Stainless steel oxygen-free copper inlaid T / R shell and preparation method thereof

Abstract

The invention discloses a stainless steel oxygen-free copper embedded T / R shell and a preparation method thereof. The shell comprises a 316L stainless steel shell body, a TU1 oxygen-free copper substrate, a radio frequency connector, a stress gradient slow release ring and a low-frequency connector. The preparation method comprises the following steps: cleaning and annealing each component; the weldability is enhanced by pre-plating nickel; the shell, the substrate and the stress slow release ring are assembled through silver-copper brazing; after nickel / gold electroplating, a plating layer on the sealing and welding surface is removed through laser; and installing the radio frequency / low frequency connector to the kovar ring through gold-tin brazing. Through gradient material design and a step-by-step brazing process, the problem of sealing failure caused by thermal expansion coefficient mismatch is solved, and the high-power heat dissipation performance and the airtight reliability are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of airtight electronic packaging, and particularly relates to a stainless steel inlaid oxygen-free copper T / R shell and a preparation method thereof. BACKGROUND

[0002] With the increasing power consumption of chips, the requirements for the shell are increasingly high, and the cost is also harshly required. Oxygen-free copper has a thermal conductivity of 390 W / m.k, and can meet the demand of most power consumption. However, laser sealing and welding of the shell is difficult, the yield of laser sealing and welding is low, and the matching with a low-frequency connector is poor, which is difficult to guarantee the reliability (airtightness). SUMMARY

[0003] The present application aims to provide a stainless steel inlaid oxygen-free copper T / R shell and a preparation method thereof, solve the problem of heat dissipation of high-power electronics, and realize airtight packaging.

[0004] In order to achieve the purpose of the present application, the present application provides a preparation method of a stainless steel inlaid oxygen-free copper T / R shell,

[0005] The shell comprises a stainless steel shell, an oxygen-free copper substrate, a radio frequency connector, a stress gradient release ring and a low-frequency connector.

[0006] The stress gradient release ring comprises an oxygen-free copper ring and a Kovar ring.

[0007] The preparation method comprises the following steps:

[0008] Step 1, cleaning and annealing the stainless steel shell, the oxygen-free copper substrate, the oxygen-free copper ring and the Kovar ring;

[0009] Step 2, pre-plating nickel on the stainless steel shell, the oxygen-free copper substrate, the oxygen-free copper ring and the Kovar ring;

[0010] Step 3, overlapping the oxygen-free copper substrate on the bottom of the stainless steel shell, overlapping the oxygen-free copper ring on one side close to the stainless steel shell, and overlapping the Kovar ring on the oxygen-free copper ring. Silver copper solder is placed at the overlapping positions, and the silver copper solder is placed in a tool clamp, and then welded through a silver copper soldering process temperature curve to form a T / R shell semi-finished product;

[0011] Step 4, electroplating nickel and gold on the T / R shell semi-finished product, and removing the plating layer of the laser sealing and welding surface through mechanical processing;

[0012] Step 5, mounting the gold-plated shell of step 4, the low-frequency connector and the radio frequency connector on the Kovar ring, placing customized gold tin solder at the overlapping position, placing the gold tin solder in a tool clamp, and welding through a gold tin soldering process temperature curve to form a T / R shell finished product.

[0013] In another aspect, the present application also provides a stainless steel inlaid oxygen-free copper T / R housing for implementing the above preparation method, comprising a stainless steel shell, an oxygen-free copper substrate, a radio frequency connector, a stress gradient release ring and a low frequency connector.

[0014] The stainless steel shell is used to provide electrical connection, support and airtight structural basis for other components.

[0015] The oxygen-free copper substrate is arranged at the bottom of the stainless steel shell and used for heat dissipation of a high-power chip.

[0016] The radio frequency connector, the stress gradient release ring and the low frequency connector are arranged on one side of the stainless steel shell and used to match the expansion coefficient of the low frequency connector to avoid air leakage caused by mismatch.

[0017] The low frequency connector is nested in the stress gradient release ring.

[0018] The radio frequency connector is arranged outside the stress gradient release ring.

[0019] The stress gradient release ring comprises an oxygen-free copper ring and a Kovar ring.

[0020] The oxygen-free copper ring is larger in size than the Kovar ring and is arranged below the Kovar ring, and the ring openings of the two rings are matched to nest the low frequency connector.

[0021] The surfaces of the stainless steel shell, the oxygen-free copper substrate and the stress gradient release ring are electroplated with nickel or electroplated with nickel-gold.

[0022] The stainless steel shell, the oxygen-free copper substrate and the stress gradient release ring are connected by silver copper brazing.

[0023] The radio frequency connector and the low frequency connector are connected by gold tin brazing.

[0024] The stainless steel shell is made of 316L, the oxygen-free copper is made of TU1, and the Kovar ring is made of 4J29.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] (1) Thermal stress matching optimization: the present application adopts an oxygen-free copper ring-Kovar ring composite structure as a stress gradient release ring, effectively absorbs stress under brazing and working temperature change through gradient transition of the material expansion coefficient, and avoids interface cracking and air leakage;

[0027] (2) Welding reliability improvement: the present application improves the wettability and bonding strength of silver copper brazing by pre-plating a nickel layer; gold tin brazing is used to connect low frequency / radio frequency devices to avoid thermal damage to the assembled components caused by high temperature secondary welding.

[0028] (3) Heat dissipation and air tightness collaborative design: the application adopts oxygen-free copper substrate to be directly brazed to the bottom of the shell to realize high-power chip high-efficiency heat dissipation; laser removes the plating layer of the sealing surface to ensure that the air tightness of subsequent laser sealing meets the standard;

[0029] (4) Strong process compatibility: the application is step brazing, silver copper brazing to gold tin brazing, combined with tool positioning, taking into account the assembly accuracy and production stability of complex components, the yield is improved by more than 30%;

[0030] (5) Material cost optimization: the main body of the application adopts 316L stainless steel locally inlaid with TU1 oxygen-free copper, which reduces the cost by 40% compared with the full copper shell, while meeting the lightweight demand.

[0031] To more clearly illustrate the functional characteristics and structural parameters of the application, the following further describes the application in conjunction with the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0032] The accompanying drawings described herein are used to provide further understanding of the application, constitute a part of this application, the schematic embodiments of the application and the description thereof are used to explain the application, and do not constitute an improper limitation on the application. In the drawings:

[0033] Figure 1 is a structural schematic diagram of the application;

[0034] Figure 2 is a stress gradient release ring structure schematic diagram of the application.

[0035] In the drawings, the reference signs are: 1-stainless steel shell; 2-oxygen-free copper substrate; 3-radio frequency connector; 4-stress gradient release ring; 5-low frequency connector; 6-oxygen-free copper ring; 7-kovar ring. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the application will be described clearly and completely below in conjunction with the drawings in the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments of the application; based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0037] A preparation method of a stainless steel inlaid oxygen-free copper T / R shell,

[0038] The shell comprises a stainless steel shell 1, an oxygen-free copper substrate 2, a radio frequency connector 3, a stress gradient release ring 4 and a low frequency connector 5;

[0039] The stress gradient release ring 4 comprises an oxygen-free copper ring 6 and a kovar ring 7;

[0040] The preparation method comprises the following steps:

[0041] Step 1, cleaning and annealing the stainless steel shell 1, oxygen-free copper substrate 2, oxygen-free copper ring 6 and Kovar ring 7, the purpose of cleaning is to remove the lubricating oil pollution in the machining process, and the purpose of annealing is to eliminate the machining stress brought by the machining process;

[0042] Step 2, pre-plating nickel on the stainless steel shell 1, oxygen-free copper substrate 2, oxygen-free copper ring 6 and Kovar ring 7, the purpose is to improve the wettability of silver copper solder, so that the solder flows more fully;

[0043] Step 3, the oxygen-free copper substrate 2 is overlapped on the bottom of the stainless steel shell 1, the oxygen-free copper ring 6 is overlapped on one side close to the stainless steel shell 1, and the Kovar ring 7 is overlapped on the oxygen-free copper ring 6, silver copper solder is placed at the overlapping position, and it is placed in a stainless steel fixture, and then it is welded through a silver copper soldering process temperature curve to form a T / R shell semi-finished product;

[0044] Step 4, electroplating nickel and gold on the T / R shell semi-finished product, and then removing the plating layer of the laser sealing surface through mechanical processing;

[0045] Step 5, mounting the gold-plated shell of step 4, the low-frequency connector 5 and the radio frequency connector 3 on the Kovar ring 7, placing customized gold tin solder at the overlapping position, and placing it in a stainless steel fixture, and then welding it through a gold tin soldering process temperature curve to form a T / R shell finished product.

[0046] In combination Figure 1 A stainless steel inlaid oxygen-free copper T / R shell for realizing the above preparation method comprises a stainless steel shell 1, an oxygen-free copper substrate 2, a radio frequency connector 3, a stress gradient release ring 4 and a low-frequency connector 5.

[0047] The stainless steel shell 1 is used to provide electrical connection, support and airtight structural basis for other components;

[0048] The oxygen-free copper substrate 2 is arranged at the bottom of the stainless steel shell 1 and is used for heat dissipation of a high-power chip;

[0049] The side surface of the stainless steel shell 1 is provided with the radio frequency connector 3, the stress gradient release ring 4 and the low-frequency connector 5, which are used to match the expansion coefficient of the low-frequency connector and avoid air leakage caused by mismatching;

[0050] The low-frequency connector 5 is nested in the stress gradient release ring 4;

[0051] The stress gradient release ring 4 is provided with the radio frequency connector 3 outside.

[0052] Combining Figure 2 , the stress gradient release ring 4 includes an oxygen-free copper ring 6 and a Kovar ring 7;

[0053] The oxygen-free copper ring 6 is larger in size than the Kovar ring 7 and is placed under the Kovar ring 7, both ring openings match for nesting the low-frequency connector 5.

[0054] The stainless steel shell 1, the oxygen-free copper substrate 2 and the stress gradient release ring 4 are plated with nickel or nickel-gold.

[0055] The stainless steel shell 1, the oxygen-free copper substrate 2 and the stress gradient release ring 4 are connected by silver brazing.

[0056] The radio frequency connector 3 and the low-frequency connector 5 are connected by gold-tin brazing.

[0057] The stainless steel shell 1 is made of 316L, the oxygen-free copper is made of TU1, and the Kovar ring 7 is made of 4J29.

[0058] The stainless steel shell 1 refers to a customized shell obtained by machining a stainless steel 316L base material according to the structural design requirements of the TR shell, which is used to provide an electrical connection, support and airtight structure for the entire assembly in the subsequent process; and is plated with nickel, silver copper brazing with the nickel-plated oxygen-free copper substrate 2 and the nickel-plated stress gradient release ring 4, and then the T / R shell after one-step brazing is plated with nickel-gold, secondary machining to remove the sealing surface plating layer, and finally gold-tin brazing with the radio frequency connector 3 and the low-frequency connector 5, assembling a complete stainless steel inlaid oxygen-free copper T / R housing.

[0059] The oxygen-free copper substrate 2 refers to a customized structure component reserved in the above 1T / R shell structure design for high-power chip mounting, and the material of the structure includes but is not limited to oxygen-free copper substrate, which has excellent thermal conductivity and can conduct the heat of T / R chip in work out of the shell in time, and through an auxiliary heat dissipation device which belongs to additional equipment, this paper does not make detailed description to cool the entire assembly; the oxygen-free copper substrate is pre-plated with nickel and assembled with the stainless steel shell 1 by silver brazing.

[0060] The radio frequency connector 3 refers to a connector with a radio frequency performance simulation design, a specific radio frequency coaxial performance, and a Kovar and glass glass sealing assembly. The glass sealing belongs to an auxiliary process, which is not described in detail herein. The radio frequency connector after sealing needs to be plated with nickel gold. The plating thickness includes but is not limited to processes suitable for gold-tin soldering; the radio frequency connector 3 is assembled with the stainless steel shell 1 through gold-tin soldering. Before this, the stainless steel shell 1 should be first silver-copper soldered with the nickel-plated oxygen-free copper substrate 2 and the nickel-plated stress gradient release ring 4, and then gold-tin soldered after nickel gold plating and removal of the sealing surface plating.

[0061] The stress gradient release ring 4 is made of oxygen-free copper and Kovar alloy. Oxygen-free copper has excellent plasticity at high temperature. When the stainless steel shell 1 is gold-tin soldered with the low-frequency connector 5, due to the mismatch of thermal expansion coefficients of Kovar alloy, glass and stainless steel, a large stress will be generated during the cooling process of soldering. By using the plastic deformation of oxygen-free copper, the stress between Kovar alloy and glass can be released, and the glass sealing failure can be avoided. The stress gradient release ring 4 should be assembled with the pre-plated nickel stainless steel shell 1 through silver-copper soldering after nickel plating. The material of the stress gradient release ring includes but is not limited to oxygen-free copper and other suitable materials with good plasticity or thermal expansion coefficient transition.

[0062] The low-frequency connector 5 is a multi-pin Kovar lead and a rectangular Kovar sleeve prepared by glass sealing. The product is a standard or customized product. This part belongs to a general part, which is not described in detail herein. The low-frequency connector 5 is assembled with the radio frequency connector 3 through gold-tin soldering after silver-copper soldering, nickel gold plating and secondary machining to remove the sealing surface plating. The low-frequency connector 5 provides an electrical input / output channel for the T / R module.

[0063] The oxygen-free copper ring 6 is made of oxygen-free copper. Oxygen-free copper has excellent plasticity, which can relieve the welding stress caused by the mismatch of thermal expansion coefficients between stainless steel, Kovar and glass during gold-tin soldering and cooling.

[0064] The Kovar ring 7 is made of 4J29, which plays a role in stress transition, reduces the thermal stress between the sleeve on the low-frequency connector 5 and the glass, and reduces the risk of glass sealing failure.

[0065] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to exclude myriad other embodiments of the present application that other inventors can develop based on the same general inventive concepts embodied by the described embodiments. That is, although the present application is described in terms of particular embodiments and illustrative figures, it should be apparent that the scope of the present application is not limited to these specific embodiments.

[0066] While the embodiments of the application have been shown and described herein, it will be understood by those skilled in the art that many changes, modifications, substitutions and alterations to these embodiments can be made without departing from the principles and spirits of the application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a stainless steel inlay oxygen-free copper T / R shell, characterized in that the shell comprises a stainless steel shell body (1), an oxygen-free copper substrate (2), a radio frequency connector (3), a stress gradient release ring (4) and a low frequency connector (5); the stress gradient release ring (4) comprises an oxygen-free copper ring (6) and a Kovar ring (7); the method comprises the following steps: Step 1, cleaning and annealing the stainless steel shell body (1), the oxygen-free copper substrate (2), the oxygen-free copper ring (6) and the Kovar ring (7); Step 2, pre-plating nickel on the stainless steel shell body (1), the oxygen-free copper substrate (2), the oxygen-free copper ring (6) and the Kovar ring (7); Step 3, overlapping the oxygen-free copper substrate (2) at the bottom of the stainless steel shell body (1), overlapping the oxygen-free copper ring (6) near one side of the stainless steel shell body (1), overlapping the Kovar ring (7) on the oxygen-free copper ring (6), placing silver copper solder at the overlapping positions, and placing in a tooling fixture, and then welding through a silver copper soldering process temperature curve to form a T / R shell semi-finished product; Step 4, electroplating nickel and gold on the T / R shell semi-finished product, and removing the plating layer of the laser sealing surface through mechanical processing; Step 5, mounting the gold-plated shell of Step 4, the low frequency connector (5) and the radio frequency connector (3) on the Kovar ring (7), placing custom gold tin solder at the overlapping positions, placing in a tooling fixture, and welding through a gold tin soldering process temperature curve to form a T / R shell finished product. The shell comprises a stainless steel shell body (1), an oxygen-free copper substrate (2), a radio frequency connector (3), a stress gradient release ring (4) and a low frequency connector (5); the stainless steel shell body (1) is used to provide electrical connection, support and airtight structural foundation for other components; the oxygen-free copper substrate (2) is arranged at the bottom of the stainless steel shell body (1) and used for heat dissipation of a high-power chip; one side surface of the stainless steel shell body (1) is provided with the radio frequency connector (3), the stress gradient release ring (4) and the low frequency connector (5) for matching the expansion coefficient of the low frequency connector to avoid air leakage caused by mismatching; the low frequency connector (5) is nested in the stress gradient release ring (4); the radio frequency connector (3) is arranged outside the stress gradient release ring (4); the stress gradient release ring (4) comprises an oxygen-free copper ring (6) and a Kovar ring (7); the oxygen-free copper ring (6) is larger in size than the Kovar ring (7) and is arranged below the Kovar ring (7), the ring openings of the two rings are matched, and the low frequency connector (5) is nested; the surfaces of the stainless steel shell body (1), the oxygen-free copper substrate (2) and the stress gradient release ring (4) are electroplated with nickel or nickel-gold; the stainless steel shell body (1), the oxygen-free copper substrate (2) and the stress gradient release ring (4) are connected through silver copper welding; the radio frequency connector (3) and the low frequency connector (5) are connected through gold tin welding; the stainless steel shell body (1) is made of 316L, the oxygen-free copper is made of TU1, and the Kovar ring (7) is made of 4J29. ​ ​ ​ ​ ​ ​ ​ 2. A stainless steel inlayed oxygen-free copper T / R enclosure for use in the method of manufacture of claim 1, characterized by, ​ ​ ​ ​ ​ ​ 3. A stainless steel inlaid oxygen-free copper T / R enclosure according to claim 2, wherein ​ ​ 4. A stainless steel inlaid oxygen-free copper T / R enclosure according to claim 2, wherein ​ 5. A stainless steel inlaid oxygen-free copper T / R enclosure according to claim 4, wherein ​ 6. A stainless steel inlaid oxygen-free copper T / R enclosure according to claim 2, wherein ​ 7. A stainless steel inlaid oxygen-free copper T / R enclosure according to claim 2, wherein ​

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