Technical requirements and operation precautions for wave soldering process

Date：2022-11-16 16:04:23Views：901

Wave soldering refers to the soldering of melted soft solders into solder peaks as required by the design by spraying them through an electric pump or an electromagnetic pump. It can also be formed by injecting nitrogen into the solder pool, so that the printed boards with components in advance can pass through the solder peaks to realize the soft soldering of mechanical and electrical connection between the component terminals or pins and the printed board pads. Next, the technical requirements and operation precautions of the down wave soldering process will be described in detail.

Technical requirements for wave soldering process

1、 Flux density of wave soldering

The welding surface of the PCB assembly to be welded shall be coated with flux. In order to ensure effective soldering, the flux density must be strictly controlled.

1. The density D of rosin based flux shall be controlled within 0.82-0.84g/cm3;

2. The density D of water-soluble flux shall be controlled within 0.82-0.86 g/cm3;

3. The density of cleaning free flux and flux with special requirements shall be controlled within the specified technical conditions.

2、 Wave soldering preheating temperature

The printed circuit board shall be preheated after being coated with flux. The preheating temperature of single side PCB is 80-90 ℃; The preheating temperature of double-sided circuit board is 90-100 ℃.

3、 Wave soldering temperature

The welding temperature depends on the temperature required to form the alloy layer at the solder joint. The lead-free wave soldering temperature T1 is (250 ± 10) ℃.

4、 Wave crest height and tin pressing depth

The height of the wave crest mainly affects the solder flow rate and the contact condition between the solder and the wave crest. Generally, the wave crest height of the wave crest welder can be adjusted between 0-10MM, and the optimal wave crest height should be controlled within 7-8MM. The tin pressing depth of printed circuit board is 1/2 --- 3/4 of the board thickness.

5、 Transport traction angle of wave soldering circuit board

The traction angle of PCB transportation has an effect on the contact and separation of solders and solders. The reasonable value of traction angle shall be controlled between 6 degrees and 10 degrees.

6、 Transport transmission speed and welding time of wave soldering

The transmission speed V of wave soldering affects the preheating effect, welding time and the separation process of solder joint and solder.

The welding time t shall be 3-4 s.

The transmission speed V can be calculated according to the following formula: V=L/t, where: L --- wave crest width, usually L is 60MM; T --- welding time, s; V --- Transmission speed, mm/s

7、 Solder requirements in wave soldering furnace

1. The solder used for wave soldering is Sn Pb eutectic alloy, with a general tin content of 63%; Or lead-free tin silver copper solder, with tin content above 96%;

2. The total solder of the wave soldering furnace shall be sampled and analyzed regularly. If the alloy content or impurities exceed the standard, it shall be adjusted or replaced in time;

3. The allowable range of solder impurities shall be used as specified.

Precautions for wave soldering

1、 Inspection before wave soldering:Before welding, check the operation of the equipment, the quality of the printed circuit board to be welded and the condition of the plug-ins on the printed circuit board. Be aware of the situation. If there are errors, correct them in time.

2、 Inspection during wave soldering:During welding, pay attention to the welding quality and the operation of the equipment at any time, analyze the composition of the solder and the consumption of the solder, replace or supplement the solder to the tin cylinder in a timely manner: deal with the oxide film on the solder surface in a timely manner. To prevent oxidation, tin oil composed of mineral oil and fatty acid is added to the solder.

3、 Inspection after wave soldering:Check the welding quality one by one after welding, and pay attention to the occurrence of defects such as missed welding and bridging. For a small number of defective solder joints, manual repair welding can be carried out. For a large number of defects, the causes must be found out to suit the remedy.

In the wave soldering process, the soldering tin is always in a circulating flow state, with oxides and pollutants at the wave, and the PCB is in relative motion with the wave, so the flux vapor is easy to volatilize, and no bubbles will be generated at the welding points, with high efficiency and quality. However, due to various factors, wave soldering is easy to cause short circuit between welding points, and has the disadvantage of large workload of repair welding.

The above is the wave soldering related content compiled by the wound core detection team, and I hope it will be helpful to you. Our company has a team of professional engineers and industry elites, and has built three standardized laboratories with an area of more than 1800 square meters, which can undertake a variety of test projects such as electronic component test verification, IC authenticity identification, product design material selection, failure analysis, functional testing, factory incoming material inspection and tape weaving.