Our company is Yixing Wencheng Chemical Co., Ltd., a production plant of polyols, including dipropylene glycol (DPG). We have been engaged in the production and sales of polyols and their derivatives for more than 30 years. PCB inks are divided into four main categories: liquid photosensitive solder resist green ink, UV solder resist ink, character ink, aluminum substrate white ink, and FPC flexible ink. Screen printing and spraying processes both have industry pain points such as screen clogging, pinholes, cavities, poor leveling, pre-baking bubbling, storage viscosity drift, and jagged printing edges. Dipropylene glycol (DPG) relies on its amphoteric molecular structure of dihydroxyl + ether bond to serve as a medium-to-high boiling point slow-drying cosolvent, film-forming aid, viscosity stabilizer, and wetting and moisturizing agent embedded in the solvent system. Unlike ether ester solvents such as DPM, DPMA, cyclohexanone, and DBE, it is a low-cost, low-irritant, and highly compatible multifunctional blending component in PCB ink formulations. Based on our production and sales experience, we will analyze and dissect the application and role of DPG in PCB inks from four dimensions: the core function and underlying working principle of DPG in PCB ink formulation; the DPG addition amount for different PCB ink categories; the core competitive advantages of DPG compared to commonly used PCB solvents; and commercial value.
Dipropylene glycol (DPG) is a multifunctional solvent with excellent compatibility with PCB ink systems due to its unique molecular structure that combines hydrogen bonding, polarity, and weak nonpolarity. It is fully compatible with main resins such as epoxy acrylic, phenolic epoxy, and modified acrylic, as well as photoinitiators, curing agents, and various pigments. It is also miscible with PMA, DPM, DPMA, DBE, and water without separation. During the production and grinding stage, DPG can effectively reduce the viscosity of the system, improve the wetting and dispersibility of pigments, improve the sedimentation of white oil and titanium dioxide, and prevent floating color and blooming. At the same time, it can partially replace cyclohexanone, reducing ink odor and VOC stimulation in the workshop. With its high boiling point and extremely low evaporation rate, DPG is compatible with PCB ink gradient baking processes. During the wet film stage, it can continuously maintain resin flow and repair micropores and orange peel defects. During the pre-baking stage, it can prevent premature skinning of the surface layer, which can cause pinholes and bursts. High-temperature curing can completely evaporate without residue, without affecting the paint film's resistance to reflow soldering, chemical gold, and acid and alkali. It significantly improves the printing yield of large boards and thick ink layers. Additionally, DPG offers excellent moisture retention and viscosity stability, effectively delaying ink drying during screen printing to prevent mesh clogging, stringing, and ragged or broken characters; this makes it suitable for high-speed automated lines and thin-layer FPC printing, significantly enhancing continuous printing stability. Its hydrogen-bonding structure stabilizes ink viscosity, mitigating fluctuations during high/low-temperature storage and transport, while extending the pot life of two-component inks and reducing scrap rates. In addition, DPG can play a wetting and coupling role, effectively improving the adhesion of inks to copper foil, FR4, and aluminum substrates, preventing ink peeling, delamination, reflow and lifting, and can replace corrosive ether solvents to protect precision circuits. Compared to traditional solvents such as cyclohexanone and isophorone, DPG is low in odor, low in toxicity, and not subject to high-risk restrictions, making it more environmentally friendly and fully meeting the environmental protection and occupational health requirements of the PCB industry. It is a high-quality, multi-functional solvent that balances ink production stability, application performance, finished product reliability, and green compliance.
Addressing the application challenges and formulation requirements of different types of PCB inks, DPG offers customized addition ratios to precisely resolve production and process defects in various inks: ① Liquid photosensitive solder resist green oil (add 3%–7%): Effectively controls the pre-baking evaporation gradient, avoids issues such as paint film skinning, pinholes, and residual adhesive, optimizes the leveling properties of large boards and thick ink layers, ensures uniform board surface gloss, smooth screen printing, and eliminates localized copper exposure defects. ②UV-curable solder resist ink (added 2%–4%): Maintains the fluidity of the paint film before curing, releases internal stress during curing, reduces the generation of micro-cracks, and improves the problems of uneven gloss and uneven brightness on matte panels. ③ PCB character ink (white/black characters, add 4%–8%, DPG optimal application scenario): efficiently wets titanium dioxide, inhibits pigment sedimentation and stratification, greatly improves the hiding power of white ink, and makes characters on dark board surfaces clear and transparent; at the same time, it has excellent moisturizing and anti-drying properties, which can support long-term continuous printing without screen clogging and without text burrs or broken lines. ④ White oil for aluminum substrates/light panels (add 5%–9%): significantly improves the wetting and spreading ability of aluminum substrates, enhances the adhesion and flexibility of the paint film, and solves defects such as baking cracking, paint peeling, and paint bursting due to thermal shock. ⑤ FPC flexible circuit ink (add 3%–5%): Extends the leveling open time of the thin oil layer, ensures the integrity and continuity of the ultra-fine circuit film, improves the bending toughness of the paint film, and avoids the problems of thin oil drying shrinkage and circuit breakage.
DPG possesses irreplaceable and unique application advantages in PCB ink systems: First, its molecules have a dual active structure of hydroxyl and ether bonds, integrating multiple functions such as dissolution and dispersion, moisturizing and anti-clogging, viscosity stability, and substrate wetting. It can replace various additives in compound formulations, greatly simplifying ink formulation systems. Second, its volatility characteristics are precisely matched to the two-stage baking process of PCBs. Low-temperature pre-baking allows for slow evaporation, effectively eliminating pinhole and orange peel defects, while high-temperature curing ensures complete evaporation without residue, without affecting the key reliability of the coating film such as reflow soldering resistance and chemical gold resistance. Third, its overall formulation cost is excellent. Compared with mainstream solvents such as cyclohexanone and DPMA, its unit price is lower and its addition amount is controllable. At the same time, it can reduce the amount of leveling, dispersing, and defoaming additives, effectively reducing the overall raw material cost. Naturally, DPG used in PCB ink production must meet stringent electronic-grade specifications: a purity of ≥99.5% with strict control over mono-propylene glycol and tri-propylene glycol isomers; moisture content ≤0.1% to prevent ink whitening or poor development; APHA color ≤10 to avoid board surface discoloration; extremely low acidity to prevent premature ink cross-linking and shelf-life reduction; and iron/heavy metal ion content ≤1ppm to ensure suitability for high-end precision circuit boards and prevent electrochemical corrosion. Additionally, the product is low-odor, leaves no baking residue, and is fully compatible with various ink resins, solvents, and pigments, without compromising core film properties such as photosensitivity, solder resistance, or chemical gold plating resistance. Yixing Wencheng Chemical Co., Ltd. is a premier manufacturer of Dipropylene Glycol (DPG); its industrial-grade DPG is widely used across various industries, including the PCB ink sector.
DPG offers significant commercial value to PCB ink manufacturers: it can substantially improve common process defects such as ink pinholes, screen clogging, character burrs, and poor adhesion, effectively reducing defect rates for end customers and helping products penetrate high-end PCB markets such as servers and new energy vehicles, thereby enhancing brand premium; with its multi-functional properties, it can replace multiple functional additives, simplifying formulation structures and reducing raw material costs by 8%–15% compared to traditional ether ester systems; relying on its low odor, low toxicity, and environmental compliance advantages, it is suitable for cleanrooms and environmental impact assessment requirements, differentiating itself from traditional cyclohexanone system products and significantly enhancing market competitiveness; at the same time, DPG has strong versatility, covering a full range of inks for solder resist, characters, aluminum substrates, and FPC, effectively reducing the types of solvents to stock and lowering enterprise warehousing and management costs.
Our company's dipropylene glycol (DPG) has been widely and long-term used in the production of PCB inks. Our DPG products are stable in performance, of excellent quality, and have a stable supply. They are sold to many countries around the world. With 30 years of experience in the industry, we always adhere to quality and stable production capacity. We sincerely welcome customers from all walks of life to consult, negotiate and cooperate with us!
