Kovar base material light modulator packaging shell and preparation method thereof

Abstract

The invention relates to the technical field of electronic packaging, in particular to a Kovar base material optical modulator packaging shell and a preparation method thereof. The light modulator packaging shell comprises a base, a high-frequency assembly mounting hole is formed in the base, a high-frequency assembly is inserted in the high-frequency assembly mounting hole, the base is made of kovar alloy, a transition ring with a high expansion coefficient is arranged between the base and the high-frequency assembly, the transition ring is made of stainless steel, and the high thermal expansion coefficient is (10-20) * 10 <-6 > / DEG C. According to the invention, the transition ring with the high expansion coefficient is arranged between the high-frequency assembly and the kovar material base with the low expansion coefficient, and the transition ring with the high expansion coefficient is used for applying an inward pressurization effect on the high-frequency assembly, so that the binding force between the assembly ring of the high-frequency assembly and the glass insulator is indirectly enhanced; therefore, the sealing reliability is improved, and the air leakage problem is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic packaging, and in particular to a packaging shell of a kovar substrate optical modulator and a preparation method thereof. Background Art

[0002] An optical modulator is a device that can change the properties of light waves, usually used to control the intensity, phase, frequency or polarization state of an optical signal. In fields such as optical fiber communications and optical data processing, optical modulators are key components for achieving optical signal transmission and processing.

[0003] The optical modulator is mainly composed of optical fiber, modulation chip, thin film resistor and packaging shell, among which the packaging shell mainly plays the role of mechanical support, internal and external electrical connection and airtight protection for the internal electronic components, especially the chip. Therefore, the airtightness and sealing reliability of the packaging shell have a vital impact on the service life of the optical modulator. The inventor's previous patent CN115113419 B discloses an optical modulator packaging shell and a preparation method thereof. The welding reliability of the optical modulator packaging shell is improved through an improved structure and welding method, thereby improving the airtightness. However, this method is relatively costly and has certain limitations in its application in low-cost optical modulator packaging shells.

[0004] The material of the optical modulator package shell is mainly Kovar 4J29. For the Kovar-based optical modulator shell, after the gold-tin soldering of the purchased high-frequency components, the interface leakage between the component ring and the glass insulator of the high-frequency component is often encountered. This is mainly because most of the purchased high-frequency components set the component ring very thin due to the need for miniaturization, resulting in a relatively weak sealing reliability between the component ring and the glass insulator. When the high-frequency component is soldered to the Kovar base by gold-tin or the finished gold-tin soldering product is tested after the subsequent temperature cycle, the weak sealing interface between the component ring and the glass insulator of the high-frequency component is damaged due to the influence of welding stress or the influence of changing thermal stress, resulting in leakage. At present, some Kovar-based bases have been replaced with materials with high expansion coefficients, such as stainless steel. However, this method has the following problems: first, it can only adapt to specific usage scenarios; second, it increases the cost of the base; third, it is necessary to change the thickness specification of the component ring in the high-frequency component, but the purchased high-frequency components have universal requirements, and suppliers are often unwilling to cooperate in changing the thickness specification of the component ring. Therefore, the sealing reliability between the component ring and the glass insulator is actually difficult to improve.

[0005] Based on this problem, providing a simple and low-cost method to improve the sealing reliability between the high-frequency component ring and the glass insulator, thereby improving the overall reliability of the packaging shell, is an issue that needs to be urgently addressed. Summary of the invention

[0006] In order to solve the above technical problems, one of the objectives of the present invention is to provide a light modulator packaging shell of a var substrate.

[0007] The present invention adopts the following technical solutions:

[0008] A light modulator package housing of a Kovar substrate comprises a base, a high-frequency component mounting hole is provided on the base, a high-frequency component is inserted into the high-frequency component mounting hole, the base is Kovar alloy, a transition ring with a high thermal expansion coefficient is arranged between the base and the high-frequency component, the transition ring is made of stainless steel, and the high thermal expansion coefficient is (10-20)×10 -6 / ℃.

[0009] Preferably, the stainless steel is 304L or 10# steel or 20# steel.

[0010] Preferably, the Kovar alloy is made of 4J29 material.

[0011] Preferably, the base and the transition ring are brazed together by silver-copper solder, and the silver-copper solder is Ag72Cu28 eutectic solder.

[0012] Preferably, the high-frequency component includes a component ring, a glass insulator and a lead, the glass insulator is made of Corning 7070 material; the component ring and the lead are made of Kovar alloy 4J29 material, and the surface of the lead and the component ring are plated with nickel and gold.

[0013] Preferably, the transition ring is connected to the high-frequency component via gold-tin solder, and the gold-tin solder is Au80Sn20 eutectic solder.

[0014] Preferably, the base is also provided with a conduit communicating with the internal cavity of the packaging shell, and the conduit is brazed with the base by silver-copper solder, and the silver-copper solder is Ag72Cu28 eutectic solder.

[0015] A second object of the present invention is to provide a method for preparing a light modulator package housing of a kovar substrate as described above, comprising the following steps:

[0016] S1. The base and the conduit are formed into a predetermined shape, and a silver-copper solder groove is reserved on the base;

[0017] S2. Processing and shaping the stainless steel transition ring, reserving a gold-tin solder groove on the transition ring, and electroplating the entire ring with nickel;

[0018] S3. Assemble the catheter and the transition ring on the base, and assemble the silver-copper solder, and use a positioning mold to fit the catheter, the silver-copper solder, the transition ring, and the base tightly to obtain a first assembly;

[0019] S4. The first assembly is placed in a brazing furnace for brazing, kept at 780 to 840 ° C for 7 ± 2min, and after cooling, the brazed first assembly is removed, the mold is removed, and the base semi-finished product is obtained;

[0020] S5. Electroplating the brazed semi-finished base with nickel and gold;

[0021] S6. Assemble the high-frequency component into the transition ring, and then assemble the gold-tin solder into the gold-tin solder groove on the transition ring, and use the high-frequency component positioning mold to make the high-frequency component, the gold-tin solder and the base fit tightly to obtain a second assembly;

[0022] S7. Place the second assembly in a brazing furnace for brazing at 300-350°C for 20±5 min. After cooling, take out the brazed second assembly, remove the mold, and obtain the finished product.

[0023] Preferably, in step S2, the thickness of the nickel layer of the transition ring electroplated with nickel is 4-10 μm.

[0024] Compared with the prior art, the beneficial effects of this application are:

[0025] In the prior art, in order to improve the air tightness of glass insulators, a series of measures are often taken to reduce the stress of brazing. Although this approach is not likely to cause cracks in glass insulators, it may cause insufficient bonding between the component ring of the high-frequency component and the glass insulator. The present application is the opposite. A transition ring with a high expansion coefficient is designed and welded between the high-frequency component and the low-expansion-coefficient Kovar base. The high-expansion-coefficient transition ring is used to apply an inward "boost" effect to the high-frequency component, thereby indirectly enhancing the bonding between the component ring of the high-frequency component and the glass insulator. The integrity of the glass insulator is protected by selecting the component ring material, the type of solder, and controlling the brazing conditions. This greatly improves the problem of air leakage after the high-frequency component is welded to the Kovar base or after temperature cycling due to insufficient sealing reliability between the component ring and the glass insulator. The present method is simple in process, low in cost, and has a wide range of applications.

[0026] The test and ANSYS simulation results show that the stress on the high-frequency component is increased after adding the stainless steel transition ring, and the measured values ​​of the airtightness and reliability of the finished product are significantly better than those of the conventional packaging process, indicating that the present application has good feasibility and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of the light modulator packaging shell of the present application.

[0028] Figure 2 for Figure 1 Schematic cross-sectional view of the package shell structure.

[0029] Figure 3 for Figure 1 Schematic cross-sectional view of the package shell structure.

[0030] Figure 4 This is a schematic cross-sectional view of the transition ring structure of this application.

[0031] Figure 5 The stress simulation results of the high-frequency component ring of the conventional Kovar base optical modulator.

[0032] Figure 6 The stress simulation results of the high-frequency component ring of the optical modulator with a stainless steel base of the same size.

[0033] Figure 7 Simulation results of stress on the high-frequency component ring of the optical modulator with a Kovar base to add a stainless steel transition ring.

[0034] The meanings of the symbols in the figure are as follows:

[0035] 10-base 11-transition ring 12-high frequency component mounting hole 13-welding hole

[0036] 20-high frequency component 21-component ring 22-glass insulator 23-lead 23

[0037] 30-catheter

[0038] 41-Silver copper solder 411-Transition ring solder groove 412-Conduit solder groove 42-Gold tin solder DETAILED DESCRIPTION

[0039] The technical solution of the present invention is described in more detail below in conjunction with the accompanying drawings and embodiments.

[0040] Example 1

[0041] See also Figure 1-Figure 4 A light modulator package housing of a Kovar substrate includes a base 10, a high-frequency component mounting hole 12 is provided on the base 10, and a high-frequency component 20 is inserted into the high-frequency component mounting hole 12. The base 10 is made of Kovar alloy, and a transition ring 11 with a high thermal expansion coefficient is arranged between the base 10 and the high-frequency component 20. The transition ring 11 is made of stainless steel, and the thermal expansion coefficient is (10-20)×10 -6 The thickness of the transition ring 11 is consistent with the thickness of the side wall of the base 10. The shape of the transition ring 11 is adapted to the installation hole of the high-frequency component and can be a circular ring or a square outside and a circular inside.

[0042] The base is made of 4J29 Kovar alloy, the transition ring 11 is preferably made of stainless steel 304L or 10# steel or 20# steel, the base 10 and the transition ring 11 are brazed and connected by silver-copper solder 41, and the silver-copper solder 41 is Ag72Cu28 eutectic solder. The base 10 is also provided with a conduit 30 connected to the cavity of the package shell, and the conduit 30 and the base 10 are brazed and connected by silver-copper solder 41, and the silver-copper solder 41 is Ag72Cu28 eutectic solder.

[0043] The high-frequency component 20 used in this application is a purchased part and is therefore not described in detail. Its structure consists of a component ring 21, a glass insulator 22 and a lead 23, wherein the glass insulator 22 is made of Corning 7070 material; the component ring 21 and the lead 23 are both made of Kovar alloy 4J29, and the surface of the lead 23 and the component ring 21 has been plated with nickel and gold.

[0044] The high-frequency component 20 is disposed in the transition ring 11 . The transition ring 11 and the high-frequency component 20 are connected via a gold-tin solder 42 . The gold-tin solder 42 is Au80Sn20 eutectic solder.

[0045] The method for preparing the light modulator package shell of the above-mentioned Kovar substrate comprises the following steps:

[0046] S1. The base 10 and the conduit 30 are formed into a predetermined shape, and a silver-copper solder groove is reserved on the base 10, and then degreasing, cleaning and annealing are performed;

[0047] S2. The stainless steel transition ring 11 is processed and formed, a gold-tin solder groove is reserved on the transition ring 11, and then degreasing, cleaning, activation, and overall nickel electroplating, the nickel electroplating layer thickness is 4 to 10 μm;

[0048] S3. Assemble the cleaned and annealed conduit 30 and the pre-nickel-plated stainless steel transition ring 11 on the base 10, and then assemble the silver-copper solder 41, and use a positioning mold to fit the conduit 30, the silver-copper solder 41, the transition ring 11, and the base 10 tightly to obtain a first assembly;

[0049] S4. The first assembly is carefully placed in a brazing furnace with a pre-set furnace temperature for brazing, 780 to 840 ° C for 7 ± 2min, and after cooling, the brazed first assembly is removed, the mold is removed, and the base 10 is obtained as a semi-finished product;

[0050] S5. The brazed base 10 semi-finished products are electroplated with nickel and gold;

[0051] S6. Assemble the high-frequency component 20 into the transition ring 11, and then assemble the gold-tin solder 42 into the gold-tin solder groove on the transition ring 11, and use the high-frequency component 20 to position the mold so that the high-frequency component 20, the gold-tin solder 42 and the base 10 fit tightly to obtain a second assembly;

[0052] S7. Carefully place the second assembly into a brazing furnace with the furnace temperature set in advance for brazing, keep the temperature at 300-350°C for 20±5min, take out the brazed second assembly after cooling, remove the mold, and obtain the finished product.

[0053] Example 2

[0054] See also Figure 1-Figure 4 , a method for preparing a light modulator package shell of a varable substrate, the steps are:

[0055] S1. The base 10 and the catheter 30 are processed and formed into a predetermined shape. The silver-copper solder groove includes a transition ring solder groove 411 and a catheter solder groove 412. The diameter of the welding hole 13 on the base 10 for arranging the catheter 30 is 3.03-3.07 mm, and the outer diameter of the catheter 30 is 2.98-3.02 mm. The catheter solder groove 412 at the catheter 30 is a groove of C0.2-C0.3 processed on the outside of the welding hole 13. The diameter of the high-frequency component mounting hole 12 is 4.95-4.99 mm. The high-frequency component mounting hole 12 is first connected to the transition ring 11. The transition ring solder groove 411 is a groove processed around the outside of the high-frequency component mounting hole 12. The diameter of the groove is 0.8-1.0 mm larger than the welding hole, and the depth is 0.2-0.4 mm. After the base is processed, it is degreased, cleaned, and annealed.

[0056] S2. The outer diameter of the transition ring 11 is 4.88-4.92 mm, slightly smaller than the high-frequency component mounting hole 12, and the inner diameter is 2.02-2.06 mm. Its thickness is equal to the side wall thickness of the Kovar base. After the transition ring 11 is processed, it is degreased, cleaned, activated, and electroplated with nickel. The thickness of the electroplated nickel is 4-10 μm.

[0057] S3. Assemble the cleaned and annealed conduit 30 and the pre-nickel-plated stainless steel transition ring 11 on the base 10, and then assemble the silver-copper solder 41, and use a positioning mold to fit the conduit 30, the silver-copper solder 41, the transition ring 11, and the base 10 tightly to obtain a first assembly;

[0058] S4. The first assembly is carefully placed in a brazing furnace with a pre-set furnace temperature for brazing, 780 to 840 ° C for 7 ± 2min, and after cooling, the brazed first assembly is removed, the mold is removed, and the base 10 is obtained as a semi-finished product;

[0059] S5. The semi-finished product 10 of the brazed base is electroplated with nickel and gold, wherein the nickel plating thickness is 3 to 8 μm and the gold plating thickness is 1 to 2 μm;

[0060] S6. Assemble the high-frequency component 20 into the transition ring 11, and then assemble the gold-tin solder 42 into the gold-tin solder groove on the transition ring 11, and use the high-frequency component 20 to position the mold so that the high-frequency component 20, the gold-tin solder 42 and the base 10 fit tightly to obtain a second assembly;

[0061] S7. Carefully place the second assembly into a brazing furnace with the furnace temperature set in advance for brazing, keep the temperature at 300-350°C for 20±5min, take out the brazed second assembly after cooling, remove the mold, and obtain the finished product.

[0062] It should be noted that the numerical values ​​used in this embodiment are only to indicate a specific optical modulator packaging shell that can be implemented, and does not mean that this application can only use the above specific parameters. Technical personnel in this field can adaptively adjust the material, size, etc. according to the actual situation of the packaging shell and the method of this application.

[0063] test

[0064] The stresses of the high-frequency component rings of three structures, namely, the conventional Kovar base optical modulator, the stainless steel base optical modulator of the same size, and the Kovar base optical modulator with a stainless steel transition ring added in the present application, were simulated. The results are shown in Tables 1 and Figure 5-Figure 7 ; The air tightness and reliability were tested, and the results are shown in Table 2.

[0065] Table 1 Stress simulation results

[0066]

[0067] Table 2 Air tightness and reliability results

[0068]

[0069] It can be seen that after adding the stainless steel transition ring, the stress on the high-frequency component is greatly increased. The measured values ​​of air tightness and reliability show that the Kovar alloy base shell of the present application can achieve basically the same effect as the stainless steel base optical modulator shell, and can greatly improve the air tightness of the packaging shell.

[0070] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A package housing for an optical modulator of a kovar substrate, comprising a base (10), wherein the base (10) is provided with a high-frequency component mounting hole (12), wherein a high-frequency component (20) is inserted into the high-frequency component mounting hole (12), wherein: The base (10) is made of Kovar alloy, and a transition ring (11) with a high thermal expansion coefficient is arranged between the base (10) and the high-frequency component (20). The material of the transition ring (11) is stainless steel, and the high thermal expansion coefficient is (10-20)×10 -6 / ℃.

2. The optical modulator package of claim 1, wherein: The stainless steel is 304L or 10# steel or 20# steel.

3. The optical modulator package of claim 1, wherein: The Kovar alloy is made of 4J29 material.

4. The optical modulator package of claim 1, wherein: The base (10) and the transition ring (11) are brazed and connected via silver-copper solder (41), and the silver-copper solder (41) is Ag72Cu28 eutectic solder.

5. The optical modulator package of claim 1, wherein: The high-frequency component (20) comprises a component ring (21), a glass insulator (22) and a lead wire (23); the glass insulator (22) is made of Corning 7070; the component ring (21) and the lead wire (23) are made of Kovar 4J29; the surfaces of the lead wire (23) and the component ring (21) are plated with nickel and gold.

6. The optical modulator package of claim 1, wherein: The transition ring (11) is connected to the high-frequency component (20) via a gold-tin solder (42), and the gold-tin solder (42) is Au80Sn20 eutectic solder.

7. The optical modulator package of claim 1, wherein: The base (10) is also provided with a conduit (30) connected to the cavity of the package shell, and the conduit (30) and the base (10) are brazed together by silver-copper solder (41), and the silver-copper solder (41) is Ag72Cu28 eutectic solder.

8. A method for preparing a light modulator package shell of a kovar substrate as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: S1. The base (10) and the conduit (30) are formed into a predetermined shape, and a silver-copper solder groove is reserved on the base (10); S2. The stainless steel transition ring (11) is processed and formed, a gold-tin solder groove is reserved on the transition ring (11), and the whole is electroplated with nickel; S3. Assemble the conduit (30) and the transition ring (11) on the base (10) respectively, and assemble the silver-copper solder (41), and use a positioning mold to tightly fit the conduit (30), the silver-copper solder (41), the transition ring (11), and the base (10) to obtain a first assembly; S4. The first assembly is placed in a brazing furnace for brazing, and the temperature is kept at 780 to 840 ° C for 7 ± 2min. After cooling, the brazed first assembly is removed, the mold is removed, and the base (10) is obtained as a semi-finished product; S5. The brazed base (10) semi-finished product is electroplated with nickel and gold; S6. Assemble the high-frequency component (20) into the transition ring (11), then assemble the gold-tin solder (42) into the gold-tin solder groove on the transition ring (11), and use the high-frequency component (20) positioning mold to make the high-frequency component (20), the gold-tin solder (42) and the base (10) fit tightly to obtain a second assembly; S7. Place the second assembly in a brazing furnace for brazing at 300-350°C for 20±5 min. After cooling, take out the brazed second assembly, remove the mold, and obtain the finished product.

9. The method for preparing a light modulator package shell of a kovable substrate as claimed in claim 8, characterized in that: In the step S2, the thickness of the nickel layer of the transition ring (11) electroplated with nickel is 4 to 10 μm.

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