How To Solve The Wave Soldering Through The Tin Bad Problem?

In the PCBA through-hole components wave soldering oven process, the rate of tin permeability is very important, whether the tin permeability is good directly affects the welding quality and product reliability. If the through-hole component wave soldering is not good, it is easy to cause problems such as false soldering.

I. Wave soldering machine through the tin rate requirements

Wave soldering oven solder joints through the tin rate should generally reach more than 75%, that is, the panel appearance test through the tin rate should be higher than 75% of the thickness of the board, through the tin rate of 75% -100% can be. Wave soldering in the welding heat is sucked by the PCB board fast, if the temperature is not enough there will be poor tin permeability. In order to get more heat from the PCB, you can adjust the corresponding tin eating depth according to different PCBs.

II. Factors affecting the rate of wave soldering through the tin

Wave soldering defects are mainly related to the raw materials (PCB boards, components), wave soldering process, flux usage, and the level of manual soldering.

III. Raw Material Factors

Under normal circumstances, melted tin has strong permeability, but not all metals can be penetrated, such as aluminum. Aluminum forms a dense protective layer on the surface of the metal and its molecular structure makes it difficult for other molecules to penetrate. In addition, if the metal surface has oxidation, tin is also difficult to penetrate, you need to use flux treatment, or clean up the oxidation layer.

IV. Wave soldering process factors

Poor tin penetration and wave soldering process is closely related to the need to reset the optimization of welding parameters, such as: wave height, temperature settings, welding time and moving speed. Orbital angle can be appropriately lowered to increase the height of the wave crest to improve the contact surface of the tin liquid and the pad. Then adjust the wave soldering temperature appropriately, the higher the soldering temperature, the stronger the penetration of tin, but the soldering temperature should be within the tolerable temperature range of the components. Finally, you can reduce the transportation speed, increase the preheating and soldering time, so that the flux can fully remove the surface oxides, penetrate the solder joints, and improve the rate of tin penetration.

V. Flux Factors

Surface oxides, and to prevent re-oxidation during the soldering process, flux selection, uneven spraying, use too little or too much will lead to poor tin penetration. First of all, use the regular brand of flux, the effect will be better, in addition to regular inspection of the flux nozzle, to prevent clogging or damage to the nozzle.

VI. Artificial welding factors

In the wave soldering quality inspection, a part of the component is only the surface of the solder joints to form a cone, and through the hole is not through the tin, the formation of virtual welding. Similar problems generally occur in manual soldering, mainly because of insufficient welding temperature or welding time is too short. Poor solder penetration in wave soldering can easily cause soldering errors, thus increasing the cost of manual rework. Selective wave soldering is much better than the wave soldering rate, if the product has high requirements for welding quality and tin permeability, you can use selective soldering, which can reduce the problem of poor tin permeability to some extent.

Features of NeoDen ND250 Wave soldering machine

Heating Method: Hot Wind

Cooling method: Axial fan cooling

Transfer Direction: Left→Right

Temperature Control: PID+SSR

Machine Control: Mitsubishi PLC+ Touch Screen

Flux tank capacity: Max 5.2L

Spray Method: Step Motor+ST-6