BGA Solder Ball Height and Diameter Measurement

Project Background

Measurement Background

The BGA (Ball Grid Array) packaging process offers more possibilities for connections between wafer integrated circuit ICs and PCB circuit boards. The BGA process comes with certain technical requirements, necessitating strict and precise control over its production, including ensuring the accuracy of the number, size, and position of BGA balls to guarantee packaging quality.

Camera Selection

Hypersen-LCF3000

Measurement Items

Height and diameter of BGA solder balls

Detection Requirements

Measurement accuracy ≤ 0.01mm
Measurement repeatability ≤ 0.004mm
Measurement cycle ≤ 1s

Solution

Utilize AI-Vision software to first acquire the positions of the BGA balls, then measure their height and diameter information through a loop measurement method. This approach is fast, highly accurate, simple in process, modular, and easy to build.

Design Concept

Execution Result Display

• Project result display:

  • Height results:

    
    

  • Diameter results:

    
    

Project Process

First, Initialization

1. Use Lua Script tool:

• Concatenate header strings to be saved into CSV files.

Experience

.. For string concatenation

part1 = "Hello, "
part2 = "world!"
result = part1 .. part2
print(result) # Outputs: Hello, world!

Use , as a separator to split each data item.

-- String for concatenating headers
writeC = ""
writeH = ""

-- If the file does not exist, concatenate header strings and write them into the file
if FileExists("./Circle.csv") == false then
    writeC = writeC .. "Time,"
    for i=1,196,1 do
        writeC = writeC .. "R" .. i .. ","
    end
end

PrintToFile("./Circle.csv",writeC)

if FileExists("./Height.csv") == false then
    writeH = writeH .. "Time,"
    for i=1,196,1 do
        writeH = writeH .. "H" .. i .. ","
    end
end

PrintToFile("./Height.csv",writeH)

2. Use Load Point Cloud tool to load point cloud data.

Second, Preprocessing

Position Adjustment

1. Use 3D Square Probe tool to get the left and top edges of the workpiece.

2. Use 3D Geometry Intersection tool, bind the two edges output from the previous operator variable as input geometry, and output the intersection point of the two lines.

3. Use 3D Position Adjustment tool, bind the intersection point output from the previous operator as the new origin to adjust the point cloud position.

Fit Plane

1. Use 3D Region tool to select the region for plane fitting.

2. Use 3D Plane tool, bind the region output from the previous operator variable as the input area, fit the plane, and set it as the zero plane.

   

Cut Out Testing Area

Use 3D Clipping tool to cut out the BGA ball from IM1 to IM2 for subsequent height and diameter measurements.

Copy IM for Different Subroutine Calls

Copy IM2 to IM3 and IM4 separately for height and diameter measurements.

Tip

When calling subroutines in parallel, each subroutine needs to be executed on different IMs.

Third, Height and Diameter Measurement

1. Use 3D Blob tool to find all the positions of the BGA balls.

2. Use 3D Height tool, bind the regions within the variables output by the 3D Blob tool as the input areas, to measure the heights of all BGA balls.

   

3. Use 3D Circle tool, bind the regions within the variables output by the 3D Blob tool as the input areas, to obtain fitted circle information of the BGA balls (center, radius, direction vector).

Fourth, Data Saving

Use Lua Script tool:

• Bind the height and diameter information output by the operator variables.

• Edit Lua scripts to concatenate height and diameter information into strings.

• Write information of the 196 measured balls into files.

Time = os.date("%Y_%m_%d %H:%M:%S")
Height = Time .. ","
Circle = Time .. ","

for i=1,196 do
    Height = Height .. string.format("%.3f,",ResultHeight[i])
    Circle = Circle .. string.format("%.3f,",ResultR[i].Radius)
end

-- Write data into Height.csv file.
WriteLineToFile("./Height.csv",Height)
-- Write data into Radius.csv file.
WriteLineToFile("./Circle.csv",Circle)