Small-size sealing cover plate with thin solder layer and preparation method of small-size sealing cover plate

Abstract

The invention discloses a small-size sealing cover plate with a thin solder layer and a preparation method of the small-size sealing cover plate, and the method comprises the following steps: pasting a mechanically punched cover plate on the adhesive surface of a sputtering process adhesive tape at a certain gap by using an automatic chip mounter, and pasting the adhesive surface of the single-sided sputtering process adhesive tape cut into a certain shape downwards at the center of the cover plate; evaporating a metal adhesion layer and a solder layer on a vacuum evaporation table; and finally, cutting the evaporation layer along the reserved cutting line by adopting laser, heating the sol to remove the sputtering process glue and the redundant evaporation layer, and cleaning and drying to obtain the required small-size sealing cover plate with the thin solder layer. The problems that the solder of a thin cover plate climbs the cover, and the thin package is fused into ball solder to easily cause short circuit between gold bonding wires and between the gold bonding wires and the cover plate and the like can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of electronic packaging, and in particular to a small-size sealing cover plate with a thin solder layer and a preparation method thereof. Background Art

[0002] High reliability integrated circuits are usually sealed with gold-tin solder. For Kovar covers with a size of 3mm×3mm and above and a thickness of 0.25mm or above, it is easy to electroplate nickel and gold; in addition, for widths of 0.3mm and above, 50μm prefabricated gold-tin solder can be used through resistance spot welding to fix it to the gold-plated Kovar cover at the four corners.

[0003] With the need for miniaturization and thinness, the size of many cover plates is gradually less than 3mm×3mm, and the thickness of the cover plates is also less than 0.25mm or even as thin as 0.05mm. It is difficult to electroplate the cover plates to obtain a uniform thickness of gold plating. In addition, if 50μm prefabricated gold-tin solder is still used for resistance spot welding, it is easy for the solder to climb the cover or even overhang into the cavity to cause a short circuit. At the same time, the width of the prefabricated gold-tin solder becomes narrower, and the gold-tin solder is prone to warping during spot welding. At this time, it is necessary to be able to electroplate gold evenly to control the cost of gold plating, and the thickness of the gold-tin solder needs to be reduced by 5μm to 20μm. While reducing costs, the problem of solder climbing the cover and overhanging in the cavity causing short circuits can be solved. In addition, as the sealing width decreases, the side of the cover plate must be 100% deposited with gold-tin solder after the sealing cap is melted to fully ensure the mechanical strength and reliability of the cover plate such as impact resistance. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides a small-sized sealing cover plate with a thin solder layer and a preparation method thereof.

[0005] In a first aspect, a small-size sealing cover plate with a thin solder layer is provided, comprising: a cover plate, an adhesive layer, and a solder layer, wherein the front sealing area and the side of the cover plate are sealed by an integral solder layer, and an adhesive layer is arranged between the cover plate and the solder layer. The thickness of the cover plate is 0.05 to 0.25 mm, and the thickness of the solder layer is 5 μm to 20 μm.

[0006] In combination with the first aspect, in some embodiments of the first aspect, the adhesion layer includes titanium and / or nickel, and the thickness of the adhesion layer is 300 to 1000 angstroms; and the solder layer includes gold and / or tin.

[0007] In combination with the first aspect, in some embodiments of the first aspect, the cover plate is 0.500-3.00 mm long and 0.500-3.00 mm wide, and the cover plate has rounded corners, and the radius of the chamfer is 0.005-0.010 mm.

[0008] In combination with the first aspect, in some embodiments of the first aspect, the cover plate includes a low thermal expansion alloy.

[0009] In a second aspect, a method for preparing a small-sized sealing cover plate with a thin solder layer is provided, comprising: attaching the cover plate to a first sputtering tape; attaching a second sputtering tape to a side of the cover plate away from the first sputtering tape, wherein the second sputtering tape is smaller than the cover plate; evaporating to form an adhesion layer, wherein the adhesion layer covers the first sputtering tape, the cover plate, and the second sputtering tape; evaporating to form a solder layer, wherein the solder layer covers the adhesion layer; removing the first sputtering tape, the second sputtering tape, and the adhesion layer and the corresponding solder layer covering the second sputtering tape portion and the second sputtering tape portion to obtain the small-sized sealing cover plate with a thin solder layer.

[0010] In combination with the second aspect, in some embodiments of the second aspect, the cover plate has a thickness of 0.05 to 0.25 mm, the solder layer has a thickness of 5 μm to 20 μm, and the adhesion layer has a thickness of 300 to 1000 angstroms.

[0011] In combination with the second aspect, in some embodiments of the second aspect, the removing of the first sputtering tape, the second sputtering tape, and the adhesive layer and the corresponding solder layer covering the first sputtering tape portion and the second sputtering tape portion to obtain the thin solder layer small-size sealing cover plate includes:

[0012] A groove is cut on the solder layer on the cover plate along the edge of the second sputtering tape, and a groove is cut on the solder layer of the first sputtering tape along the edge of the solder layer on the side of the cover plate, wherein the depth of the groove is greater than the sum of the thicknesses of the solder layer and the adhesive layer; and the first sputtering tape and the second sputtering tape are dissolved by a sol liquid to obtain the thin solder layer small-size sealing cover plate.

[0013] Specifically, the groove has a width of 0.05 mm and a depth of 0.015 mm to 0.030 mm.

[0014] In combination with the second aspect, in some embodiments of the second aspect, the adhesion layer includes titanium and / or nickel, and the solder layer includes gold and / or tin.

[0015] In combination with the second aspect, in some embodiments of the second aspect, before attaching the cover plate to the first sputtering tape, the preparation method further includes: attaching the first sputtering tape to the adhesive layer.

[0016] Compared with the prior art, the method of the present invention has the following beneficial effects:

[0017] (1) The existing cover plates all have no solder on the side. The solder in the sealing area needs to be melted and squeezed out and accumulated on the side of the cover plate to form a meniscus welding surface to improve the impact resistance. This is easy to cause cover creeping, weld breakpoints due to poor wetting and other appearance quality issues. In the embodiment of the present application, the side of the cover plate is tin-containing solder, which directly forms a meniscus solder morphology on the side after melting, and the suitable thickness of the cover plate is 0.05-0.25 mm, thereby avoiding the above problems.

[0018] (2) The cover plate with gold-tin solder in the present application is directly evaporated, and does not require spot welding or cladding, which reduces micro-voids and oxidized impurities introduced by sunken solder joints and slight oxidation of cladding, and solves the problems of spot welding of cover plates smaller than 3mm×3mm, difficult control of cladding position, and low yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a small-sized sealing cover plate structure with a thin solder layer provided in this application.

[0020] Figure 2 A schematic diagram of mounting a small-size sealing cover plate with a thin solder layer provided in this application.

[0021] Figure 3 A schematic diagram of a thin solder layer and a small-size sealing cover plate evaporated adhesion layer provided in the present application.

[0022] Figure 4 A schematic diagram of a thin solder layer and a small-size sealing cover plate evaporated solder layer provided in the present application.

[0023] Figure 5 A schematic diagram of laser cutting of a thin solder layer and a small-sized sealing cover plate evaporated layer provided in this application.

[0024] 1. Cover plate; 2. Adhesive layer; 3. Solder layer; 4. Adhesive layer; 5. First sputtering process tape; 6. Groove; 7. Second sputtering process tape. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the production process of some small-size sealing cover plates with thin solder layers, the Au80Sn20 solder has a uniform thickness and there is no prefabricated solder sheet. When it melts, it first forms a ball and then wets and spreads, which can easily cause the solder to climb the thin cover plate. The thin package melts into a ball solder, which can easily cause short circuits between the bonding wires and the cover plate.

[0027] The present application provides a small-sized sealing cover plate with a thin solder layer and a preparation method thereof. An automatic chip mounter is used to stick a mechanically punched cover plate on the adhesive surface of a sputtering process tape with a certain gap, and then a single-sided sputtering process tape cut into a certain shape is stuck on the center of the cover plate with the adhesive surface facing downward. A vacuum evaporation table is then used to evaporate a metal adhesion layer and a solder layer. Finally, a laser is used to cut the evaporated layer along a reserved dividing line. The sputtering process glue and the excess evaporated layer are removed by heating the sol, and the required small-sized sealing cover plate with a thin solder layer is obtained after cleaning and drying. The problem of solder climbing on the thin cover plate and the problem of short circuits between bonding gold wires and the cover plate caused by the melted ball solder of the thin package can be avoided.

[0028] like Figure 1 As shown, the present application provides a small-size sealing cover plate with a thin solder layer, comprising: a cover plate 1, an adhesive layer 2, and a solder layer 3, wherein the front sealing area and the side of the cover plate are sealed by an integral solder layer 3, and the adhesive layer 2 is arranged between the cover plate 1 and the solder layer 3. The thickness of the cover plate 1 may be 0.05 to 0.25 mm, and the thickness of the solder layer 3 may be 5 μm to 20 μm.

[0029] In some embodiments, the cover plate may also become the substrate.

[0030] In some embodiments, the adhesion layer 2 may include titanium (Ti) and / or nickel (Ni), and the thickness of the adhesion layer 2 may be 300 to 1000 angstroms. Exemplarily, the adhesion layer 2 may be TiNi.

[0031] In some embodiments, the solder layer 3 includes gold (Au) and / or tin (Sn). Exemplarily, the solder layer 3 may be Au80Sn20.

[0032] In some embodiments, the cover plate 1 may be 0.500-3.00 mm long and 0.500-3.00 mm wide, and the cover plate may have rounded corners, and the radius of the rounded corners may be 0.005-0.010 mm. Specifically, the cover plate 1 may include a low thermal expansion alloy. Exemplarily, the cover plate 1 may be a 4J42 alloy.

[0033] like Figures 2 to 5 The present application also provides a method for preparing a small-size sealing cover plate with a thin solder layer, comprising:

[0034] S100, attaching the cover plate 1 to the first sputtering process tape 5;

[0035] S200: attaching a second sputtering tape 7 to a side of the cover plate 1 away from the first sputtering tape 5, wherein the second sputtering tape 7 is smaller than the cover plate 1;

[0036] S300, evaporating to form an adhesive layer 2, wherein the adhesive layer 2 covers the first sputtering tape 5, the cover plate 1, and the second sputtering tape 7;

[0037] S400, evaporating to form a solder layer 3, wherein the solder layer 3 covers the adhesion layer 2;

[0038] S500, removing the first sputtering tape 5, the second sputtering tape 7, the adhesive layer covering the second sputtering tape portion and the second sputtering tape portion, and the corresponding solder layer to obtain the thin solder layer small-size sealing cover plate.

[0039] Specifically, the thickness of the cover plate 1 can be 0.05-0.25 mm. The metal plate is first punched out into the cover plate 1 of the designed size and shape by precision machinery, and the cover plate 1 can be rounded.

[0040] Before step S100, the first sputtering tape 5 may be attached to the adhesive layer 4. In step S100, specifically, the cleaned and appearance-screened cover plate 1 may be attached to the sputtering tape with a frame with a certain gap by an automatic placement machine, and arranged in a full array. Exemplarily, the gap may be 0.05-0.50 mm.

[0041] In step S200, specifically, a single-sided tape cut into a certain shape, i.e., a preformed single-sided sputtering process tape, i.e., the second sputtering process tape 7, can be attached to the center of the cover plate 1, with the adhesive surface facing the cover plate 1 downward. The adhesive surface is bonded to the cover plate, and the area of ​​the cover plate 1 not covered by the tape is the solder evaporation area. Step S200 obtains Figure 2 Schematic diagram of small size hermetic lid mounting with thin solder layer shown.

[0042] In step S300, specifically, the frame can be sent to a vacuum evaporation table. The thickness of the adhesive layer 2 can be 300 to 1000 angstroms. The thin solder layer obtained in step S300 is a small-size sealing cover plate with an evaporation adhesive layer. Figure 3 shown.

[0043] In some embodiments, in step S400, the solder layer 3 may be Au80Sn20, and the thickness of the solder layer 3 may be 5 μm to 20 μm. In this step, Au with a thickness of 500 to 1000 angstroms may be evaporated on the surface. Figure 4 This is a schematic diagram of a thin solder layer and a small-size sealing cover plate evaporated solder layer obtained in step 400. The solder layer 3 and the adhesive layer 2 are both evaporated layers.

[0044] In some embodiments, the sealing design dimensions may be specifically determined based on the thickness of the cover plate, the flatness of the sealing area of ​​the housing, and the sealing width.

[0045] In some embodiments, in step S500, the first sputtering tape 5, the second sputtering tape 7, and the adhesive layer 2 and the corresponding solder layer 3 covering the first sputtering tape 7 and the second sputtering tape 7 are removed to obtain the thin solder layer small-sized sealing cover plate, which may specifically include: cutting a groove 6 on the solder layer 3 on the cover plate 1 along the edge of the second sputtering tape 7, and cutting a groove 6 on the solder layer 3 of the first sputtering tape 5 along the edge of the solder layer on the side of the cover plate 1, wherein the depth of the groove 6 is greater than the sum of the thicknesses of the solder layer 3 and the adhesive layer 2; and using a sol solution to dissolve the first sputtering tape 5 and the second sputtering tape 7 to obtain the thin solder layer small-sized sealing cover plate.

[0046] For example, after being taken out from the vacuum evaporation table, the evaporated layer can be cut along the reserved dividing line using an ultraviolet picosecond / femtosecond laser. Specifically, the groove 6 can be 0.05 mm wide and 0.015 mm to 0.030 mm deep. Figure 5 , which is a schematic diagram of laser cutting of a thin solder layer and a small-sized sealing cover plate vapor-deposited layer according to an embodiment of the present application.

[0047] Finally, the excess evaporation layer is removed by heating the sol, the adhesive layer and the support film are removed, and the ultra-clean cleaning and drying are performed to obtain the following Figure 1 The thin solder layer shown seals the small size cover plate.

[0048] The following is a description with reference to specific embodiments.

[0049] Embodiment 1:

[0050] The Au80Sn20 solder with a thickness of about 12μm and a width of 0.15mm is clad, and the cover plate is a 4J42 alloy with a thickness of 1.20mm×1.20mm×0.15mm. The details are as follows:

[0051] First, a 4J42 alloy cover plate with a size of 1.20 mm × 1.20 mm × 0.15 mm (thickness) was punched out using a precision punching die. The radius of the four top corners was 0.10 mm, and vibration grinding was used to remove burrs. The radius of the side of the cover plate was set to 0.01 mm to 0.03 mm, and the cover plate was cleaned and dried after degreasing and deoxidation.

[0052] Next, a Datacon 2200evo automatic placement machine was used to attach a 1.20mm×1.20mm×0.15mm cover plate to the 50μm thick adhesive layer 4 of the SP-UV-RT-230TV-158-50T sputtering process tape on the 8-inch stainless steel frame with a gap of 0.15mm, covering the entire 8 inches; then, the SP-UV-RT-230TV-158-50T sputtering process tape cut into 0.88mm×0.88mm single-sided tape was attached to the center of the cover plate, with the adhesive surface facing the cover plate;

[0053] The 8-inch stainless steel frame and its upper cover are placed on the 8-inch planetary plate of the ei-5z vacuum evaporation table, and the vacuum is 4×10 -4 After Pa, it was cleaned with an electron gun, followed by evaporation of 300 angstroms of Ti, 300 angstroms of Ni layer, 12 μm Au80Sn20 layer, and 500 angstroms of Au layer;

[0054] Finally, a 355nm picosecond laser machine is used to cut a 0.05mm wide and 0.015mm to 0.030mm deep groove along the 0.88mm×0.88mm tape edge on the cover plate. Then the 8-inch stainless steel frame and the objects on it are put into a 30-50℃ sol solution. The adhesive layer and the support film are dissolved, and the excess vapor-deposited layer and the cover plate fall off and sink to the bottom. The cover plate that has sunk to the bottom is sucked out by a magnet and is ultra-cleaned and dried with hot air at 60-80℃.

[0055] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0056] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A small size sealing cover with thin solder layer, It is characterized in that include: Cover, adhesive layer, and solder layer, The front sealing area and the side of the cover plate are sealed by an integral solder layer, and an adhesive layer is provided between the cover plate and the solder layer. The thickness of the cover plate is 0.05-0.25 mm, and the thickness of the solder layer is 5 μm-20 μm.

2. The thin solder layer small size sealing cover plate according to claim 1, It is characterized in that The adhesion layer includes titanium and / or nickel, and the thickness of the adhesion layer is 300 to 1000 angstroms; The solder layer includes gold and / or tin.

3. The small-size sealing cover plate with a thin solder layer according to claim 1 or 2, It is characterized in that The cover plate is 0.500-3.00 mm long and 0.500-3.00 mm wide. Furthermore, the cover plate has rounded corners, and the radius of the rounded corners is 0.005-0.010 mm.

4. The small-size sealing cover plate with a thin solder layer according to claim 1 or 2, It is characterized in that The cover plate includes a low thermal expansion alloy.

5. A method for preparing a small-size sealing cover plate with a thin solder layer, It is characterized in that include: attaching the cover plate to the first sputtering process tape; Attaching a second sputtering tape to a side of the cover plate away from the first sputtering tape, wherein the second sputtering tape is smaller than the cover plate; Vapor deposition to form an adhesive layer, wherein the adhesive layer covers the first sputtering tape, the cover plate, and the second sputtering tape; Vapor deposition to form a solder layer, wherein the solder layer covers the adhesion layer; The first sputtering tape, the second sputtering tape, and the adhesive layer and the corresponding solder layer covering the first sputtering tape portion and the second sputtering tape portion are removed to obtain the thin solder layer small-size sealing cover plate.

6. The preparation method according to claim 5, It is characterized in that The thickness of the cover plate is 0.05-0.25 mm, the thickness of the solder layer is 5 μm-20 μm, and the thickness of the adhesion layer is 300-1000 angstroms.

7. The preparation method according to claim 5 or 6, It is characterized in that The method of removing the first sputtering tape, the second sputtering tape, and the adhesive layer and the corresponding solder layer covering the second sputtering tape portion and the second sputtering tape portion to obtain the thin solder layer small-size sealing cover plate includes: Cutting a groove on the solder layer on the cover plate along the edge of the second sputtering tape, and cutting a groove on the solder layer of the first sputtering tape along the edge of the solder layer on the side of the cover plate, wherein the depth of the groove is greater than the sum of the thicknesses of the solder layer and the adhesive layer; The first sputtering process tape and the second sputtering process tape are dissolved by using a sol solution to obtain the thin solder layer small-size sealing cover plate.

8. The preparation method according to claim 7, It is characterized in that The groove has a width of 0.05 mm and a depth of 0.015 mm to 0.030 mm.

9. The preparation method according to claim 5 or 6, It is characterized in that The adhesion layer includes titanium and / or nickel, and the solder layer includes gold and / or tin.

10. The preparation method according to claim 5 or 6, It is characterized in that Before attaching the cover plate to the first sputtering process tape, the preparation method further includes: The first sputtering process tape is attached to the adhesive layer.

Images