KIC start, Руководство пользователя

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Version 1.1.0.x KICstart
46 KICstart User Manual
For example: if a profile is run with six thermocouples, and four profile statistics are logged for each
thermocouple, then there will be a set of twenty-four statistics for that profile, and the PWI will be the
worst case (highest number expressed as a percentage) in that set of profile statistics. Note that Figure 3
shows the user designated critical statistics for a single thermocouple (See Figure 3).
100%
80%
60%
40%
20%
0%
-20%
-40%
-60%
-80%
-100%
70
55
40
PWI Sec
Time Above
183 o C
100%
80%
60%
40%
20%
0%
-20%
-40%
-60%
-80%
-100%
225
223
221
219
217
215
213
211
209
207
205
PWI
Temp o C
Peak
Temperature
100%
80%
60%
40%
20%
0%
-20%
-40%
-60%
-80%
-100%
90
86
82
78
74
70
66
62
58
54
50
PWI
Sec
Soak Time Between
140 o C ~ 170 o C
0
2.0
3.0 100%
80%
60%
40%
20%
0%
-20%
-40%
-60%
-80%
-100%
PWI
o C/Sec
Slope
PWI = 0% PWI = 20%
PWI = 60%
PWI = -40% PWI = 60%
Typical Leaded Process Window
H
ow
P
rocess
W
indow
I
ndex
(PWI)
is
D
etermined
Figure 3: The Process Window Index
(Multiple Statistics for a Single Thermocouple and Final PWI Calculation)
Calculating the PWI
To calculate the Process Window Index: i =1 to N (number of thermocouples); j =1 to M (number of
statistics per thermocouple); measured_value
[i,j]
is the [ i,j ]
th
statistic’s value; average_limits
[i,j]
is the
average of the [ i,j ]
th
statistic’s high and low limits; and range
[i,j]
is the [ i,j ]
th
statistic’s high limit minus the
low limit.
Table 1: Process Window Index Formula
( measured_value
[ i,j ]
average_limits
[ i,j ]
)
( range
[ i,j ]
2 )
i,j=1
N,M
= 100 MAX
PWI
Thus, the PWI calculation includes all thermocouple statistics for all thermocouples. The profile PWI is
the worst case profile statistic (maximum, or highest percentage of the process window used), and all other
values are less.
Benefits of Ranking Thermal Profile Performance
The analysis of thermal profiles with the Process Window Index offers four significant benefits. The first
is that profiles can be easily compared, and users can be confident that they are using the best profile their
process can achieve. Before the PWI was available for profile analysis, comparing profiles was subjective,
and users could never be certain they had the best profile for their product. The PWI provides an excellent
opportunity for process improvement and its use is a significant step towards Zero-defect Production.
The second benefit is that the PWI greatly simplifies the profiling process. When used in advanced
profiling tools, all profile statistics are reduced to a single number (the PWI) that even the most
inexperienced operator can understand. This means significant savings in terms of training costs and a
reduction in defects caused by operator error. It further means that in a few minutes, an inexperienced
operator can setup an oven with the optimal profile, a job that formerly could take an experienced engineer
hours.