Vacuum-assisted BGA joint formation

Patent metadata

Field	Value
Publication number	US-11963307-B2
Application number	US-202117216863-A
Country	US
Kind code	B2
Filing date	Mar 30, 2021
Priority date	Mar 30, 2021
Publication date	Apr 16, 2024
Grant date	Apr 16, 2024

Abstract

A ball-grid-array component of a ball-grid array assembly is analyzed prior to reflow. A predicted warping pattern of the ball-grid-array component that is likely to occur during reflow is predicted based on the analyzing. A solder ball ball-grid-array defect that could be caused by the predicted warping pattern is predicted. An initial via suction pattern to mitigate the ball-grid-array defect is assigned. A vacuum head is applied to a via in the ball-grid-array assembly. The solder ball is located at the opposite end of the via from the vacuum head. Suction is applied to the via based on the via suction pattern. The suction draws a portion of the solder ball into the via during reflow.

First claim

What is claimed is:

1. A method comprising:
predicting a solder ball ball-grid-array defect that could occur during reflow of a ball- grid-array assembly;
assigning an initial via suction pattern to mitigate the solder ball ball-grid-array defect;
applying a vacuum head to a via in the ball-grid-array assembly, wherein a solder ball is located at the opposite end of the via; and
applying a first amount of suction to the via and a second amount of suction to a second via in the ball-grid-array assembly based on the initial via suction pattern, wherein the first amount of suction draws a portion of the solder ball into the via during reflow and wherein the first amount of suction does not equal the second amount of suction.

2. The method of claim 1 , further comprising:
analyzing, during reflow, a real-time warping pattern of the ball-grid-array assembly;
adjusting, based on the real-time warping pattern, the initial via suction pattern, resulting in an updated via suction pattern; and
applying a third amount of suction to the via based on the updated via suction pattern.

3. The method of claim 2 , wherein applying the third amount of suction to the via based on the updated via suction pattern comprises reducing the suction applied to the via from the first amount to the third amount.

4. The method of claim 1 , further comprising:
applying, before reflow, extra solder to the solder ball before reflow;
drawing the extra solder into the via during reflow; and
releasing, during reflow, a portion of the extra solder from the via.

5. The method of claim 1 , further comprising:
analyzing a ball-grid-array component of the ball-grid-array assembly prior to reflow; and
predicting, based on the analyzing, a predicted warping pattern of the ball-grid-array component that is likely to occur during reflow;
wherein the solder ball ball-grid-array defect is predicted to be caused by the predicted warping pattern.

6. The method of claim 5 , wherein the predicted warping pattern includes a reduced space between the ball-grid-array component and a printed circuit board, and wherein the assigning comprises:
determining that the warpage pattern is expected to cause a short if the solder ball is larger than a threshold percentage of its original size.

7. The method of claim 5 , wherein the predicted warping pattern includes an increased space between the ball-grid-array component and a printed circuit board, and wherein the assigning comprises:
determining that the warpage pattern is expected to cause a short if the solder ball is smaller than a threshold percentage of its prescribed pre-warpage size;
wherein the initial suction plan comprises reducing, during reflow, the first amount of suction to release a sufficient amount of solder to the solder ball for the solder ball to grow to at least the threshold percentage.

8. A system comprising:
a processor; and
a memory in communication with the processor, the memory containing program instructions that, when executed by the processor, are configured to cause the processor to perform a method, the method comprising:
predicting a solder ball ball-grid-array defect that could occur during reflow of a ball-grid-array assembly;
assigning an initial via suction pattern to mitigate the solder ball ball-grid-array defect;
applying a vacuum head to a via in the ball-grid-array assembly, wherein a solder ball is located at the opposite end of the via;
applying suction to the via based on the initial via suction pattern, wherein the suction draws a portion of the solder ball into the via during reflow;
analyzing, during reflow, a real-time warping pattern of the ball-grid-array assembly;
adjusting, based on the real-time warping pattern, the initial via suction pattern, resulting in an updated via suction pattern; and
applying suction to the via based on the updated via suction pattern.

9. The system of claim 8 , wherein the method performed by the processor further comprises:
applying, before reflow, extra solder to the solder ball before reflow;
drawing the extra solder into the via during reflow; and
releasing, during reflow, a portion of the extra solder from the via.

10. The system of claim 8 , wherein the vacuum head is attached to a repositionable arm.

11. The system of claim 8 , wherein the method performed by the processor further comprises:
analyzing a ball-grid-array component of the ball-grid-array assembly prior to reflow; and
predicting, based on the analyzing, a predicted warping pattern of the ball-grid-array component that is likely to occur during reflow;
wherein the solder ball ball-grid-array defect is predicted to be caused by the predicted warping pattern.

12. The system of claim 11 , wherein the predicted warping pattern includes a reduced space between the ball-grid-array component and a printed circuit board, and wherein the assigning comprises:
determining that the warpage pattern is expected to cause a short if the solder ball is larger than a threshold percentage of its original size.

13. The system of claim 11 , wherein the predicted warping pattern includes an increased space between the ball-grid-array component and a printed circuit board, and wherein the assigning comprises:
determining that the warpage pattern is expected to cause a short if the solder ball is smaller than a threshold percentage of its prescribed pre-warpage size;
wherein the initial suction plan comprises reducing, during reflow, the first amount of suction to release a sufficient amount of solder to the solder ball for the solder ball to grow to at least the threshold percentage.

14. The system of claim 8 , wherein the method performed by the processor further comprises applying a second amount of suction to a second via based on the initial via suction pattern, wherein the suction applied to the via based on the initial via suction pattern does not equal the second amount of suction.

15. A computer program product, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a computer to cause the computer to:
predict a solder ball ball-grid-array defect that could occur during reflow of a ball-grid- array assembly;
assign an initial via suction pattern to mitigate the solder ball ball-grid-array defect;
apply a vacuum head to a via in the ball-grid-array assembly, wherein a solder ball is located at the opposite end of the via; and
apply a first amount of suction to the via and a second amount of suction to a second via in the ball-grid-array assembly based on the via suction pattern, wherein the first amount of suction draws a portion of the solder ball into the via during reflow and wherein the first amount of suction does not equal the second amount of suction.

16. The computer program product of claim 15 , wherein the program instructions further cause the computer to:
analyze, during reflow, a real-time warping pattern of the ball-grid-array assembly;
adjust, based on the real-time warping pattern, the initial via suction pattern, resulting in an updated via suction pattern; and
apply a third amount of suction to the via based on the updated via suction pattern.

17. The computer program product of claim 16 , wherein analyzing the real-time warping pattern comprises determining a warping-pattern deviation between the real-time warping pattern and the predicted warping pattern.

18. The computer program product of claim 15 , wherein the program instructions further caus

Assignees

• IBM

Inventors

• Doyle Matthew
• Liang Thomas W
• Berge Layne A
• Dangler John R
• Bjorgaard Jason J
• Schoneck Kyle
• Walther Matthew A

Classifications

• H05K3/3478 Primary

  Application of solder preforms; Transferring prefabricated solder patterns · CPC title

• B23K1/0008

  specially adapted for particular articles or work · CPC title

• B23K3/0623

  for shaped solder piece feeding, e.g. preforms, bumps, balls, pellets, droplets · CPC title

• B23K3/08

  Auxiliary devices therefor · CPC title

• H05K3/3436

  having an array of bottom contacts, e.g. pad grid array or ball grid array components · CPC title