A package lid with low glass insulator stress and its applications and preparation

Abstract

The present application relates to the field of electronic component packaging, in particular to a packaging shell with low glass insulator stress and a preparation method thereof. The packaging shell is arranged on a circuit board and cooperates with leads, glass insulators and caps to form airtight packaging of electronic components. The size and shape of the cap are adapted to the electronic components to be packaged. On the inner side of the cap, a cavity structure is provided which protrudes towards the outer side and is used to accommodate the fused glass insulator. The cap further comprises a flat flash which is integrally arranged around the edge of the cavity structure. An anti-overflow structure is further arranged around the inner wall of the cavity structure. The cap is provided with a through hole for inserting leads at the wall structure position. The present application sets a metal ring to make the fused glass insulator structure regular in shape, avoiding stress concentration of the glass, thereby solving the problem of cracks and edge collapse of the fused glass.

Description

Technical Field

[0001] This invention relates to the field of electronic component packaging, and more specifically to a packaging cap with low glass insulator stress, its application, and its preparation. Background Technology

[0002] Electronic components generally consist of internal chips and circuits, a substrate, and a hermetically sealed enclosure. The rapid development of electronic components relies heavily on the support of hermetically sealed enclosures, and vice versa. Core and fundamental electronic components possess strong versatility and interchangeability, and are widely used in various electronic information fields such as telecommunications transmission and intelligent control. They have high requirements for quality stability and mass production. The hermetically sealed enclosure, as a key component, not only interconnects internal and external circuits but also protects the internal circuitry and performs other functions, directly reflecting the performance indicators of electronic components. Therefore, achieving large-scale, stable production and use of hermetically sealed enclosures is a challenge facing the industry.

[0003] The factors directly determining the packaging quality of high-reliability electronic components are the quality of the packaging shell itself and the quality of the sealing or capping process. For the packaging shell, high-reliability shells typically use traditional packaging materials such as Kovar alloy and cold-rolled steel for the base material, while insulators are made of glass. Considering factors such as product size, mass production, and specific usage requirements, large-format glass-metal shells account for a significant proportion in the industry.

[0004] These types of enclosures use integral large glass insulators. However, due to the inherent physical properties of glass, after the glass and metal casing are fused at high temperatures, structural irregularities such as overflow and flow can easily occur, leading to stress concentration and defects such as cracks in the glass. This is especially true for larger integral glass units, where the impact is more severe. Furthermore, regarding the capping / covering process for these enclosures, the unevenness in the shape, regularity, and structure of the glass insulator after sintering means that the pressure applied to the casing during capping or covering is directly transferred to the glass insulator, further exacerbating stress damage and making the glass more prone to cracks. This ultimately affects the quality and reliability of electronic components.

[0005] This problem has limited the rapid development of packaging shells and also hindered the rapid rise of core and basic electronic components. How to effectively solve the stress concentration problem after the metal-cased large glass insulator is sealed, while also reducing or avoiding damage to the glass insulator caused by subsequent capping or sealing pressure, is a difficult problem facing the industry. Summary of the Invention

[0006] To address the problem of glass defects that easily occur in stamped and integral large glass fusion sealing processes, this invention first provides a sealing cap with low glass insulator stress.

[0007] The technical solution adopted in this invention is as follows:

[0008] A low-stress glass insulator encapsulation cover is mounted on a circuit board and used to cooperate with leads, glass insulators, and caps to form a hermetically sealed encapsulation of electronic devices. The size and shape of the cover are adapted to the electronic devices to be encapsulated. On the inner side of the cover near the circuit board, there is a cavity structure that protrudes towards the outer side away from the circuit board to accommodate the fused glass insulator. The cover also includes a flat flash integrally formed around the edge of the cavity structure. The bottom surface of the flash is parallel to the surface of the circuit board used for encapsulation to ensure a close fit. An anti-overflow structure is also provided around the inner wall of the cavity structure. The cover has a through hole for inserting leads at a designated position in the cavity structure.

[0009] Preferably, the anti-overflow structure is a ring of protrusions on the inner wall of the cavity structure, and the cross-sectional shape of the protrusion is angular, circular, semi-circular, rectangular, or trapezoidal; more preferably, it is triangular.

[0010] Preferably, the material of the anti-overflow structure is the same as the material of the inner side of the cap, and the length of the anti-overflow structure in the horizontal direction is 50 to 80% of the thickness of the cap wall, and the height in the vertical direction is 1 to 1.2 times the length in the horizontal direction.

[0011] Preferably, the overflow prevention structure is positioned below 1 / 2 of the total height of the cavity structure, and the distance from the bottom of the overflow prevention structure to the bottom edge of the cap is greater than or equal to 1 / 2 of the burr width.

[0012] Preferably, the sealing material is Kovar alloy 4J29, iron-nickel alloy 4J42, expansion alloy 4J50, or cold-rolled steel.

[0013] Preferably, the sealing substrate is composed of oxygen-free copper disposed on the outer side and Kovar alloy disposed on the inner side.

[0014] Preferably, the oxygen-free copper is TU1, and the Kovar alloy is 4J29 or the iron-nickel alloy 4J42.

[0015] Preferably, the total thickness of the composite of oxygen-free copper and Kovar alloy is 0.1 to 1.0 mm, wherein the thickness ratio of oxygen-free copper to Kovar alloy is 7:3.

[0016] The present invention also provides an airtight encapsulation housing, the encapsulation housing comprising an encapsulation cap with low glass insulator stress as described above, a glass insulator disposed in the cavity structure of the cap, and leads inserted in the glass insulator and the cap.

[0017] The above-mentioned method for preparing a hermetic encapsulation shell includes the following steps:

[0018] S1. Using the required materials, a stamping, turning, or milling process is used to process a sealing cap of the required size, and an anti-overflow structure is integrally processed; the sealing cap includes a cavity structure and flash, and through holes are provided in corresponding positions;

[0019] S2. A lead hole adapted to the position of the through hole is machined on the glass insulator that matches the cover;

[0020] S3. Assemble the glass insulator into the cavity structure, insert the lead wire into the through hole and lead wire hole, place the opening side of the cover upward, and sinter the cover, glass insulator and lead wire together at high temperature to fuse them into a whole, thus obtaining the required hermetic encapsulation shell.

[0021] The hermetic encapsulation shell provided by this invention can also be used with a cap to form a hermetic encapsulation.

[0022] An airtight package includes an airtight package housing as described above, and a cap disposed on the surface of the airtight package housing.

[0023] Preferably, the size of the cap matches the cover, and the edge of the cap has an edge whose shape is adapted to the burr of the cover, the lower surface of which fits against the upper surface of the burr of the cover.

[0024] The beneficial effects of this invention are as follows:

[0025] Metal encapsulation housings are typically formed using processes such as turning, milling, and stamping, and have a certain cavity structure to house the glass insulator and its mating leads. For metal encapsulation housings of integral large glass insulators, traditional technology generally designs and manufactures the cavity housing the glass insulator with a straight sidewall structure. This leads to problems such as the glass insulator creeping and wetting along the straight sidewall after fusion sealing, resulting in overflow and flow defects. This causes stress concentration in the glass insulator, making it prone to cracking and affecting the sealing reliability of the metal encapsulation housing. Furthermore, after the glass insulator melts, the applied pressure during subsequent capping and sealing processes is transferred to the glass insulator, increasing the risk of glass breakage.

[0026] The sealing cap provided by this invention can overcome the design defects of existing products, reduce the stress on glass insulators, and improve product reliability, both in the preparation of the encapsulation shell before encapsulation and in the assembly of electronic components after encapsulation. Specifically:

[0027] By designing a raised anti-overflow structure around the inner wall of the cavity structure of the cap, the glass insulator can be confined within a certain area after fusion sealing, making the shape of the glass insulator more regular and effectively avoiding stress concentration problems caused by the overflow and flow of large glass insulators after fusion sealing. At the same time, this cap design can also effectively reduce or avoid the pressure directly acting on the glass insulator during the capping and sealing process, reducing the risks associated with it and further improving the sealing reliability of the encapsulated electronic components.

[0028] In this invention, the vertical cross-section of the anti-overflow structure protrusion can be triangular, circular, semi-circular, rectangular, trapezoidal, etc., preferably triangular. Triangular protrusions are easy to process and have low cost; they also occupy a small volume, do not affect the control of the glass quantity, and provide strong restriction on the glass area after fusion sealing, resulting in a more regular glass shape and lower stress after fusion sealing. However, the specific shape used depends on actual needs and processing technology.

[0029] The protrusion design of this invention is positioned as close as possible to the centerline of the fusion-sealing cavity. This serves two purposes: firstly, to ensure sufficient fusion-sealing cavity to better accommodate a certain amount of glass, thereby effectively guaranteeing the insulation and sealing performance of the metal encapsulation shell; secondly, to allow sufficient space at the bottom of the fusion-sealing cavity to prevent the pressure applied to the edge of the shell during metal shell sealing from being directly transmitted to the glass, thereby reducing the stress on the glass insulator and preventing cracks.

[0030] During sintering and sealing, the opening of the sealing cavity in this invention must be kept facing upwards. This is because, considering assembly issues, the overall dimensions of the large, integral glass must be smaller than the dimensions of the inner protrusion boundary to ensure smooth assembly of the glass into the cavity structure. Furthermore, to guarantee sufficient glass usage, the height of the glass insulator is higher compared to other solutions. Keeping the opening of the sealing cavity facing upwards not only accommodates the increased glass height but also better confines the sealed glass within the protruding area of ​​the sealing cavity, resulting in a more regular shape and preventing stress concentration.

[0031] Finally, in traditional hermetic packaging, when the shell and cover are welded together by parallel seam welding or energy storage welding, foreign matter splashing will occur to varying degrees. Once the splashed foreign matter contaminates the internal circuitry of the device, it will cause unimaginable adverse consequences. The generation of this splashing is caused by the inherent limitations of the process itself, and it cannot be completely solved or eliminated at the root.

[0032] Mechanical pressure welding is a method of solid-state welding that uses pressure to induce plastic deformation in the metals to be welded, achieving close contact and intergranular bonding through plastic deformation. This process does not produce spatter, making it an effective means of ensuring the stability of high-end electronic components. The prerequisite for mechanical pressure welding is that the components to be welded must have sufficient plastic compression and deformation. Commonly applicable materials include aluminum and copper. However, conventional packaging materials such as Kovar alloy (4J29) and cold-rolled steel have limitations on the application of mechanical pressure welding for capping due to their physical properties.

[0033] The cap of this invention is further made of a composite material of oxygen-free copper (TU1) and Kovar alloy (4J29). On the one hand, the oxygen-free copper (TU1) material on the outer surface is relatively soft and has good plastic deformation ability, which enables the cap to perform mechanical pressure sealing, fundamentally solving the problem of spatter from hot-press energy storage welding and greatly improving the stability of electronic components. On the other hand, the Kovar (4J29) material on the inner surface can perform highly reliable fusion sealing with glass, improving the reliability of the shell seal. Attached Figure Description

[0034] Figure 1 A schematic diagram of the encapsulation and sealing structure for low glass insulator stress provided by the present invention;

[0035] Figure 2 for Figure 1 Top view;

[0036] Figure 3 for Figure 1 Enlarged view of Part I;

[0037] Figure 4 A schematic diagram showing the encapsulation cover for low-stress glass insulators and the hermetically sealed outer shell formed by the fusion sealing of glass insulators and leads;

[0038] Figure 5 for Figure 4 Enlarged view of section II;

[0039] Figure 6 This is a schematic diagram of the cap's structure;

[0040] Figure 7 This is a schematic diagram showing the hermetic seal formed after the encapsulation cover and cap are connected to the low-stress glass insulator.

[0041] The meanings of the symbols marked in the figure are as follows:

[0042] 10-Cap 11-Outer side 12-Inner side 13-Cavity structure 131-Overflow prevention structure 14-Flash 15-Through hole

[0043] 30-Block 31-Fringe

[0044] 41-Lead wire 42-Glass insulator Detailed Implementation

[0045] The technical solution of the present invention will now be described in conjunction with the accompanying drawings to facilitate understanding by those skilled in the art.

[0046] like Figure 1-7 As shown, a packaging cover with low glass insulator stress is disposed on a circuit board and is used to cooperate with lead wire 41 and glass insulator 42 to form an airtight packaging shell for electronic devices.

[0047] The size and shape of the cover 10 are adapted to the electronic device to be packaged. On the inner side 11 of the cover near the circuit board, there is a cavity structure 13 that protrudes in the direction away from the circuit board, i.e., the outer side 11, for accommodating the fused glass insulator 42. The cover 10 also includes a burr 14 integrally provided around the edge of the cavity structure 13. The burr 14 is flat and the bottom surface of the burr 14 is parallel to the surface of the circuit board used for packaging to ensure a good fit.

[0048] A spill prevention structure 131 is also provided around the inner wall of the cavity structure 13. The spill prevention structure 131 is a ring of protrusions on the inner wall of the cavity structure 13. The vertical cross-sectional shape of the protrusion is triangular, circular, semi-circular, rectangular, or trapezoidal, etc., and in this embodiment, it is preferably triangular. The material of the spill prevention structure 131 is the same as that of the inner wall of the sealing cavity 13. In this embodiment, it is Kovar alloy. The horizontal length of the spill prevention structure 131 is 50-80% of the wall thickness of the cap 10, and the vertical height is 1-1.2 times the horizontal length. In order to ensure the cavity volume of the glass sealing and reduce the stress of the glass after sealing, the spill prevention structure 131 is set below 1 / 2 of the total height of the cavity structure 13, more preferably set from top to bottom at 1 / 2 to 4 / 5 of the total height of the cavity, and the distance from the bottom of the spill prevention structure 131 to the bottom edge of the cap 10 is greater than or equal to 1 / 2 of the width of the burr 14.

[0049] The cover 10 has a through hole 15 at a set position on the cavity structure 13 for inserting the lead wire 41.

[0050] Furthermore, in this invention, the substrate of the cap 10 is composed of oxygen-free copper disposed on the outer side 11 and Kovar alloy disposed on the inner side 12. In this embodiment, the oxygen-free copper is TU1, the Kovar alloy is 4J29, and the total thickness of the composite of oxygen-free copper and Kovar alloy is 0.1-1.0 mm, wherein the thickness ratio of oxygen-free copper to Kovar alloy is 7:3.

[0051] When the cover 10 of the present invention is used for circuit assembly, a cap 30 is also provided on the outer side of the cover 10. In order to achieve a better fit, the cap 30 is made of oxygen-free copper TU1, the size of the cap 30 matches the cover 10, the inside of the cap has a cavity to accommodate the cover cavity structure 13, and the edge of the cap 30 has an edge 31 whose shape is adapted to the burr 14 of the cover 10, so as to better form a seal with the cover 10.

[0052] The above-mentioned method for preparing a package with low glass insulator stress and the method for encapsulating using this cap comprises the following steps:

[0053] S1. Using oxygen-free copper and Kovar alloy materials, a sealing cap 10 of the required size is processed by stamping, turning or milling, and an anti-overflow structure 131 is integrally processed; the sealing cap 10 includes a cavity structure 13 and a flash 14, and through holes 15 are provided in the corresponding positions.

[0054] S2. A lead hole adapted to the position of the through hole 15 is machined on the glass insulator 42 that matches the cover 10;

[0055] S3. Assemble the glass insulator 42 into the cavity structure 13, insert the lead wire 41 through the through hole 15 and the lead wire hole, place the opening side of the cover 10 upward, and sinter the cover 10, glass insulator 42 and lead wire 41 at high temperature. After cooling by glass melting and deformation, firmly connect the cover 10, metal ring 131 and lead wire 41 into a whole, thus obtaining a low glass insulator stress encapsulation shell.

[0056] S4. Use oxygen-free copper TU1 to process the cap 30, and electroplate the cap 30, the lead wire 41 in S3 and the cover 10, wherein the cap 30 is plated with gold or nickel, and the lead wire 41 and the cover 10 are plated with gold, in order to meet the welding requirements and facilitate the implementation of the electroplating process.

[0057] S5. Assemble the cap 30 onto the outer side 11 of the cover in S2, so that the lower surface of the edge 31 of the cap fits against the upper surface of the burr 14 of the cover;

[0058] S6. The cover 10 processed by S4 is encapsulated on the required circuit board, and the electronic components are sealed in the space formed by the cover 10 and the cap 30, thereby forming an airtight packaged device with airtight function.

[0059] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled 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 within the scope of protection of the present invention.

Claims

1. A package lid having low glass insulator stress, which is provided on a circuit board, for cooperating with a lead (41), a glass insulator (42) and a cap (30) to form a hermetically sealed package of an electronic device, characterized in that, The size and shape of the cover (10) are adapted to the electronic device to be packaged, and the cover has a cavity structure (13) for accommodating a sealing glass insulator (42) on the inner side (12) of the cover close to the circuit board, the cover (10) further comprises a flash (14) integrally arranged around the edge of the cavity structure (13), the flash (14) is flat, and the bottom surface of the flash (14) is parallel to the surface of the circuit board for packaging to ensure the fit; a spill-proof structure (131) is further arranged around the inner wall of the cavity structure (13), and the cover (10) is provided with a through hole (15) for inserting a lead (41) at a specified position of the cavity structure (13); The spill-proof structure (131) is a protrusion arranged on the inner wall of the cavity structure (13), and the cross-sectional shape of the protrusion is angular, circular, rectangular or trapezoidal; the material of the spill-proof structure (131) is the same as that of the inner side of the cover (10); The setting position of the spill-proof structure (131) is lower than 1 / 2 of the total height of the cavity structure (13), and the distance from the bottom of the spill-proof structure (131) to the bottom edge of the cover (10) is greater than or equal to 1 / 2 of the width of the flash (14).

2. A package lid having low glass insulator stress according to claim 1, wherein, The length of the spill-proof structure (131) in the horizontal direction is 50-80% of the wall thickness of the cover (10), and the height in the vertical direction is 1-1.2 times the length in the horizontal direction.

3. A package lid having low glass insulator stress according to claim 1, wherein, The material of the cover (10) is Kovar 4J29 or iron-nickel alloy 4J42 or expanded alloy 4J50 or cold-rolled steel.

4. A package lid having low glass insulator stress according to claim 1, wherein, The base material of the cover (10) is composed of oxygen-free copper arranged on the outer side (11) and Kovar arranged on the inner side (12).

5. A package lid having low glass insulator stress according to claim 4, wherein, The oxygen-free copper is TU1, and the Kovar is 4J29 or iron-nickel alloy 4J42.

6. A package lid having low glass insulator stress according to claim 5, wherein, The total thickness of the oxygen-free copper and Kovar after compounding is 0.1-1.0 mm, and the thickness ratio of the oxygen-free copper and Kovar is 7:

3.

7. A hermetically sealed package housing, characterized by, The packaging shell comprises the cover (10) according to any one of claims 1-6, and a glass insulator (42) arranged in the cavity structure (13) of the cover (10), and a lead (43) inserted into the glass insulator (42) and the cover (10).

8. A method of producing a hermetically sealed package according to claim 7, characterized in that, The steps are as follows: S1. Using the required materials, using punching or turning or milling processing technology, processing the cover (10) of the required size, and integrally processing the spill-proof structure (131); the cover (10) comprises a cavity structure (13) and a flash (14), and is provided with a through hole (15) at a corresponding position; S2. Machining a lead hole on the glass insulator (42) matched with the cover (10) and matched with the position of the through hole (15); S3. Assembling the glass insulator (42) inside the cavity structure (13), inserting the lead wire (41) into the through hole (15) and the lead wire hole, placing the opening side of the cover (10) upward, and high-temperature sintering the cover (10), the glass insulator (42) and the lead wire (41) together to fuse into a whole, that is, obtaining the required airtight packaging shell.

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