Void evaluation apparatus and void evaluation method in the solder

• US 9,965,849 B2
• Filed: 11/10/2014
• Issued: 05/08/2018
• Est. Priority Date: 11/15/2013
• Status: Active Grant

• Current Assignee: Beamsense Co., Ltd., Osaka University
• Original Assignee: Beamsense Co., Ltd., Osaka University
• Inventors: Suzuki, Takashi, Baba, Sueki
• Primary Examiner(s): Lee, Jonathan S
• Application Number:
  US15/034,302
• Publication Number:
  US 20160267646A1
• Time in Patent Office: 1,275 Days
• CPC Class Codes: G01N 2223/401 image processing
• CPC Class Codes: G01N 2223/6113 printed circuit board [PCB]
• CPC Class Codes: G01N 2223/648 voids
• CPC Class Codes: G01N 23/04 and forming images of the material
• CPC Class Codes: G06T 2207/10116 X-ray image
• CPC Class Codes: G06T 2207/30152 Solder
• CPC Class Codes: G06T 2207/30164 Workpiece; Machine component
• CPC Class Codes: G06T 7/0008 checking presence/absence
• CPC Class Codes: H05K 2201/10734 Ball grid array [BGA]; Bump grid array
• CPC Class Codes: H05K 2203/162 Testing a finished product, e.g. heat cycle testing of solder joints
• CPC Class Codes: H05K 2203/163 Monitoring a manufacturing process
• CPC Class Codes: H05K 3/3436 having an array of bottom contacts, e.g. pad grid array or ball grid array components
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A void evaluation apparatus in a solder includes an evaluation function calculation unit for calculating a solder evaluation function by using a pixel value pi contained in the voids that is set to 1 and the pixel value pi not contained in the voids is 0 for each pixel constituting an image in the solder, and by using a weight function w(ri), which is maximum at a solder center (ri=0), and is 0 at a maximum radius (ri=r0) for a distance ri from the solder center. The apparatus further has a void evaluation unit for evaluating that the influence of voids is larger as the evaluation function is relatively larger for the each solder.

$\frac{\sum _{i=1}^{N}w\left(r_i\right)p_i}{\sum _{i=1}^{N}w\left(r_i\right)}\times 100$

• i: pixel number (1−N)
• pi: pixel value (0 or 1)
• w(ri): weighting function

Claims

1. A void evaluation apparatus in a solder comprising:

an evaluation function calculation unit for calculating a solder evaluation function by using a pixel value pi, contained in the voids, that is set to 1, and a pixel value pi not contained in the voids is 0 for each pixel constituting an image in the solder, and by using a weight function w(ri), which is maximum at a solder center (ri=0) and is 0 at a maximum radius (ri=r0) for a distance ri from the solder center; and

a void evaluation unit for evaluating that influence of voids is larger as the evaluation function is relatively larger for each solder, wherein the void evaluation unit uses the function;

2. The void evaluation apparatus in the solder according to claim 1, further comprising an image extraction unit that extracts an image in each solder from two-dimensional X-ray images.

3. The void evaluation apparatus in the solder according to claim 1, further comprising a void detection unit that detects voids for the images in the solder.

4. The void evaluation apparatus in the solder according to claim 1, wherein the weighting function w (ri) is (r0-ri).

5. A void evaluation method in a solder comprising:

a step for calculating a solder evaluation function, by using a pixel value pi contained in the voids is set to 1 and a pixel value pi not contained in the voids is 0 for each pixel constituting an image in the solder, and by using a weight function w(ri), which is maximum at the solder center (ri=0) and is 0 at the maximum radius (ri=r0) for the distance ri from the solder center; and

a step for evaluating that influence of voids is larger as the value of the evaluation function is relatively larger for each solder, wherein the step for evaluating further comprises the function;

6. The void evaluation method in the solder according to claim 5, further comprising an image extraction step that extracts an image in each solder from the two-dimensional X-ray images;

and a void detecting step that detects the voids from images in the solder.

7. The void evaluation method in the solder according to claim 5, wherein the weighting function w (ri) is (r0-ri).

8. The void evaluation method in the solder according to claim 5, wherein each step of the void evaluation method in the solder is executed by a computer, which performs the evaluation of voids in the solder.

9. A computer-readable recording medium, which is stored the void evaluation computer program in the solder according to claim 8.