User-Manual-NeoDen-IN12-Reflow-oven.pdf - 第18页

17 Figure 4:Set too high/low temperature of active z one Figure 5:Soldering too much/li ttle

example, the automatic trigger of 38°C (100°F) allows the thermometer to start

working as soon as the PCB is put on the conveyor chain and into the furnace, so

that the thermocouple will not be triggered by mistake when it is handled by the

human.

Once the initial temperature profile is generated, it can be compared with the

profile recommended by the solder paste manufacturer or the profile shown in

Figure 2.

First, it must be verified that the total time from the ambient temperature to the

peak temperature of the reflux is compatible with the desired stay time of the

heating curve. If it is too long, increase the conveyor speed proportionally; if it is

too short, decrease the conveyor speed proportionally.

In the next step, the shape of the temperature profile must be compared with the

desired one (Figure 2). If the shape is not compatible, then compare it with the

following figures (Figures 3-6). Choose the most compatible temperature profile

compared to the actual shape of the profile. Should consider the deviation from left

to right (process sequence). For example, if there is a difference between the

preheating and soldering zones, first adjust the difference in the preheating zone

correctly. Generally, it is best to adjust one parameter at a time and test in run

before making further adjustments.Because a change in a given zone will also

affect the results of subsequent zones. We also recommend that novices had better

make small adjustments. Once you gain experience on a particular oven, you will

have a better "feel" to make more big adjustments.

Figure 3:Preheat too much/little soldering profile

Figure 4:Set too high/low temperature of active zone

Figure 5:Soldering too much/little

Figure 6:Cooling too much/little

When the final temperature profile is as close as possible to the desired profile, tke

record or store of the parameters for later use. Although this process is slow and

laborious at first, it can eventually gain proficiency experience, resulting in high-

efficiency production of high-quality PCBs.

6. Temperature profile setting method

♦Set the temperature of each zone and the speed of the conveyor chain from the initial

value. For cold oven, preheat for ~30 minutes.

♦After the preheating is completed, let the PCB go through the heating soldering

system. If soldering does not occur, the conveyor chain speed can be appropriately

reduced. Or on the premise of not changing the transmission chain speed,increase the

set temperature appropriately, and pay attention to not exceeding the bearing capacity

of the PCB and components when adjusting the set temperature.

♦Let the PCB go through the new conveyor chain under new speed or the adjusted set

temperature,if no soldering occurs,then do the adjustment of the previous step,

otherwise proceed to the next step to fine-tune the temperature profile.

♦The temperature profile can be adjusted appropriately according to the complexity of

the PCB.Can reduce the speed of the conveyor chain and increase the soldering time;

on the contrary, add the speed of the conveyor chain will reduce the soldering time.

♦Generally, when the PCB with components mounted on passes through the soldering

system but is not completely slodered, it can be properly adjusted and then put into the

soldering system for soldering again. Generally, it won’t effect on the PCB and

components.

♦The temperature setting is generally from low to high. If the soldering temperature

range exceeds the set temperature much, should increase the speed of the conveyor

chain or reduce the set temperature.

♦Different PCB boards have different heat transfer rates and heat absorption, then the

heating time and temperature required by soldering are also different. For double-layer

boards and multilayer boards and PCBs with more areas and pads, the setting

temperature is relatively higher , And for single-sided boards or paper plastic boards or