409-32048
Rev A
20
of 64
1. Move the head from the tool clearance height (as given in the Tool Database) down to .030 in. above
the unseated top of tool. The s
peed will ramp linearly from the press “Run Speed” to .300 in. per
second. When the height is reached, the sequence will continue on the next step. If more than 50
pounds is detected before the height is reached, terminate and display error #1, typically “
Premature
contact detected”.
2. Continue to move down to until the connector is .030 in. above its seated height. The speed is
reduced to .150 in./second. This line tests to see if a connector is actually detected. If it is, as
indicated by detecting at least the minimum force per pin multiplied by the number of pins, the process
continues on the next line. If not, the process continues on line 5.
3. Press until the connector is within .010 in. of the desired seated height. When this position is reached,
the connector will be within a generally accepted tolerance of seated height. The .010 in. can be
adjusted as needed for specific circumstances. If the force exceeds the maximum force per pin
multiplied by the number of pins before the height is reached, an error message is displayed, in this
case Error 4.
4. The destination of this step will theoretically over press the connector, but the process will actually be
complete as soon as the force reaches the PARS force plus 25%. The height given simply provides a
destination that is not intended to be reached because the force condition will be satisfied first. If the
destination is reached before the PARS force is reached, then there is most likely an error in the
parameters used to calculate the distance relationship between connector, tool, and board surface. If
this occurs, review the tool height, the connector base thickness, the backup fixture thickness, and the
board thickness.
5.
This “GO TO” step tests to see if there is a connector below the head. If the normal sea
ted height is
reached without generating at least 100 pounds of force, it is determined that the connector is missing.
If the force is reached, the process continues on the next line.
6. This line verifies the connector is pressed to within generally accepted height tolerance, and the
maximum force per pin is not exceeded.
7. This line gives a destination below the nominal seated height, and terminates on the maximum force
per pin * # of pins. This variable here could also be “user force per pin” rather then maxi
mum.
A typical resulting screen plot using 30% PARS is shown in Figure 22. The PARS average force is given
as 9.62 pounds per pin, or a total of 1,203 pounds total. With 30% added to ensure seating, the force
becomes 12.56 pounds per pin. Note the average
is taken between the vertical ‘PARS Sample’ lines.
Figure 22
