Laser optical path detection in integrated circuit packaging
View Patent ↗A method is provided for detecting laser optical paths in integrated circuit (IC) packages. The method provides an IC die encapsulated as a package in a compound of glass spheres and epoxy. Power is supplied to the IC. The IC is scanned with a laser. Typically, a laser wavelength is used that is minimally absorbed by the glass spheres in the epoxy compound of the IC package, and changes in current to the IC are detected. A detected current change is cross-referenced against a scanned IC package surface region. This process identifies an optical pathway underlying the scanned IC package surface region. In some aspects, this process leads to the identification of a glass sphere-collecting package structure underlying the optical pathway. Examples of a glass sphere-collecting structure might include an inner lead wire, lead frame edge, or die edge.
1. A method for detecting laser optical paths in integrated circuit (IC) package/dies, the method comprising:
providing an IC die encapsulated as a package in a compound of glass spheres and epoxy, where the glass spheres have a diameter of greater than 30 microns;
supplying power to the IC package/die;
scanning the IC package/die with a laser; and,
detecting changes in current to the IC package/die.
2. The method of claim 1 further comprising:
cross-referencing a detected current change against a scanned IC package/die surface region; and,
identifying an optical pathway underlying the scanned IC package surface region.
3. The method of claim 2 further comprising:
identifying a glass sphere-collecting package structure underlying the optical pathway.
4. The method of claim 1 wherein supplying power to the IC package/die includes connecting current sense amplifiers between IC power pins and IC ground pins.
5. The method of claim 4 wherein connecting current sense amplifiers includes dc biasing the IC power pins.
6. The method of claim 1 wherein scanning the IC package/die with the laser includes scanning with a laser having a wavelength that is minimally absorbed by the glass spheres in the epoxy compound of the IC package/die.
7. The method of claim 6 wherein scanning the IC with the laser includes scanning with a laser selected from a group consisting of an Optical Beam Induced Current (OBIC) laser having a wavelength of about 1065 nanometers (nm), a Thermally Induced Voltage Alteration (TIVA) laser having a wavelength of about 1340 nm, and a combination of the above-mentioned lasers.
8. The method of claim 1 wherein providing the IC die encapsulated with the compound of glass spheres and epoxy includes encapsulating with an epoxy/glass sphere layer having a thickness of less than 300 microns.
9. The method of claim 3 wherein identifying the glass sphere-collecting package structure underlying the optical pathway includes identifying a package structure selected from a group consisting of a die bonding wire, the die, and the lead frame.
10. The method of claim 9 further comprising:
scanning a plurality of IC package/dies; and,
identifying an optical pathway overlying a package structure common to the plurality of IC package/dies.
11. The method of claim 2 wherein identifying the optical pathway underlying the scanned IC package/die surface region includes identifying a column of vertically aligned glass spheres.
12. A method for detecting laser optical paths in integrated circuit (IC) packages, the method comprising:
providing an IC die encapsulated as a package in a compound of glass spheres and epoxy, where the epoxy and glass spheres are formed as a layer having a thickness of less than 300 microns;
supplying power to the IC package/die;
scanning the IC package/die with a laser; and,
detecting changes in current to the IC package/die.
13. The method of claim 12 further comprising:
cross-referencing a detected current change against a scanned IC package/die surface region; and,
identifying an optical pathway underlying the scanned IC package/die surface region.
14. The method of claim 13 further comprising:
identifying a glass sphere-collecting package structure underlying the optical pathway.
15. The method of claim 13 wherein identifying the optical pathway underlying the scanned IC surface region includes identifying a column of vertically aligned glass spheres.
16. The method of claim 12 wherein scanning the IC package/die with the laser includes scanning with a laser having a wavelength that is minimally absorbed by the glass spheres in the epoxy compound of the IC package/die.
17. A method for detecting laser optical paths in integrated circuit (IC) packages, the method comprising:
providing an IC die encapsulated as a package in a compound of glass spheres and epoxy;
supplying power to the IC package/die;
scanning the IC package/die with a laser having a wavelength that is minimally absorbed by the glass spheres in the epoxy compound of the IC package/die;
detecting changes in current to the IC package/die; and,
wherein scanning the IC package/die with the laser includes scanning with a laser selected from a group consisting of an Optical Beam Induced Current (OBIC) laser having a wavelength of about 1065 nanometers (nm), a Thermally Induced Voltage Alteration (TIVA) laser having a wavelength of about 1340 nm, and a combination of the above-mentioned lasers.
18. The method of claim 17 further comprising:
cross-referencing a detected current change against a scanned IC package surface region; and,
identifying an optical pathway underlying the scanned IC package surface region.
19. The method of claim 18 further comprising:
identifying a glass sphere-collecting package structure underlying the optical pathway.
20. The method of claim 18 wherein identifying the optical pathway underlying the scanned IC package/die surface region includes identifying a column of vertically aligned glass spheres.