SER testing for an IC chip using hot underfill

1. A method for detecting soft errors in an integrated circuit (IC) due to transient-particle emission, the IC comprising at least one chip and a substrate, the method comprising:

mixing an epoxy with a radioactive source to form a hot underfill (HUF);

underfilling the chip with the HUF;

sealing the underfilled chip;

measuring a radioactivity of the HUF at an edge of the chip;

measuring the radioactivity of the HUF on a test coupon;

testing the IC for soft errors by determining a current radioactivity of the HUF at the time of testing based on the measured radioactivity; and

after completion of testing the IC for soft errors and after the expiration of a radioactive decay period of the radioactive source, using the IC in a computing device by an end user.

2. The method of claim 1 , wherein the radioactive source comprises one of 210 lead (Pb); 210 pollonium (Po); a combination of 210 Pb and 210 Po; 225 actinium (Ac); and 223 radium (Ra).

3. The method of claim 1 , wherein the radioactive decay period is equal to about 12 times a half life of the radioactive source.

4. The method of claim 1 , further comprising treating the chip with an oxygen plasma treatment before underfilling the chip with the HUF.

5. The method of claim 1 , further comprising vacuum degassing the HUF after mixing.

6. The method of claim 1 , wherein underfilling the chip with the HUF comprises dispensing the HUF at a leading edge of the chip.

7. The method of claim 6 , further comprising forming a barrier comprises a thixotropic, non-radioactive material at the leading edge of the chip to contain the HUF under the chip.

8. The method of claim 6 , further comprising placing a glass slide at the leading edge of the chip to contain the HUF under the chip.

9. The method of claim 1 , wherein sealing the underfilled chip comprises:

applying a first cold underfill (CUF) over the HUF at an edge of the chip;

applying a second CUF over the first CUF;

determining an alpha count of the HUF, and in the event the alpha count is above a predetermined limit, applying a third CUF over the second CUF;

wherein the first, second, and third CUF each comprise an epoxy.

10. The method of claim 1 , wherein the HUF further comprises a fluorescent dye, and further comprising detecting a portion of HUF that is not located under the chip using a fluorescent light after sealing the underfilled chip.

11. The method of claim 1 , further comprising determining whether a void is present in the HUF under the chip before testing the IC for soft errors; and

in the event it is determined that a significant void is not present, testing the IC for soft errors; and

in the event it is determined that a significant void is present, discarding the chip.

12. The method of claim 1 , wherein determining whether a void is present in the HUF under the chip comprises at least one of acoustic microscopy or two-dimensional beta radiation detection.

13. A system for detecting soft errors in an integrated circuit (IC) due to transient-particle emission, the IC comprising at least one chip and a substrate, the system comprising:

a hot underfill (HUF) located under the chip, the HUF comprising an epoxy mixed with a radioactive source;

a first cold underfill (CUF) located over the HUF at an edge of the chip; and

a second CUF located over the first CUF, wherein the first CUF and the second CUF comprise an epoxy;

wherein the IC is located on a circuit board that is for use by an end user in a computing device after completion of testing the IC for soft errors and after an expiration of a radioactive decay period of the radioactive source.

14. The system of claim 13 , wherein the radioactive source comprises one of 210 lead (Pb); 210 pollonium (Po); a combination of 210 Pb and 210 Po; 225 actinium (Ac); and 223 radium (Ra).

15. The system of claim 13 , wherein the HUF further comprises a fluorescent dye.

16. The system of claim 13 , further comprising a third CUF located over the second CUF, the third CUF comprising an epoxy.

17. The system of claim 13 , further comprising forming a barrier comprises a thixotropic, non-radioactive material at the leading edge of the chip to contain the HUF under the chip.

18. The system of claim 17 , further comprising placing a glass slide at the leading edge of the chip to contain the HUF under the chip.

19. The system of claim 13 , wherein a surface of the chip is cleaned with an oxygen plasma treatment.

20. The system of claim 13 , wherein the radioactive decay period is equal to about 12 times a half life of the radioactive source.