N,N'-(4,4'-diphenylmethane)bismaleimide is an aromatic bismaleimide resin known for its excellent high temperature resistance and mechanical properties. It is a high melting point yellow powder with strong chemical resistance.In the electronics field, BMI resins manufactured by Yangchen tech is used to make heat-resistant laminates and electrical insulation materials for harsh conditions (H/F grades). In contrast, traditional epoxy resins are widely used in PCB laminates and adhesives due to their low cost and ease of use, but they begin to lose strength and degrade at high temperatures. This blog compares the material properties and application differences of 4,4′-bismaleimide (BMI) and epoxy resins in electronic devices. N,N'-(4,4'-diphenylmethane)bismaleimide Whatever you needs, Yangchen Tech is at your side. Warehouse of Yangchen Tech Whatever you needs, Yangchen Tech is at your side. Warehouse of Yangchen Tech Whatever you needs, Yangchen Tech is at your side.   The rigid, highly conjugated structure of N,N'-(4,4'-diphenylmethane) bismaleimide gives it a high melting point (about 150-160°C) and glass transition temperature. It is almost insoluble in water/ethanol, but soluble in polar organic solvents such as acetone or DMF. High curing temperatures (usually 200-250°C) make BMI crosslinked into a dense three-dimensional network structure with excellent thermal stability.Commercial systems usually mix BMI with vinyl or allyl comonomers (e.g. DABA, vinyl phenol) to improve toughness. Cured BMI is still harder and stronger than most epoxies at high temperatures.   Technical Indicators   Appearance Melting point Acid value Volatile Specification Gel time 200℃ Toluene Solubility Yellow powder 150-160℃ ≤1mgKOH/g ≤1% ＞98% ＜300 S Totally soluble or a small amount of insoluble matter, transparent solution   The significant advantage of 4,4′-bismaleimide (BMI) resins is thermal stability. Unlike standard epoxy resins, which soften and lose modulus above about 120-150°C, BMI-based networks maintain mechanical integrity at temperatures well above 200°C. BMIs maintain strength and stiffness in high temperature environments (e.g., aerospace engines, gas turbines) where epoxies tend to fail. In fact, high-Tg BMI laminates or prepregs maintain excellent mechanical properties up to about 250°C. In contrast, most epoxy-based electronic materials have a Tg below 150°C, limiting them to low-grade insulation applications. BMI also has excellent mechanical strength and stiffness. Its rigid aromatic backbone gives it high tensile and flexural strength. Compared to epoxies, BMI composites can withstand greater static and dynamic loads without deformation. For example, parts made with a 4,4′-BMI matrix, such as aircraft fuselage panels or connector housings, will exhibit higher compression and impact resistance than equivalent epoxy-based parts. In tests, BMI composites have demonstrated improved durability under heavy loads and high-velocity impacts, thereby extending the service life and improving the safety of high-performance equipment. While epoxies are tough at room temperature, they tend to become brittle or creep at elevated temperatures, while the network rigidity of BMI remains strong. Another key advantage is its chemical and environmental resistance. BMI resins are more resistant to corrosion from solvents, acids, and other chemicals than typical epoxy formulations.   Property 4,4′-BMI (Bismaleimide Resin) Epoxy Resin Glass Transition (Tg) >200 °C (often ~250 °C); stable mechanical/dielectric at high temps ~100–150 °C; mechanical properties degrade above ~120 °C High-Temp Strength Retains strength up to ~250 °C Softens and may creep/fail well below 200 °C Mechanical Modulus Stiffer at all temperatures (especially when toughened) Less stiff overall; can be toughened but weakens at high temp Density Lightweight vs. metal; potentially lighter than epoxy formulations Lightweight vs. metal; but slightly denser than BMI in some cases Thermal Conductivity Poor conductor; can be filled for thermal applications Poor conductor; also fillable with ceramics or carbon Electrical Insulation Meets Class F/H (155–180 °C); suitable for motors, coils, high-temp circuits Often limited to Class B (130 °C); may not meet high-temp specs Flame Rating Inherently flame-retardant; low smoke/toxicity, fewer additives needed Needs more additives for flame retardancy