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A defoamer manufacturer explains the applications of defoamers in electronic circuit board cleaning.
Release Date:
2021-02-08
Throughout the entire process of cleaning electronic circuit boards, the chemicals used at each stage vary, and the requirements for defoamers differ accordingly. When selecting a defoamer, it is essential to consider its intended purpose and compatibility; otherwise, emulsion-breaking performance may be poor or ineffective, and there is even a risk of triggering safety incidents.
Defoamer manufacturer Let me tell you about the applications of defoamers in electronic circuit board cleaning.
I. Classification of residual materials from printed electronic device circuit boards and soldering processes
1. Particulate contaminants—dust, lint, and solder balls.
2. Non-polar contaminants—rosin resins, paraffin wax, and antioxidant oils used in wave soldering machines;
3. Skincare products, hand sanitizers, and other items left behind by workers.
4. Optically active contaminants—halides, acids, and salts.
II. Harm Caused by Residuals from Printed Electronic Circuit Boards and Welding Processes
Particulate contaminants can cause electrical short circuits; optically active contaminants may lead to dielectric breakdown, resulting in leakage currents and corrosion of components or circuitry; non‑polar contaminants can degrade the appearance—manifesting as white powder spots or adhering dust—and may also give rise to abnormal conditions such as poor electrical contact.
III. Stages at Which Residues Appear in Printed Electronic Device Circuit Boards and Soldering Processes
1. Developer solution: During the development process, residual developer (such as potassium carbonate) may remain on printed electronic circuit boards.
2. Etching process: Primarily involves residual sulfuric acid and hydrogen peroxide, which exhibit optical activity and corrosive properties.
3. Stripping: Primarily involves residual sodium hydroxide solution, which is optically active and corrosive.
4. Soldering: The process typically leaves behind residual solder balls and flux, among other residues. These residues are compositionally complex, comprising particulate contaminants, nonpolar contaminants, optically active contaminants, and more.
IV. Selection and Application of Defoamers in the Cleaning of Residues from Cotton Yarn and Welding in Printed Electronic Circuits
1. Developer‑solution stage: The solution is typically a 1–2% aqueous sodium carbonate solution, with a recommended rinsing temperature of 20–40°C. Due to equipment design, spray‑type systems, ultrasonic cleaning, and other methods, significant foam can accumulate in the bath; therefore, an antifoaming agent must be added when initially setting up the bath (and again when the liquid level is low). Either silicone‑based or non‑silicone antifoams may be used, provided they are resistant to acids and strong electrolytes and exhibit excellent emulsion‑breaking performance. From a cost‑effectiveness standpoint, silicone‑based antifoams are generally preferable.
2. Etching Process Stage: The etchant typically consists of hydrochloric acid solution and hydrogen peroxide, with the temperature maintained at 40–50°C. Defoamers should generally be non-silicone types, added to the return tank (at low liquid level), and characterized by good water solubility, acid resistance, antioxidant properties, and compatibility with tank materials.
3. Demolding/De‑molding Stage: The etchant is typically a 1.5–3% aqueous sodium hydroxide solution, with the temperature generally maintained at 30–50°C. A non‑silicone defoamer is usually selected; when added in the replenishment tank (at low liquid level), it should be soluble in strong electrolytes, resistant to alkali and high temperatures, and non‑corrosive to tank plates.
4. Electro‑welding stage: Typically, a specialized cleaning agent (with a pH generally slightly alkaline) is used; its concentration and temperature are determined according to the specific requirements. In some cases, ultrasonic cleaning may reach temperatures as high as 80°C. The defoamer should be non‑silicone, soluble in strong electrolytes, corrosion‑resistant, heat‑stable, and free from plate‑forming tendencies.
V. Frequently Asked Questions
Throughout the entire process of cleaning electronic circuit boards, the chemicals used at each stage vary, and the requirements for defoamers differ accordingly. When selecting a defoamer, it is essential to consider its intended purpose and compatibility; otherwise, emulsion breaking may be ineffective or fail altogether, and there is even a risk of triggering safety incidents.
Today, most manufacturers adopt zero‑discharge practices for cleaning, with all cleaning and chemical solutions being recirculated. Under these conditions, cooling water at each stage should be circulated separately rather than mixed—particularly when the defoamers used in different stages vary (e.g., silicone‑based vs. silicone‑free, or differing corrosion‑resistance properties)—to prevent excessive material consumption and potential safety incidents.
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