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CN-122000153-A - Electrode for low-cost high-surge-resistance thermistor chip and preparation method thereof

CN122000153ACN 122000153 ACN122000153 ACN 122000153ACN-122000153-A

Abstract

The invention discloses an electrode for a low-cost high-surge-resistance thermistor chip and a preparation method thereof. The high-resistance transition layer is eliminated, the contact resistance is stable, the circulation requirement of a power NTC thermistor is completely met, the copper paste is low in cost, the electrode porosity is low, the through-current density is high, surge current can be born, no ablation works for more than 1000 hours under steady-state through-current, the contact resistance is low in amplification, the reducing atmosphere sintering can be adapted to the transformation of the existing thick film production line, the magnetron sputtering process has no extra equipment investment, and the high-resistance high-temperature ceramic material can be directly produced in a large scale.

Inventors

  • WU LIANGYOU

Assignees

  • 江苏时恒电子科技有限公司

Dates

Publication Date
20260508
Application Date
20260306

Claims (10)

  1. 1. The electrode for the low-cost high-surge-resistance thermistor chip is characterized by comprising a substrate, a composite barrier layer, a silver seed layer, a thick film electrode layer and an oxidation-resistant layer, wherein the upper surface and the lower surface of the substrate are covered with 30-50nm of composite barrier layers, the bottom of each composite barrier layer is 20-30nm of Ti, the upper part of each composite barrier layer is covered with 30-50nm of Ta, the composite barrier layers are covered with 20-30nm of silver seed layers, the silver seed layers are covered with 8-10 mu m of thick film electrode layers, the oxidation-resistant layers are sputtered on the surfaces of the thick film electrode layers, the oxidation-resistant layers are silver, the thick film electrode layers are made of copper, and the glass glaze protective layer is arranged around the periphery of the substrate and covers the sides of each composite barrier layer, the silver seed layers, the thick film electrode layers and the oxidation-resistant layers.
  2. 2. The electrode for a low-cost high-surge-resistance thermistor chip according to claim 1, wherein the substrate is a spinel ceramic substrate and the thickness of the oxidation-resistant layer is 50nm.
  3. 3. The preparation method of the electrode for the low-cost high-surge-resistance thermistor chip according to claim 1 is characterized by comprising the following steps, Step one, preprocessing a substrate, namely selecting a spinel ceramic substrate, and sequentially performing ultrasonic cleaning and plasma cleaning to remove surface impurities and an oxide layer; Sputtering the composite barrier layer, namely respectively adopting a magnetron sputtering process to deposit a Ti-Ta composite barrier layer on the upper surface and the lower surface of the pretreated substrate; sputtering the silver seed layer, namely continuing magnetron sputtering the silver seed layer on the surface of the sputtered Ta layer, wherein the uniformity deviation of the thickness of the sputtered silver seed layer is less than +/-5%; Step four, preparing a thick film electrode, namely selecting copper paste as a thick film electrode material, and printing high-density copper paste on the surface of a silver seed layer by adopting a thick film printing process; step five, surface activation treatment, namely after electrode sintering, adopting plasma cleaning to remove a trace oxide layer on the surface, and forming a rough structure on the surface; and step six, antioxidation treatment, namely performing magnetron sputtering on a thick silver layer on the surface of the thick film electrode subjected to surface activation treatment to form an antioxidation layer.
  4. 4. The copper electrode for the low-cost high-surge-resistance thermistor chip according to claim 3, wherein in the fourth step, a nitrogen protection furnace is selected for electrode sintering, the thick film electrode is sintered under the protection of nitrogen, the sintering time is 40-60min, the high-temperature sintering time is 3-8min, the high-temperature sintering temperature is 500-600 ℃, and after the sintering is completed, the temperature is reduced to below 100 ℃ and discharged from the furnace, so that the sintering of the thick film electrode is completed.
  5. 5. The method for manufacturing an electrode for a low-cost high-surge-resistance thermistor chip according to claim 3, wherein in the fifth step, ar plasma cleaning is adopted for plasma cleaning, the cleaning power is 180W, the time is 6min, the processing temperature is 130 ℃, the thickness of an oxide removal layer is less than 5nm, and the roughness Ra is about 0.25 μm.
  6. 6. The method for preparing the electrode for the low-cost high-surge-resistance thermistor chip according to claim 3, wherein in the first step, a neutral cleaning agent is adopted for ultrasonic cleaning, the cleaning time is 8min, the temperature is 45 ℃, the plasma cleaning power is 100W, the time is 3min, the argon flow is 15sccm, and the low-temperature annealing is 300 ℃ and the time is 30min.
  7. 7. The method for preparing the electrode for the low-cost high-surge-resistance thermistor chip according to claim 3, wherein in the second step, argon pressure of the Ti layer magnetron sputtering is 0.6Pa, sputtering power is 220W, target base distance is 90mm, argon pressure of the Ta layer is 0.7Pa, sputtering power is 240W, and target base distance is 90mm.
  8. 8. The method for preparing the electrode for the low-cost high-surge-resistance thermistor chip according to claim 3, wherein in the third step, the magnetron sputtering argon pressure of the silver seed layer is 0.4Pa, the sputtering power is 200W, and the sputtering rate is 6nm/min.
  9. 9. The method for manufacturing an electrode for a low-cost high-surge-resistance thermistor chip according to claim 3, wherein in the fourth step, the screen mesh number is 250 during thick film printing, the doctor blade pressure is 0.45MPa, and the printing speed is 40mm/s.
  10. 10. The method for manufacturing an electrode for a low-cost high-surge-resistance thermistor chip according to claim 3, wherein in the sixth step, the sputtering temperature of the oxidation-resistance thick silver layer is 160 ℃, the argon pressure is 0.4Pa, and the sputtering power is 190W.

Description

Electrode for low-cost high-surge-resistance thermistor chip and preparation method thereof Technical Field The invention belongs to the technical field of thermistor materials, relates to a manufacturing technology of a rate-type NTC thermistor, and particularly relates to an electrode for a low-cost high-surge-resistance thermistor chip and a preparation method thereof. Background The ceramic substrate of the power NTC thermistor is metal oxide (manganese, cobalt, copper, nickel and the like) spinel semiconductor ceramic, and the core application scene is power supply loop surge suppression and steady-state large-current operation. In the prior art, a thick film silver electrode is a mainstream scheme, but the continuous surge of silver price leads to high cost, namely a 5-8 mu m thick silver electrode, so that the cost pressure of the product is remarkable, and the cost of the 10 mu m thick silver electrode which is suitable for larger surge/steady-state current is further increased. Therefore, it is urgent to select an ideal alternative material to be a power type NTC thermistor. Among them, copper paste is the first choice of alternative materials because of its low price and excellent electrical conductivity. However, when the copper paste NTC spinel ceramic is directly sintered, the problems that an interface reaction is easy to generate a high-resistance oxidation transition layer to form non-ohmic contact (contact resistance is more than 50mΩ), so that the through-flow is blocked, the ablation is easy to occur under the surge impact, the interlayer binding force is weak, the separation is easy to occur after the thermal cycle, and the silver electrode cannot be directly replaced are all existed. Therefore, developing an electrode preparation method which can solve the ohmic contact problem and has the advantages of cost reduction, surge resistance and long steady state performance becomes a technical problem to be solved urgently in the industry. Disclosure of Invention Aiming at the problems, the main purpose of the invention is to design the electrode preparation method which can solve the ohmic contact problem and has the advantages of cost reduction, surge resistance and long steady-state performance. The invention adopts the following technical scheme for realizing the purposes: An electrode for a low-cost high-surge-resistance thermistor chip comprises a substrate, a composite barrier layer, a silver seed layer, a thick film electrode layer and an oxidation-resistant layer, wherein the upper surface and the lower surface of the substrate are both covered with 30-50nm of composite barrier layer, the bottom of the composite barrier layer is 20-30nm of Ti, the upper part of the composite barrier layer is covered with 30-50nm of Ta, the composite barrier layer is covered with 20-30nm of silver seed layer, the silver seed layer is covered with 8-10 mu m of thick film electrode layer, the surface of the thick film electrode layer is sputtered with the oxidation-resistant layer, the oxidation-resistant layer is silver, the thick film electrode layer is made of copper, and a glass glaze protective layer is arranged around the substrate and covers the side surfaces of the composite barrier layer, the silver seed layer, the thick film electrode layer and the oxidation-resistant layer. As a further description of the invention, the substrate is a metal oxide (manganese, cobalt, copper, nickel, etc.) spinel ceramic substrate with an oxidation resistant layer thickness of 50nm. The preparation method of the electrode based on the high anti-surge thermistor chip with low cost mainly comprises the following steps, Step one, preprocessing a substrate, namely selecting a spinel ceramic substrate, and performing ultrasonic cleaning and plasma cleaning to remove surface impurities and an oxide layer; Sputtering the composite barrier layer, namely respectively adopting a magnetron sputtering process to deposit a Ti-Ta composite barrier layer on the upper surface and the lower surface of the pretreated substrate; sputtering the silver seed layer, namely continuing magnetron sputtering the silver seed layer on the surface of the sputtered Ta layer, wherein the uniformity deviation of the thickness of the sputtered silver seed layer is less than +/-5%; Step four, preparing a thick film electrode, namely selecting copper paste as a thick film electrode material, and printing high-density copper paste on the surface of a silver seed layer by adopting a thick film printing process; step five, surface activation treatment, namely after electrode sintering, adopting plasma cleaning to remove a trace oxide layer on the surface, and forming a rough structure on the surface; and step six, antioxidation treatment, namely performing magnetron sputtering on a thick silver layer on the surface of the thick film electrode subjected to surface activation treatment to form an antioxidation layer. In the fourth step, the electrode