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SMT reflow oven operation guide

Time:2019-09-03   |   Source: grandseed   |   Compile :9

SMT reflow oven is most widely used way to connect surface mounted components with printed PCB . The purpose is preheating components/PCB/bonding pad then melted solder paste to take of shape acceptable solder joints. SMT reflow oven is the main parts of effect  quality factor in SMT technology, will lead to mass rack of fusion if misoperation. Here, Grandseed shares the SMT reflow oven operation guide with an example of 8 temperature zone reflow oven.

First、The start of SMT reflow oven.

1、Close the main power supply of the equipment (open it in the electric cabinet at the lower left of the machine) and turn on the switch of the smoke exhaust system in the workshop to make it run normally

2、Press machine right-left side POWER button, turn on computer, enter reflow oven system interface. After confirmed system communication regular, call lead-free solder paste procedure. Check 8 temperature zone target temperature(lead) SV should be :165、160、175、185、190、190、240、200. conveying belt speed should be 75cm±10cm/min.

3、Click the general start button on reflow oven control system interface, close blowing、conveying、heating、cooling switch, made machine into running.

4、Cooling machine need after heating 20~30 minutes, Observe whether the actual temperature PV and set value SV in the window are stable, Yes: move to next step, No: reset the PID parameter values temperature-controlled meter, and observe whether it became stable in 5~10 minutes then move to next step.

The calibration is adjusted by the technician 

1、Place the thermometer and its three probes on the test board with the same size as the test PCB, And make it carry out temperature measurement in furnace with conveyor belt, read out the actual temperature of the board at each time point on PC temperature measuring software

2、Compared the above test results with standard curve, if test curve with standard curve same or nearly, allow to starting produce;otherwise, to set SV value again (increase or decrease with gradient of about 5) on the temperature control meter with large temperature difference compared with the standard curve, or match conveyor steel belt speed to overall adjust, to reach actual production of the workpiece temperature control curve.

Second、SMT reflow oven function area description.

First zone-preheating zone, Second zone-preheating zone, 

Third zone-preheating zone, Fourth zone-arid zone

Fifth zone-arid zone, sixth zone-activation zone

Seventh zone-welding zone, Eighth zone-fast cooling zone

Third、SMT reflow oven setting temperature of each zone(SV value)

First zone—165 ±2℃ Second zone—160 ±2℃ Third zone-175 ±2℃ Fourth zone -185 ±2℃ Fifth zone-190±2℃ Sixth-190 ±2℃ Seventh-240±2℃ Eighth zone -200±2℃ Ninth zone-indoor temperature cooling zone

Fourth、SMT reflow oven temperature control curve adjust and setting.

1, Setting main control value- Move the mouse pointer to the reflow furnace control software HMI main screen and click in the corresponding temperature area of the reflow furnace to be adjusted, input the desired SV setting on the jump - out pad; Press OK to exit the set, value range of 0~399.

2, Setting PID parameter- Choose the ‘setting’ in option menu of reflow oven control system software, click the ;password’ option in menu, input the username and password in pop-up screen, after system confirm the legal operator(technical)then start inter PID parameter setting: Click in the value window of the corresponding upper and lower temperature area of the reflow soldering furnace that jumps out, and input the required P (or I) parameter setting value on the little keyboard of the standing number that jumps out; Press OK to exit the set value range of 0~399.

Fifth、SMT reflow soldering quality request.

1, Welding components in the process of welding should not be affected by vibration and askew erect displacement

2, PCB components reflow soldering process time should be control in 3~5 minutes

3, solder paste reflow well, after welding, the welding spot on the plate surface should be bright and even, solder wetting pad element leads evenly

4, No PCB color changing copper foil warping off and other undesirable phenomena

Sixth、 SMT reflow oven power off operation.

1, Under normal state;

①Check the all PCB in reflow oven whether soldered finish.

② Close heating, after 20~30 minutes, click general switch、close blowing、conveying、heating、cooling switch, close computer.

③ Or adopt automatic delay close down model, click automatic close down button directly.

④ Close machine general power supply(back lower left of machine)

2, In emergency state;

①Press machine emergency button on left side of machine.

② Close machine general power supply(back lower left of machine)

Seventh、SMT reflow oven operation;

1.The setting of the temperature zone cannot be adjusted at will. The parameters of the above temperature zone are basically 90% of the effective area of the steel mesh transferred in the welding furnace according to the area of the welded PCB board、best speed normally being 75cm±10cm/S (depends on better actual curing effect). when the processed PCB board area is large, the belt speed should be fine-tuned to achieve good welding effect. the general principle of adjustment is: when the PCB board area is small, the net will take away faster; when the PCB board area is large, the net will take away slower.

2. PID parameters of temperature control meter shall not be set arbitrarily

3. The inlet and outlet of the reflow welder should avoid the external natural wind blowing in the process of use, which will affect the dynamic temperature balance in the furnace and affect the welding quality

4. When PCB workpiece is sent out of the discharge port of reflow welding furnace, the accident of burning operator's hand should be avoided; It is also necessary to prevent PCB boards from piling up at the outlet, causing PCB boards to fall or PCB boards with low solder strength at high temperature at the exit. SMD components may fall off due to falling or extrusion impact.

5. Do the daily maintenance of reflow oven: Clean the surface of the equipment daily to make it free from dirt. When refueling manually, press the refueling button once a week to lubricate the rolling chain with high temperature lubricating oil (BIO-30): during continuous production, at least twice a month: check to add high temperature lubricating oil to the furnace motor and each rotating shaft wheel

6.Check whether the grounding wire of the welding machine is connected reliably before starting the machine daily

7.After troubleshooting, close the main power supply of the equipment, turn the red mushroom emergency stop switch clockwise, and then return to the original working state. PCB and transfer steel mesh belt should not be stopped in the furnace under high temperature when shut down, it should be stopped after the temperature drops in the machine!