Our company, Yixing Wencheng Chemical Co., Ltd., is a manufacturer of acrylate series products, including pentaerythritol triacrylate (PETA). We have been engaged in the production and sales of acrylate series and their derivatives for over 15 years. In our previous article, we mentioned that with the rapid advancements in technology in recent years, the explosive growth of AI servers, new energy vehicles, optical communications, and optical modules has led to a surge in global demand for high-end PCBs. Dipentaerythritol hexaacrylate (DPHA) is the core skeletal monomer of high-end PCB inks. Ordinary PCBs can use TMPTA and HDDA to make up the formula; high-end PCBs must rely on DPHA to support the performance. DPHA is a hexafunctional ultra-high crosslinking monomer and is an essential raw material for high-end solder resist green ink, text ink and photosensitive ink to meet the standards. It cannot be easily replaced. In this article, we will share our experience with DPHA's "golden partner," pentaerythritol triacrylate (PETA), based on our daily production and sales experience.

If DPHA enhances the "defense" (high heat resistance and solderability) of high-end PCB inks, then PETA is the "Thor's hammer" (responsible for toughening, reducing shrinkage, and strengthening adhesion). The combination of "spear" and "shield" provides a good balance to the overall performance of high-end PCB inks. A table can clearly illustrate how DPHA and PETA complement each other.

DPHA and PETA Compatibility Logic

Toughness Framework: PETA is responsible for bonding the substrate and buffering stress, solving the cracking and delamination problems that DPHA easily encounters when used alone.

Performance Capping: DPHA increases cross-linking density, achieving solderability above 260℃, chemical resistance, and high insulation.

General DPHA and PETA Mixing Ratio Ranges

1. Conventional Solder Resist Inks

PETA: 5%~9%, DPHA: 4%~7%, with a ratio of approximately 1:0.7~1:1.

2. High-End AI/Automotive PCB Inks

PETA: 6%~8%, DPHA: 6%~10%, with a ratio of approximately 1:1.

3. PCB Text Inks

PETA: 7%~10%, DPHA: 3%~5%, focusing on preventing lettering from fading and resisting abrasion.

Common PCB Circuit Board Problems and DPHA and PETA Adjustment Solutions:

1. Edge cracking, board warping: Increase PETA and reduce DPHA (PETA ratio is too low; increase to 7%–8%, DPHA to 6%–7%).

2. Solderability blistering, deterioration in solvent resistance: Increase DPHA ratio (This could also be due to excessive PETA moisture (>0.1%) or high acid value; replace with high-quality PETA).

3. Insufficient ink adhesion, film peeling: Increase PETA ratio (This could also be due to insufficient PETA purity or high ionic impurities; strictly control Cl⁻/Na⁺ < 50 ppm).

4. Thick ink difficult to print: Fine-tune and reduce DPHA, then optimize system viscosity with PETA (This could also be due to high PETA viscosity > 1200 cps; use a batch with 800–1000 cps).

High-end PCB inks have extremely high requirements for PETA quality. Purity and impurity control are core indicators for pentaerythritol triacrylate used in high-end PCB inks. The ester content of the product must reach 98% or higher, far exceeding the standard of 95% for ordinary grades. The proportion of monoester and diester impurities must be strictly controlled to be less than 1.5%, and the content of tetraacrylate impurities must not exceed 0.5%. The acid value limit is 0.3 mgKOH/g, which is more stringent than the 1.0 mgKOH/g limit for ordinary products. Excessive acid value can easily corrode the copper plate surface, weaken the insulation performance, and interfere with the acid-base stability of development. The moisture content must be controlled within 0.1%, while the upper limit for ordinary grades is 0.2%. High moisture content will cause curing blistering, reduced solderability, and shorten the product storage period. The color APHA value must be ≤30, which is different from the requirement of ≤100 for ordinary products. The material is colorless or very light yellow, which can ensure the stability of ink color without yellowing. Excellent light transmittance also helps to achieve deep and full curing. Regarding ionic impurities, the chloride and bromide ion contents must both be below 50 ppm to meet the requirement of a total chloride and bromide content of less than 150 ppm in the halogen-free standard. The sodium, potassium, and iron ion contents must all be controlled below 10 ppm to effectively avoid problems such as line leakage, electrochemical migration, and deterioration of insulation performance. The content of the polymerization inhibitor MEHQ must be stably maintained in the range of 200 to 300 ppm. If the content is too low, the material is prone to self-polymerization and gelation, while if the content is too high, it will inhibit the curing reaction and reduce the sensitivity of photosensitive imaging.

Our high-quality pentaerythritol triacrylate (PETA) and dipentaerythritol hexaacrylate (DPHA) series products are known for their stable performance and excellent quality. They are exported to many countries worldwide and are widely used in industries such as PCB inks, 3C and plastic UV coatings, printing inks, 3D printing, and adhesives. With fifteen years of experience in the industry, we have always adhered to the principles of quality and stable production capacity. We sincerely welcome customers from all walks of life to inquire, discuss cooperation, and collaborate!