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CN-121985854-A - Chip packaging welding method and online vacuum sintering furnace

CN121985854ACN 121985854 ACN121985854 ACN 121985854ACN-121985854-A

Abstract

The invention relates to the technical field of chip packaging, and provides a chip packaging welding method, wherein a chip workpiece and a jig enter a preheating area and are vacuumized and then preheated, after the chip workpiece and the jig enter the welding area, infrared heating is started to a first welding temperature, the chip workpiece and the jig travel at a first conveying speed, vacuum degree and temperature are monitored in real time, the vacuum degree is not lower than a threshold value, if the vacuum continuously drops to the upper threshold value or the temperature fluctuation exceeds the threshold value, infrared heating is suspended, the chip workpiece and the jig are accelerated according to an actual pumping speed formula of a molecular pump, the chip workpiece and the jig enter a cooling area after welding, the chip workpiece and the jig are cooled at a vacuum degree of 5 multiplied by 10 ‑4 -8×10 ‑4 Pa, finally a main pumping valve of the molecular pump is closed, an inflation valve is slowly opened, dry nitrogen is inflated according to an inflation time formula, and the pressure in the furnace is balanced with atmospheric pressure. The process stability is good, the consistency of the packaging quality of the chips in batches can be ensured, and the defects of welding spots are low.

Inventors

  • ZHANG YANZHONG
  • ZHAO YONGXIAN
  • DENG YAN
  • ZHOU YONGJUN
  • Wen Aixin

Assignees

  • 中科同帜半导体(江苏)有限公司

Dates

Publication Date
20260505
Application Date
20260202

Claims (11)

  1. 1. A method of die package bonding, comprising: the chip workpiece and the jig enter a preheating zone, and a vacuumizing step is carried out; the chip workpiece and the jig execute a preheating step; The welding area is started to be heated by infrared rays, the temperature of the welding area is increased to a first welding temperature, and a chip workpiece and a jig enter the welding area at a first conveying speed; Monitoring the vacuum degree and the temperature of the welding area in real time, wherein the vacuum degree of the welding area is not lower than the vacuum threshold of the welding area, if the vacuum degree of the welding area continuously drops to exceed the vacuum threshold of the welding area or the temperature fluctuation exceeds the temperature threshold, suspending infrared heating, adjusting parameters through a practical pumping speed calculation formula of the molecular pump, and improving the rotating speed of the molecular pump; After the welding is finished, the chip workpiece and the jig are conveyed into a cooling area, the vacuum degree of the cooling area is maintained at 5 multiplied by 10 -4 -8×10 -4 Pa, and a cooling step is carried out; and closing a main pumping valve of the molecular pump, slowly opening an on-line vacuum sintering furnace inflation valve, and filling dry nitrogen into the on-line vacuum sintering furnace according to an inflation time calculation formula until the pressure of a cooling area is balanced with the atmospheric pressure.
  2. 2. The method of die package bonding according to claim 1, wherein the step of evacuating specifically comprises: starting a backing pump, slowly starting a rough pumping valve between the backing pump and the online vacuum sintering furnace, performing rough pumping on the online vacuum sintering furnace to a first pressure, and monitoring the first pressure by using a thermocouple vacuum gauge; Closing a rough pumping valve, slowly opening a connecting valve between the backing pump and the molecular pump, and simultaneously starting the molecular pump for preheating; after the preheating of the molecular pump is finished, starting the molecular pump, gradually increasing the rotating speed of a rotor of the molecular pump to the rated rotating speed, starting a main pumping valve between the molecular pump and an online vacuum sintering furnace, finely pumping vacuum to a second pressure, and switching to an ionization vacuum gauge to monitor the second pressure; And recording a vacuum degree change curve of the air suction time and the preheating zone, and ensuring that the vacuum degree of the preheating zone rises steadily and the fluctuation amplitude is less than or equal to +/-1 multiplied by 10 -4 Pa.
  3. 3. The die package bonding method according to claim 2, wherein the first pressure is less than or equal to 8-10 Pa and the second pressure is less than or equal to 3 x 10 -4 -5×10 -4 Pa.
  4. 4. The die package bonding method according to claim 1, wherein the first bonding temperature is 70% -80% of the bonding temperature.
  5. 5. The die package bonding method according to claim 1, wherein the preheating step specifically comprises: opening an infrared heating pipe, realizing the temperature uniformity control of the online vacuum sintering furnace through a partition temperature control system, and heating at a first heating rate; the molecular pump continuously runs at full load, and the early warning threshold value is monitored in real time through an ionization vacuum gauge; If the vacuum degree of the preheating zone is larger than the early warning threshold value, the rotation speed of the molecular pump is increased through a molecular pump actual pumping speed calculation formula, the infrared heating pipe is closed, the current temperature is maintained for 3-5 minutes, and the infrared heating pipe is opened for heating after the vacuum degree of the preheating zone is raised to be higher than the second pressure.
  6. 6. The die package bonding method according to claim 5, wherein the first ramp rate is 2-5 ℃ per minute.
  7. 7. The die package bonding method according to claim 5, wherein the pre-warning threshold is 2 x 10 -4 Pa-3×10 -4 Pa.
  8. 8. The die package bonding method according to claim 5, wherein the molecular pump actual pumping speed calculation formula is: S Real world = S Forehead (forehead) ×η×（P Front part / P Forehead (forehead) ）,S Real world is the actual pumping speed of the molecular pump, S Forehead (forehead) is the rated pumping speed of the molecular pump, eta is the pumping efficiency of the molecular pump, and P Front part is the inlet pressure provided by the backing pump.
  9. 9. The die package bonding method according to claim 1, wherein the cooling step specifically comprises: according to a molecular pump energy consumption and rotating speed relation formula, when the temperature is reduced to be below a first cooling temperature at a specific cooling rate, the rotating speed of the molecular pump is reduced to 80% -90% of the rated rotating speed; when the temperature is reduced to be below the second cooling temperature at a specific cooling rate, the rotation speed of the molecular pump is reduced to 60% -70% of the rated rotation speed; And reducing the molecular pump rotation speed to 50% of the rated rotation speed when the temperature is reduced to below the third cooling temperature at a specific cooling rate, wherein the specific cooling rate is 1-3 ℃ per minute.
  10. 10. The die package bonding method according to claim 1, wherein the inflation time calculation formula is: t=v×ln (P 2 /P 1 ）/Q Filling material ; t: charge time; V: oven cavity effective volume; P 2 : charge forehearth pressure; Q Filling material : charge post-hearth pressure).
  11. 11. An in-line vacuum sintering furnace, characterized in that the in-line vacuum sintering furnace is used for performing the method according to any of the preceding claims 1 to 10.

Description

Chip packaging welding method and online vacuum sintering furnace Technical Field The invention relates to the technical field of chip packaging, in particular to a chip packaging welding method and an online vacuum sintering furnace. Background The vacuum welding equipment in the prior art is professional equipment for welding workpieces, and the structure of the vacuum welding equipment mainly comprises a controller, a sealable cavity, a vacuumizing device, a heating plate, a cooling device and the like. The heating plate is positioned in the sealable cavity and is used for placing workpieces. The heating device and the cooling device are respectively corresponding to the lower parts of the heating plates and are respectively connected with the controller, and the heating or cooling process of the heating plates is completed under the regulation and control of the controller. The vacuumizing device is arranged on the outer side of the sealable cavity, and performs vacuumizing treatment on the sealable cavity, so that the welding process is performed in an anaerobic state, the welding quality is ensured, the cavity rate inside welding is reduced, and the reliability of a weldment is improved. The prior art cannot realize quantitative control of chip packaging process parameters, conventional empirical operation is poor in process stability, consistency of batch chip packaging quality cannot be guaranteed, and welding spot defects are high. Disclosure of Invention The invention provides a chip packaging welding method which is used for solving the problems that the prior art cannot realize quantitative control of chip packaging process parameters, the traditional empirical operation is poor in process stability, the consistency of batch chip packaging quality cannot be ensured, and the welding spot defect is high. A die package bonding method, comprising: the chip workpiece and the jig enter a preheating zone, and a vacuumizing step is carried out; the chip workpiece and the jig execute a preheating step; The welding area is started to be heated by infrared rays, the temperature of the welding area is increased to a first welding temperature, and a chip workpiece and a jig enter the welding area at a first conveying speed; Monitoring the vacuum degree and the temperature of the welding area in real time, wherein the vacuum degree of the welding area is not lower than the vacuum threshold of the welding area, if the vacuum degree of the welding area continuously drops to exceed the vacuum threshold of the welding area or the temperature fluctuation exceeds the temperature threshold, suspending infrared heating, adjusting parameters through a practical pumping speed calculation formula of the molecular pump, and improving the rotating speed of the molecular pump; After the welding is finished, the chip workpiece and the jig are conveyed into a cooling area, the vacuum degree of the cooling area is maintained at 5 multiplied by 10 -4 -8×10-4 Pa, and a cooling step is carried out; and closing a main pumping valve of the molecular pump, slowly opening an on-line vacuum sintering furnace inflation valve, and filling dry nitrogen into the on-line vacuum sintering furnace according to an inflation time calculation formula until the pressure of a cooling area is balanced with the atmospheric pressure. According to the chip package welding method provided by the invention, the vacuumizing step comprises the following steps: starting a backing pump, slowly starting a rough pumping valve between the backing pump and the online vacuum sintering furnace, performing rough pumping on the online vacuum sintering furnace to a first pressure, and monitoring the first pressure by using a thermocouple vacuum gauge; Closing a rough pumping valve, slowly opening a connecting valve between the backing pump and the molecular pump, and simultaneously starting the molecular pump for preheating; after the preheating of the molecular pump is finished, starting the molecular pump, gradually increasing the rotating speed of a rotor of the molecular pump to the rated rotating speed, starting a main pumping valve between the molecular pump and an online vacuum sintering furnace, finely pumping vacuum to a second pressure, and switching to an ionization vacuum gauge to monitor the second pressure; And recording a vacuum degree change curve of the air suction time and the preheating zone, and ensuring that the vacuum degree of the preheating zone rises steadily and the fluctuation amplitude is less than or equal to +/-1 multiplied by 10 -4 Pa. According to the chip package welding method, the first pressure is less than or equal to 8-10 Pa, and the second pressure is less than or equal to 3 multiplied by 10 -4 -5×10-4 Pa. According to the chip package welding method, the first welding temperature is 70% -80% of the welding temperature. According to the chip package welding method, the preheating step specifically comprises the following step