It’s Only Common Sense: Become the Person Who Knows What Happens Next
Happy’s Tech Talk #50: Start Your Digitalization Strategy With Automation
The Chemical Connection: A Few Things That Still Scare Me
Each factor that emerges from the ranking process is calibrated by assigning values from one to 100 as seen in Figure 6. The "1" factor are easy to manufacture and the "100" factor are impossible today but merely very difficult in a few years. In my example, the measure is “minimum drill diameter size” and values are assigned for 1-25-50-75 and 100.
Figure 6: The Factor Weighting Table is used to calibrate the ‘measured’ group from one to 100.
9. Create lLinear model for FOM
The resulting scoring equation will look like the linear equation below (sum of CnFWn) and would be used like this:
SCORE = (C1) (FW1) + (C2) (FW2) + (C3) (FW3) + (Cn) (FWn) + ....
For example, if we assume the producibility of a bare PWB may be scored with the above equation if the following factors were established by the F.O.M. Process:
1. Size of the substrate C1 = 1.5
2. Number of drilled holes C2 = 3.0
3. Minimum trace width C3 = 4.0
Where the proposed PWB design has:
1. Size of the substrate FW1 = 36
2. Number of drilled holes FW2 = 18
3. Minimum trace width FW3 = 31
The producibility score would equal: (1.5 x 36) + (3.0 x 18) + (4.0 x 31) = 54 + 54 + 124 = 232
As I sometimes tell people about the process, “It’s based on expert opinions, used over and over, but it is surprisingly accurate!”
References
- Holden, H., “Wiring Demand,” CircuiTree, June 1998.
- Holden, H., “First Pass Yield,” CircuiTree, Sept. 1998.
- Holden, H., “Producibility,” CircuiTree, Aug. 1998.
Happy Holden has worked in printed circuit technology since 1970 with Hewlett-Packard, NanYa/Westwood, Merix, Foxconn and Gentex. Currently, he is the co-editor, with Clyde Coombs, of the Printed Circuit Handbook, 7th Ed. To contact Holden, click here.
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