High-reliability salt-spray-corrosion-resistant parallel seam welding alloy cover plate and preparation method thereof
By forming a WC-Co/Ni layer on the surface of the alloy cover plate and preparing welding and protective layers, the corrosion problem caused by the brittleness of the coating in high-temperature welding of parallel seam welded cover plates is solved, achieving high reliability in salt spray corrosion resistance and sealing effect, and adapting to the harsh salt spray environment of integrated circuits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-04-03
AI Technical Summary
In the prior art, the brittleness of the nickel-phosphorus plating layer during the high-temperature welding process of the parallel seam weld cover plate leads to the exposure of the constant expansion alloy substrate, resulting in corrosion and sealing failure during salt spray testing, which affects the reliability of integrated circuits.
A WC-Co/Ni layer is formed on the surface of the alloy cover plate, and a welding layer and a protective layer are formed on it. A highly reliable parallel seam welded alloy cover plate resistant to salt spray corrosion is prepared by chemical plating and electroplating techniques. The WC-Co/Ni layer has a high coefficient of thermal expansion and a high melting point, protecting the alloy cover plate from damage.
It enhances the cover plate's resistance to salt spray corrosion, ensures the sealing effect of welding and the high reliability of integrated circuits, and meets the requirements of harsh salt spray environments.
Smart Images
Figure CN121793818A_ABST
Abstract
Description
Technical Field
[0001] This invention pertains to integrated circuit electronic packaging, and in particular to a highly reliable salt spray corrosion resistant parallel seam welded alloy cover plate and its preparation method. Background Technology
[0002] Parallel seam welding is one of the most commonly used packaging methods for high-reliability, hermetic ceramic encapsulation. This technology utilizes the principle of resistance welding, where heat generated by pulsed power applied to the cover plate surface by roller electrodes melts and re-solidifies the plating on the underside of the cover plate and the surface of the weld frame, achieving welding between the cover plate and the weld frame. As the roller electrodes roll on the cover plate, under the action of pulsed power, elliptical weld points are formed, overlapping each other to eventually form a continuous fish-scale weld seam, thus achieving hermetic encapsulation. During parallel seam welding, the welding heat is mainly concentrated in the weld seam area, and the duration of pulsed power in a welding cycle is much shorter than the cooling time. Most of the heat can be transferred to the environment in a timely manner through heat conduction and heat radiation, so the internal components of the core cavity are not affected by high temperatures.
[0003] To minimize the adverse effects of thermal shock during welding on the ceramic circuit core, conventional parallel seam welded cover plates typically undergo electroless nickel-phosphorus alloy plating on the surface of a constant expansion alloy substrate. The phosphorus content in the electroless nickel-phosphorus plating layer is generally between 8% and 12% by weight, and the melting point of the plating is 860-880℃. To obtain a continuous weld seam and ensure good sealing performance, the temperature at the contact point between the cover plate and the outer shell weld ring often needs to reach 1000℃ or even higher. Higher temperatures are beneficial for improving the yield rate of the parallel seam welded sealing process. However, due to the high brittleness of the electroless nickel-phosphorus plating layer, excessively high temperatures can cause melting and cracking of the surface nickel-phosphorus layer, exposing the Kovar alloy or iron-nickel constant expansion alloy substrate, severely reducing the corrosion resistance of the cover plate. This is the root cause of frequent rusting in the welded area of the cover plate during salt spray tests, leading to seal failure. Therefore, improving the salt spray corrosion resistance of parallel seam welded cover plates is an urgent problem to be solved. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a highly reliable salt spray corrosion resistant parallel seam welded alloy cover plate and its preparation method. The highly reliable salt spray corrosion resistant parallel seam welded alloy cover plate provided by this invention can solve the problem that conventional parallel seam welded cover plates using electroless nickel-phosphorus plating suffer from corrosion and sealing failure during salt spray tests due to the melting of the plating layer during parallel seam welding, leading to a decrease in the reliability of integrated circuits.
[0005] To achieve the above technical objectives, the technical solution adopted in the embodiments of the present invention is as follows: In a first aspect, embodiments of the present invention provide a highly reliable salt spray corrosion resistant parallel seam welded alloy cover plate, comprising an alloy cover plate body, wherein a WC-Co / Ni layer is disposed on the surface of the alloy cover plate body, a welding layer is disposed on the surface of the WC-Co / Ni layer, and a protective layer is disposed on the surface of the welding layer.
[0006] Furthermore, the alloy cover plate body is a constant expansion alloy, and the coefficient of thermal expansion of the constant expansion alloy is 4.5 × 10⁻⁶. -6 ~5.8×10 -6 / K.
[0007] Furthermore, the constant expansion alloy is Kovar alloy 4J29 or 4J42.
[0008] Furthermore, the coefficient of thermal expansion of the WC-Co / Ni layer is 5.5 × 10⁻⁶. -6 ~6.5×10 -6 / K; The weight percentage of Co and / or Ni in the WC-Co / Ni layer is 10%~30%, with the balance being WC.
[0009] Furthermore, the weld layer is a nickel-phosphorus alloy layer with a thickness of 2–8.89 μm.
[0010] Furthermore, the weight ratio of phosphorus in the nickel-phosphorus alloy layer is 8% to 12%.
[0011] Furthermore, the melting point of the nickel-phosphorus alloy layer is 860~880℃.
[0012] Furthermore, the protective layer is a gold layer with a thickness of 0.1~6μm.
[0013] Secondly, embodiments of the present invention provide a method for preparing a highly reliable salt spray corrosion resistant parallel seam welded alloy cover plate, comprising the following steps: Step S1: The alloy cover plate body is obtained by machining or etching the expansion alloy sheet. Step S2: After cleaning and drying, a WC-Co / Ni layer is formed on the surface of the alloy cover plate body, and then it is cleaned and dried. Step S3: After forming a welding layer on the WC-Co / Ni layer using chemical plating technology, the layer is cleaned and dried. Step S4: A protective layer is formed on the weld layer by electroplating. Step S5: After cleaning and drying, the parallel seam welded alloy cover plate is completed.
[0014] Further, in step S2, the thickness of the WC-Co / Ni layer is 5~20μm, and the WC-Co / Ni layer is formed by one of the following methods: supersonic flame spraying, ultrasonic spraying, plasma spraying, explosive spraying, magnetron sputtering, and chemical vapor deposition.
[0015] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows: (1) The WC-Co / Ni layer of the present invention has the strength and hardness of WC ceramic phase and the toughness of Co / Ni metal phase, and also has high thermal shock resistance. The melting point of WC is above 2800℃. The WC-Co / Ni layer can effectively prevent the electrode from damaging the alloy cover plate substrate during parallel seam welding. It can avoid the exposure of constant expansion alloy (4J29 or 4J42) in salt spray test. While ensuring the integrity of the cover plate, it enhances the salt spray corrosion resistance of the cover plate.
[0016] (2) The coefficient of thermal expansion of the WC-Co / Ni layer of the present invention is 5.5 × 10⁻⁶. -6 / K~6.5×10 -6 / K has a high matching coefficient of thermal expansion with the constant expansion alloy (4J29 or 4J42). When subjected to thermal shock and temperature cycling, it generates less thermal stress with the constant expansion alloy matrix, and has good thermal shock resistance and high reliability.
[0017] (3) The welding process of the high-reliability salt spray corrosion resistant parallel seam welded cover plate provided by the present invention is compatible with the conventional parallel seam welded electroless nickel plated cover plate, and the same sealing effect can be obtained without using a larger welding power.
[0018] (4) Compared with conventional parallel seam welded electroless nickel-plated cover plates, the high-reliability salt spray corrosion resistant parallel seam welded cover plate provided by the present invention has better salt spray corrosion resistance, which can meet the more demanding salt spray environment application requirements of integrated circuit products and realize the high reliability requirements of parallel seam welded packaged devices. Attached Figure Description
[0019] Figure 1 This is a cross-sectional schematic diagram of the high-reliability salt spray corrosion resistant parallel seam weld cover plate body in Embodiment 1 of the present invention.
[0020] Figure 2 This is a schematic cross-sectional view of the outer surface of the high-reliability salt spray corrosion resistant parallel seam weld cover plate body after the formation of a WC-Co / Ni layer in Embodiment 1 of the present invention.
[0021] Figure 3 This is a schematic cross-sectional view of the high-reliability salt spray corrosion resistant parallel seam welded cover plate after the formation of the welded layer outside the WC-Co / Ni layer in Embodiment 1 of the present invention.
[0022] Figure 4This is a cross-sectional schematic diagram of the outer surface of the welded layer of the high-reliability salt spray corrosion resistant parallel seam weld cover plate after a protective layer has been formed in an embodiment of the present invention.
[0023] Figure 5 This is a cross-sectional schematic diagram of the high-reliability salt spray corrosion resistant parallel seam weld cover plate body in Embodiment 2 of the present invention.
[0024] Figure 6 This is a schematic cross-sectional view of the outer surface of the high-reliability salt spray corrosion resistant parallel seam weld cover plate body after the formation of a WC-Co / Ni layer in Embodiment 2 of the present invention.
[0025] Figure 7 This is a schematic cross-sectional view of the high-reliability salt spray corrosion resistant parallel seam welded cover plate after the formation of the welded layer outside the WC-Co / Ni layer in Embodiment 2 of the present invention.
[0026] Figure 8 This is a cross-sectional schematic diagram of the outer surface of the welded layer of the high-reliability salt spray corrosion resistant parallel seam weld cover plate after the formation of a protective layer in Embodiment 2 of the present invention.
[0027] Explanation of reference numerals in the attached drawings: 1-Alloy cover plate body; 2-WC-Co / Ni layer; 3-Welding layer; 4-Protective layer. Detailed Implementation
[0028] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "inner" and "outer", "upper" and "lower", "left" and "right" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention.
[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0030] Example 1 like Figure 4 As shown, a highly reliable salt spray corrosion resistant parallel seam welded alloy cover plate includes an alloy cover plate body 1, a WC-Co layer 2 formed on the outer surface of the alloy cover plate body 1, a welding layer 3 formed outside the WC-Co layer 2, and a protective layer 4 formed outside the welding layer 3.
[0031] The alloy cover plate body 1 is made of constant expansion alloy 4J29, and the coefficient of thermal expansion of constant expansion alloy is 5.8×10. -6 / K.
[0032] The coefficient of thermal expansion of WC-Co layer 2 is 5.5 × 10⁻⁶. -6 / K, the weight ratio of Co in WC-Co layer 2 is 10%.
[0033] Welding layer 3 is a nickel-phosphorus alloy layer with a thickness of 2μm and a phosphorus weight ratio of 8%. The melting point of the nickel-phosphorus alloy layer is 880℃.
[0034] The protective layer 4 is a gold layer with a melting point of 1064.4℃ and a thickness of 0.1μm.
[0035] The preparation method of the above-mentioned salt spray corrosion resistant parallel seam welded alloy cover plate includes the following steps: Step 1: After cleaning, the expansion alloy 4J29 is dried. Step 2, as follows Figure 1 As shown, the T-shaped alloy cover plate body is obtained by machining or etching the constant expansion alloy 4J29; Step 3, as follows Figure 2 As shown, plasma spraying is performed on the surface of the alloy cover plate body 1 to form a WC-Co layer 2 with a thickness of 5μm, followed by cleaning and drying. Step Four: As Figure 3 As shown, chemical plating technology is applied to the surface of WC-Co layer 2 to form welding layer 3, followed by cleaning and drying. Step 5: Cut the alloy cover plate into individual alloy cover plates, and deburr the individual alloy cover plates after cutting. Step Six: As Figure 4 As shown, a single alloy cover plate body 1 is electroplated with gold to form a protective layer 4 on the outer surface of the alloy cover plate body 1. Step 7: After cleaning and drying, the parallel seam welded alloy cover plate is completed.
[0036] Example 2 like Figure 8 As shown, a highly reliable salt spray corrosion resistant parallel seam welded alloy cover plate includes an alloy cover plate body 1, a WC-Co / Ni layer 2 formed on the outer surface of the alloy cover plate body 1, a welding layer 3 formed outside the WC-Co / Ni layer 2, and a protective layer 4 formed outside the welding layer 3.
[0037] The alloy cover plate body 1 is made of constant expansion alloy 4J29, and the coefficient of thermal expansion of constant expansion alloy is 5.0×10⁻⁶. -6 / K.
[0038] The coefficient of thermal expansion of the WC-Co / Ni layer 2 is 6.0 × 10⁻⁶. -6 / K; The weight ratio of Co to Ni in WC-Co / Ni layer 2 is 15%, where the weight ratio of Co to Ni is 1:1; Welding layer 3 is a nickel-phosphorus alloy layer with a thickness of 5 μm and a phosphorus weight ratio of 10%. The melting point of the nickel-phosphorus alloy layer is 870℃.
[0039] The protective layer 4 is a gold layer with a melting point of 1064.4℃ and a thickness of 3μm.
[0040] The preparation method of the above-mentioned salt spray corrosion resistant parallel seam welded alloy cover plate includes the following steps: Step 1: After cleaning, the expansion alloy 4J29 is dried. Step 2, as follows Figure 5 As shown, a straight alloy cover plate body 1 is obtained by machining or etching the expansion alloy 4J29. Step 3, as follows Figure 6 As shown, plasma spraying is performed on the surface of the alloy cover plate body 1 to form a WC-Co / Ni layer 2 with a thickness of 12μm, followed by cleaning and drying. Step Four: As Figure 7 As shown, chemical plating technology is applied to the surface of WC-Co / Ni layer 2 to form welding layer 3, followed by cleaning and drying. Step 5: Cut the alloy cover plate body 1 into individual alloy cover plate bodies 1, and deburr the individual alloy cover plate bodies 1 after cutting. Step Six: As Figure 8 As shown, a single alloy cover plate body 1 is electroplated with gold, and a protective layer 4 is formed on the outer surface of the alloy cover plate body 1 by electroplating. Step 7: After cleaning and drying, the parallel seam welded alloy cover plate is completed.
[0041] Example 3 A highly reliable salt spray corrosion resistant parallel seam welded alloy cover plate includes an alloy cover plate body 1, a WC-Ni layer 2 formed on the outer surface of the alloy cover plate body 1, a welding layer 3 formed outside the WC-Ni layer 2, and a protective layer 4 formed outside the welding layer 3.
[0042] The alloy cover plate body 1 is made of constant expansion alloy 4J42, and the coefficient of thermal expansion of constant expansion alloy is 4.5×10. -6 / K.
[0043] The coefficient of thermal expansion of the WC-Ni layer 2 is 6.5 × 10⁻⁶. -6 / K; The weight ratio of Ni in WC-Ni layer 2 is 30%.
[0044] Welding layer 3 is a nickel-phosphorus alloy layer with a thickness of 8.89 μm. The phosphorus content in the nickel-phosphorus alloy layer is 12% by weight. The melting point of the nickel-phosphorus alloy layer is 860℃.
[0045] The protective layer 4 is a gold layer with a melting point of 1064.4℃ and a thickness of 6μm.
[0046] The preparation method of the above-mentioned salt spray corrosion resistant parallel seam welded alloy cover plate includes the following steps: Step 1: After cleaning, the expansion alloy 4J42 is dried. Step 2: After machining or etching the expansion alloy 4J42, the T-shaped alloy cover plate body 1 is obtained; Step 3: Plasma spraying is performed on the surface of the alloy cover plate body 1 to form a WC-Ni layer 2 with a thickness of 20μm, followed by cleaning and drying. Step 4: Apply chemical plating technology to the surface of WC-Ni layer 2 to form weld layer 3, then clean and dry; Step 5: Cut the alloy cover plate body 1 into individual alloy cover plate bodies 1, and deburr the individual alloy cover plate bodies 1 after cutting. Step 6: Electroplating gold onto the individual alloy cover plate body 1, forming a protective layer 4 on the outer surface of the alloy cover plate body 1. Step 7: After cleaning and drying, the parallel seam welded alloy cover plate is completed.
[0047] The high-reliability salt spray corrosion resistant parallel seam welded cover plate described in this invention maintains the same shape as conventional alloy cover plates and is fully compatible with existing parallel seam welding processes. The principle of parallel seam welding is to form weld points by melting and then solidifying the coating. Damage to the coating and the substrate is unavoidable during this process. Currently, the damage is mainly controlled by reducing energy input. However, reducing energy carries the risk of poor welding and low sealing yield. Therefore, the scope for energy reduction is limited and cannot fundamentally solve the problem of weld edge damage. The high-reliability salt spray corrosion resistant parallel seam welded alloy cover plate provided in this embodiment has a WC-Co / Ni coating structure with high melting point, high hardness, high thermal shock resistance, and toughness on the surface of the alloy cover plate body. The WC-Co / Ni coating can remain intact during the seam welding process, thus protecting the alloy cover plate body from damage. At the same time, the WC-Co / Ni coating also has good resistance to acid, alkali and salt spray corrosion, which can ensure that the cover plate has better salt spray corrosion resistance, meet the salt spray test requirements of high-reliability ceramic packaging, and adapt to the more demanding salt spray environment application requirements of integrated circuit products, thus achieving the high reliability requirements of parallel seam welded packaged devices.
[0048] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the claims of the present invention.
[0049] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A highly reliable salt spray corrosion resistant parallel seam welded alloy cover plate, characterized in that, It includes an alloy cover plate body (1), the surface of which is provided with a WC-Co / Ni layer (2), the surface of which is provided with a welding layer (3), and the surface of which is provided with a protective layer (4).
2. The high-reliability salt spray corrosion resistant parallel seam welded alloy cover plate according to claim 1, characterized in that, The alloy cover plate body (1) is a constant expansion alloy, and the coefficient of thermal expansion of the constant expansion alloy is 4.5×10⁻⁶. -6 ~5.8×10 -6 / K.
3. The high-reliability salt spray corrosion resistant parallel seam welded alloy cover plate according to claim 2, characterized in that, The constant expansion alloy is Kovar alloy 4J29 or 4J42.
4. The high-reliability salt spray corrosion resistant parallel seam welded alloy cover plate according to claim 1, characterized in that, The coefficient of thermal expansion of the WC-Co / Ni layer (2) is 5.5 × 10⁻⁶. -6 ~6.5×10 -6 / K; The weight percentage of Co and / or Ni in the WC-Co / Ni layer (2) is 10%~30%, and the balance is WC.
5. The high-reliability salt spray corrosion resistant parallel seam welded alloy cover plate according to claim 1, characterized in that, The weld layer (3) is a nickel-phosphorus alloy layer with a thickness of 2 to 8.89 μm.
6. The high-reliability salt spray corrosion resistant parallel seam welded alloy cover plate according to claim 5, characterized in that, The weight ratio of phosphorus in the nickel-phosphorus alloy layer is 8% to 12%.
7. The high-reliability salt spray corrosion resistant parallel seam welded alloy cover plate according to claim 1, characterized in that, The melting point of the nickel-phosphorus alloy layer is 860~880℃.
8. The high-reliability salt spray corrosion resistant parallel seam welded alloy cover plate according to claim 1, characterized in that, The protective layer (4) is a gold layer with a thickness of 0.1~6μm.
9. A method for preparing a highly reliable salt spray corrosion resistant parallel seam welded alloy cover plate, characterized in that, Includes the following steps: Step S1: The alloy cover plate body (1) is obtained by machining or etching the expansion alloy plate. Step S2: After cleaning and drying, a WC-Co / Ni layer (2) is formed on the surface of the alloy cover plate body (1), and then cleaned and dried. Step S3: After forming a welding layer (3) on the WC-Co / Ni layer (2) using chemical plating technology, the layer is cleaned and dried. Step S4: A protective layer (4) is formed on the welding layer (3) by electroplating. Step S5: After cleaning and drying, the parallel seam welded alloy cover plate is completed.
10. The high-reliability salt spray corrosion resistant parallel seam welded alloy cover plate according to claim 9, characterized in that, In step S2, the thickness of the WC-Co / Ni layer (2) is 5~20μm, and the WC-Co / Ni layer (2) is formed by one of supersonic flame spraying, ultrasonic spraying, plasma spraying, explosive spraying, magnetron sputtering and chemical vapor deposition.