4OM-1625-004_w.pdf - 第333页

4OM-1603 5-2 1.ClassicationofFailureSymptomsandHelpfulHintsonCountermeasuresagainstFailure:Chap.5 Failures can further be classied as shown in the table below. Classicationof Failures Contents of Failure…

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4OM-1603
5-1
1.ClassicationofFailureSymptomsandHelpfulHintsonCountermeasuresagainstFailure:Chap.5
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1. ClassicationofFailureSymptomsandHelpfulHints
on Countermeasures against Failure
1.1 ClassicationofFailureSymptoms
The machine processes can be classied into Processes A, B, C, D, and E as
shown below.
Reference
Refer to "4. Surface Mounting Mechanism" in "Chapter 1 (Vol. 1: Guide)" for
the outline of actions.
Process A : The placement head moves to the feeder base and picks up a
component.
Process B : The head moves to the area where the component recognition
camera is installed and a component recognition process is
taken there.
Process C : The placement angle is corrected while the head is moving to
the PCB positioning section.
Process D : The component is placed on the PCB.
Process E : The component-placed PCB is discharged.
1
2
3
Feeder Base Section
Component Recognition Camera
PCB Positioning Section
Process A
Process B
Process C
Process D
Process E
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Based on these processes, failures can be divided roughly into the following two
types.
Failure before Component Placement : This type of failure occurs mainly in
Processes A, B, and C.
Failure after Component Placement : This type of failure occurs mainly at
Processes D and E.
4OM-1603
5-2
1.ClassicationofFailureSymptomsandHelpfulHintsonCountermeasuresagainstFailure:Chap.5
Failures can further be classied as shown in the table below.
Classicationof
Failures
Contents of
Failures
Symptom of Failures
Failure before
Component
Placement
Component Pickup
Error
Components cannot be picked up.
Components are turned vertically.
A recognition error occurs.
Components fall down.
Others
Failure after
Component
Placement
Component
Placement Error
The positional and angular deviation of
component occurs.
Components are turned over and placed.
Some components are missing.
Some components are cracked or nicked.
Others
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1.2 Helpful Hints on Countermeasures against Failure
•
The rst helpful hint on countermeasures against failure is to catch precisely
what kind of symptom is produced and how frequently the symptom appears.
•
The second helpful hint is to grasp the tendency (environment and condition) of
a failure.
Shown below are the concrete items to be checked.
(1)
Check if the failure occurs on specic components.
(2) Check if the failure occurs on a specic production lot.
(3) Check if the failure occurs on a specic machine.
(4) Check if the failure occurs at a limited stage.
•
The third helpful hint is to nd in which process the failure occurs.
In normal cases, a failure after component placement is found in the nal
inspection process. In such a case, it is required to track the failure by checking
all processes and specify the process in which the failure has occurred.
It is very important to grasp a failure symptom precisely on these helpful hints.
Precise capture of a failure symptom makes it possible to track the factor and
make a plan to take countermeasures against the failure.
In the case that the present status is not grasped correctly, the countermeasure
for the error takes time due to the execution of ineffective measures.
In particular
, for the errors with low occurrence rate, it is required to collect the
data accurately, estimate the factors based on the data collection results, and
take the countermeasure.
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4OM-1603
5-3
2. Troubleshooting on Pickup Errors : Chap.5
2. Troubleshooting on Pickup Errors
2.1 Cause and Remedy of Pickup Errors
(1) Component-Based Factors
When the cause of a failure lies in specic components or lots, the
components must be examined rst of all.
Shown below are the cases of failures whose factors lie in components.
[Factors of Pickup Errors on Component Side]
(1-1) A component adheres to the bottom tape.
(1-2) The shape of a cavity is defective.
(1-3) The shape of a component is defective.
(1-4) A component turns sideways because the tape cavity is too large.
(1-5) The atness of the cavity bottom is defective.
(1-6) Oil or mold lubricant adheres to the bottom of a component.
The failures described in (1-1) through (1-4) have a tendency to occur easily
due to the components packaged in a paper tape and the failures described in
(1-4) through (1-6) due to the components packaged in an embossed tape.
Special caution should be paid to minute components such as 0603 and
1005 types because such components are directly affected by how they are
packaged in the tape.
To determine whether or not the taped components are packaged in good
condition, turn the tape upside down and check to see how the components
fall down from the cavities. If the components fall down freely, it means that
they were packaged in good condition.
The specications of taping are specied in "JIS-C0806". However, as the
detailed regulations are not provided as for the failures described in (1-1)
through (1-6), it is required to ask the component maker about the details
when the components are purchased.
ExemplicationofTroubledTapedComponentsF4E2
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