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Wave soldering refers to the melted soft platinum solder (lead-tin alloy), through the electric pump or electromagnetic pump jet into the design requirements of the solder wave,can also be formed by injecting nitrogen into the solder pool, so that the pre-installed components of the printed board through the solder wave,the components of the solder end or pin and the printed board pads of the soft platinum soldering between the mechanical and electrical connection. Wave soldering machine is mainly composed of transport belt, flux adding area, preheating area and wave soldering furnace.
PCBA OEM wave soldering process:fixture installation → flux system → preheating system → primary wave soldering → secondary wave soldering → cooling.
Wave soldering process
Face iPCB introduced wave soldering process step by step content and role:
1.Fixture installation
Fixture installation refers to the PCBA to be soldered to install support fixtures,which can limit the degree of heat deformation of the substrate in the soldering,to prevent the substrate from bending, liquid tin wave out of the board; in addition to the fixtures can protect the solder paste printing patch material is not washed out by the tin wave.
2.Flux System
Flux system is the first link to ensure the quality of soldering,the main role is to evenly coated flux, remove the components, pad surface oxidation layer and prevent re-oxidation of the soldering process;play an active role in the interface, to improve the wetting of liquid solder on the surface of the metal to be soldered.
3.Preheating system The role of the preheating system:
Solvent components in the flux in the preheating area by the heat volatilisation,to avoid the solvent components in the high temperature liquid tin surface through the explosion,the explosion will produce tin particles,that is,we usually say that the small tin beads;
The product warms up slowly as it passes through the preheat zone,avoiding damage to components caused by the sudden rise in thermal shock during soldering;
Components through the preheating zone to make up the temperature,will not be due to its own temperature is lower than the substantial reduction in the soldering temperature of the soldering joints,so as to ensure that the soldering in the specified time to meet the requirements of the soldering temperature.Preheat temperature setting is generally 130 ° C -170 ° C,time 1-3MIN,preheat temperature control can effectively prevent pulling the tip,false soldering, tin beads, tin, as well as thermal shock on the damage to the components, and PCB warpage, deformation, delamination and other issues.
4.Soldering System
Soldering area is generally a double wave, when soldering the PCBA first contact the first wave, and then contact the second wave.The first wave from a narrow nozzle spray turbulent wave, fast flow rate, the vertical pressure on the weldment, the device weld end of the better penetration; for welding layout complexity, masking effect has a greater role,upward injection of tin wave can also make the welding of the gas generated by the effective discharge; effectively reduce the lack of tin permeability, tin holes, leakage welding and other issues.
After the first wave, due to the short soldering time, devices, fixtures, PCB heat dissipation and other factors,a wave of soldering there are tin, tin, soldering strength is not enough and other problems. So the wave peak two will play a role, its nozzle is wider, tin wave width, slow flow, also known as the level of flow wave, conducive to the formation of a solid welding,while removing excessive solder end of the tin, to achieve a good wetting of the weld surface of the solder to correct the weld surface, eliminating the pulling of the tip, even tin, to achieve a solid welding effect to ensure the reliability of the weld.
5.Cooling system
After wave soldering, cooling helps to enhance the bonding strength of the solder joints and reduce the temperature of the product as well as help the personnel to work after the furnace.
wave soldering
Wave soldering preparation
1.Turn on the power, turn on the tin furnace heater (under normal circumstances, this can be controlled by the timer switch);
2.Check whether the wave soldering machine timer switch is normal;
3.Check whether the wave soldering machine ventilation equipment is good;
4.Check whether the tin furnace temperature indicator is normal: with a glass thermometer or contact thermometer to measure the temperature of the tin furnace liquid surface below l0 ~ 15mm,the difference between the two should be ± 5 ℃ range;
5.Check whether the preheater is normal,set the temperature is in line with the requirements of the process: open the preheater switch, check whether it is warming up,and whether the temperature is normal;
6.Check the work of the foot-cutting machine:According to the thickness of the PCB, adjust the height of the blade, the requirements of the component foot length of 14 ~ 20mm, and then screw the blade holder, start the machine to visually inspect the rotation of the blade, and then check the insurance device is out of order;
7.Check whether the flux container compressed air supply is normal: pour flux,adjust the air intake valve, switch on the machine to check whether the flux foam or spray;
8.Check the adjustment of flux specific gravity is in line with the requirements:check the height of the flux tank level, and measure the specific gravity,when the specific gravity is high add diluent, when the specific gravity is low add flux for adjustment (foaming);
9.Solder temperature reaches the required value,check the tin surface height,if lower than the furnace l5mm,should be timely to add solder,add attention to the batch to add, each batch of no more than 5k9;
10.Remove the tin surface slag, clean and add antioxidant;
11.Adjust the angle of the transport track: according to the width of the PCB to be welded, adjust the track width,so that the PCB is subject to the right clamping force.
Wave soldering operation specification
1.Wave soldering operation preparation
a.Check whether the wave soldering with good ventilation equipment;
b.Check whether the wave soldering machine timing switch is good;
c.Check whether the tin tank temperature indicator is normal; adjust the temperature indicator up and down, and then use a thermometer to measure the temperature at 10-15 mm below the liquid level of the tin tank,to determine whether the temperature varies with it.
2.Check whether the preheater system is normal or not: open the preheater switch and check whether it is warming up and whether the temperature is normal or not.
3.Check the working condition of the cutting foot knife: According to the thickness of the printed board and the length of the components retained by the lead line to adjust the height of the blade,and then screw the blade holder and stable, start the visual inspection of the blade's rotation, and finally check the insurance device has not failed.
4.Check whether the flux container compressed air supply is normal:pour flux,adjust the air intake valve,start the machine after the flux foam,use the sample printed board will be adjusted to the foam to the board thickness of 1/2,and then tighten the eye pressure valve, to be formally operated when no longer move this valve, only open the air intake switch.
5.Waiting for the above programme all normal,the party can be required for a variety of process parameters preset to the relevant position of the equipment.
The above is iPCB shared in the PCBA foundry wave soldering welding process and operation specifications.