Page 126 - Six Sigma for electronics design and manufacturing

Six Sigma and Manufacturing Control Systems
3.4.1.3 Checksheets. A checksheet is a form used to identify, gather,
organize, and evaluate data. A well-designed checksheet can elimi-
nate confusion, enhance accuracy, and reduce time needed to take
data.
There are two types of checksheets:
1. Recording check sheet. This is used for recording data on types of
defects. The types should be listed in categories, and a mark made
each time a defect is found in the sample. It is important not to col-
lect too many types of defects. 95
It is difficult to properly train production operators to distin-
guish between very similarly worded types of defects, even if pho-
tographs and other methods of graphically presenting them are
used. Count the total number of checks for each defect.
2. Location check sheet. This is used to collect the location of the
defects, and list how often they occur. This technique is useful to
identify concentration of defects on a printed circuit board (PCB).
Other information should be included when available, such as date,
part number, lot number, supplier name, supplier date code, area lo-
cation, etc. Using automatic means of collecting and categorizing
data, such as bar code readers and scanners, can speed up the record-
ing of data. The defects data categories could be arranged in bar code
format so that an operator with a bar code wand could enter all the
data without writing down any information by hand.
3.4.1.4 Flowcharts. A flowchart is a picture of a process. It represents
a step-by-step sequence. It can help in reaching a common under-
standing of how the manufacturing process is run and can act as a
base for enhancing or changing the process. It can also be used as a
documentation and training tool for pointing out areas for data collec-
tion and control, and as the basis of brainstorming for enhancing and
troubleshooting the manufacturing process. Recently, it has been
mostly replaced with process mapping. Figure 3.6 is flowchart repre-
sentation of control charts.
The flowcharting process consists of these steps:

Identify the first and last steps of the process.
Fill in each process step. Include any time the product is handled,
transferred, joined, or changed in form.
Show feedback loops such as rework paths; they indicate inefficien-
cy and possible low quality.