; heigh t1.7 ; bump diameter 0.3 ; pitch, 0.8*0.8 ; bump array 14*14

Before the underfilll we check the electric function .All are good ones .But after curing , some phone failed because "can not power on ", and some failed for "check SIM card ", the defect sample is closed to 3%. I think "check card "issue" may caused by the underfill material emission which cover the SIM card lead .

But I can not get any idea for further.

Thanks
Tony