Our company, Yixing Wencheng Chemical Co., Ltd., is a manufacturer of acrylate series products, including dipropylene glycol diacrylate (DPGDA). We have been engaged in the production and sales of acrylate series and their derivatives for over 15 years. In the previous two articles, 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) and pentaerythritol triacrylate (PETA) are irreplaceable essential raw materials for high-end PCB inks. High-end PCBs rely on DPHA and PETA to support their performance. DPHA enhances the high heat resistance and solderability of high-end PCB inks, while PETA is responsible for toughening, reducing shrinkage, and stabilizing adhesion. In this article, we will share another "golden partner" of DPHA and PETA based on our daily production and sales experience: dipropylene glycol diacrylate (DPGDA).
DPGDA is a difunctional UV acrylate monomer. It is a mainstream diluent and fleximetric monomer for PCB inks. As a reactive diluent and flexibility modifier, its role lies between that of a solvent and a functional monomer. DPGDA, in combination with PETA and DPHA, achieves a four-dimensional balance of viscosity, toughness, hardness, and heat resistance in high-end PCB inks. I can clearly describe how DPGDA, DPHA, and PETA are compounded and complement each other in a single table.
| Complementary Roles & Positioning of DPGDA, PETA and DPHA in High-End PCB Inks | |||
| Dimension | Dipropylene Glycol Diacrylate (DPGDA) | Pentaerythritol Triacrylate (PETA) | Dipentaerythritol Hexaacrylate (DPHA) |
| Core Positioning in High-End PCB Ink System | Reactive Diluent + Flexible Rheology RegulatorThe "basic conditioning base" of the system, responsible for solving printability issues | Toughness Skeleton + Adhesion CarrierThe "core connecting link" of the system, responsible for balancing performance and stability | Performance Capping Monomer + High-Strength Crosslinking SkeletonThe "performance ceiling" of the system, responsible for achieving the extreme indicators of high-end PCBs |
| Functionality & Core Structural Characteristics | 2-functional, linear flexible molecular structure with evenly distributed double bonds | 3-functional, branched molecular structure, balancing flexibility and crosslinking ability | 6-functional, highly branched stereo molecular structure with extremely high double bond density and ultra-strong crosslinking ability |
| Typical Viscosity at 25℃ (cps) | 10~30 (ultra-low viscosity, mainstream low-viscosity reactive monomer in the industry) | 800~1200 (medium viscosity, excellent rheological adaptability) | 4000~8000 (high viscosity, must be used with low-viscosity monomers) |
| Core Functional Roles in High-End PCB Inks | 1. Significantly reduce the overall viscosity of the system, optimize the printability of screen printing/coating and screen permeability, and solve the construction difficulties of high-viscosity monomers 2. Improve the dispersibility of pigments/fillers, and reduce printing defects such as pinholes, bubbles and shrinkage cavities 3. Provide basic flexibility, reduce the overall curing shrinkage of the system, and adapt to the processing of multi-layer boards/thin boards 4. Excellent substrate wetting ability, assisting to improve the adhesion effect between ink and copper foil/substrate |
1. Connect the preceding and the following, link low-functional and high-functional monomers, and balance the crosslinking density and rheological properties of the system 2. Core improvement of film toughness, buffer curing stress, and solve the problems of easy cracking and warping caused by high-functional monomers 3. Strengthen the substrate anchoring effect, greatly improve the adhesion between ink and copper surface, and eliminate peeling and film falling off 4. Assist to improve the chemical resistance and insulation of the system, without dragging down the core performance indicators of high-end boards |
1. Raise the overall crosslinking density of the system, and meet the high temperature and solder resistance requirements of 260~288℃ lead-free wave soldering and multiple reflow soldering 2. Endow the film with extremely high hardness, scratch and wear resistance, adapting to the subsequent processing of precision circuits 3. Form a dense crosslinking structure to achieve excellent resistance to flux, acid and alkali, and solvents 4. Improve the insulation resistance and ion migration resistance of the system, adapting to the high-voltage and high-frequency signal scenarios of AI servers and high-frequency & high-speed PCBs |
| Inherent Performance Shortcomings (When Used Alone) | 1. Low crosslinking density, unable to achieve the high temperature resistance, high hardness and high insulation requirements of high-end PCBs when used alone 2. Poor heat resistance, easy blistering and falling off during high temperature soldering when used alone 3. Weak chemical resistance, unable to pass the chemical immersion test for high-end boards |
1. Insufficient ultimate crosslinking ability, unable to reach the high heat resistance and high solder resistance indicators of high-end boards when used alone 2. Hardness and wear resistance are weaker than 6-functional monomers, unable to achieve high-hardness protection requirements alone |
1. Extremely high viscosity, unable to perform normal screen printing/coating when used alone, with extremely poor printability 2. High curing shrinkage rate, easy to cause board warping, film cracking and edge falling off when used alone 3. High film brittleness, poor bending resistance and mechanical impact resistance 4. Weak substrate adhesion, easy to cause peeling and film falling off when used alone |
| Core Complementary Logic with the Other Two Monomers | 1. Complementary with PETA: DPGDA provides low-viscosity leveling, PETA provides toughness and adhesion. The combination forms a stable flexible base system, solving the problems of insufficient performance of single low-viscosity monomer and poor printability of single medium-viscosity monomer 2. Complementary with DPHA: DPGDA greatly offsets the high viscosity and high shrinkage defects of DPHA, solves the problems of difficult construction and easy cracking of DPHA, and does not affect the exertion of DPHA's high crosslinking performance |
1. Complementary with DPGDA: PETA supplements crosslinking density, hardness and chemical resistance for the flexible system of DPGDA, solving the problem of insufficient performance upper limit of single low-viscosity monomer 2. Complementary with DPHA: PETA perfectly makes up for the core shortcomings of DPHA, greatly reduces the brittleness of the system, improves adhesion, offsets curing shrinkage, and does not affect the exertion of DPHA's high heat resistance and high insulation performance. It is the "best golden partner" of DPHA |
1. Complementary with DPGDA: DPGDA provides a low-viscosity leveling base for the high crosslinking system of DPHA, solves the core pain point of poor printability of DPHA, and makes the high crosslinking formula adaptable to industrial production 2. Complementary with PETA: PETA provides toughness buffer and adhesion guarantee for the high-strength system of DPHA, solves the problems of easy cracking and easy film falling off of DPHA, and makes the high crosslinking formula adaptable to the complex manufacturing processes and harsh environments of high-end PCBs |
| Scenario Adaptation Priority for High-End PCBs | ★★★☆☆Universal adaptation, dosage must be strictly controlled in high-end scenarios to avoid dragging down core performance | ★★★★★Full scenario adaptation, an essential core monomer for high-end PCB inks | ★★★★★A necessary monomer for high-end PCB inks, replaceable for ordinary civil boards |
| Typical Addition Ratio in High-End PCB Ink System (mass fraction) | 10%~15%(12%~18% for general solder mask inks, no more than 15% for high-end scenarios) | 6%~8%(5%~9% for general solder mask inks, core ratio 6%~8% for high-end scenarios) | 6%~10%(4%~7% for general solder mask inks, core ratio 6%~10% for high-end scenarios) |
| Core Quality Control Indicators for High-End PCB Grade | 1. Purity ≥98% 2. Acid Value ≤0.3mgKOH/g 3. Moisture Content ≤0.1% 4. Color APHA ≤30 5. Halide ions ＜50ppm, Metal ions ＜10ppm |
1. Purity ≥98% 2. Acid Value ≤0.3mgKOH/g 3. Moisture Content ≤0.1% 4. Color APHA ≤30 5. Halide ions ＜50ppm, Metal ions ＜10ppm |
1. Purity ≥98%, Hexaacrylate content ≥90% 2. Acid Value ≤0.5mgKOH/g 3. Moisture Content ≤0.2% 4. Color APHA ≤60 5. Halide ions ＜50ppm, Metal ions ＜10ppm |
Common production/process issues and parameter tuning solutions for DPGDA, DPHA, and PETA.
1. High ink viscosity, screen clogging, stringing, poor leveling: Slightly increase DPGDA (+2%~3%), appropriately decrease DPHA (-1%~2%), and keep PETA unchanged at 6%~8%. Utilize the low viscosity of DPGDA to quickly reduce viscosity, improve screen printing transmittance, and without compromising ink toughness and adhesion.
2. Board warping, edge cracking, brittle paint film: Increase PETA to 7%~8%, maintain DPGDA at 12%~15%, and decrease DPHA to 5%~6%. Reduce the proportion of high-shrinkage, high-brittleness DPHA, and rely on PETA for toughening and stress relief, and DPGDA to reduce overall shrinkage, to solve the cracking and warping of thin boards and multilayer boards.
3. Solderability issues such as blistering, high-temperature porosity, and substandard heat resistance: Reduce DPGDA (-2%~3%, controlled at 10%~13%), increase DPHA to 7%~9%, and maintain PETA at 6%~7%. Reduce the proportion of low-heat-resistant flexible monomers and improve high-temperature solderability through highly cross-linked DPHA; simultaneously, use high-purity PETA with ≤0.1% moisture and low acid value to eliminate the risk of high-temperature blistering.
4. Poor chemical resistance, flux whitening, and color bleeding corrosion: Reduce DPGDA to 10%~12%, increase DPHA to 7%~8%, and maintain a stable PETA ratio of 6%~8%. Increasing the DPHA proportion enhances the dense cross-linked structure of the coating film, preventing chemical penetration, preserving PETA's toughness, and preventing the coating film from hardening, becoming brittle, and peeling off.
5. Poor adhesion, peeling, and delamination:PETA increased to 7%~9%, DPGDA slightly increased by 1%~2%, DPHA reduced to 5%~6%. PETA strengthens the adhesion to the copper surface, DPGDA improves substrate wetting, and the reduced proportion of high-hardness DPHA reduces brittle delamination. Simultaneously, PETA is kept low in ionic impurities.
6. Soft film, easily scratched, insufficient abrasion resistance:DPGDA reduced to below 10%, DPHA increased to 8%~10%, PETA maintained at 6%~7%. Reducing flexible components and increasing crosslinking density improves film hardness and abrasion resistance, while retaining an appropriate amount of PETA ensures the film does not crack.
7. Text ink fading, blurring, and poor abrasion resistance:PETA 8%~10%, DPGDA 15%~18%, DPHA reduced to 3%~5%. The text ink prioritizes adhesion toughness and printing clarity, reducing the brittleness of DPHA, relying on PETA to fix the lettering and prevent detachment, and DPGDA to optimize leveling and imaging.
8. Ink storage instability, viscosity fluctuations, and easy gelation. Maintain a fixed standard mixing ratio range: DPGDA 10%~15%, PETA 6%~8%, DPHA 6%~10%, avoiding arbitrary over-addition of flexible monomers; simultaneously strictly control the high purity indicators of the three monomers and the standard polymerization inhibitor content, control production temperature ≤45℃, and avoid light during feeding to ensure ink storage stability.
DPHA determines the upper limit of performance for high-end PCB inks, PETA determines the lower limit of ink toughness and adhesion, while DPGDA determines whether high-end inks can be stably mass-produced and precision printed. Our high-quality dipropylene glycol diacrylate (DPGDA), pentaerythritol triacrylate (PETA), and dipentaerythritol hexaacrylate (DPHA) series products are stable in performance and excellent in quality, exported to many countries worldwide, and widely used in PCB inks, 3C and plastic UV coatings, printing inks, 3D printing, and adhesives industries. With fifteen years of experience in the industry, we have always adhered to quality and stable production capacity, and sincerely welcome customers from all walks of life to inquire, discuss cooperation, and work together!
