Presentation of my research dealing with pull test systems and creating one to use in our laboratory for our chips.

1. Wire Bond PullTestSystems Iheanyi Ekechukwu University of Notre Dame

3. What is a pull test system?

4. Two methods of pull testing

5. How do you perform a pull test?

6. What do you need for a pull test?

7. What are the standards?

8. Shared standards

9. Nondestructive standards

11. The microchips

12. The equipment and setup

13. The standards

14. What equipment is used in our pull test system?

15. Which pull test method does ours use?

16. What are the standards for our pull test system?

17. What is the procedure for our pull test?

19. 1 pound (lb) = 4.4482 Newtons (N) [4]

21. A pull test is… According to IEEE member George Harman, the pull test is an accepted method used to test the quality of wire bond interconnections used in microchips. [1] A pull tester is a machine used to perform the pull test on microchips. The pull test was first used by Bell Laboratories to test the strength of wire bonds in their semiconductor devices. [1]

22. There are two different methods of pull tests… #1. Destructive This method is used to measure bond strength or evaluate bond strengthdistributions. [2] #2. Nondestructive This method is used to reveal unacceptable wire bonds while avoiding damage to the acceptable ones. [2]

23. How do you perform a pull test? [2] The most common way to perform a pull test, both destructive and nondestructive, is by attaching a hook to a flat loop wire (either aluminum or gold) and then applying a vertical pull force to the wire with a pull tester. [1]

24. What do you need for a pull test? In order to accurately measure the vertical pull force applied to a wire bond, a pull test machine must be used. The majority of models sold today come with a force gage programmed inside of them. Also, you need to have the chips that you want to use for the pull test. [3]

25. Standards The standards for the destructive and nondestructive method aredescribed within MIL-STD-883 [2], a military document which has set the guidelines for the standards since the 1960s. Between the destructive method and nondestructive method, there are differences in the standards. But there are similarities as well…

26. Standards shared between the destructive and nondestructive methods Wire Composition: Aluminum (Al) or Gold (Au) Wire Sizes: 0.0007 - 0.0030 inches Pull Force Units: grams force (gf) [2] Now for the differences...

27. Nondestructive Pull Test Standards Failure Criteria: According to Mil-STD-883, any wire bond pull which causes a separation at an applied pull force value less than the value assigned to the wire composition in the table is considered a failure. [2]

28. Destructive Pull Test Standards Failure Criteria: Any wire bond pull which causes a separation at an applied pull force value less than the value assigned to the wire composition in the table is considered a failure. [2]

29. So what makes our pull test different from others?

30. Our pull test is different because… #1. The Microchips Quilt packaged chips are not connected by wire bonds, they physically connected to one another like squares in a quilt. #2. The equipment and setup Instead a long hook, our pull test system uses 10 lb fishing line threaded through two small fishing hooks. Also, it utilizes a horizontal pull test machine and an external force gauge for the setup with the microchips mounted on a platform.

31. Our pull test is different because… Notice the differences between our pull test and the pull test shown earlier…

32. Our pull test is different because… #3. The standards In Mil-STD-883, there are minimum pull force values for both aluminum and gold wire bonds. With our pull test, we do not have a set standard since quilt packaging is newly invented.

34. Accuforce CADET 5 lb force gage

35. AccuforceElectrim 1 lb force gage

36. AccuforceElectrim 50 g force gage

37. Quilt packaged chips (for testing)

38. Perfboard (For mounting chips)

39. 10 lb fishing line

41. Nondestructive method is not suitable for this, as it is only useful for determining unacceptable wire bonds.

43. Also, it is unknown whether the size of the quilt packaged chips affect the size.

45. Quilt Packaged Chips Pull Test Procedure

46. Step 1: The quilt packaged chips are attached to the perfboard using glue and a vacuum collett to place the quilt packaged chips on top of the boards. Afterwards, the glued chips should be pushed together and connected. .

47. Step 2: Move the connected chips to the pull test system, taking care to keep them as flat as possible. Afterwards, secure one end to the pull test system and the other to the force gauge using the small fish hooks.

48. Step 3: Turn on the video camera and the force gage (shown with arrows) prior to turning on the pull tester. Make sure that you clear any prior data from the force gage before use.

49. Step 4: After everything is connected and camera and force gage have been turned on, turn on the drive on the pull tester in the direction opposite of your chips until the chips tear apart.

50. Finally… Step 5: After chips separate, turn the drive switch off. Then by using the camera or the force gage’s peak button, observe the maximum pull force value exerted on the chips.

51. References G. Harman, C. Cannon, 1st Initial. , "The Microelectronic Wire Bond Pull Test - How to Use It, How to Abuse It," IEEE Transactions on Components, Hybrids, and Manufacturing Technology, Vol. 1, no. 3, pp. 203-210, Sep. 1978. Test Methods and Procedures for Microelectronics MIL-STD-883G, 2006. http://cgi.ebay.com/330458644134 http://en.wikipedia.org/wiki/Gram-force