Warpage control of array packaging
View Patent ↗During the curing process of the package strips, especially during post encapsulant cure (PEC), undesirable warpage of package strips occurs. A carrier having angled lands and side-insertion clamp structures with angled clamp fins may be used to control this cure-induced warpage of package strips during PEC. In one embodiment, the angled lands and angled side-insertions clamps are used to clamp the edges of the package strip in order to introduce an intentional deformation which counters warpage which occurs during PEC. The angled lands and side-insertion clamps may be at any angle (fixed or adjustable). The side-insertion clamps may be inserted before or after insertion of the package strips into the carrier. Once the package strips are in the carrier and resting on the angled lands, a force may be applied to the side-insertion clamps to clamp the edges of the package strips between a clamp fin and an angled land.
1. A method for controlling warpage of a package strip during curing, the package strip including a plurality of integrated circuit dies encapsulated on a package substrate, the method comprising:
clamping edges of the package substrate to hold the package substrate in a position to decrease cure-induced warpage of the package substrate during curing of the encapsulant, wherein clamping comprises engaging a major surface portion of the package substrate near an edge of the package substrate with non-zero angled fins disposed at a non-zero angle to the major surface to apply a force to the package substrate to cause an initial deformation to the package substrate to counter an expected cure-induced warpage of the encapsulant on the package substrate;
curing the encapsulant;
releasing the edges of the cured package substrate; and
partially curing the encapsulant before clamping the edges of the package substrate.
2. The method of claim 1 , further comprising:
terminating the application of the force, wherein the terminating is performed after the curing of the encapsulant.
3. The method of claim 1 further comprising:
selecting an angle based on an amount of estimated curing warpage.
4. The method of claim 1 further comprising:
measuring an amount of warpage without applying the force;
selecting an angle based on the amount of measured warpage.
5. The method of claim 1 wherein the clamping comprises:
supporting the package strip on a non-zero angled land of a package strip carrier assembly; and
applying a clamping force to constrain the package strip between the land and a non-zero angled fin.
6. The method of claim 1 wherein the force is applied by at least one of rotating a screw, releasing a spring, and actuating a lever.
7. The method of claim 1 , wherein prior to the clamping the edges of the substrate, the method further comprises:
placing the package substrate into a carrier having non-zero angled lands which are at a non-zero angle as measured from a horizontal axis that is substantially parallel with a top or a bottom of the carrier.
8. The method of claim 7 , wherein the engaging the major surface portion comprises engaging the major surface portion of package substrate near the edge of the package substrate between a non-zero angled fin and a corresponding non-zero angled land, wherein the corresponding non-zero angled fin is substantially parallel to the non-zero angled land.
9. A method for controlling warpage of a package strip during curing, the package strip including a plurality of integrated circuit dies encapsulated on a package substrate, the method comprising:
placing the package strip into a package strip carrier assembly, the package strip carrier assembly having a plurality of non-zero angled lands which are disposed at a non-zero angle with respect to a horizontal axis that is substantially parallel to a first major surface of the package strip;
clamping edges of the package strip between non-zero angled lands of the plurality of non-zero angled lands and corresponding non-zero angled fins that are substantially parallel to the non-zero angled lands to apply a force to the package substrate to cause an initial deformation to the package substrate to counter an expected cure-induced warpage of the encapsulant on the package substrate during curing of the encapsulant;
curing the encapsulant; and
releasing the edges of the cured package substrate.
10. The method of claim 9 , wherein during the clamping, the non-zero angled lands of the plurality of non-zero angled lands engage the first major surface of the package substrate, and the non-zero angled fins engage a second major surface of the package substrate, opposite the first major surface.
11. The method of claim 9 further comprising:
selecting a non-zero angle for the non-zero angled lands and corresponding non-zero angled fins based on an amount of estimated curing warpage.
12. The method of claim 9 further comprising:
measuring an amount of warpage without applying the force;
selecting a non-zero angle for the non-zero angled lands and corresponding non-zero angled fins based on the amount of measured warpage.
13. The method of claim 9 , wherein the horizontal axis is also substantially paralled to a top or a bottom of the package strip carrier assembly.