Screen structure and power module for printing solder paste

Abstract

The present invention discloses a screen structure and a power module for printing solder paste, wherein the screen structure comprises: a screen body, a through hole formed on the screen body, the through hole being suitable for being opposite to the chip of the power module, and the cross-sectional area of ​​the through hole in the thickness direction of the screen body being smaller than the cross-sectional area of ​​the power chip; wherein the inner wall surface of the through hole protrudes in the direction toward the center of the through hole on the projection surface in the thickness direction of the screen body. According to the screen structure for printing solder paste of the present invention, by making the cross-sectional area of ​​the through hole smaller than the cross-sectional area of ​​the chip, and the inner wall surface of the through hole protrudes in the direction toward the center of the through hole. Therefore, compared with the traditional printed steel mesh, during the mounting process, the excess solder paste can be prevented from diffusing to the periphery of the chip after the solder paste is melted, that is, the excess solder paste substrate or the surface of the copper frame and the surface of the chip can be prevented, thereby ensuring the normal progress of the wire bonding and plastic encapsulation processes.

Description

Technical Field

[0001] The invention relates to the technical field of surface mounting, and in particular to a screen structure and a power module for printing solder paste. Background Art

[0002] In the related art, the printed steel mesh has openings. During the mounting process, the substrate to be printed is placed under the printed steel mesh, and the solder paste (flux + solder beads) is filled near the opening. The solder paste is scraped through the opening with a scraper to fill the opening, so as to achieve the effect of solder paste and substrate bonding. Then, the chip is placed on the solder paste of the substrate and reflow soldering is performed to achieve chip mounting. However, since the opening of the printed steel plate is rectangular in shape, during the reflow soldering process, as the temperature rises, the flux in the solder paste melts, and the flux and solder beads move freely. The excess solder paste will diffuse to the outer peripheral surface of the chip due to the extrusion of the chip and the substrate, and the flux will move to the surface of the substrate and the surface of the chip, causing the surface of the substrate and the surface of the chip to be contaminated, affecting the wire bonding and plastic packaging process. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the present invention is to provide a screen structure for printing solder paste, which can prevent excess solder paste from spreading to the periphery of the chip after the solder paste is melted during the mounting process, thereby ensuring the normal progress of the wire bonding and plastic packaging processes.

[0004] Another object of the present invention is to provide a power module manufactured using the above-mentioned screen structure.

[0005] According to an embodiment of the first aspect of the present invention, a screen structure for printing solder paste comprises: a screen body, a through hole formed on the screen body, the through hole is suitable for being opposite to the chip of the power module, the cross-sectional area of ​​the through hole in the thickness direction of the screen body is smaller than the cross-sectional area of ​​the chip, and the solder paste is printed on the screen body to form a connector, and the connector is used to connect the chip and the substrate; wherein, on the projection surface of the screen body in the thickness direction, the inner wall surface of the through hole protrudes in the direction toward the center of the through hole; the thickness of the chip in the thickness direction of the screen body is greater than the thickness of the connector; the inner wall surface of the through hole in the projection surface of the screen body in the thickness direction is an arc surface, and the inner wall surface of the through hole comprises two first side walls and two second side walls, the two second side walls are connected between the two first side walls, the two first side walls are located on both sides of the length direction of the through hole, and the two second side walls are located on both sides of the width direction of the through hole; each of the first side walls in the width direction of the through hole is symmetrical about the central axis of the through hole, and in the length direction of the through hole Each of the second side walls is symmetrical about the central axis of the through hole; the connection point of the first side wall and the second side wall on the projection surface of the thickness direction of the mesh body coincides with the end point of the chip; the connection line between the two end points of each of the first side walls on the projection surface of the thickness direction of the mesh body is a first connection line, the connection line between the midpoint and the end point of each of the first side walls on the projection surface of the thickness direction of the mesh body is a second connection line, and the angle between the first connection line and the second connection line is ɑ, wherein ɑ satisfies: 5︒≤ɑ≤20︒; the connection line between the two end points of each of the second side walls on the projection surface of the thickness direction of the mesh body is a third connection line, the connection line between the midpoint and the end point of each of the second side walls on the projection surface of the thickness direction of the mesh body is a fourth connection line, and the angle between the third connection line and the fourth connection line is β, wherein β satisfies: 5︒≤β≤20︒; the angle between the first connection line and the second connection line is 15︒; the angle between the third connection line and the fourth connection line is 15︒.

[0006] According to the screen structure for printing solder paste in the embodiment of the present invention, the cross-sectional area of ​​the through hole is made smaller than the cross-sectional area of ​​the chip in the thickness direction of the screen body, and the inner wall surface of the through hole is convex in the direction toward the center of the through hole. Therefore, compared with the traditional printed steel screen, the excess solder paste after melting can be prevented from diffusing to the periphery of the chip during the mounting process, and the solder flux can be prevented from contaminating the surface of the substrate or the copper frame and the surface of the chip, thereby ensuring the normal progress of the lead bonding and plastic packaging process.

[0007] According to some embodiments of the present invention, on the projection surface of the mesh body in the thickness direction, the minimum distance between the midpoint of each first side wall and the first connecting line is (Y / 2)×tanɑ, where Y is the minimum distance between the two endpoints of each first side wall; and / or on the projection surface of the mesh body in the thickness direction, the minimum distance between the midpoint of each second side wall and the third connecting line is (X / 2)×tanβ, where X is the minimum distance between the two endpoints of each second side wall.

[0008] According to some embodiments of the present invention, the thickness of the mesh body is D, wherein D satisfies: 0.06 mm ≤ D ≤ 0.1 mm.

[0009] According to an embodiment of the second aspect of the present invention, a power module comprises: a substrate; a chip, wherein the chip is arranged on one side of the substrate in the thickness direction; a connector, wherein the connector is arranged between the substrate and the chip, and the connector is formed by printing solder paste through a screen structure, wherein the screen structure is the screen structure for printing solder paste according to the embodiment of the first aspect of the present invention.

[0010] According to some embodiments of the present invention, on a projection plane in the thickness direction of the substrate, a side wall of the connector protrudes in a direction toward the center of the chip.

[0011] According to some embodiments of the present invention, an endpoint of the chip coincides with an endpoint of the connector on a projection plane in the thickness direction of the substrate.

[0012] According to some embodiments of the present invention, the thickness of the chip in the thickness direction of the substrate is greater than the thickness of the connecting member.

[0013] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0015] Figure 1 is a schematic diagram of a screen structure according to an embodiment of the present invention;

[0016] Figure 2 is a partial enlarged view of a screen structure according to an embodiment of the present invention;

[0017] Figure 3 is a schematic diagram of printing solder paste according to a screen structure of an embodiment of the present invention;

[0018] Figure 4is a schematic diagram of a power module according to an embodiment of the present invention.

[0019] Reference numerals:

[0020] 100: Screen structure;

[0021] 10: mesh body; 101: through hole; 102: first side wall; 103: second side wall;

[0022] 200: power module;

[0023] 201: substrate; 202: chip; 203: connector;

[0024] 300: scraper; 400: solder paste. DETAILED DESCRIPTION

[0025] Reference below Figure 1-Figure 3 A screen structure 100 for printing solder paste according to an embodiment of the first aspect of the present invention is described.

[0026] like Figure 1 As shown, the screen structure 100 for printing solder paste according to the first aspect of the embodiment of the present invention includes a screen body 10.

[0027] Specifically, a through hole 101 is formed on the grid body 10, and the through hole 101 is suitable for being opposite to the chip 202 of the power module 200, and the cross-sectional area of ​​the through hole 101 in the thickness direction of the grid body 10 is smaller than the cross-sectional area of ​​the chip 202. Figure 1-Figure 3 In the example, the number of through holes 101 can be the same as the number of chips 202, and the arrangement of the through holes 101 is consistent with the arrangement of the chips 202, so that during the chip mounting process, the chips 202 can be fixed on the substrate 201 or the copper frame of the power module 200 by solder paste.

[0028] Specifically, the substrate 201 or copper frame to be printed is placed under the screen structure 100, and the solder paste (flux + tin beads) is filled near the through hole 101. The solder paste is scraped through the through hole 101 with a scraper to fill the solder paste in the through hole 101, so that the solder paste and the substrate 201 or the copper frame are bonded. At this time, the shape of the solder paste on the substrate 201 or the copper frame is the same as the shape of the through hole 101; then the chip 202 is placed on the solder paste of the substrate 201 or the copper frame and reflow soldering is performed, the solder paste melts and the chip 202 is soldered to the substrate 201 or the copper frame; finally, the flux in the solder paste is cleaned off to achieve the mounting of the chip 202.

[0029] Reference Figure 3During the reflow soldering process, the solder paste will melt as the temperature rises. If the cross-sectional area of ​​the through hole 101 is larger than the cross-sectional area of ​​the chip 202, the cross-sectional area of ​​the solder paste on the substrate 201 or the copper frame will be larger than the cross-sectional area of ​​the chip 202. After the solder paste melts, the excess solder paste will diffuse to the periphery of the chip 202, and the solder flux in the solder paste will contaminate the surface of the substrate 201 or the copper frame and the surface of the chip 202, thereby affecting the wire bonding and plastic encapsulation process. Therefore, by making the cross-sectional area of ​​the through hole 101 smaller than the cross-sectional area of ​​the chip 202, the excess solder paste after the solder paste melts is prevented from diffusing to the periphery of the chip 202, and the solder flux is prevented from contaminating the surface of the substrate 201 or the copper frame and the surface of the chip 202, thereby ensuring the normal progress of the wire bonding and plastic encapsulation process.

[0030] Among them, the inner wall surface of the through hole 101 on the projection surface in the thickness direction of the grid body 10 is protruding in the direction toward the center of the through hole 101. In this way, the middle part of the inner wall surface of the through hole 101 converges toward the center of the through hole 101, so that the cross-sectional area of ​​the solder paste on the substrate 201 or the copper frame is smaller than the cross-sectional area of ​​the chip 202, thereby preventing the excess solder paste from spreading to the periphery of the chip 202 after the solder paste is melted.

[0031] According to the screen structure 100 for printing solder paste in the embodiment of the present invention, the cross-sectional area of ​​the through hole 101 is made smaller than the cross-sectional area of ​​the chip 202 in the thickness direction of the screen body 10, and the inner wall surface of the through hole 101 protrudes in the direction toward the center of the through hole 101. Therefore, compared with the traditional printed steel screen, the excess solder paste after the solder paste is melted can be prevented from diffusing to the periphery of the chip 202 during the mounting process, and the solder flux can be prevented from contaminating the surface of the substrate 201 or the copper frame and the surface of the chip 202, thereby ensuring the normal progress of the wire bonding and plastic packaging processes.

[0032] According to some embodiments of the present invention, Figure 2 As shown, the inner wall surface of the through hole 101 is an arc-shaped surface on the projection surface in the thickness direction of the grid body 10. When there is more solder paste used to connect the chip 202, the excess solder paste will be squeezed on the periphery of the chip 202 under the action of shear stress, and it will be crescent-shaped. Therefore, by making the inner wall surface of the through hole 101 inwardly concave crescent shape, the solder paste will fill the gap between the inner wall surface of the through hole 101 and the outer wall of the chip 202 under the action of shear stress, so that the chip 202 can be firmly connected to the substrate 201 or the copper frame, while avoiding the excess solder paste from diffusing to the periphery of the chip 202, thereby reducing the amount of solder paste used and reducing costs.

[0033] According to some embodiments of the present invention, Figure 2As shown, the inner wall surface of the through hole 101 includes two first side walls 102 and two second side walls 103. The two second side walls 103 are connected between the two first side walls 102. The two first side walls 102 are located in the length direction of the through hole 101 (for example, Figure 2 The two second side walls 103 are located on both sides of the through hole 101 in the width direction (for example, Figure 2 In the width direction of the through hole 101 and the length direction of the through hole 101, each first side wall 102 is symmetrical about the central axis of the through hole 101, and each second side wall 103 is symmetrical about the central axis of the through hole 101. In this way, the first side wall 102 and the second side wall 103 are regular arc-shaped surfaces, with a simple structure and easy processing.

[0034] Furthermore, if Figure 2 As shown, the connecting line between the two end points of each first side wall 102 on the projection surface in the thickness direction of the mesh body 10 is the first connecting line, and the connecting line between the midpoint and the end point of each first side wall 102 on the projection surface in the thickness direction of the mesh body 10 is the second connecting line. The angle between the first connecting line and the second connecting line is ɑ, where ɑ satisfies: 5︒≤ɑ≤20︒. It should be noted that the length between the midpoint and the end point of each first side wall 102 on the projection surface in the thickness direction of the mesh body 10 is half the length of the first side wall 102.

[0035] When ɑ<5︒, the angle between the first connecting line and the second connecting line is small, the cross-sectional area of ​​the through hole 101 is large, and the gap between the first side wall 102 and the outer wall of the chip 202 is small, while the size of the solder paste on the substrate 201 or the copper frame is large, resulting in excess solder paste extending to the periphery of the chip 202 when the chip 202 is mounted; when ɑ>20︒, the angle between the first connecting line and the second connecting line is large, the cross-sectional area of ​​the through hole 101 is small, and the gap between the first side wall 102 and the outer wall of the chip 202 is large, while the size of the solder paste on the substrate 201 or the copper frame is small, resulting in the solder paste being unable to fill the gap between the first side wall 102 and the outer wall of the chip 202 when the chip 202 is mounted, thereby resulting in poor connection reliability between the chip 202 and the substrate 201 or the copper frame. Therefore, by making the angle ɑ between the first connecting line and the second connecting line satisfy: 5︒≤ɑ≤20︒, while ensuring the connection reliability between the chip 202 and the substrate 201 or the copper frame, it is possible to prevent excess solder paste from extending to the periphery of the chip 202 and prevent flux from contaminating the surface of the substrate 201 or the copper frame and the surface of the chip 202.

[0036] Likewise, if Figure 2As shown, the connection line between the two end points of each second side wall 103 on the projection surface in the thickness direction of the mesh body 10 is the third connection line, and the connection line between the midpoint and the end point of each second side wall 103 on the projection surface in the thickness direction of the mesh body 10 is the fourth connection line. The angle between the third connection line and the fourth connection line is β, where β satisfies: 5︒≤β≤20︒. It should be noted that the length between the midpoint and the end point of each second side wall 103 on the projection surface in the thickness direction of the mesh body 10 is half the length of the second side wall 103.

[0037] When ɑ<5︒, the angle between the third connecting line and the fourth connecting line is small, the cross-sectional area of ​​the through hole 101 is large, and the gap between the second side wall 103 and the outer wall of the chip 202 is small, while the size of the solder paste on the substrate 201 or the copper frame is large, resulting in excess solder paste extending to the periphery of the chip 202 when the chip 202 is mounted; when ɑ>20︒, the angle between the third connecting line and the fourth connecting line is large, the cross-sectional area of ​​the through hole 101 is small, and the gap between the second side wall 103 and the outer wall of the chip 202 is large, while the size of the solder paste on the substrate 201 or the copper frame is small, resulting in the solder paste being unable to fill the gap between the second side wall 103 and the outer wall of the chip 202 when the chip 202 is mounted, thereby resulting in poor connection reliability between the chip 202 and the substrate 201 or the copper frame. Therefore, by making the angle ɑ between the third connecting line and the fourth connecting line satisfy: 5︒≤ɑ≤20︒, while ensuring the connection reliability between the chip 202 and the substrate 201 or the copper frame, it is possible to prevent excess solder paste from extending to the periphery of the chip 202 and prevent flux from contaminating the surface of the substrate 201 or the copper frame and the surface of the chip 202.

[0038] Optionally, the connection point between the first side wall 102 and the second side wall 103 on the projection surface in the thickness direction of the grid body 10 coincides with the endpoint of the chip 202. In this way, during the reflow soldering process, the melted solder paste will fill the gap between the first side wall 102 and the outer wall of the chip 202, and the gap between the second side wall 103 and the outer wall of the chip 202, thereby preventing excess solder paste from diffusing to the periphery of the chip 202 and preventing flux from contaminating the surface of the substrate 201 or the copper frame and the surface of the chip 202.

[0039] In some optional embodiments, the angle between the first connection line and the second connection line is 15°; and / or the angle between the third connection line and the fourth connection line is 15°.

[0040] When there is a lot of solder paste, the excess solder paste will be squeezed on the periphery of the chip 202 and will be in a crescent shape with an angle of 15°. By setting the angle between the first connecting line and the second connecting line to be 15° and the angle between the third connecting line and the fourth connecting line to be 15°, the solder paste will fill the gap between the inner wall of the through hole 101 and the outer wall of the chip 202 under the action of shear stress. This will further ensure the connection reliability between the chip 202 and the substrate 201 or the copper frame while preventing the excess solder paste from spreading to the periphery of the chip 202 and preventing the flux from contaminating the surface of the substrate 201 or the copper frame and the surface of the chip 202.

[0041] Thus, on the projection surface in the thickness direction of the grid body 10, the minimum distance between the midpoint of each first side wall 102 and the first connecting line is (Y / 2)×tanɑ, where Y is the minimum distance between the two end points of each first side wall 102, for example (Y / 2)×tan15︒; on the projection surface in the thickness direction of the grid body 10, the minimum distance between the midpoint of each second side wall 103 and the third connecting line is (X / 2)×tanβ, where X is the minimum distance between the two end points of each second side wall 103, for example (X / 2)×tan15︒.

[0042] According to some embodiments of the present invention, the thickness of the grid body 10 is D, where D satisfies: 0.06mm≤D≤0.1mm. When D is less than 0.06mm, the depth of the through hole 101 is small, so that the size of the solder paste on the substrate 201 or the copper frame is small, and the solder paste cannot completely fill the gap between the inner wall surface of the through hole 101 and the outer wall of the chip 202 after melting, resulting in poor connection reliability between the chip 202 and the substrate 201 or the copper frame; when D is greater than 0.1mm, the depth of the through hole 101 is large, so that the size of the solder paste on the substrate 201 or the copper frame is large, and the solder paste fills the gap between the inner wall surface of the through hole 101 and the outer wall of the chip 202 after melting, and the excess solder paste will spread to the periphery of the chip 202. Therefore, by making the thickness D of the grid body 10 satisfy 0.06mm≤D≤0.1mm, the size of the solder paste on the substrate 201 or the copper frame is more reasonable, while ensuring the connection reliability between the chip 202 and the substrate 201 or the copper frame, it can prevent excess solder paste from extending to the periphery of the chip 202 and prevent flux from contaminating the surface of the substrate 201 or the copper frame and the surface of the chip 202.

[0043] like Figure 4As shown, the power module 200 according to the embodiment of the second aspect of the present invention includes a substrate 201, a chip 202 and a connector 203. The chip 202 is arranged on one side of the thickness direction of the substrate 201, and the connector 203 is arranged between the substrate 201 and the chip 202. The connector 203 is formed by printing solder paste through a screen structure 100. The screen structure 100 is the screen structure 100 for printing solder paste according to the embodiment of the first aspect of the present invention.

[0044] According to the power module 200 of the embodiment of the present invention, the solder paste on the substrate 201 is prepared by the above-mentioned screen structure 100. During the mounting process of the chip 202, while ensuring the connection reliability between the chip 202 and the substrate 201, it is possible to prevent excess solder paste from extending to the periphery of the chip 202 and prevent flux from contaminating the surface of the substrate 201 or the copper frame and the surface of the chip 202, thereby avoiding solder paste waste and reducing the cost of the power module 200.

[0045] According to some embodiments of the present invention, referring to Figure 4 , the side wall of the connector 203 protrudes in the direction toward the center of the chip 202 on the projection plane in the thickness direction of the substrate 201. In this way, the chip 202 shields the connector 203 in the thickness direction of the substrate 201, preventing the connector 203 from being exposed on the chip 202 and affecting the wire bonding and plastic packaging process, reducing the risk in the production process and ensuring that the power module 200 has better electrical performance.

[0046] Further, refer to Figure 4 , the end points of the chip 202 and the end points of the connector 203 coincide with each other on the projection plane in the thickness direction of the substrate 201. Therefore, during the reflow process, as the temperature rises, the solder paste on the substrate 201 will melt, and the melted solder paste will spread under the extrusion of the substrate 201 and the chip 202 to fill the gap between the solder paste and the outer wall of the chip 202 when it is not melted, so as to obtain the connector 203. At this time, the cross-sectional area of ​​the connector 203 is roughly the same as the cross-sectional area of ​​the chip 202, so that the chip 202 can completely cover the connector 203, and the contact area between the connector 203 and the chip 202 and the contact area between the connector 203 and the substrate 201 are increased as much as possible, thereby increasing the connection reliability of the connector 203 with the chip 202 and the substrate 201.

[0047] According to some embodiments of the present invention, referring to Figure 4 In the thickness direction of the substrate 201, the thickness of the chip 202 is greater than the thickness of the connector 203, so that the chip 202 can be firmly connected to the substrate 201 or the copper frame while preventing excess solder paste from diffusing to the periphery of the chip 202, thereby reducing the amount of solder paste used and reducing costs.

[0048] Other structures and operations of the power module 200 according to the embodiment of the present invention are known to those skilled in the art and will not be described in detail here.

[0049] In the description of the present invention, it should be understood that the terms "center", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0050] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0051] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0052] Although the 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 claims and their equivalents.

Claims

1. A screen structure for printing solder paste, characterized in that: include: A mesh body, wherein a through hole is formed on the mesh body, wherein the through hole is suitable for being opposite to a chip of a power module, wherein a cross-sectional area of ​​the through hole in a thickness direction of the mesh body is smaller than a cross-sectional area of ​​the chip, and a connector is formed after solder paste is printed on the mesh body, wherein the connector is used to connect the chip and a substrate; Wherein, on the projection surface of the mesh body in the thickness direction, the inner wall surface of the through hole protrudes in the direction toward the center of the through hole; The thickness of the chip in the thickness direction of the grid body is greater than the thickness of the connecting member; The inner wall surface of the through hole is an arc-shaped surface on the projection surface of the mesh body in the thickness direction, and the inner wall surface of the through hole includes two first side walls and two second side walls, the two second side walls are connected between the two first side walls, the two first side walls are located on both sides of the length direction of the through hole, and the two second side walls are located on both sides of the width direction of the through hole; Each of the first side walls is symmetrical about the central axis of the through hole in the width direction of the through hole, and each of the second side walls is symmetrical about the central axis of the through hole in the length direction of the through hole; On the projection plane of the mesh body in the thickness direction, the connection point of the first side wall and the second side wall coincides with the end point of the chip; The connecting line between the two end points of each of the first side walls on the projection surface of the thickness direction of the mesh body is a first connecting line, and the connecting line between the midpoint and the end point of each of the first side walls on the projection surface of the thickness direction of the mesh body is a second connecting line, and the angle between the first connecting line and the second connecting line is ɑ, wherein ɑ satisfies: 5︒≤ɑ≤20︒; The connecting line between the two end points of each second side wall on the projection surface of the mesh body in the thickness direction is the third connecting line, and the connecting line between the midpoint and the end point of each second side wall on the projection surface of the mesh body in the thickness direction is the fourth connecting line. The angle between the third connecting line and the fourth connecting line is β, wherein β satisfies: 5︒≤β≤20︒; The angle between the first connecting line and the second connecting line is 15°; The angle between the third connecting line and the fourth connecting line is 15°.

2. The screen structure for printing solder paste according to claim 1, characterized in that: On the projection plane of the mesh body in the thickness direction, the minimum distance between the midpoint of each first side wall and the first connecting line is (Y / 2)×tanɑ, where Y is the minimum distance between the two end points of each first side wall; and / or On the projection plane of the mesh body in the thickness direction, the minimum distance between the midpoint of each second side wall and the third connecting line is (X / 2)×tanβ, where X is the minimum distance between two end points of each second side wall.

3. The screen structure for printing solder paste according to claim 1 or 2, characterized in that: The thickness of the mesh body is D, wherein D satisfies: 0.06 mm ≤ D ≤ 0.1 mm.

4. A power module, characterized in that: include: substrate; A chip, wherein the chip is arranged on one side of the substrate in a thickness direction; A connector, wherein the connector is disposed between the substrate and the chip, and wherein the connector is formed by printing solder paste through a screen structure, wherein the screen structure is a screen structure for printing solder paste according to any one of claims 1 to 3.

5. The power module according to claim 4, characterized in that: On a projection plane in the thickness direction of the substrate, a side wall of the connector protrudes in a direction toward the center of the chip.

6. The power module according to claim 5, characterized in that: On a projection plane in the thickness direction of the substrate, an end point of the chip coincides with an end point of the connector.

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