User-Manual-NeoDen3V-PNP-machine.pdf - 第42页
37 3.2.5.3. Instruc tion about S oldering Printing Excellent p rinting graph ics should be unifo rm in both vertical a nd ho rizontal direction ,full,clean all roun d, sold er paste fill solder pa d. Using ab ove such pr…
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3.2.4. Maintenance of Device
Routine check and maintenance policy should be established.
3.2.4.1. Check Below Points Daily
Inspection Items
Please check below
before turn on the
machine
1) Temperature and humidity: temperature range from 20℃ to 26℃, humidity
range from 45% to 70％.
2) No stuff on dual rails or the whole placement area.
3) No stuff on the fix camera lens. Make it clean and tidy.
4) No stuff around the head nozzles.
5) Check if nozzle is dirty or out of shape. Clean it or change it into a new one.
6) No stuff on the feeders, and make sure they’re well installed.
7) Check if the air hose is well connected with the machine.
Please check below
after turn on the
machine
1) Check if the monitor’s screen could display well after system starting working.
2) Check if emergency switch could work well.
3) Check if the placement head could return to the original place correctly.
4) Check if noise happens when placement head moving.
5) Check if negative pressure could under a normal range.
6) Check the PCB’s transmission on dual rails to see if the sensor still works
well.
7) Check the positioning column and holes are correct and fastened.
3.2.4.2. Check Below Points Monthly
Checking Points
Checking List
X、Y axis
Make sure no abnormal noise when placement head move.
X、Y motor
Make sure motors working well, no abnormal heating appearance.
Nozzle
Check if nozzles stretch well with no bending and check if the suction surface is
horizontal.
Air hose
Check the air hose and connector, make sure hose is fine without broken, abrasion or
air-leak etc.
Step Motor
Make sure no dust on the step motor, synchronous belt and synchronous wheel; the Z
axis motor can rotate and fluctuate without obstacles.
Z axis Motor
Check if the placement head could move up and down smoothly. Push up the nozzle by
hand to see whether it can move smoothly. Move the placement head up and down in
the proper range.
Negative pressure
check all nozzles’ negative pressure.If abnormal,please clean nozzles.
Positive pressure
check whether they’re normal.
Optical axis
please check whether it is covered dusk. Please keep it clean and lubricated.
Operation button
check each button to make sure they are well-worked
Connector
check if well-connected of the air connector and air hose.
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3.2.5. Related Issues During Solder Paste Printing Process
3.2.5.1. Stencil Printer Technology
Screen printing technology refer to using ready-made stencil, directly contact to the printer in a certain way, make
the solder paste evenly flow on the stencil and then leak into the mesh through the holes. When getting the stencil
away, solder paste had been covered to the printed circuit board solder graphics corresponding, thus complete the
solder paste printing on the PCB.
3.2.5.2. Inspecting of Solder Paste Printing
Printing process is one of the key working procedure to ensure the quality of surface mounting. According to the
statistics,under the premise of guaranteed quality about components and PCB,correctly PCB design, 70% of the
surface quality problem caused during printing process. In order to ensure the quality of SMT assembly, it is
necessary to strictly control the quality of the solder paste printing.
The amount of solder paste printing requirements are as follows:
The using amount of solder paste should be uniform, good consistency. Solder paste graphics should be clear,
try to avoid adhesion between adjacent graphics. Solder paste graphics and solder graphics should be
consistent.
In general,keep unit area amount of solder paste about 0.8 mg/mm². For fine pitch components, should be 0.5
mg/mm² (using stencil thickness and hole size to control in the actual operation).
Printed on the substrate of solder paste compared with required value, a certain deviation is permissible, the
covering area of the solder paste on each solder pad should be more than 75%.
Should be no seriously collapsing problem and edges neatly after solder paste had been printed, the
dislocation shouldn’t be larger than 0.2 mm, for solder pad of fine pitch components,dislocation shouldn’t be
larger than 0.1MM,pollution by solder paste is not permitted to the PCB.
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3.2.5.3. Instruction about Soldering Printing
Excellent printing graphics should be uniform in both vertical and horizontal direction,full,clean all round, solder
paste fill solder pad. Using above such printing graphics device, after reflow soldering,will get good welding
effect then.
Defects
Reasons
Issues
Solutions
Solder paste
graphics
dislocation
Holes on the stencil not good
match with solder pad; No
enough precision of the Printing
machine
Easily cause
bridge connection
Adjust the stencil position;
Adjust the printing machine.
Solder paste
graphics have
icicles and dents
Scraper’s pressure is too large;
Rubber scraper’s hardness is not
enough;
Holes are too big in the stencil
Solder paste’s required
volume is not enough,
easy to appear faulty
soldering;solder joint
strength is not enough.
Adjust the printing pressure;
Use metal scraper; Improved
holes designing in the
stencil.Too much solder paste
Too much solder
paste
Holes are too big in the stencil;
The gap is too big between
stencil and PCB.
Easily cause
bridge connection
Check the holes size in
stencil; Adjust the parameters
of printing, especially the gap
between PCB and stencil
Graphic
uneven(have
breakpoints)
Holes’ wall are not smoothness
enough; not wipe residual solder
paste in using for many times;
Solder paste’s thixotropy is bad.
Easy cause no enough
solder paste, lead to
the problem such as
faulty soldering.
Wipe the stencil
Contamination of
the graphics
Not wipe residual solder paste in
stencil after using for many
times; Poor quality of solder
paste; Shake problem when
getting the stencil way
Easily cause
bridge connection
Wipe and clean stencil;
replace solder paste;adjust
the machine.