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Various Functions of PCB Ink

Release time:

2025-07-22 16:55

Various Functions of PCB Ink
Various Functions of PCB Ink

In the electronics manufacturing sector, printed circuit boards (PCBs) play a pivotal role, and PCB inks are an indispensable key material. These inks not only provide protection and identification during circuit fabrication but also directly influence the performance and reliability of the circuit board. This article focuses on the three core types of PCB inks—circuit‑etching ink, solder‑mask ink, and legend ink—examining their functions, characteristics, and applications throughout the manufacturing process.

I. Circuit Etching Ink

Circuit‑etching ink is primarily used in the printed circuit board manufacturing process to protect copper‑foil areas that are not intended to be etched. This ink typically appears blue, which is why it is also referred to as circuit blue ink or photosensitive blue ink. Its main function is to define precise circuit patterns during the etching process.

1. Role in the process flow

During the manufacturing process, circuit‑etching ink is applied to the copper foil surface via screen printing, forming a photosensitive resist layer. Following exposure, development, and curing, the copper foil areas not covered by the ink are etched away, while the regions protected by the ink remain intact. Finally, the ink is removed using an aqueous sodium hydroxide solution, yielding the desired circuit pattern.

2. Performance Characteristics

Etch resistance: Able to effectively withstand the corrosive action of etching solutions.

Acid–alkali resistance and electroplating resistance: Ensures the structural integrity of the circuit during chemical processing.

Good adhesion: remains stable during manufacturing and subsequent use.

These characteristics of circuit‑etching inks make them a critical material for ensuring circuit accuracy and stability.

II. Solder Mask Ink

Solder resist ink, also known as solder mask ink, is one of the most widely used inks in PCB manufacturing. Its primary function is to prevent solder from inadvertently flowing onto non‑solderable areas during the soldering process, while also providing protection for the circuit board.

1. Main Functions

Insulation protection: prevents solder from adhering to non-soldered areas, thereby improving soldering quality.

Environmental Protection: Protects copper foil circuits from chemical exposure, moisture, and physical abrasion.

Extended service life: By isolating the board from the external environment, its stability and durability are enhanced.

2. Classification of Curing Methods

Solder resist inks can be classified into the following three categories based on their curing methods:

Photosensitive development type: Cured by ultraviolet light, suitable for fabricating fine circuits and widely used in various rigid PCBs.

Thermosetting type: Cured by heating after printing, commonly used in specialized products such as mobile phone antenna boards and light‑bar boards.

UV-curable type: fast curing speed, suitable for automated production lines, and high production efficiency.

3. Performance Advantages

High insulation: effectively prevents short circuits.

High-temperature and chemical resistance: Suitable for demanding processes such as reflow soldering and electroless plating.

Excellent adhesion: ensures it does not easily come off during long-term use.

These characteristics of solder resist ink enable it to play an irreplaceable role in ensuring the stability and reliability of printed circuit boards.

III. Text Ink

Text ink is used to print characters, part numbers, markings, and other information onto circuit boards, providing clear guidance for subsequent assembly, inspection, and maintenance. Although its function may appear straightforward, it is indispensable in practical applications.

1. Application Form

Color options: White and black are the most common, with white being more widely used.

Curing method: Primarily thermosetting; a portion also employs UV curing technology.

2. Performance Requirements

High opacity: Ensures characters are clear and easily legible.

Printability: Suitable for a variety of printing processes.

Durability: The characters remain intact and do not fade or peel off over prolonged use.

The presence of ink markings not only enhances the readability of the circuit board but also facilitates subsequent production management and maintenance.

IV. Summary

Although PCB inks account for only a small fraction of the overall volume of a circuit board, their role is far from negligible. Circuit‑etching inks ensure precise formation of the circuit pattern, solder‑resist inks enhance soldering quality and extend the board’s service life, and legend inks provide clear, legible information for manufacturing and maintenance. Each type of ink fulfills its specific function, together forming an indispensable material system in PCB fabrication.

Disclaimer: The above content has been compiled from publicly available sources and is provided for reference only. If any infringement occurs, please contact us, and we will address it promptly.

Bossin Related Product Recommendations – Solder Mask Ink
Product Model/English Abbreviation Product Name/Product Type Product Features
B-05 Phosphate ester acrylate Enhance adhesion to substrates such as metal, glass, and plastic.
B-191A Phenolic epoxy acrylate Fast curing and excellent heat resistance
B-196S Modified o‑methylphenol‑formaldehyde epoxy acrylate Fast curing, excellent heat resistance, and superior development performance.
BM3231 (TMPTA) Trimethylolpropane triacrylate High crosslink density, high hardness, high gloss, and excellent wear resistance.
BM6261 (DPHA-80) Dipentaerythritol hexaacrylate High crosslink density, high hardness, chemical and wear resistance, and water resistance.
BM6263 (DPHA-90) Dipentaerythritol hexaacrylate High crosslink density, high hardness, chemical and wear resistance, and water resistance.

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