CN110767609A - A kind of sapphire insulator metal shell and its production process - Google Patents

Abstract

The invention relates to the technical field of electronic components, and discloses a sapphire insulator metal shell, comprising a frame body and a cover plate, a bottom plate is fixedly installed on the bottom of the frame body, and a bottom plate is fixedly installed on the top of the bottom plate inside the frame body A carrier, a ring frame is fixedly installed on the top of the frame body, a connection ring is fixedly installed on the right side of the frame body, and a lead wire is fixedly installed inside the connection ring. The sapphire insulator metal shell and its production process achieve the purpose of improving the use performance of the semiconductor integrated circuit package shell by changing the material, structure and connection process of the semiconductor integrated circuit package shell in the prior art, and solve the problem of the current semiconductor integrated circuit package shell. When the package shell is in use, the connection performance between the package shell structures is general, because the sealing and welding process is not perfect, and the selected insulating medium cannot withstand the ultra-high withstand voltage, which reduces the performance.

Description

A kind of sapphire insulator metal shell and its production process

technical field

The invention relates to the technical field of electronic components, in particular to a sapphire insulator metal shell and a production process thereof.

Background technique

With the continuous advancement of thinning and miniaturization of electronic components, semiconductor integrated circuits require packaging with better electrical performance, higher power density, higher reliability, and lighter weight. Therefore, high thermal conductivity materials such as tungsten copper/molybdenum copper are more and more widely used in the packaging field. Materials such as ceramics/sapphire are gradually replacing glass, and plastics have become a trend.

At present, when the semiconductor integrated circuit package shell is in use, the connection performance between the package shell structures is general, because the sealing and welding process is not perfect, and the selected insulating medium cannot withstand the ultra-high withstand voltage, which reduces the performance, and there is a large room for improvement. Therefore, a sapphire insulator metal shell and a production process thereof are proposed to solve the above-mentioned problems.

SUMMARY OF THE INVENTION

(1) Technical problems solved

In view of the deficiencies of the prior art, the present invention provides a sapphire insulator metal casing and a production process thereof, which have the advantages of improving the use performance of the semiconductor integrated circuit packaging casing and the like, and solve the problem of the packaging casing structure when the current semiconductor integrated circuit packaging casing is in use. The connection performance between them is general, because the sealing and welding process is not perfect, and the selected insulating medium cannot withstand the ultra-high withstand voltage, which reduces the performance.

(2) Technical solutions

In order to achieve the above-mentioned purpose of improving the usability of the semiconductor integrated circuit package casing, the present invention provides the following technical solutions: a sapphire insulator metal casing, comprising a frame body and a cover plate, the bottom of the frame body is fixedly mounted with a bottom plate, and the bottom plate is The top of the frame body is fixedly installed with a carrier located inside the frame body, the top of the frame body is fixedly installed with a ring frame, the right side of the frame body is fixedly installed with a connecting ring, and the inside of the connecting ring is fixedly installed with lead wires.

Preferably, the frame body is made of zirconia ceramics, and the bottom plate is provided with a circular groove on the left side of the frame body.

Preferably, the bottom plate is made of tungsten copper, the top of the bottom plate is provided with a groove, the bottom of the carrier is located in the groove, and the carrier is made of molybdenum copper.

Preferably, the area of the cover plate is larger than that of the ring frame, and the cover plate is made of expanded alloy.

Preferably, the ring frame is 4J50 alloy, the leads are 4J50 (Cu), the connecting ring is sapphire, the number of connecting rings is three, and the number of leads is the same as the number of connecting rings.

A sapphire insulator metal shell and a production process thereof, characterized in that, comprising the following steps:

1) Material selection; the frame body is made of zirconia ceramics, and the Al2O3 additive mass fraction is 10% zirconia ceramics. The bottom plate should be selected according to the applicable requirements. , The ring frame is 4J50 alloy, the carrier is made of molybdenum copper with thermal expansion coefficient of 6.8-11.5 (10-6/K) and thermal conductivity from 160-270W/(M.K), the lead wire is 4J50 clad copper, and the connecting ring is sapphire.

2) The welding of the connecting ring can be divided into two methods, the first method is brazing; the second method is diffusion welding and ceramic and metal sealing technology.

3) Inspection; material insulation performance inspection, withstand voltage performance inspection, product strength inspection and appearance sealing inspection.

(3) Beneficial effects

Compared with the prior art, the present invention provides a sapphire insulator metal shell and a production process thereof, which have the following beneficial effects:

1. The metal shell of the sapphire insulator and its production process are formed by brazing the bottom plate and the ring frame after the frame is metallized by zirconia ceramics. The bottom plate in the cavity is welded and connected to the internal circuit through the carrier to realize heat dissipation at the bottom of the circuit and oxidation The zirconium ceramic side wall is then brazed and connected to the lead through the metallized connecting ring to realize the conduction of internal and external electrical signals and the electrical insulation between the lead-shell and the lead-lead. Finally, the cover plate is sealed to form a closed cavity. , to protect and support the internal circuit. The connecting ring is sapphire, commonly known as corundum. The main component is Al2O3. It is a common simple coordination oxide crystal. The sapphire in nature shows different appearances due to the inclusion of some impurity ions. For example, sapphire containing titanium ions (Ti3+) and iron ions (Fe3+) will appear blue, containing chromium ions (Cr3+) will appear red, and when containing nickel ions (Ni3+), it will make the crystal appear yellow. , pure alumina crystal is colorless and transparent, because it has a unique crystal structure, excellent mechanical properties, optical properties and chemical stability, can be used in a high temperature environment of 2000 ° C, so it is widely used in infrared military Devices, satellite space technology, window materials and semiconductors for high-intensity lasers, substrate materials for large-scale integrated circuits, by comparing the electrical and mechanical properties of different doped sapphire, the optimal sapphire material is finally determined for sealing, sapphire ( α-Al2O3 single crystal) has high strength, high hardness, high temperature resistance, corrosion resistance, good friction resistance and high resistivity, and has good thermal conductivity and electrical insulation, as well as good light transmittance, etc. The frame is zirconia Ceramics have the characteristics of high toughness, high flexural strength and high wear resistance, excellent heat insulation performance and high temperature resistance, and the thermal thermal expansion coefficient is close to that of steel. Nano zirconia ceramics can greatly improve fracture toughness and flexural strength. In electronic ceramics, it is mostly used as a backing plate, etc. The content of Al2O3 additive has a great influence on the thermal shock resistance of zirconia ceramics. When 10% Al2O3 is added, its thermal shock resistance is the best, and the bottom plate is tungsten copper. As an electronic packaging and heat sink material, it not only has the low expansion characteristics of tungsten, but also has the high thermal conductivity characteristics of copper, and at the same time has the thermal expansion coefficient matching silicon wafer, gallium arsenide and ceramic materials, suitable for high-power device packaging materials, Heat sink materials, heat dissipation components, ceramics and gallium arsenide bases, etc., need to choose different grades according to the applicable requirements. With the increase of copper content, the thermal conductivity will be greatly improved, and the expansion coefficient will also increase 5.5 rises 8.8 (10-6/K), the carrier is molybdenum copper, which is a material to replace copper and tungsten copper. It has fine structure, good arc breaking, good electrical and thermal conductivity, and small thermal expansion. Small, but thermal conductivity and thermal expansion will increase, heat resistance is not as good as tungsten copper, molybdenum copper with low copper content, if the density after infiltration is low, it will affect air tightness, electrical conductivity and thermal conductivity, suitable for It is used in the manufacture of military high-power microelectronic devices as a heat sink sealing material and aluminum oxide ceramic sealing, and its thermal expansion is from 6.8 to 11.5 (10-6/K), The thermal conductivity ranges from 160 to 270W/(M.K), and the ring frame is made of 4J50 alloy, which has good welding performance and can be brazed and spot welded. At the same time, as a transition metal for parallel sealing and welding, it can realize the problem of non-conduction between the ceramic and the cover metal. The lead wire is made of 4J50 copper-clad material, and an oxygen-free copper core is added on the basis of 4J50. Because copper has good electrical conductivity It can effectively reduce the resistance and reduce the loss. It is a better choice of lead material. The cover plate is 4J42, which is a constant expansion thin plate material commonly used for metal casings. Selecting the material can not only improve its performance, but also effectively improve the stability between the connecting structures, thereby achieving the purpose of improving the performance of the semiconductor integrated circuit package.

2. The metal shell of the sapphire insulator and its production process are welded including brazing and diffusion welding. The key to brazing and welding is to improve the wettability between the sapphire insulator and the solder. The commonly used method is metallization, that is, coating a surface The layer has a metal film with high conductivity and strong bonding, such as nickel, etc., so as to achieve wetting with the solder. There are mainly electroless plating, electroplating, high-temperature sintering, active metal powder method and vapor deposition method. However, with Compared with 95% A1203 porcelain and 99.5% Al2O3 porcelain, sapphire does not contain glass phase and gas phase, and there is no grain boundary. During metallization, the glass phase cannot migrate effectively, so metallization is much more difficult, and traditional theories cannot. Effectively explain the mechanism of metallization. Diffusion welding of sapphire does not require the use of solder, electrodes, fluxes and shielding gases, and does not require subsequent mechanical processing. The diffusion welding of intermediate layers can reduce the chemical inhomogeneity of the continuous area and alleviate the residual Stress, eliminate the difference in linear expansion of welding materials, prevent plastic deformation, reduce welding temperature, pressure and duration, diffusion welding, there are two methods of adding no intermediate layer and adding intermediate layer. The advantage of the former is that there is no intermediate layer and base metal. The thermal expansion coefficient difference is too large and the large residual stress is generated during the cooling process, and the welding strength is high. There are still many technologies to be studied. Adding an intermediate layer can provide a transient liquid phase or a partial transient liquid phase to promote the initial material. Wetting and diffusion can reduce temperature pressure and connection time, prevent plastic deformation, relieve residual stress, and reduce the inhomogeneity of the bonding layer. The traditional interlayer system exists because the connection phase formed by the interlayer usually cannot withstand high temperature, limiting For its use, in recent years, the intermediate layer system containing several oxide ceramics has been studied to improve the temperature resistance. In the ceramic-metal sealing technology, ceramic metallization is the key, and the metallization layer is essentially a composite of Mo particles and glass phases. , the sintered Mo and glass phases are interpenetrated, interlaced and wrapped to form a network structure. The method of ceramic metallization includes metallization of sapphire by activated Mo-Mn method, microscopic analysis of sapphire metallization layer, and exploration of sapphire metallization. In terms of the activated Mo-Mn metallization mechanism, we continue to optimize the process method. The metallization mechanism is glass phase migration. At high temperature, the activator glass phase in the metallization layer first migrates to the sintering aid glass phase in the ceramic. The "activation" of the latter, so that the latter migrates back to the metallization layer, the source of the glass phase should include two aspects of the glass phase in the ceramic and the glass phase in the metallization layer, both of which are important and complement each other, the oxide solder method Mechanism: The high temperature liquid phase infiltrates the ceramic surface on one side, and the micro-oxidized metal surface on the other side, forming the bonding between ceramic and metal. Active metal method: The ceramic-metal sealing is completed in one heating process, and some small tubes are decomposed together with the cathode. , exhaust and sealing are completed at one time, which is little affected by the composition and performance of ceramics. Different types and sources of ceramics can be sealed in the same process, but it is not suitable for continuous production, suitable for large, single or small batch production. The first condition is that there is active metal (such as titanium), and the other is that it has the ability to form a low-melting alloy or Solders that can dissolve active metals (such as silver-copper eutectic alloys), the third is the presence of inert atmosphere or vacuum (5 × 10 ^-3 Pa), oxide solder method: oxide solder (such as high alumina porcelain, transparent alumina Porcelain, etc.) melt into a viscous liquid (glass) at the welding temperature (above 1500 degrees), and act on the surface of metal and ceramics to form a bonding layer. After cooling, most of them precipitate out to form various crystallites (sealing strength). high), into a solid intermediate layer, solid-phase process: the ceramic and metal surfaces are ground flat, sandwiched together in a solid form, and under certain external conditions (such as high pressure and high temperature or electrostatic attraction), the two planes are made close. Contact, no liquid phase appears to achieve hermetic sealing, including pressure sealing, solid-state diffusion sealing and electrostatic sealing, etc. Pressure diffusion sealing: the polished surface of the medium and the metal are assembled together, heated in dry hydrogen or vacuum, If it is glass, the temperature rise can only reach 200 degrees below the softening point of the glass. If the melting point of the medium is higher than that of the metal, the temperature will rise to 0.9 times the melting point of the metal, so that the connection process between the metal shell structures of the sapphire insulator can be improved to ensure its The stability between the connection structures achieves the purpose of improving the use performance of the packaging shell of the semiconductor integrated circuit.

Description of drawings

Fig. 1 is the sapphire insulator metal shell that the present invention proposes and its production process structure schematic diagram;

2 is a top view of the sapphire insulator metal casing and its production process structure proposed by the present invention;

3 is a schematic structural diagram of the sapphire insulator metal casing and its production process connection ring proposed by the present invention.

In the figure: 1 frame body, 2 bottom plate, 3 cover plate, 4 ring frame, 5 carrier, 6 lead wire, 7 connection ring.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

1-3, a sapphire insulator metal shell includes a frame body 1 and a cover plate 3, a bottom plate 2 is fixedly mounted on the bottom of the frame body 1, the frame body 1 is a zirconia ceramic, and the bottom plate 2 is The inside is provided with a circular groove on the left side of the frame body 1, the top of the bottom plate 2 is fixedly installed with a carrier 5 located inside the frame body 1, the bottom plate 2 is tungsten copper, the top of the bottom plate 2 is provided with a groove, and the carrier The bottom of 5 is located in the groove, the carrier 5 is molybdenum copper, the top of the frame body 1 is fixedly installed with a ring frame 4, the area of the cover plate 3 is larger than that of the ring frame 4, and the cover plate 3 is an expansion alloy, The right side of the frame body 1 is fixedly installed with a connecting ring 7, the ring frame 4 is 4J50 alloy, the lead 6 is 4J50 (Cu), the connecting ring 7 is sapphire, the number of the connecting ring 7 is three, and the lead 6 The number is the same as that of the connecting ring 7 , and the inside of the connecting ring 7 is fixedly installed with the lead wire 6 .

A sapphire insulator metal shell and a production process thereof, characterized in that, comprising the following steps:

1) Material selection; frame 1 selects zirconia ceramics, zirconia ceramics with Al2O3 additive mass fraction of 10%, bottom plate 2 selects according to applicable requirements, bottom plate 2 selects expansion coefficient of 5.5-8.8 (10-6/K), cover Board 3 is made of 4J42, ring frame 4 is made of 4J50 alloy, carrier 5 is made of molybdenum copper with thermal expansion coefficient of 6.8-11.5 (10-6/K) and thermal conductivity from 160-270W/(M.K), lead 6 is 4J50 clad copper , the connecting ring 7 is sapphire.

2) The welding of the connecting ring 7 can be divided into two methods, the first method is brazing; the second method is diffusion welding and ceramic and metal sealing technology.

3) Inspection; material insulation performance inspection, withstand voltage performance inspection, product strength inspection and appearance sealing inspection.

The sapphire insulator metal shell and its production process are formed by brazing with the bottom plate 2 and the ring frame 4 after the frame body 1 is metallized by zirconia ceramics. To dissipate heat, the zirconia ceramic side wall is then soldered to the lead 6 through the metallized connecting ring 7 to realize the conduction of internal and external electrical signals and the electrical insulation between the lead 6-shell and the lead 6-lead 6, and finally cover The cover plate 3 forms a closed cavity, which protects and supports the internal circuit. The connecting ring 7 is sapphire, commonly known as corundum. The main component is Al2O3, which is a common simple coordination oxide crystal. It shows different colors due to the inclusion of some impurity ions. For example, sapphire containing titanium ions (Ti3+) and iron ions (Fe3+) will appear blue, and sapphire containing chromium ions (Cr3+) will appear red, and when it contains nickel ions ( Ni3+), it will make the crystal yellow, and the pure alumina crystal is colorless and transparent, because it has a unique crystal structure, excellent mechanical properties, optical properties and chemical stability, can be applied to high temperature of 2000 ℃ Therefore, it is widely used in infrared military devices, satellite space technology, window materials and semiconductors for high-intensity lasers, and substrate materials for large-scale integrated circuits. By comparing the electrical and mechanical properties of different doped sapphire, the most Excellent sapphire material is used for sealing, sapphire (α-Al2O3 single crystal) has high strength, high hardness, high temperature resistance, corrosion resistance, good friction resistance and high resistivity, and has good thermal conductivity and electrical insulation, as well as good Light transmittance, etc. The frame body 1 is made of zirconia ceramics with high toughness, high bending strength and high wear resistance, excellent heat insulation performance and high temperature resistance, and the thermal expansion coefficient is close to that of steel, while nano-zirconia ceramics It can greatly improve the fracture toughness and flexural strength. It is mostly used as a backing plate in electronic ceramics. The content of Al2O3 additives has a great influence on the thermal shock resistance of zirconia ceramics. When 10% of Al2O3 is added, its The thermal shock resistance is the best. The bottom plate 2 is made of tungsten copper as the electronic packaging and heat sink material, which not only has the low expansion characteristics of tungsten, but also has the high thermal conductivity characteristics of copper, and is compatible with silicon wafers, gallium arsenide and ceramic materials. The thermal expansion coefficient is suitable for high-power device packaging materials, heat sink materials, heat dissipation components, ceramics and gallium arsenide bases, etc. When selecting, it is necessary to choose different grades according to the applicable requirements. With the increase of copper content, its The thermal conductivity will be greatly improved, and the expansion coefficient will also increase from 5.5 to 8.8 (10-6/K). The carrier 5 is molybdenum copper, which is a material to replace copper and tungsten copper. It has a fine structure, good arc breaking and good electrical and thermal conductivity. The thermal expansion is small. With the increase of copper content, the specific gravity will decrease, while the thermal conductivity and thermal expansion will increase. The heat resistance is not as good as that of tungsten copper. It will affect air tightness, electrical conductivity and thermal conductivity. It is suitable for the manufacture of military high-power microelectronic devices as a heat sink sealing material and aluminum oxide ceramic sealing. Its thermal expansion is from 6.8 to 11.5 (10-6/K), thermal conductivity from 160 to 270W/(M.K), ring frame 4 is 4J50 alloy with good welding performance, can be brazed and spot welded, is a common constant expansion coefficient alloy, and oxidation The expansion coefficient of zirconium ceramics is close, which can realize reliable brazing. At the same time, as a transition metal for parallel sealing, it can realize the problem of inability to conduct between the ceramics and the metal of the cover plate 3. The lead wire 6 is made of 4J50 copper-clad material, which is based on 4J50. Adding oxygen-free copper core, because copper has good electrical conductivity, can effectively reduce resistance and reduce loss, it is a better choice of lead wire 6 material, cover plate 3 is 4J42, which is a constant expansion sheet material commonly used in metal casings, and has similar properties to 4J50. The expansion coefficient is suitable for the common parallel welding process, and the reasonable selection of materials can not only improve its performance, but also effectively improve the stability between the connecting structures, thus achieving the improvement of the performance of the semiconductor integrated circuit packaging shell. The purpose of welding includes brazing and diffusion welding. The key to brazing welding is to improve its wettability with the solder. The commonly used method is metallization, that is, coating the surface with a layer of metal with high conductivity and strong bonding. Thin films such as nickel, etc., to achieve wetting with solder, mainly include electroless plating, electroplating, high temperature sintering, active metal powder method and vapor deposition method, etc. However, with 95% A1203 porcelain and 99.5% Al2O3 porcelain phase In contrast, sapphire does not contain glass phase and gas phase, and there is no grain boundary. During metallization, the glass phase cannot migrate effectively, so metallization is much more difficult, and traditional theories cannot effectively explain the mechanism of metallization. The diffusion of sapphire Soldering does not require the use of solders, electrodes, fluxes and shielding gases, and does not require subsequent machining. Diffusion welding with an intermediate layer reduces the chemical inhomogeneity of the continuous area, relieves residual stress, and eliminates differences in linear expansion of welding materials. Prevent plastic deformation, reduce welding temperature, pressure and duration, diffusion welding, there are two methods of adding no intermediate layer and adding intermediate layer. The advantage of the former is that there is no excessive difference between the thermal expansion coefficient of the intermediate layer and the base metal, and during the cooling process The problem of large residual stress and high welding strength, there are still more technologies to be studied. Adding an intermediate layer can provide a transient liquid phase or a partial transient liquid phase to promote the wetting and diffusion of the initial material, which can reduce the temperature and pressure. and connection time, prevent plastic deformation, relieve residual stress, and reduce the inhomogeneity of the bonding layer. The traditional interlayer system exists because the connection phase formed by the interlayer usually cannot withstand high temperature, which limits its use. In recent years, researches include several The interlayer system of oxide ceramics improves temperature resistance. In the ceramic-metal sealing technology, ceramic metallization is the key. The metallization layer is essentially a composite of Mo particles and glass phase. Sintered Mo and glass phase are interpenetrating, Staggered and wrapped to form a network structure, the method of ceramic metallization includes metallization of sapphire by the activated Mo-Mn method, microscopic analysis of the sapphire metallization layer, and continued on exploring the mechanism of activated Mo-Mn metallization of sapphire. Process optimization, metallization mechanism It is the glass phase migration. At high temperature, the activator glass phase in the metallization layer first migrates to the sintering aid glass phase in the ceramic. After the former "activates" the latter, the latter migrates back to the metallization layer. The source of the glass phase should include two aspects: the glass phase in the ceramic and the glass phase in the metallization layer, both of which are important and complement each other. The mechanism of the oxide solder method: the high temperature liquid phase wets the ceramic surface on one side, and the slightly oxidized metal on the other side. On the surface, the bonding between ceramic and metal is formed. Active metal method: ceramic-metal sealing is completed in one heating process, and some small tubes are completed together with cathode decomposition, exhaust and sealing at one time, which is greatly affected by the composition and performance of ceramics. Small, different types and different sources of ceramics can be sealed in the same process, but not suitable for continuous production, suitable for large-scale, single-piece or small-batch production, the first condition is that there is active metal (such as titanium), and the other is that it has active metal The formation of low-melting alloys or solders that can dissolve active metals (such as silver-copper eutectic alloys), the third is the presence of inert atmosphere or vacuum (5 × 10-3Pa), oxide solder method: oxide solder (such as high alumina ceramics) , transparent alumina porcelain, etc.) melt into a viscous liquid (glass) at the welding temperature (above 1500 degrees), which acts on the surface of metal and ceramics to form a bonding layer, and most of them precipitate out after cooling to form various crystallites (high sealing strength), it becomes a solid intermediate layer, solid-phase process: the ceramic and metal surfaces are ground flat and sandwiched together in solid form, under certain external conditions (such as high pressure and high temperature or electrostatic attraction), The two planes are brought into close contact, and the liquid phase does not appear to achieve hermetic sealing, including pressure sealing, solid-state diffusion sealing and electrostatic sealing. The temperature rises in a vacuum. If it is glass, the temperature rise can only reach 200 degrees below the softening point of the glass. If the melting point of the medium is higher than that of the metal, the temperature rises to 0.9 times the melting point of the metal, so that the connection process between the sapphire insulator metal shell structures can be carried out. The improvement ensures the stability between the connection structures thereof, and achieves the purpose of improving the use performance of the packaging shell of the semiconductor integrated circuit.

High voltage capability design

Material insulation properties:

The resistivity of sapphire is about ρ=1014Ω×cm, and the empirical formula for checking the insulation resistance is as follows:

R—insulation resistance (Ω) between the two ends of the sapphire insulator connection;

ρ—resistivity of sapphire insulator material (Ω·cm);

h—the height of the sapphire insulator (cm);

r1, r2—inner diameter and minimum outer diameter (cm) of the sapphire insulator;

This product can be drawn from the design drawings:

h=2mm=0.2cm;

r1=0.76/2mm=0.38mm=0.038cm;

r2=2/2mm=1mm=0.1cm;

Substituting into the formula to calculate can get R≈0.34×1014Ω=3.4×1013Ω>>1×1010Ω.

According to the above calculation, the reliability of the designed insulation resistance of this product meets the requirements.

B. Withstand voltage performance:

Calculated according to withstand voltage reliability:

V—the breakdown voltage (kV) between the metal parts at both ends of the glass insulator connection;

ρ—resistivity of glass insulator material (Ω·cm);

h—the height of the glass insulator (cm);

r1, r2—inner diameter and minimum outer diameter (cm) of the glass insulator;

I—glass insulator leakage current (mA);

ω—AC frequency (Hz);

ε—dielectric coefficient of glass insulator;

Among them, ρ=1014Ω×cm, h=2.0mm, r1=0.38mm, r2=1mm, I=50nA (specified by GJB), ε=(11.5);

Substitute into the formula to calculate V=1.67×106V=1670KV>>8000V, considering the air resistivity near the surface ρ=3×1011Ω×cm, the same creepage distance, the sapphire resistivity is much higher than the air resistivity, so under high voltage conditions, The air has priority breakdown, and the air data is brought into the formula to calculate V=0.56×104V=5600V<8000V. Therefore, the current structure cannot meet the withstand voltage requirements, and the structure needs to be improved. By increasing the bumps, the creepage distance is increased and the withstand voltage is improved.

After improvement, the creepage distance is doubled, and the calculated withstand voltage V=1.12×104V=11200V>8000V, which meets the design requirements.

Lead 6 Resistor Design

The composite lead 6 axial resistivity is as follows: In the formula, ρc and ρs represent the resistivity of the inner and outer skin materials, respectively, θ=(d/D)2, and d and D represent the diameters of the inner core and the entire composite lead 6, respectively. For DC, the higher the area occupied by the low-resistance core, the lower the overall resistivity of the composite lead 6 . Therefore, under the condition that the length of the lead 6 is constant, increasing the area of the oxygen-free copper in the low-resistance inner core can effectively reduce the resistivity.

The lead wire 6 of this project is 0.76mm in diameter and 16mm in length. The resistivity of Kovar 4J50 is 0.44×10-6Ω*mm2/m, and the oxygen-free copper is 0.017×10-6Ω*mm2/m. According to the resistance calculation formula:

R=ρL/Wt

where ρ is the resistivity of the material, L is the length of the material, W is the width of the material, and t is the thickness of the material

It can be calculated that the resistance of lead 6 of 4J50 at room temperature is R=15.5×10-6mΩ<4mΩ, which meets the design requirements, because the resistivity of oxygen-free copper is much lower than that of 4J50, so the resistance of lead 6 is better than that of 4J50, and a better conductive effect is obtained.

DC withstand voltage: 8000Vdc

Air leakage rate: <1×10-9Pa.m3/s

Plating thickness: nickel plating > 2.0 μm, gold plating > 1.3 μm

Insulation resistance: >1×1010Ω

Thermal shock: -65℃～+150℃, 15 times

Temperature cycle: -65℃～+175℃, cycle 100 times

-65℃～+300℃, cycle 10 times

Moisture resistance: 264h, cycle 10 times

Lead 6 resistance: <4mΩ

Mechanical shock: 1500g

Constant acceleration: 20000g

Working temperature Storage temperature: 250℃.

When in use, the frame body 1 is metallized by zirconia ceramics and then brazed with the bottom plate 2 and the ring frame 4, wherein the bottom plate 2 in the cavity is welded and connected to the internal circuit through the carrier 5 to realize heat dissipation at the bottom of the circuit, and the zirconia ceramic side The wall is then brazed and connected to the lead 6 through the metallized connecting ring 7 to realize the conduction of internal and external electrical signals and the electrical insulation between the lead 6-shell and the lead 6-lead 6, and finally cover the cover plate 3 to form a closed 's cavity.

To sum up, the sapphire insulator metal shell and its production process are formed by brazing with the bottom plate 2 and the ring frame 4 after metallizing the frame body 1 with zirconia ceramics, wherein the bottom plate 2 in the cavity is welded with the internal circuit through the carrier 5 . Connect to realize heat dissipation at the bottom of the circuit, and the zirconia ceramic side wall is then soldered and connected to the lead 6 through the metallized connecting ring 7 to realize the conduction of internal and external electrical signals and the electrical insulation between the lead 6-shell and the lead 6-lead 6 , and finally cover the cover plate 3 to form a closed cavity, which protects and supports the internal circuit. The connecting ring 7 is sapphire commonly known as corundum, the main component is Al2O3, which is a common simple coordination type oxide crystal. , Sapphire in nature shows different colors due to the inclusion of some impurity ions. For example, sapphire containing titanium ions (Ti3+) and iron ions (Fe3+) will appear blue, and sapphire containing chromium ions (Cr3+) will appear red, while When it contains nickel ions (Ni3+), it will make the crystal yellow. The pure alumina crystal is colorless and transparent, because of its unique crystal structure, excellent mechanical properties, optical properties and chemical stability, it can be applied Under the high temperature environment of 2000 °C, it is widely used in infrared military devices, satellite space technology, window materials and semiconductors for high-intensity lasers, and substrate materials for large-scale integrated circuits. By comparing the electrical properties and mechanical properties of different doped sapphire performance, and finally determine the optimal sapphire material for sealing, sapphire (α-Al2O3 single crystal) has high strength, high hardness, high temperature resistance, corrosion resistance, good wear resistance and high resistivity, and has good thermal conductivity and electrical insulation. The frame body 1 is made of zirconia ceramics with high toughness, high bending strength and high wear resistance, excellent thermal insulation performance and high temperature resistance, and the thermal thermal expansion coefficient is close to that of steel. The nano-zirconia ceramics can greatly improve the fracture toughness and flexural strength, and are mostly used as support pads in electronic ceramics. The content of Al2O3 additives has a great influence on the thermal shock resistance of zirconia ceramics. When Al2O3 is used, it has the best thermal shock resistance. The bottom plate 2 is made of tungsten copper as the electronic packaging and heat sink material, which not only has the low expansion characteristics of tungsten, but also has the high thermal conductivity of copper, and is compatible with silicon wafers, gallium arsenide and gallium arsenide. The thermal expansion coefficient matching the ceramic material is suitable for high-power device packaging materials, heat sink materials, heat dissipation components, ceramics and gallium arsenide bases. With the increase of the content, the thermal conductivity will be greatly improved, and the expansion coefficient will also increase from 5.5 to 8.8 (10-6/K). The carrier 5 is molybdenum copper, which is a material to replace copper and tungsten copper. It has good electrical and thermal conductivity and small thermal expansion. With the increase of copper content, the specific gravity will decrease, while the thermal conductivity and thermal expansion will increase. The heat resistance is not as good as that of tungsten copper. Low density will affect air tightness, electrical conductivity and thermal conductivity. It is suitable for the manufacture of military high-power microelectronic devices as a heat sink sealing material and aluminum oxide ceramic sealing. Its thermal expansion From 6.8 to 11.5 (10-6/K), thermal conductivity from 160 to 270W/(M.K), ring frame 4 is 4J50 alloy with good welding performance, can be brazed and spot welded, and is a common constant expansion coefficient alloy , which is close to the expansion coefficient of zirconia ceramics, which can achieve reliable brazing. At the same time, as a transition metal for parallel sealing, it can achieve the problem of inability to conduct between the ceramic and the metal of the cover plate 3. The lead 6 is made of 4J50 copper-clad material. Oxygen-free copper core is added on the basis of 4J50. Because copper has good electrical conductivity, it can effectively reduce resistance and reduce loss. It is a better choice for lead 6 material. 4J50 has a similar expansion coefficient, which is suitable for common parallel sealing and soldering processes. Reasonable selection of materials can not only improve its performance, but also effectively improve the stability between the connecting structures, thereby improving the stability of the semiconductor integrated circuit packaging shell. Use for performance purposes.

Moreover, through welding, including brazing and diffusion welding, the key to brazing welding is to improve its wettability with the solder. The commonly used method is metallization, that is, coating the surface with a layer of metal with high conductivity and strong bonding. Thin films such as nickel, etc., to achieve wetting with solder, mainly include electroless plating, electroplating, high temperature sintering, active metal powder method and vapor deposition method, etc. However, with 95% A1203 porcelain and 99.5% Al2O3 porcelain phase In contrast, sapphire does not contain glass phase and gas phase, and there is no grain boundary. During metallization, the glass phase cannot migrate effectively, so metallization is much more difficult, and traditional theories cannot effectively explain the mechanism of metallization. The diffusion of sapphire Soldering does not require the use of solders, electrodes, fluxes and shielding gases, and does not require subsequent machining. Diffusion welding with an intermediate layer reduces the chemical inhomogeneity of the continuous area, relieves residual stress, and eliminates differences in linear expansion of welding materials. Prevent plastic deformation, reduce welding temperature, pressure and duration, diffusion welding, there are two methods of adding no intermediate layer and adding intermediate layer. The advantage of the former is that there is no excessive difference between the thermal expansion coefficient of the intermediate layer and the base metal, and during the cooling process The problem of large residual stress and high welding strength, there are still more technologies to be studied. Adding an intermediate layer can provide a transient liquid phase or a partial transient liquid phase to promote the wetting and diffusion of the initial material, which can reduce the temperature and pressure. and connection time, prevent plastic deformation, relieve residual stress, and reduce the inhomogeneity of the bonding layer. The traditional interlayer system exists because the connection phase formed by the interlayer usually cannot withstand high temperature, which limits its use. In recent years, researches include several The interlayer system of oxide ceramics improves temperature resistance. In the ceramic-metal sealing technology, ceramic metallization is the key. The metallization layer is essentially a composite of Mo particles and glass phase. Sintered Mo and glass phase are interpenetrating, Staggered and wrapped to form a network structure, the method of ceramic metallization includes metallization of sapphire by the activated Mo-Mn method, microscopic analysis of the sapphire metallization layer, and continued on exploring the mechanism of activated Mo-Mn metallization of sapphire. To optimize the process method, the metallization mechanism is the glass phase migration. At high temperature, the activator glass phase in the metallization layer first migrates to the sintering aid glass phase in the ceramic. After the former "activates" the latter, the latter becomes For the reverse migration in the metallization layer, the source of the glass phase should include the glass phase in the ceramic and the glass phase in the metallization layer. Both are important and complement each other. The mechanism of the oxide solder method: the high temperature liquid phase wets the ceramic surface on one side, One side infiltrates the slightly oxidized metal surface to form the bonding between ceramic and metal. Active metal method: ceramic-metal sealing is completed in one heating process, and some small tubes are completed together with cathode decomposition, exhaust and sealing at one time. The influence of ceramic composition and performance is very small. Different types and sources of ceramics can be sealed in the same process, but it is not suitable for continuous production. It is suitable for large-scale, single-piece or small-batch production. The first condition is that there are active metals (such as titanium) , and the second is a solder that forms a low-melting alloy with the active metal or can dissolve the active metal (such as silver-copper eutectic). Alloy), the third is the presence of an inert atmosphere or vacuum (5×10 ^-3 Pa), oxide solder method: oxide solder (such as high alumina porcelain, transparent alumina porcelain, etc.) is melted at the welding temperature (above 1500 degrees) It forms a viscous liquid (glass), which acts on the surface of metals and ceramics to form a bonding layer. After cooling, most of them precipitate out to form various crystallites (with high sealing strength), which become a firm intermediate layer. Process: The ceramic and metal surfaces are ground flat and sandwiched together in a solid state. Under certain external conditions (such as high pressure and high temperature or electrostatic attraction), the two planes are brought into close contact, and no liquid phase appears to achieve a hermetic connection, including Pressure sealing, solid-state diffusion sealing and electrostatic sealing, etc. Pressure diffusion sealing: The polished surface of the medium and the metal are mounted together and heated in dry hydrogen or vacuum. For glass, the temperature can only be increased to 200 degrees below the softening point of the glass. If the melting point of the dielectric is higher than that of the metal, the temperature will increase to 0.9 times the melting point of the metal, thereby improving the connection process between the sapphire insulator metal shell structures, ensuring the stability of the connection structures, and improving semiconductor integration. The purpose of the performance of the circuit package shell is to solve the general connection performance between the package shell structures when the current semiconductor integrated circuit package shell is in use, because the sealing and welding process is not perfect, and the selected insulating medium cannot withstand the ultra-high withstand voltage. , the problem of reducing performance.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (6)

1. The utility model provides a sapphire insulator metal casing, includes framework (1) and apron (3), its characterized in that: the bottom fixed mounting of framework (1) has bottom plate (2), the top fixed mounting of bottom plate (2) has carrier (5) that are located framework (1) inside, the top fixed mounting of framework (1) has ring frame (4), the right side fixed mounting of framework (1) has go-between (7), the inside fixed mounting of go-between (7) has lead wire (6).

2. The sapphire insulator metal can of claim 1, wherein: the frame body (1) is made of zirconia ceramics, and a circular groove located on the left side of the frame body (1) is formed in the bottom plate (2).

3. The sapphire insulator metal can of claim 1, wherein: the bottom plate (2) is made of tungsten copper, the top of the bottom plate (2) is provided with a groove, the bottom of the carrier (5) is located in the groove, and the carrier (5) is made of molybdenum copper.

4. The sapphire insulator metal can of claim 1, wherein: the area of the cover plate (3) is larger than that of the ring frame (4), and the cover plate (3) is made of expansion alloy.

5. The sapphire insulator metal can of claim 1, wherein: the ring frame (4) is made of 4J50 alloy, the leads (6) are made of 4J50(Cu), the connecting rings (7) are made of sapphire, the number of the connecting rings (7) is three, and the number of the leads (6) is the same as that of the connecting rings (7).

6. A sapphire insulator metal shell and a production process thereof are characterized by comprising the following steps:

1) selecting materials; the frame body (1) is made of zirconia ceramic with the mass fraction of 10% of Al2O3 additive, the bottom plate (2) is made of zirconia ceramic with the expansion coefficient of 5.5-8.8(10-6/K), the cover plate (3) is made of 4J42, the ring frame (4) is made of 4J50 alloy, the carrier (5) is made of molybdenum copper with the thermal expansion coefficient of 6.8-11.5(10-6/K), the thermal conductivity of 160 plus 270W/(M.K), the lead (6) is made of 4J50 copper-clad, and the connecting ring (7) is made of sapphire.

2) Welding; the welding of the connecting ring (7) can be divided into two methods, wherein the first method is brazing; the second method is diffusion welding and ceramic-metal sealing technology.

3) Checking; the method comprises the following steps of material insulation performance inspection, voltage resistance performance inspection, product strength inspection and appearance sealing inspection.

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