A semiconductor chip packaging metal pin tin climbing structure and its forming method

Abstract

The present invention discloses a semiconductor chip package metal pin tin climbing structure and a forming method thereof, and relates to the field of metal pin tin climbing technology. The tin climbing structure is arranged on the side and upper edge of the metal pin, the metal pin is arranged on the surrounding sides of the package body, and drainage parts are arranged on both sides of the tin climbing structure. The metal pin and the tin climbing structure are both provided with a metal tin plating layer; the drainage part can promote the solder paste on the printed circuit board pad to climb from the bottom of the tin climbing structure to the top of the tin climbing structure, so that the solder paste forms a tin climbing part. By setting the tin climbing structure, the present invention increases the contact area between the metal pin and the solder paste, forms a pin lock printed circuit board structure, and reduces the possibility of poor welding caused by slight warping of the metal pin or the printed circuit board pad surface, organic pollution and oxidation.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor chip packaging, and in particular to a semiconductor chip packaging metal pin tin climbing structure and a forming method thereof. Background Art

[0002] Traditional semiconductor chip packaging is a metal lead frame (such as Figure 1 The key processes of semiconductor chip mounting, wire bonding, plastic encapsulation, metal tin layer electroplating, rib removal, laser printing, singulation, electrical function testing, vacuum packaging, etc. are carried out on the surface of the device (as shown), thereby completing the semiconductor chip packaging and electrical function testing until it can be soldered on the printed circuit board.

[0003] The singulation process is to separate the plastic package containing the semiconductor chip (such as Figure 2 As shown in FIG) , a separate plastic package containing a semiconductor chip is punched or cut out from the original matrix arrangement of the metal lead frame (as shown in FIG). Figure 3 As shown), the separate plastic package containing the semiconductor chip can be soldered on the printed circuit board after high-temperature reflow using the adhesive material of the metal solder paste.

[0004] Since the metal tin layer electroplating on the surface of the metal pins has been completed before the singulation process, each metal pin of the plastic package body will be exposed on the cut surface after being punched or cut by the tool after singulation (such as Figure 3 As shown). When the plastic package containing the semiconductor chip is punched or cut off from the metal lead frame arranged in the matrix by a tool, the metal tin layer can no longer be electroplated on the cut surface of the metal pin using the conventional electrolytic plating method. Because the cut surface of the metal pin is not electroplated with the metal tin layer, when the plastic package containing the semiconductor chip is soldered to the printed circuit board, the solder paste on the surface of the solder pad of the printed circuit board cannot cover the cut surface of the metal pin during the high-temperature reflow sintering because there is no metal tin layer on the cut surface of the metal pin (as shown). Figure 4 and Figure 5 As shown in the figure, the height of the tin climbing on the cut surface of the metal pin is not enough), which causes poor welding between the metal pin and the pad and reduces the reliability of welding.

[0005] The contamination of metal pins or pads on the printed circuit board will also directly affect the welding quality. The area of ​​the input or output electrode metal pins of each plastic package containing a semiconductor chip is very small, especially the high-density plastic package, the structural area is even smaller, so there is often some dirt and organic grease pollution under the plastic package, the bottom of the metal pins on the side of the plastic package, and the pads of the printed circuit board, or the solder paste is not fully applied to the soldering area of ​​the metal pins and the printed circuit board, the solder paste does not cover the area of ​​the metal pins sufficiently, or there are voids, etc., which often lead to poor welding between the metal pins and the printed circuit board pads, thus seriously affecting the quality and reliability of welding (such as Figure 5 and Figure 6 As shown, pores are generated in the tin crawling part or the solder paste printing is not completely welded).

[0006] The existing metal pin welding quality cannot be visually identified by the naked eye, because the plastic package containing the semiconductor chip and the metal pins are both solid objects. When the metal pins of the plastic package containing the semiconductor chip are welded to the pads of the printed circuit board, it is impossible to directly observe the welding condition between the metal pins and the pads with the naked eye or a microscope in a top-down state (such as Figure 6 As shown, when viewing the pad from above, it's difficult to visually determine whether there's sufficient solder paste beneath the metal pins because the soldering is obscured by the metal pins. If the soldering quality between the metal pins and the printed circuit board is poor, temperature fluctuations and vibrations during use can cause the metal pins to separate from the pads, resulting in an electrical open circuit or poor contact. If the plastic package containing the semiconductor chip has electrical characteristics in the high-voltage range, and insufficient solder paste creates a gap between the metal pins and the pads, high-voltage discharge can easily cause tip discharge, sparking, and a short circuit or premature electrical failure.

[0007] Therefore, the problem of the metal pins not being covered with a tin layer after punching or cutting is a technical issue that the industry needs to focus on. If it is not possible to fully punch out the metal pins or electroplate the cut surface with a tin layer, the area of ​​the cut surface of the base material exposed after the metal pins are punched or cut should be made as small as possible. Summary of the Invention

[0008] The present invention provides a semiconductor chip packaging metal pin tin creeping structure to solve the problems of insufficient welding and insufficient tin creeping between the metal pin and the pad in the above-mentioned prior art.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] A semiconductor chip package metal pin tin climbing structure is arranged on the metal pin, and the metal pin is arranged on the four sides of the package body. Drainage parts are provided on both sides of the tin climbing structure. The metal pin and the tin climbing structure are both provided with a metal tin plating layer; the drainage part can promote the solder paste on the printed circuit board pad to climb from the bottom of the tin climbing structure to the top of the tin climbing structure, so that the solder paste forms a tin climbing part.

[0011] Specifically, the drainage portion is in a stepped shape, and the cross-sectional shape of the tin climbing structure is in a right T shape or an inverted T shape.

[0012] Specifically, the drainage portion is in an inclined shape, and the cross-sectional shape of the tin climbing structure is a regular trapezoid or an inverted trapezoid.

[0013] A method for forming a metal pin tin-climbing structure for semiconductor chip packaging, comprising the following steps:

[0014] S1, during the manufacturing process of the metal lead frame, processing a notch in the metal pin portion of the metal lead frame;

[0015] S2, using an extrusion forming tool to extrude the notch to form a tin climbing structure;

[0016] S3, sequentially performing semiconductor chip mounting, wire bonding, plastic encapsulation, metal tin layer electroplating, rib removal, laser printing, and singulation from the tin climbing structure on the lead frame;

[0017] S4, a tin climbing structure with a metal tin plating layer is formed on the metal pins of the plastic package body after being cut into pieces.

[0018] Specifically, during the electroplating process of the metal tin layer, a metal tin plating layer is formed on both the metal pins and the tin climbing structure.

[0019] Specifically, the notch can be made by etching or punching.

[0020] Specifically, the extrusion forming tool includes a tool body and a groove pressing portion, and the width of the groove pressing portion is smaller than the width of the notch.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. By setting up the tin climbing structure, the contact area between the metal pin and the solder paste is increased, reducing the possibility of poor welding caused by small organic contamination and oxidation on the surface of the metal pin or printed circuit board pad;

[0023] 2. Due to the increase in the contact area between the metal pin and the metal solder paste, and the appearance of the drainage portion makes the side of the metal pin no longer a vertical surface, this can effectively increase the locking performance of the soldering between the printed circuit board and the metal pin;

[0024] 3. After the metal pins and the printed circuit board are welded to each other, the welding condition can be easily and directly observed with the naked eye, a magnifying glass or a microscope when looking down, especially the tin creeping condition of the metal pin cross section and the locking condition of the metal pin by the printed circuit board pad. This virtually increases the convenience of monitoring the production process, thereby ensuring the welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of a metal lead frame in the prior art;

[0026] Figure 2 This is a schematic diagram of the metal lead frame structure after the plastic-encapsulated chip in the prior art;

[0027] Figure 3 This is a schematic diagram of the structure of a single plastic package body after singulation in the prior art;

[0028] Figure 4 A schematic diagram showing insufficient solder creep height on metal pins in the prior art;

[0029] Figure 5 A schematic diagram of pores appearing in the creeping tin of metal pins in the prior art;

[0030] Figure 6 A schematic diagram of incomplete soldering of metal solder paste in the prior art;

[0031] Figure 7 Schematic diagram of punching out notches in the metal pins on the metal lead frame of the present invention;

[0032] Figure 8 This is a schematic structural diagram of the metal pin notch of the present invention;

[0033] Figure 9 This is a stamping schematic diagram of the first form of the tin climbing structure of the present invention with the cross section being an inverted T-shape;

[0034] Figure 10 This is a schematic diagram of the first form of the tin climbing structure of the present invention being punched out in an inverted T shape and then subjected to electroplating of a metal tin layer after plastic encapsulation;

[0035] Figure 11 This is a schematic diagram of a plastic package body with semiconductor chips cut out after adopting the first form of the inverted T-shaped solder climbing structure of the present invention;

[0036] Figure 12 This is a stamping schematic diagram of the tin climbing structure of the present invention when the cross section is in the second inverted T-shape;

[0037] Figure 13 This is a schematic diagram of the tin climbing structure when the second inverted T-shape is punched according to the present invention and the metal tin layer is electroplated after plastic sealing;

[0038] Figure 14 This is a schematic diagram of a plastic package body with semiconductor chips cut out after adopting the second form of the inverted T-shaped tin climbing structure of the present invention;

[0039] Figure 15 This is a stamping schematic diagram of the first form of the tin climbing structure of the present invention in a regular T shape;

[0040] Figure 16 This is a stamping schematic diagram of the second form of the tin climbing structure of the present invention in the form of a positive T-shape;

[0041] Figure 17 This is a schematic diagram of soldering a plastic package body with a semiconductor chip on a printed circuit board using the second form of the positive T-shaped solder climbing structure of the present invention;

[0042] Figure 18 This is a stamping schematic diagram of the first form of the tin climbing structure of the present invention being a regular trapezoid;

[0043] Figure 19 This is a schematic diagram of the present invention wherein a first type of tin climbing structure of a regular trapezoid is punched and then plastic-sealed and then electroplated with a metal tin layer;

[0044] Figure 20 This is a schematic diagram of a plastic package body with semiconductor chips cut out after adopting the first form of regular trapezoidal tin climbing structure of the present invention;

[0045] Figure 21 This is a stamping schematic diagram of the second form of the tin climbing structure of the present invention in the form of a regular trapezoid;

[0046] Figure 22 This is a schematic structural diagram of the present invention using the second form of regular trapezoidal tin climbing structure and performing metal tin layer electroplating after plastic packaging;

[0047] Figure 23 This is a schematic diagram of a plastic package body with semiconductor chips cut out after adopting the second form of regular trapezoidal tin climbing structure of the present invention;

[0048] Figure 24 This is a schematic diagram of a solder creeping portion when a plastic package body with a semiconductor chip adopting the second form of regular trapezoidal solder creeping structure of the present invention is soldered to a printed circuit board;

[0049] Figure 25 This is a schematic diagram of another situation of the tin climbing portion when the plastic package body with a chip adopting the second form of the regular trapezoidal tin climbing structure of the present invention is soldered on a printed circuit board;

[0050] Figure 26 This is a stamping schematic diagram of the first form of the inverted trapezoidal tin climbing structure of the present invention;

[0051] Figure 27This is a stamping schematic diagram of the second inverted trapezoidal form of the tin climbing structure of the present invention.

[0052] In the figure: 1. Metal lead frame, 11. Metal pin, 111. Metal tin plating, 112. Incomplete tin climbing, 113. Air hole, 2. Plastic package, 3. Printed circuit board, 31. Metal solder paste, 4. Notch, 41. First inverted T-shaped tin climbing structure, 411. First inverted T-shaped extrusion molding tool, 412. First inverted T-shaped tin climbing structure metal tin layer, 42. Second inverted T-shaped tin climbing structure, 421. Second inverted T-shaped extrusion molding tool, 422. Second inverted T-shaped tin climbing structure metal tin layer, 43. First positive T-shaped tin climbing structure, 431. First positive T-shaped extrusion molding tool, 44. Second positive T-shaped tin climbing structure, 441. Second Positive T-shaped extrusion forming tool, 442, the second positive T-shaped climbing tin structure metal tin layer, 443, the climbing tin part of the second positive T-shaped climbing tin structure, 45, the first positive trapezoidal climbing tin structure, 451, the first positive trapezoidal extrusion forming tool, 452, the first positive trapezoidal climbing tin structure metal tin layer, 46, the second positive trapezoidal climbing tin structure, 461, the second positive trapezoidal extrusion forming tool, 462, the second positive trapezoidal climbing tin structure metal tin layer, 463, half climbing tin, 464, full climbing tin, 47, the first inverted trapezoidal climbing tin structure, 471, the first inverted trapezoidal extrusion forming tool, 48, the second inverted trapezoidal climbing tin structure, 481, the second inverted trapezoidal extrusion forming tool. DETAILED DESCRIPTION

[0053] The following is a clear and complete description of the technical solutions implemented in the present invention in conjunction with the accompanying drawings. The embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0054] like Figures 1 to 6 As shown, in the prior art, the metal lead frame 1 includes a connecting rib, a base island and a metal pin 11. The base island is used to carry the semiconductor chip, and the metal pin 11 is arranged on the inner side of the connecting rib for connecting the semiconductor chip. After the semiconductor chip is plastic-encapsulated on the metal lead frame 1 to form a plastic-encapsulated body 2, the metal pin 11 on the metal lead frame 1 is electroplated with tin to form a metal tin coating 111, and then cut into pieces. When the plastic-encapsulated body 2 with the semiconductor chip is soldered to the printed circuit board 3, the bottom surface of the metal pin 11 contacts the metal solder paste 31, and a tin climbing portion is formed between the metal pin 11 and the printed circuit board. Due to the defects of the prior art, the height of the tin climbing portion is not enough, and air holes 113 and incomplete tin climbing 112 are prone to occur.

[0055] like Figures 7 to 27As shown, an embodiment of the present invention provides a semiconductor chip package metal pin tin climbing structure, which is arranged on the metal pin 11 of the metal lead frame 1, as shown in FIG. Figure 7 As shown, the metal pins 11 are located at both ends of the metal lead frame 1. According to actual needs, the metal pins 11 may also be arranged on the four sides of the metal lead frame 1. Figure 10 As shown, after the semiconductor chip is plastic-encapsulated, the metal pins 11 are located on the four sides of the plastic encapsulation body 2. Drainage portions are provided on both sides of the creeping tin structure. The drainage portions are stepped or inclined. When the drainage portions are stepped, the cross-sectional shape of the creeping tin structure is a right T-shape or an inverted T-shape; when the drainage portions are inclined, the cross-sectional shape of the creeping tin structure can be a right trapezoid or an inverted trapezoid.

[0056] During the reflow and high-temperature sintering process, the solder paste can more effectively climb from the solder pad of the printed circuit board 3 to the metal pin 11 due to the surface tension diffusion and the ability of the hair gap diffusion formed by the same interface material by setting a beveled or stepped drainage portion. By utilizing the expansion of the surface tension and the hair gap diffusion ability of the metal solder paste 31, the metal solder paste 31 can fully utilize the stepped or beveled drainage portion to climb from the solder pad of the printed circuit board 3 to the metal pin 11, thereby fully climbing the solder.

[0057] Since a tin climbing structure is provided on the metal pin 11, the cross-section of the tin climbing structure is in a positive T-shape, an inverted T-shape, a positive trapezoid or an inverted trapezoid. When the metal solder paste 31 on the soldering pad of the printed circuit board 3 climbs up the metal pin 11 and cools and hardens, the metal solder paste 31 can firmly lock the soldering pad of the printed circuit board 3 to the metal pin 11.

[0058] The present invention proposes a method for forming a tin-climbing structure of a semiconductor chip package metal pin 11:

[0059] The first step, such as Figure 7 As shown, the metal pins 11 on the metal lead frame 1 are punched or cut by a punching tool to reduce the cross-sectional area of ​​the metal pins 11 and punch out the notches 4, as shown in FIG. Figure 8 As shown, the cross-sectional area of ​​the notch 4 is smaller than that of other parts, and the notch 4 can also be processed by etching;

[0060] In the second step, an extrusion forming tool is used to extrude the notch 4 to change the shape of the notch 4 and extrude a tin climbing structure. The extrusion forming tool includes a tool body and a groove pressing part. The width of the groove pressing part is smaller than the width of the notch 4. In this way, when the tool is pressed down, the metal pin 11 at the notch 4 is squeezed, causing the metal pin 11 to deform and form a tin climbing structure.

[0061] The third step is to sequentially carry out semiconductor chip mounting, wire bonding, plastic encapsulation, metal tin layer electroplating, rib removal, laser printing, and singulation on the metal lead frame 1. The singulation here is to cut off from the tin climbing structure.

[0062] In the fourth step, a tin-climbing structure with a metal tin plating layer 111 is formed on the metal pins 11 of the plastic package body 2 after being cut into pieces.

[0063] In the third step, there are many optional tin climbing structures;

[0064] like Figures 9 to 11 As shown, the first inverted T-shaped extrusion forming tool 411 is used to extrude the notch 4, so that the notch 4 becomes the first inverted T-shaped climbing tin structure 41. Correspondingly, during the electroplating process of the metal tin layer, the first inverted T-shaped climbing tin structure metal tin layer 412 appears on the metal pin 11. Since the inverted T-shaped climbing tin structure is narrow at the top and wide at the bottom and has stepped transition drainage parts on both sides, the metal solder paste 31 can easily climb up to form a better climbing tin part during welding.

[0065] like Figures 12 to 14 As shown, a second inverted T-shaped extrusion tool 421 is used to extrude the notch 4, so that the notch 4 forms a second inverted T-shaped tin climbing structure 42. Correspondingly, during the electroplating process of the metal tin layer, a second inverted T-shaped tin climbing structure metal tin layer 422 appears on the second inverted T-shaped tin climbing structure 42. The steps of the second inverted T-shaped tin climbing structure 42 are inclined, which is more conducive to the drainage and climbing of the metal solder paste 31.

[0066] like Figure 15 As shown, the notch 4 is extruded using a first positive T-shaped extrusion tool 431, so that the notch 4 forms a first positive T-shaped creeping tin structure 43. The first positive T-shaped creeping tin structure 43 has a narrower bottom and a wider top, which can gather more metal solder paste 31 at the bottom and increase the contact area between the metal solder paste 31 and the metal pin 11.

[0067] like Figure 16 and 17 As shown, the second positive T-shaped extrusion forming tool 441 is used to extrude the notch 4, so that the notch 4 becomes a second positive T-shaped climbing tin structure 44. Correspondingly, during the electroplating process of the metal tin layer, a second positive T-shaped climbing tin structure metal tin layer 442 appears on the second positive T-shaped climbing tin structure 44. Figure 17 It can be seen that the metal solder paste 31 on the printed circuit board 3 can be mostly gathered at the bottom of the second positive T-shaped tin climbing structure 44, forming a relatively good tin climbing portion 443 of the second positive T-shaped tin climbing structure, and the welding is sufficient.

[0068] like Figures 18 to 20As shown, a first regular trapezoidal extrusion forming tool 451 is used to extrude the notch 4, so that the notch 4 forms a first regular trapezoidal climbing tin structure 45. Correspondingly, during the electroplating process of the metal tin layer, a first regular trapezoidal climbing tin structure metal tin layer 452 appears on the first regular trapezoidal climbing tin structure 45. Since the bottom edge of the first regular trapezoidal climbing tin structure 45 is relatively short, the metal solder paste 31 can easily flow and climb along the sidewalls, forming a relatively sufficient climbing tin portion.

[0069] like Figures 21 to 25 As shown, the second regular trapezoidal extrusion forming tool 461 is used to extrude the notch 4, so that the notch 4 becomes a second regular trapezoidal climbing tin structure 46. Correspondingly, during the electroplating process of the metal tin layer, a second regular trapezoidal climbing tin structure metal tin layer 462 appears on the second regular trapezoidal climbing tin structure 46. Figure 24 As shown, the metal solder paste 31 of the printed circuit board can be drained from the bottom of the second positive trapezoidal solder climbing structure 46 and climb up the metal pin 11. The height of the solder climbing can be easily seen from the top view. Figure 24 In the middle, the creeping tin part forms a semi-climbing tin 463, while in Figure 25 The creeping soldering part forms a full creeping soldering 464. The formation of the semi-climbing soldering 463 and the full creeping soldering 464 also depends on the specific welding conditions. The creeping soldering structure designed in the present invention is easy to observe. When viewed from above, the creeping soldering part can be clearly observed with the naked eye or a magnifying glass, so as to judge the welding effect.

[0070] like Figure 26 As shown, the first inverted trapezoidal extrusion forming tool 471 is used to extrude the notch 4, so that the notch 4 forms a first inverted trapezoidal tin climbing structure 47. Correspondingly, during the electroplating process of the metal tin layer, a first inverted trapezoidal tin climbing structure 47 also appears on the first inverted trapezoidal tin climbing structure 47. Similar to the effect of the first positive T-shaped tin climbing structure 43, the first inverted trapezoidal tin climbing structure 47 also allows the solder paste to be more fully accumulated at the bottom.

[0071] like Figure 27 As shown, the notch 4 is extruded using a second inverted trapezoidal extrusion forming tool 481 , so that the notch 4 becomes a second inverted trapezoidal tin climbing structure 48 , which also forms a better tin climbing portion.

[0072] It should be noted that the bottom of the climbing tin structure of the present invention can contact the soldering pad of the printed circuit board 3 and will not be suspended in the air, thereby ensuring that the metal solder paste 31 can climb toward the climbing tin structure. When the notch 4 is cut into the metal pin 11 and the climbing tin structure is extruded, the substrate of this part is exposed because it has not been tinned yet. However, the metal tin layer is electroplated before cutting, and the notch 4 and the substrate of the climbing tin structure are not exposed after electroplating. After cutting, since the climbing tin structure part of the metal pin 11 is cut, only the cut surface of the climbing tin structure is exposed, and other parts of the metal pin 11 are not exposed. Therefore, the exposed area of ​​the substrate becomes smaller, thereby improving the connection between the metal pin 11 and the soldering pad.

[0073] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit and essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0074] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A semiconductor chip package metal pin tinning structure, arranged on a metal pin (11), characterized in that: The metal pins (11) are arranged on the sides of the package body, drainage parts are arranged on both sides of the tin climbing structure, and the metal pins (11) and the tin climbing structure are both provided with a metal tin plating layer (111); the drainage part can promote the solder paste on the solder pad of the printed circuit board (3) to climb from the bottom of the tin climbing structure to the top of the tin climbing structure, so that the solder paste forms a tin climbing part, and the drainage part is narrow at the top and wide at the bottom; When the drainage portion is in a stepped shape, the cross-sectional shape of the tin climbing structure is in an inverted T shape; When the drainage portion is in an inclined shape, the cross-sectional shape of the tin climbing structure is a regular trapezoid.

2. A method for forming the metal pin tin creeping structure of the semiconductor chip package according to claim 1, characterized in that: The following steps are involved: S1, in the process of manufacturing the metal lead frame (1), a notch (4) is processed at the metal pin (11) of the metal lead frame (1); S2, using an extrusion forming tool to extrude the notch (4) to extrude a tin climbing structure; S3, sequentially performing semiconductor chip mounting, metal wire bonding, plastic encapsulation, metal tin layer electroplating, center rib removal, laser printing, and singulation from the tin climbing structure on the metal lead frame (1); S4, forming a tin-climbing structure with a metal tin plating layer (111) on the metal pins (11) of the plastic package body (2) after singulation.

3. A method for forming a semiconductor chip package metal pin tin creeping structure as claimed in claim 2, characterized in that: During the electroplating process of the metal tin layer, the metal pin (11) and the tin climbing structure will both form a metal tin plating layer (111).

4. A method for forming a semiconductor chip package metal pin tin creeping structure as claimed in claim 2, characterized in that: The notch (4) can be made by etching or punching.

5. A method for forming a semiconductor chip package metal pin tin creeping structure as claimed in claim 2, characterized in that: The extrusion forming tool comprises a tool body and a groove pressing portion, wherein the width of the groove pressing portion is smaller than the width of the notch (4).

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