4M184002w_F8S - 第308页
4OM-1840 5-1-9 1604-001 (1-3) Positional or Angular Deviation in Process D or E When a positional deviation is not generated on the double-faced tape, it indicates that positional and angular deviations occur in Process …
4OM-1840
5-1-81604-001
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
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
•
Vibration 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 F4E7 are
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.
Easily-Dislocated Components during Placement (Example 1) F4E7
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
4OM-1840
5-1-91604-001
(1-3) Positional or Angular Deviation in Process D or E
When a positional deviation is not generated on the double-faced tape, it
indicates 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.
shape of the component, the condition of the PCB, or the condition of solder
paste or glue.
F4E8 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.
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
It is required to check these conditions and take individual countermeasures.
Easily-Dislocated Component during Placement (Example 2) F4E8
3.1 Cause and Remedy of Placement Errors
4OM-1840
5-1-101604-001
(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
F4E9
3.1 Cause and Remedy of Placement Errors