A ball mounting device and ball mounting method for the bottom of a ceramic package cavity

Abstract

This invention discloses a ball-planting fixture and method for the bottom of a ceramic-sealed tube shell cavity, belonging to the field of encapsulation technology. The ball-planting plate has several recessed structures on its upper surface, the positions of which correspond to multiple solder points at the bottom of the deep cavity of the ceramic-sealed tube shell. A ball-leaking screen has ball-leaking through-holes, the positions of which correspond to the positions of the recessed structures. The fixture base and the shape and position of the ball-planting plate match the shape of the ceramic-sealed tube shell cavity after it is inverted. In use, solder paste is applied to the bottom of the ceramic-sealed tube shell; the ball-planting plate is placed in a limiting groove, the ball-leaking screen is positioned on the ball-planting plate, solder balls are poured in, allowing them to pass through the screen, one solder ball is assigned to each recessed position, excess solder balls are removed, and the ceramic-sealed tube shell cavity is inverted onto the ball-planting plate, achieving contact between the solder balls on the ball-planting plate and the solder paste. The ceramic-sealed tube shell, fixture base, and ball-planting plate are then reflow soldered together. The self-alignment and height self-limitation of the solder balls are achieved based on the molten solder tension, the gravity of the ceramic-sealed tube shell, and the height limitation of the ball-planting plate.

Description

Technical Field

[0001] This invention relates to the field of packaging technology, specifically to a ball-planting fixture and method for the bottom of a ceramic-sealed tube cavity. Background Technology

[0002] Ceramic-based packaging is widely used in semiconductor device integration. To achieve multifunctional integrated modules, dual-layer and multi-layer integrated modules are becoming increasingly common, requiring the placement of solder balls with controllable height on the substrate surface inside the cavity.

[0003] Currently, the industry mostly uses stencil printing of solder paste and direct solder ball placement on the top of the solder paste to place the solder balls. The ball placement surface is a planar structure, so it is necessary to place the balls on the substrate plane first and then assemble the metal frame. This imposes significant limitations on the metal frame assembly process. Furthermore, stencil printing of solder balls has poor control over the height consistency of the pre-placed solder balls, which is detrimental to subsequent three-dimensional stacking. How to achieve highly consistent solder ball placement at the bottom of the ceramic encapsulation cavity is a problem worth considering in the three-dimensional integration of multilayer stacked ceramic packaging devices.

[0004] Patent CN115565894A discloses a ball-mounting fixture and method for semiconductor devices. This patent uses the design of the positioning part of the arrangement board to transplant solder balls to the points corresponding to the chip pins. The ball-mounting fixture and method do not rely excessively on the personal skills and experience of engineers, and effectively avoid the problems of empty solder joints and cold solder joints generated during the ball-mounting process. However, this fixture and method are mainly used for ball-mounting on the surface of the device and are not suitable for high-consistency ball-mounting and batch ball-mounting applications on the surface of deep cavity substrates. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a tooling and method for ball-planting at the bottom of a ceramic-sealed tube shell cavity. The technical solution of this invention is shown below.

[0006] A ball-planting fixture for the bottom of a ceramic-sealed tube shell cavity includes a fixture base, a ball-distributing plate, and a ball-draining mesh. The ball-distributing plate is detachably and positioned within a limiting groove of the fixture base. The upper surface of the ball-distributing plate has several recessed structures, the positions of which correspond one-to-one with multiple welding points at the bottom of the ceramic-sealed tube shell cavity. The surface of each recessed structure is hemispherical, with a radius matching the radius of the welding ball. The ball-draining mesh has ball-draining through holes, the positions of which correspond one-to-one with the positions of the recessed structures. The shape and position of the fixture base and the ball-distributing plate match the inverted shape of the ceramic-sealed tube shell cavity, and the bottom of the ceramic tube shell is aligned with the ball-planting position.

[0007] Furthermore, the tooling base is positioned in the collector by a limiting block.

[0008] Furthermore, the upper end of the collector is positioned with the ball-leaking mesh plate by a positioning pin.

[0009] Preferably, the side of the ball-collecting mesh plate is provided with a collection hole for excess welding balls, and a collector is located below the collection hole.

[0010] Furthermore, the tooling base has several limiting grooves arranged in an array.

[0011] Furthermore, the thickness of the solder ball screen is less than half the radius of the solder ball.

[0012] A method for implanting balls at the bottom of a ceramic-sealed tube shell cavity includes the following steps: (1) Apply solder paste to the bottom of the ceramic-sealed tube shell; (2) Place the ball-separating plate in the limiting groove of the tooling base, position the ball-spinning screen on the ball-separating plate, pour the welding balls into the ball-spinning screen so that the welding balls pass through the ball-spinning screen and are distributed in the recessed structure of the ball-separating plate. (3) Collect excess solder balls and remove the screen from the ball-straining process; (4) The ceramic tube shell cavity is inverted onto the ball-splitting plate so that the solder balls on the ball-splitting plate come into contact with the solder paste. The ceramic-sealed tube shell, the tooling base, and the ball-splitting plate are then reflow welded together. (5) During reflow soldering, the self-alignment and height self-limitation of the solder balls are achieved based on the tension of the molten solder, the gravity of the ceramic tube shell, and the height limit of the ball separator.

[0013] Furthermore, the solder ball is a non-collapseable solder ball.

[0014] Furthermore, the solder paste used is Pb92.5Sn5Ag2.5.

[0015] Preferably, in step (3), excess solder balls are allowed to leak into the collector from the collection via by tilting.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The ball-planting fixture and ball-planting method of the ceramic-sealed tube shell cavity bottom of the present invention can realize rapid and highly consistent ball-planting at the bottom of the ceramic-sealed tube shell cavity, meeting the mass production application requirements of ball-planting at the bottom of the ceramic-sealed tube shell cavity; (2) The efficient ball-planting fixture designed in the present invention realizes the one-to-one distribution of welding balls corresponding to multiple welding ball positions at the bottom of the ceramic-sealed tube shell through the ball-separating plate, which can ensure high precision of ball-planting. (3) The efficient ball-planting tool designed in this invention collects the through holes of the ball-planting screen and, combined with the collector, can realize the rapid collection of excess solder balls during the ball-planting process, which is convenient for mass ball-planting production. (4) The ball-separating plate mounting slots on the ball-planting fixture base designed in this invention are arranged in an array. The assembled ball-separating plate can be disassembled and can be matched with batch ball-planting applications at the bottom of the deep cavity of multiple ceramic-sealed tube shells. (5) The Pb-type boll-planting method used in this invention is selected. 92.5 Sn5Ag 2.5High-temperature solder paste and non-collapsed solder balls, based on the tension of molten solder, the gravity of ceramic tube shell, and the limiting effect of the concave structure on the ball distribution plate of the ball placement tool, can achieve self-alignment of the horizontal position and self-limitation of the height of the solder balls, which can ensure the uniformity of the surface height of the solder balls after placement. At the same time, the selection of high-temperature solder paste can create a temperature gradient with the subsequent assembly. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the inverted ball-planting method at the bottom of the ceramic-sealed tube shell cavity designed according to the present invention; Figure 2 A schematic cross-sectional view of the ball-planting fixture at the bottom of the ceramic-sealed tube shell cavity designed for this invention; Figure 3 A top view of the ceramic-sealed tube shell cavity bottom ball-planting fixture designed for this invention (after removing the leaking ball mesh). Figure 4 This is a top view of the netting layout; Figure 5 This is a cross-sectional view of the ceramic-sealed tube shell. Figure 6 A top view of the ceramic-sealed tube shell; Figure 7 A schematic diagram showing the application of solder paste spraying to the bottom of the ceramic-sealed tube shell cavity. Figure 8 This is a schematic diagram of using a ball-planting fixture for positioning solder balls; Figure 9 A schematic diagram showing how excess solder balls are collected into a collector after the solder balls have been positioned. Figure 10 A schematic diagram showing the contact between the solder and the solder balls at the bottom of the ceramic-sealed tube shell cavity, with the ceramic-sealed tube shell upside down on the ball-separating plate of the ball-planting fixture. Figure 11 This is a schematic diagram showing the ball placement at the bottom of the ceramic-sealed tube shell cavity after reflow welding.

[0018] In the diagram: 1 is the solder ball; 2 is the ball separator plate; 3 is the tooling base; 4 is the metal frame of the ceramic-sealed tube shell; 5 is the solder; 6 is the bottom substrate of the ceramic-sealed tube shell; 7 is the limiting block; 8 is the collector; 9 is the pin; 10 is the ball leakage mesh plate; 11 is the positioning pin hole; 12 is the collection through hole; 13 is the ball leakage through hole; 14 is the recessed structure; 15 is the steel mesh; 16 is the solder pad; 17 is the excess solder ball. Detailed Implementation

[0019] The technical solution of the present invention will be further explained below with reference to the accompanying drawings.

[0020] As shown in the figure, a ball-planting fixture for the bottom of a ceramic-sealed tube shell cavity includes a fixture base 3, a ball-distributing plate 2, and a ball-leaking mesh plate 10. The ball-distributing plate 2 is detachably positioned and installed in the limiting groove of the fixture base 3. Several recessed structures 14 are provided on the upper surface of the ball-distributing plate 2, and the positions of the recessed structures 14 correspond one-to-one with multiple welding points at the bottom of the ceramic-sealed tube shell cavity. The surface of the recessed structure 14 is hemispherical, and its radius matches the radius of the welding ball 1. The ball-leaking mesh plate 10 is provided with ball-leaking through holes 13, and the positions of the ball-leaking through holes 13 correspond one-to-one with the positions of the recessed structures 14. The shape and position of the fixture base 3 and the ball-distributing plate 2 match the ceramic-sealed tube shell cavity after it is upside down, and the bottom position of the ceramic tube shell is aligned with the ball-planting position. The fixture base 3 is positioned in a collector 8 by a limiting block 7. The upper end of the collector 8 is positioned with the ball-leaking mesh plate by a positioning pin 9. The side of the ball-dispensing mesh plate is provided with a collection through-hole 12 for excess solder balls 17, and a collector 8 is located below the collection through-hole 12. The tooling base 3 has several limiting grooves arranged in an array. The thickness of the ball-dispensing mesh plate 10 is less than half the radius of the solder ball 1. This prevents multiple solder balls from being dispensed into one through-hole during the solder ball distribution process.

[0021] like Figure 2 and Figure 3 As shown, a ball-planting fixture is fabricated according to the ball-planting requirements at the bottom of the ceramic-sealed tube shell cavity. The fixture includes a fixture base 3, a ball-distributing plate 2, a ball-leaking mesh 10, and a collector 8. The fixture base 3 is designed with cavities matching the size of the ball-distributing plate 2. These cavities are arranged in an array, with each cavity capable of housing one ball-distributing plate 2. Multiple ball-distributing plates 2 can be installed simultaneously on the fixture base 3. The fixture base 3 is positioned at a specific location on the collector 8 based on the limiting block 7 structure. The ball-leaking mesh 10 can be fitted onto the ball-planting fixture collector 8, achieving a one-to-one correspondence between the ball-leaking holes 13 on the mesh and the ball-welding recessed structures 14 on the ball-distributing plate 2. Positioning pin holes 11 and pins 9 are matched for the positions of the ball-leaking mesh 10 and the collector 8.

[0022] like Figure 1 As shown, the edge of the ceramic-sealed tube shell is the metal frame 4 of the ceramic-sealed tube shell, and the bottom of the cavity is the bottom substrate 5 of the ceramic-sealed tube shell. Based on the cavity depth (h1), the mounting groove depth (h2) of the ball-distributing plate 2 on the tooling base 3, and the ball placement position at the bottom of the cavity (e.g., ... Figure 6 As shown, a ball-mounting plate 2 is fabricated, and a recessed structure 14 (as shown) is fabricated on the upper surface of the ball-mounting plate 2, corresponding one-to-one with the ball-mounting pads 16 in the cavity. Figure 3 As shown), the recessed structure 14 is hemispherical, and the recessed radius is the same as the radius of the solder ball 1. The length and width of the ball-separating plate 2 are (LD / 2) × (WD / 2), and the height of the ball-separating plate 2 is h3, which must satisfy h3 > h1 + h2 - D / 2. Where: L is the length of the ceramic tube shell cavity, W is the width of the ceramic tube shell cavity, and D is the diameter of solder ball 1. Common sizes for D are 0.4mm, 0.5mm, 0.6mm, and 0.76mm.

[0023] like Figure 4 As shown, according to the requirements of the ball distribution plate 2 for distributing welding balls 1 during the ball planting process, a ball leakage mesh plate 10 is made. The ball leakage mesh plate 10 can be positioned by pins 9 and collectors 8. The main body of the ball leakage mesh plate 10 is a frame and a steel mesh 15. A ball leakage through hole 13 is prepared on the steel mesh 15. The through hole is circular and the diameter of the through hole is D+0.05mm. The ball leakage through hole 13 corresponds one-to-one with the recessed structure 14 on the ball distribution plate 2. The thickness of the steel mesh 15 is D / 2-0.1mm, which ensures that the welding balls 1 are distributed in the recessed structure 14 of the ball distribution plate 2 during the ball planting process, and avoids multiple welding balls 1 from being concentrated in a single recessed structure 14. like Figure 7 As shown, high-temperature solder paste such as Pb92.5Sn5Ag2.5 is sprayed on the bottom of the ceramic-sealed tube shell cavity. The solder paste spraying position corresponds one-to-one with the ball pad 16. The solder paste thickness can be set to 0.08mm~0.15mm. like Figure 8 As shown, the tooling base 3 is placed in the collector 8, the ball-separating plate 2 is installed in the corresponding cavity of the tooling base 3, and the ball-leaking screen 10 is fitted onto the limiting pin 9 of the collector 8, so that the ball-leaking through hole 13 on the ball-leaking screen 10 corresponds to the position of the recessed structure 14 on the ball-separating plate 2. The non-collapseable welding balls 1 with a diameter of D are distributed to the upper side of the ball-leaking screen 10. The welding balls 1 are positioned to the recessed position on the surface of the ball-separating plate 2 by their own gravity and mutual collision. A small number of recessed positions are missing balls, which can be positioned to the recessed position by shaking the ball-planting tool in the horizontal direction. like Figure 9 As shown, after a solder ball 1 is positioned in each recessed position on the ball-separating plate 2, the fixture is tilted at a certain angle, and the excess solder balls 171 are collected into the collector 8 through the screen collection hole 12. Then, the fixture base 3 and the ball-separating plate 2 are taken out from the collector 8 together, and the solder balls 1 in the collector 8 can continue to be used. like Figure 10 As shown, the ceramic-sealed tube shell cavity, after solder paste spraying and coating, is inverted onto the ball-splitter plate 2. Each ball-splitter plate 2 corresponds to one ceramic-sealed tube shell. The solder paste on the ball-planting pad 16 at the bottom of the ceramic-sealed tube shell cavity corresponds one-to-one with the solder balls on the ball-splitter plate 2, so that the solder paste at the bottom of the cavity contacts the solder balls. The design ensures that the position of the metal frame of the ceramic tube shell does not contact the surface of the ball-splitter plate 2. The ceramic-sealed tube shell, the tooling base 3, and the ball-splitter plate 2 are reflow soldered together. During the reflow soldering process, the solder paste melts. Based on the tension of the molten solder 5, the gravity of the ceramic tube shell, the gravity of the solder balls, and the height limitation of the ball-splitter plate 2, the horizontal position of the solder balls is self-aligned and the height is self-limited, ensuring the height consistency of the solder ball surface after ball planting.

[0024] like Figure 11 As shown, after reflow soldering, the ceramic tube shell is removed from the tooling, completing the ball placement at the bottom of the ceramic-sealed tube shell cavity.

Claims

1. A tooling for ball-planting at the bottom of a ceramic-sealed tube shell cavity, characterized in that, The device includes a tooling base, a ball-separating plate, and a ball-drilling mesh. The ball-separating plate is detachably and positioned within a limiting groove in the tooling base. Several recessed structures are provided on the upper surface of the ball-separating plate, with each recessed structure corresponding to a specific welding point at the bottom of the deep cavity of the ceramic-sealed tube shell. The surface of each recessed structure is hemispherical, with a radius matching the radius of the welding ball. The ball-drilling mesh is provided with ball-drilling through holes, the positions of which correspond one-to-one with the positions of the recessed structures. The shape and position of the tooling base and the ball-separating plate match the inverted deep cavity of the ceramic-sealed tube shell, and the bottom of the ceramic tube shell is aligned with the ball-planting position.

2. The ball-planting fixture at the bottom of the ceramic-sealed tube shell cavity according to claim 1, characterized in that, The tooling base is positioned in the collector by a limiting block.

3. The ball-planting fixture at the bottom of the ceramic-sealed tube shell cavity according to claim 1, characterized in that, The upper end of the collector is positioned with the ball-leaking mesh plate by a positioning pin.

4. The ball-planting fixture at the bottom of the ceramic-sealed tube shell cavity according to claim 3, characterized in that, The side of the ball-collecting mesh plate is provided with a collection hole for excess welding balls, and a collector is located below the collection hole.

5. The ball-planting fixture at the bottom of the ceramic-sealed tube shell cavity according to claim 1, characterized in that, The tooling base has several limiting grooves arranged in an array to position several ball-splitting plates.

6. The ball-planting fixture at the bottom of the ceramic-sealed tube shell cavity according to claim 1, characterized in that, The thickness of the stencil is less than half the radius of the solder balls.

7. A method for planting balls at the bottom of a ceramic-sealed tube shell cavity, characterized in that, Includes the following steps: (1) Apply solder paste to the bottom of the ceramic-sealed tube shell; (2) Place the ball-separating plate in the limiting groove of the tooling base, position the ball-spinning screen on the ball-separating plate, pour the welding balls into the ball-spinning screen so that the welding balls pass through the ball-spinning screen and are distributed in the recessed structure of the ball-separating plate. (3) Collect excess solder balls and remove the screen from the ball-straining process; (4) The ceramic tube shell cavity is inverted onto the ball-splitting plate so that the solder balls on the ball-splitting plate come into contact with the solder paste. The ceramic-sealed tube shell, the tooling base, and the ball-splitting plate are then reflow welded together. (5) During reflow soldering, the self-alignment and height self-limitation of the solder balls are achieved based on the tension of the molten solder, the gravity of the ceramic tube shell, and the height limit of the ball separator.

8. The method for planting balls at the bottom of a ceramic-sealed tube shell cavity according to claim 7, characterized in that, The solder balls are non-collapseable solder balls.

9. The method for planting balls at the bottom of a ceramic-sealed tube shell cavity according to claim 7, characterized in that, The solder paste used is Pb92.5Sn5Ag2.

5.

10. The method for planting balls at the bottom of a ceramic-sealed tube shell cavity according to claim 7, characterized in that, In step (3), excess solder balls are allowed to leak into the collector through the collection via by tilting.

Images