Photovoltaic graphite thermal field components are the core core components of solar silicon wafer crystal pulling furnaces, including graphite heaters, heat insulation barrels, heat insulation plates, crucible brackets and conductive structural parts. The purity, structural stability and thermal uniformity of graphite thermal field directly determine the conversion efficiency, yield and production cycle of photovoltaic silicon wafers. In the P-type battery era, the industry has low requirements for graphite thermal field, and medium-purity spliced graphite components can basically meet production needs. However, after the large-scale popularization of N-type high-efficiency photovoltaic technology in 2026, the technical standards of photovoltaic graphite thermal field have been completely updated, and traditional low-end products have been completely eliminated from the mainstream photovoltaic supply chain.
The essential difference between N-type and P-type photovoltaic graphite thermal field lies in the ultra-high purity and ultra-uniform thermal field environment requirements. N-type high-efficiency silicon wafers have extremely high sensitivity to metal impurities and thermal field fluctuations. Trace metal impurities such as iron, chromium and nickel in graphite will volatilize at high temperature above 1400℃ and penetrate into molten silicon, forming minority carrier recombination centers inside silicon wafers, resulting in reduced cell conversion efficiency and increased light attenuation rate. Therefore, N-type photovoltaic production strictly requires that the ash content of graphite thermal field components is lower than 10ppm, which is far stricter than the 50ppm standard of P-type thermal field.
In terms of structural design, N-type long-cycle crystal pulling technology puts forward higher requirements on the integrity and stability of thermal field components. Modern large-size 210mm silicon wafer production adopts uninterrupted long-time crystal pulling of more than 220 hours per furnace. The traditional segmented spliced thermal field has assembly gaps, which are prone to temperature field distortion, local oxidation and silicon vapor erosion residue during long-term high-temperature operation, resulting in frequent furnace shutdown maintenance and low production efficiency. The integrated integral graphite thermal field structure has no assembly gaps, which can realize ultra-uniform temperature field distribution, effectively resist high-temperature silicon vapor erosion, and greatly extend the continuous service cycle of thermal field components.
The manufacturing process of N-type photovoltaic high-purity graphite thermal field has exclusive professional technical points in blank selection, purification treatment and structural optimization. In terms of blank selection, only ultra-fine grain high-density isostatic synthetic graphite can be used, and natural graphite and ordinary molded graphite are completely excluded due to unstable impurity content and loose structure. In terms of purification technology, secondary high-temperature halogen purification and multi-cycle vacuum pressure impregnation processes are required. The first purification removes macroscopic impurities, and the secondary deep purification eliminates trace volatile impurities, ensuring that the component impurity content is stably within the N-type standard range.
In terms of service life optimization, professional photovoltaic graphite manufacturers need to carry out targeted density enhancement and anti-oxidation treatment for thermal field components. High-density impregnation treatment can fill the internal micro-pores of graphite, reduce the adsorption of silicon vapor and oxygen, and avoid component oxidation and corrosion failure. At the same time, the integrated structural design optimizes the thermal stress distribution of the components, reduces the thermal fatigue damage caused by repeated temperature rise and fall, and increases the service life of the thermal field by more than 40% compared with traditional spliced products.
Huixian Jincheng Abrasive & Graphite Mold Factory has mastered the full set of core manufacturing technologies for N-type photovoltaic high-purity graphite thermal field components, and is one of the early domestic manufacturers to complete the technical iteration of N-type photovoltaic thermal field products. The company takes the lead in abandoning all medium and low-purity graphite raw materials, and uses high-quality ultra-fine grain isostatic synthetic graphite blanks for all photovoltaic thermal field products. Through self-developed secondary high-temperature deep purification process, the company stably controls the ash content of thermal field components below 8ppm, which is higher than the international N-type photovoltaic industry standard.
Aiming at the pain points of short service life and unstable thermal field of traditional photovoltaic graphite parts, Jincheng Graphite optimizes the integrated integral structural design of thermal field components, replaces segmented splicing structures with large-size integral heaters and heat insulation barrels, and realizes zero gap assembly of the whole thermal field system. Combined with multi-cycle vacuum high-density impregnation technology, the company effectively improves the anti-oxidation and anti-silicon vapor erosion ability of components, and the continuous service life of thermal field products is increased by more than 45% compared with the industry average level.
In addition to customized manufacturing of new thermal field components, Jincheng Graphite also provides professional thermal field renovation, purification regeneration and maintenance services for old photovoltaic equipment of global customers. For traditional P-type thermal field components that cannot meet N-type production standards, the company conducts deep impurity removal, density enhancement and structural optimization transformation, helping photovoltaic enterprises complete low-cost technical upgrades and improve production efficiency. At present, the company's N-type high-purity graphite thermal field products and supporting services have been exported to many photovoltaic manufacturing bases in Southeast Asia, Europe and the Middle East, and have been widely recognized by global high-efficiency photovoltaic enterprises.
With the continuous iteration of HJT and next-generation ultra-high-efficiency photovoltaic technologies, the purity and stability standards of photovoltaic graphite thermal field will be further improved. Jincheng Graphite will continue to optimize purification processes and structural design schemes, upgrade high-efficiency photovoltaic graphite thermal field supporting solutions, and help the global photovoltaic industry continue to reduce costs and increase efficiency.
