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Pcb manufacturer china PCBA cleaning method and technics

 

For pcb manufacturer china, the water cleaning technics can be divided into saponified water cleaning and water cleaning according to the type of flux used in the printed circuit assembly.

(1) Saponified water cleaning technics. For printed circuit assemblies soldered with rosin flux, pcb manufacturer china should use a saponified cleaning technics. This is because the rosin acid, the main component of the rosin, is insoluble in water, and it is necessary to use water as a solvent to convert the rosin into a water-soluble rosin fatty acid salt under the action of a saponifier, and then spray it under high pressure water. Only after the rosin fatty acid can be removed, and finally washed with clean water to achieve the purpose of cleaning. Saponified water cleaning technics process:

 

Wave soldering or reflow soldering → Rosin flux residue → 60% saponified water cleaning → Deionized water rinsing → Drying

 

The saponified water cleaning process can remove a wide range of contaminants, and pcb manufacturer china can select appropriate saponifiers for cleaning according to the flux used, affecting the performance and quality of printed circuit components. In addition, the saponified water cleaning technics is unstable for the cleaning of non-rosin flux residues.

 

(2) Clean water cleaning technics. Water purification is the use of clean water or pure water for washing and rinsing during washing. Compared with the saponified water cleaning technics, the water purification cleaning is mainly applied to the printed circuit assembly using the water-soluble flux for soldering. This cleaning method is very simple, and the technics flow is as follows:

 

Wave soldering or reflow soldering → water soluble flux residue → deionized water rinse → deionized water rinse → dry

 

The water purification technics is simple in operation and low in cost, but the quality of the water-soluble flux is not stable enough, the technics is not easy to control, and it is used less in actual production.

 

  1. Semi-aqueous cleaning method

(1) Principle of semi-aqueous cleaning. Semi-aqueous cleaning is a cleaning method between the solvent cleaning and water cleaning processes, that is, the components are first cleaned with a solvent, rinsed with water, and finally the cleaned components are dried. A semi-aqueous cleaner is one of the keys to both dissolving rosin and dissolving in water. When cleaning, pcb manufacturer china first dissolves the rosin residue on the component quickly, then cleans the component with water, and the solvent is mutually soluble with water. At this time, the rosin residue will float out of the component and float in the water to achieve the purpose of removing pollutants. .

 

(2) Characteristics of semi-aqueous cleaning technology. Semi-aqueous cleaning First clean the welded SMA with terpene or other semi-aqueous cleaning solvent, then rinse with deionized water. Semi-aqueous cleaning process using terpene semi-aqueous cleaning solvent:

 

Wave soldering or reflow soldering → solvent cleaning → deionized water rinsing → deionized water rinsing → drying

 

Since the terpene-based semi-aqueous cleaning solvent has slight side effects on the circuit components, the solvent must be rinsed with deionized water after cleaning. It can be rinsed with flowing deionized water or a steam spray rinse technics. In practical applications, an important part of different semi-water cleaning should be selected according to the needs, so that the emissions comply with environmental protection requirements. In addition, since the solvent in the semi-aqueous cleaning is relatively expensive, the solvent is extracted by the solvent and water separation technique after the “deionized water rinsing” step, and the solvent is recycled.

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