1、Purpose To improve NSOP in 8.5sq & 5.5sq mass production. To improve the problem that capillary mark out of B.P.O in reverse bonding.BackgroundNSOP has being taking a high rate even top2 or top 3 for a long time in our 8.5sq & 5.5sq mass production Capillary mark on 2nd bond pt is always out of the

2、BSOB ball area and bond pad opening. To improve the problem that missing ball after stand off ball formation. High frequency of missing ball happened after bonding a stand off ball on die. (this case need J.C S detail description ,did it the problem of machine or no fit parameter actually, because L

3、.H has controlled this case well already)第1頁/共16頁Analysis & actionBased on our professional technique and experience on Eagle60 machine, we conclude it may main caused by one parameter not fit. The parameter is 2nd bond pt offset ,present setting is 50.D=2nd pt offset X 0.8um(X,Y motor 0.8um/step)BS

4、OB standoff ballActual capillary markThe ball diameter is about 7580 um, so the radius is about 37.540um,D=50X0.8um=40um,naturally the capillary center shift out of the ball, even over the BPO, may cause some E- problem.Tail break point at the edge of the ball ,may easily pull the ball up in some me

5、chanics reason like the principle of lever.2nd bond offset第2頁/共16頁It seems that moving the 2nd bond center to the ball center can solve both the problems in theory, like this:Whole Capillary mark on ballTail break point move to center, make the pull power above intermetallic surfaceUpon the theoreti

6、c research above, we suggest to adjust only one parameter 2nd pt offset lower. Also we did DOE as fellow第3頁/共16頁SEM photoHigh power scope inspection(500X)2nd pt offset =502nd pt offset =452nd pt offset =402nd pt offset =352nd pt offset =302nd pt offset =252nd pt offset =20Check itemBall shear test (

7、on die) 第4頁/共16頁.Hook position 1Hook position 2 Break mode Break modeWire pull testWire pull test第5頁/共16頁 Using 2nd offset 30,35,40,the fish tail is not too small and it shows good wire pull test ,as well as the ball shear test, also has the correct wire broken mode. Bigger 2nd pt offset has a bigge

8、r fish tail, but too much cause capillary mark outside.Compare the results of the experiment，we can see easily that Our recommended setting is 35 , with a range 3040第6頁/共16頁Does it have influence on loop height ? We measured the loop height L1&L2 to compare 2nd offset settings 30/35/40 with setting

9、50 (present setting ).D D a at ta a2nd offset =502nd offset =402nd offset =352nd offset =3062. 560. 057. 555. 052. 550. 047. 545. 0B Bo ox xp pl lo ot t o of f 2 2n nd d o of ff fs se et t= =3 30 0, , 2 2n nd d o of ff fs se et t= =3 35 5, , 2 2n nd d o of ff fs se et t= =4 40 0, , 2 2n nd d o of ff

10、 fs se et t = =5 50 0Source DF SS MS F PS = 3.521 R-Sq = 5.98% R-Sq(adj) = 0.00% Individual 95% CIs For Mean Based on Pooled StDevLevel N Mean StDev -+-+-+-+-2nd offset=30 12 52.000 2.523 (-*-)2nd offset=35 12 51.333 4.163 (-*-)2nd offset=40 12 53.667 3.085 (-*-)2nd offset =50 12 52.250 4.048 (-*-)

11、-+-+-+-+- p value 0.433 0.05, loop height L1 with 2nd offset 30/35/40/50 are nearly the sameLoop height L1第7頁/共16頁D D a at ta a2nd of f set =502nd of f set =402nd of f set =352nd of f set =307570656055B Bo ox xp pl lo ot t o of f 2 2n nd d o of ff fs se et t = =3 30 0, , 2 2n nd d o of ff fs se et t

12、 = =3 35 5, , 2 2n nd d o of ff fs se et t = =4 40 0, , 2 2n nd d o of ff fs se et t = =5 50 0Loop height L2Source DF SS MS F PS = 4.236 R-Sq = 5.46% R-Sq(adj) = 0.00% Individual 95% CIs For Mean Based on Pooled StDevLevel N Mean StDev -+-+-+-+2nd offset =30 12 64.583 4.295 (-*-)2nd offset =35 12 65

13、.917 6.345 (-*-)2nd offset =40 12 67.083 2.503 (-*-)2nd offset =50 12 64.917 2.610 (-*-) -+-+-+-+ p value 0.476 0.05, loop height L2 with 2nd offset 30/35/40/50 are nearly the same第8頁/共16頁Scrub distanceJ.C s idea that adjust the BSOB parameter scrub distance 10 to 0 can solve the missing ball proble

14、m, we agreed. But we think this way is not the best one. Scrub distance ,this function due to X/Y motors motion to form a smooth slope above the bump ball, also it weaken the tail for it can be cut of easier .No slope if there is no scrub distance, too much makes the tail broken before tail bonding

15、,then missing ball happens. We did a DOE to prove that as fellow:DOE conditions: ball offset = 40 2nd bond offset = 50scrub distance-1001020304050第9頁/共16頁Stand off ball (ball offset = 40 ,2nd offset = 50)StitchScrub distance = -10Scrub distance = 0Scrub distance =1 0Scrub distance = 20Scrub distance

16、 =3 0Scrub distance = 40Scrub distance = 50Scrub distance = -10Scrub distance = 0Scrub distance =1 0Scrub distance = 20Scrub distance =3 0Scrub distance = 40Scrub distance = 50第10頁/共16頁Pictures showed that :Scrub distance influence the slope formation. Using positive setting , its direction is consi

17、st with the wire direction that meet our request. But too much make the slope sudden, may cause the second bond wire broken .Using negative setting ,.the direction of the slope is against the wire direction .Using 0,we can see theres no any slope formation, it does no good for the second bond and ta

18、il bond .It seems that scrub distance 10 is already a optimal setting .第11頁/共16頁Loop base/ ball offsetAs we all known ,BSOB ball offset has to be used matching with loop base. Loop base should be bigger than ball offset ,so that when capillary moving a ball offset distance cant pull the wire up from ball which is a root cause of missing ball .第12頁/共16頁Loop Base/Ball Offset=Loop Base/Ball Offset=Loop Base/Ball Offset=Loop Base/Ball Offset=Loop Base/Ball Offset=Loop Base/Ball Offset=Loop Base