4OM-1208-011_w.pdf - 第230页
5-9 AIVEMT -ID 0606-009 (1-3) Positional and Angular Deviations in Process D or E When a positional deviation is not generated on the double-faced tape, it in dic ate s th at p osit ion al a nd a ngul ar devi atio ns occ…
5-8
AIVEMT-ID
0606-009
3. Troubleshooting on Placement Errors
3.1 Cause and Remedy of Placement Errors
(1) Positional and Angular Deviations of Component Placement
(1-1) Situational Grasp of Error Generation
Positional and angular deviations may be generated in either Process C
or D and E.
See Fig. 4E1.
By placing a component on the PCB where a double-faced adhesive
tape is affixed, it can be checked and determined in which process
positional and angular deviations are generated.
When a positional deviation is generated on the double-faced tape, it
indicates that positional and angular deviations occur in Process C.
When no positional deviation is generated, it means that positional and
angular deviations occur in Process D or E.
(1-2) Positional and Angular Deviations in Process C
When a positional deviation is generated due to the movement of the
head
after component recognition or a rotational deviation by placement
angle correction, the deviation may be caused mainly by the following
two factors.
•
Deterioration of Vacuum Suction Force
•
V
ibration or Shock during Nozzle (Head) Movement
When one of the above factors exists, unstable components (components
that cannot be picked up in stable condition) such as those shown in
Fig. 4E7 are directly affected.
When a positional deviation is generated on the components (the
components of the same type that have been used in the past actual
production), check for the above-described factors.
As for vacuum suction force, check the nozzle and the vacuum line.
As for vibration during nozzle movement, check the related spots in the
range of Process C.
Fig. 4E7 Easily-Dislocated Components during Placement (Example 1)
Note
When there is a protruding portion on the upper surface of a component,
the lower surface of the vacuum nozzle may be worn out, causing an error
during the teaching operation through component recognition lighting.
3. Troubleshooting on Placement Errors
5-9
AIVEMT-ID
0606-009
(1-3) Positional and Angular Deviations in Process D or E
When a positional deviation is not generated on the double-faced tape,
it in
dicates that positional and angular deviations occur in Process D or E.
As a symptom at this time
•
The component is dislocated right after it is placed.
•
The component is dislocated during operation subsequent to the
placement.
•
The component is dislocated during PCB discharge operation
subsequent to the placement.
The causes in the above cases lie in the factors affected commonly by
the shape of the component, the condition of the PCB, or the condition
of solder paste or glue.
Fig. 4E8 is an example, which shows that a component is dislocated
right after it is placed due to the upper and lower surfaces of the
component not parallel to each other
.
A force is generated and moves the component in the X direction at the
moment when the lower surface touches the PCB during placement.
This leads to the positional and angular deviations of the component
placement.
When this type of component is used, this failure may be avoided by
slowing down the placement speed or slightly increasing the nozzle
descent level for the placement.
Some components may be dislocated easily during the backup base
movement or a PCB discharge operation after they are placed.
The factor may be weak holding power of solder paste or glue or
imperfect fixation of PCB.
It is required to check these conditions and take individual
countermeasures.
Fig. 4E8 Easily-Dislocated Component during Placement (Example 2)
3.1 Cause and Remedy of Placement Errors
5-10
AIVEMT-ID
0606-009
3.1 Cause and Remedy of Placement Errors
(2) Missing Components on PCB
(2-1) Situational Grasp of Error Generation
The following three symptoms can be assumed regarding why some
components are missing.
•
Some components were lifted up during placement.
•
Some components sprang out due to vibrating PCB or vacuum break
during placement.
•
A component sprang out while the PCB is being discharged after
placement.
The smaller the touch area with the PCB (solder paste) is in comparison
with the component size, the more frequently this type of failure occurs.
This applies commonly to these symptoms.
As shown in Fig. 4E9, power enough to hold a component will be given
when square components (resistors, capacitors, etc.) are used. However,
the above symptoms may appear more frequently when leaded
components (transistors, diodes, etc.) are handled because of the small
touch areas.
Square Component
Leaded Component
Shadowed are the touch areas between the components
and the solder paste.
Solder Paste
PCB
Note
Fig. 4E9