Semiconductor package structure and preparation method thereof, intermediate product

Abstract

The application provides a semiconductor packaging structure and a preparation method thereof, and an intermediate product. The preparation method of the semiconductor packaging structure comprises the following steps: providing a plastic packaging structure, the plastic packaging structure comprising a plurality of plastic packaging units arranged at intervals, two adjacent plastic packaging units being connected through a cutting channel, the cutting channel comprising a metal substrate layer and a plastic packaging layer covering the surface of the metal substrate layer; and performing half cutting on the plastic packaging structure along the cutting channel to obtain an intermediate product with a cutting groove, the cutting groove comprising a bottom wall and a protruding part protruding from the bottom wall, the bottom wall exposing the metal substrate layer, and the protruding part comprising the metal substrate layer and a remaining part of the plastic packaging layer. In this way, the cutting channel forms a concave-convex cutting groove after half cutting, and the remaining plastic packaging layer in the protruding part can reduce metal chips and the exposed area of the metal substrate layer after half cutting, thereby facilitating the reduction of the amount of tin plating in the subsequent tin plating process, avoiding the short circuit caused by the extrusion of tin to the pin area, and improving the reliability of the product.

Description

Technical Field

[0001] This application relates to the field of semiconductor packaging technology, and in particular to a semiconductor packaging structure, its preparation method, and intermediate products. Background Technology

[0002] Quad Flat No-lead Package (QFN) is primarily used for integrated circuit chips, featuring miniaturization, excellent heat dissipation, and high electrical performance. In QFN products, the leads are arranged in a gull-wing pattern around the bottom perimeter of the package structure, typically with exposed solder pads on the bottom. This enhances both heat dissipation efficiency and mechanical stability. Compared to traditional leaded packages, QFNs are smaller and have narrower lead pitch, making them suitable for high-density circuit board designs and widely used in chip packaging for communications, consumer electronics, and automotive electronics.

[0003] However, existing cutting processes are prone to generating a large amount of metal debris or wire residue, which can easily cause bridging between the pins of the final semiconductor package unit, leading to short circuit failure of the product. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a method for fabricating a semiconductor packaging structure to solve the above-mentioned technical problems.

[0005] To achieve the above objectives, this application provides a method for fabricating a semiconductor packaging structure, comprising:

[0006] A molding structure is provided; wherein the molding structure includes a plurality of spaced molding units, and two adjacent molding units are connected by a slit, the slit including a metal substrate layer and a molding layer covering the surface of the metal substrate layer; The molding structure is partially cut along the cutting groove to obtain an intermediate product with a cutting groove; wherein the cutting groove includes a bottom wall and a protrusion protruding from the bottom wall, the bottom wall exposes the metal substrate layer, and the protrusion includes the metal substrate layer and a portion of the molding layer remaining.

[0007] Optionally, the step of partially cutting the molding structure along the cutting groove to obtain an intermediate product with a cutting groove includes: The molding structure is partially cut along the cutting groove using a first cutting blade to obtain an intermediate product with a cutting groove.

[0008] Optionally, the step of using a first cutting blade to partially cut the encapsulated structure along the cutting path includes: The molding structure is partially cut along the cutting path using a first cutting blade at a target feed rate; wherein the target feed rate is in the range of 20mm / s-40mm / s.

[0009] Optionally, the step of using a first cutting blade to partially cut the encapsulated structure along the cutting path includes: The encapsulated structure is partially cut along the cutting path using a diamond blade.

[0010] Optionally, the surface of the cutting channel is flush with the surface of the molding unit; in the cutting channel, the thickness of the molding layer ranges from 0.1mm to 0.12mm, and the thickness of the metal substrate layer ranges from 0.08mm to 0.09mm.

[0011] Optionally, in the cutting channel, the thickness of the molding layer is 0.12 mm, and the thickness of the metal substrate layer is 0.08 mm; the thickness of the molding layer in the protrusion ranges from 0.035 mm to 0.045 mm.

[0012] Optionally, in the cutting channel, the thickness of the molding layer is 0.12 mm, and the thickness of the metal substrate layer is 0.08 mm; in the direction perpendicular to the surface of the molding unit, the distance from the bottom wall to the surface of the molding unit ranges from 0.12 mm to 0.15 mm.

[0013] Optionally, after partially cutting the molding compound along the dicing groove to obtain an intermediate product of the semiconductor package structure with dicing grooves, the method further includes: A coating is formed within the cutting groove; A second cutting blade is used to make a full cut at the cutting groove between two adjacent molding units, removing the protrusion and parts of the metal substrate layer on both sides of the protrusion, thereby separating the adjacent molding units from each other to obtain a semiconductor package structure.

[0014] Based on the same inventive concept, this application also provides an intermediate product of a semiconductor packaging structure, characterized in that it is prepared using the above-described method for preparing a semiconductor packaging structure, and the intermediate product includes: Multiple encapsulation units, wherein the multiple encapsulation units are arranged at intervals; A cutting groove is disposed between two adjacent molding units. The cutting groove includes a bottom wall and a protrusion protruding from the bottom wall. The protrusion includes a metal substrate layer and a molding layer.

[0015] Based on the same inventive concept, this application also provides a semiconductor packaging structure, which is prepared using the above-described semiconductor packaging structure preparation method.

[0016] The method for fabricating a semiconductor packaging structure provided in this application includes: providing a molding compound structure comprising a plurality of spaced molding compound units, with adjacent molding compound units connected by a dicing channel, the dicing channel comprising a metal substrate layer and a molding compound layer covering the surface of the metal substrate layer; and half-cutting the molding compound structure along the dicing channel to obtain an intermediate product with a dicing groove, the dicing groove comprising a bottom wall and a protrusion protruding from the bottom wall, the bottom wall exposing the metal substrate layer, and the protrusion comprising the metal substrate layer and a portion of the molding compound layer remaining. Thus, the dicing channel forms a concave-convex dicing groove after half-cutting. By retaining the molding compound layer in the protrusion, metal chips and the exposed area of ​​the metal substrate layer after half-cutting can be reduced, thereby reducing the amount of tin plating during subsequent tin plating, preventing tin from being squeezed into the pin area and causing a short circuit, and improving product reliability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of a method for fabricating a semiconductor packaging structure according to an embodiment of this application; Figure 2 This is a schematic structural diagram of a molding compound according to an embodiment of this application; Figure 3 This is a schematic structural diagram of a half-cut metal substrate layer according to an embodiment of this application; Figure 4 This is a schematic structural diagram of a fully cut metal substrate layer according to an embodiment of this application.

[0019] Marker explanation: 1. Molding structure; 11. Molding unit; 12. Cutting channel; 121. Metal substrate layer; 122. Molding layer; 21. Bottom wall; 22. Protrusion; 31. Plating layer. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0021] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "inner," and "outer" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0022] The QFN package structure is integrated through the connecting bridges and dicing channels of the substrate to form a rectangular QFN package array board. The side pads and bottom exposed heat dissipation pads of the QFN package are tightly bonded to the substrate, and the pin pitch is small and the structure is precise.

[0023] The inventors discovered that directly cutting the entire package array would cause defects such as pin warping, delamination of the pads from the substrate, and chipping of the encapsulated components due to the cutting stress of the high-speed cutting tool. Therefore, it is necessary to first cut halfway to create stress relief grooves, and then cut the entire package to separate the individual molded units on the array board, resulting in a finished product that can be soldered.

[0024] In QFN packaging, the dicing channel is composed of a metal substrate and a molding compound. Traditional half-cut processes produce a lot of copper shavings, which completely remove the molding compound within the dicing channel, exposing the entire metal substrate. In the subsequent tin plating process, this fully exposed structure will form a large amount of tin layer and tin whiskers due to the full contact between the metal substrate and the molten tin. Thus, during the full cut separation, the high-speed rotating blade will squeeze and scrape the tin layer within the dicing channel, causing tin shavings or molten tin to be carried to the side pads and pin areas of adjacent molding compounds, ultimately leading to short circuit failures.

[0025] Based on this, embodiments of this application provide a method for fabricating a semiconductor packaging structure to solve the above-mentioned problems.

[0026] like Figures 1-4 As shown in the figure, this application provides a method for fabricating a semiconductor packaging structure, the method comprising: Step S100: Provide a molding structure 1; wherein the molding structure 1 includes a plurality of molding units 11 arranged at intervals, and two adjacent molding units 11 are connected by a cutting channel 12, the cutting channel 12 includes a metal substrate layer 121 and a molding layer 122 covering the surface of the metal substrate layer 121. Step S200: The encapsulation structure 1 is partially cut along the cutting groove 12 to obtain an intermediate product with a cutting groove; wherein, the cutting groove includes a bottom wall 21 and a protrusion 22 protruding from the bottom wall 21, the bottom wall 21 exposes the metal substrate layer 121, and the protrusion 22 includes the metal substrate layer 121 and a portion of the encapsulation layer 122 remaining.

[0027] In this embodiment, the cutting groove 12 is partially cut to form a concave-convex cutting groove. By retaining the molding compound 122 in the protrusion 22, metal chips and the exposed area of ​​the metal substrate layer 121 after the partial cut can be reduced. This helps to reduce the amount of tin plating during subsequent tin plating, avoids tin being squeezed into the pin area and causing a short circuit, and improves product reliability. In addition, the molding compound 122 of the protrusion 22 can form a physical barrier during the subsequent full cut process, avoiding direct large-area contact between the blade and the tin layer, and further preventing tin from being squeezed into the pin area.

[0028] In some embodiments, the molding structure 1 is composed of a plurality of molding units 11 arranged in an array, and adjacent molding units 11 are connected by a slit 12. The interior of the slit 12 is a composite structure of molding layer 122 and metal substrate layer 121 from top to bottom. The molding layer 122 plays a role in protecting the metal substrate layer 121 and maintaining the stability of the array board structure.

[0029] In step S200, a half-cutting process is performed along the preset path of the cutting channel 12 using a cutting blade or laser, so that a cutting groove is formed in the cutting channel 12. The cutting groove helps to alleviate the cutting stress during the subsequent full cut and avoids defects such as pin warping, pad delamination, and colloid chipping.

[0030] This partial cut does not completely remove the molding compound 122. Instead, it precisely controls the cutting depth and path to form a cutting groove with a bottom wall 21 and a protrusion 22. The bottom wall 21 of the cutting groove completely removes the molding compound 122, exposing the underlying metal substrate layer 121 and providing necessary metal adhesion sites for subsequent tin plating. The protrusion 22 retains a portion of the molding compound 122, and together with the underlying metal substrate layer 121, forms a complete protrusion structure.

[0031] Compared to the fully exposed state of the metal substrate in the traditional half-cut process, this embodiment reduces the exposed area of ​​the metal substrate layer 121 by forming a protrusion 22 that retains part of the molding compound 122, while reducing the amount of metal chips generated during the half-cut process, which is beneficial to reducing the base carrier for tin layer deposition.

[0032] In the subsequent tin plating process, due to the significant reduction in the exposed area of ​​the metal substrate layer 121 within the cutting groove, the molten tin can only be deposited in the exposed metal area of ​​the bottom wall 21, which helps to reduce the amount of tin plating and the amount of tin whiskers generated. The molding compound 122 of the protrusion 22 does not react with the molten tin and therefore does not form a tin layer.

[0033] During the full dicing process, the high-speed rotating blade makes a deep cut along the dicing groove. The molding compound layer 122 of the protrusion 22 can physically limit and block the blade, avoiding large-area scraping and squeezing between the blade and the solder layer. This effectively prevents solder chips or molten solder from being carried to the side pads and pin areas of the molding compound unit 11, avoiding short circuits caused by solder on the blade during full dicing. At the same time, the stress relief function of the dicing groove can still effectively alleviate the cutting stress during full dicing, ensuring the structural integrity of the semiconductor package structure and avoiding defects such as pin warping and pad delamination.

[0034] In some embodiments, the molding layer 122 may be a resin layer. The metal substrate layer 121 may be a copper layer.

[0035] In some embodiments, step S200 may involve partially cutting the molding structure 1 along the cutting groove 12 to obtain an intermediate product with a cutting groove, including: The first cutting blade is used to cut the plastic seal structure 1 in half along the cutting groove 12 to obtain an intermediate product with a cutting groove.

[0036] Here, the blade size of the first cutting blade is controllable, which can precisely control the depth of the half-cut, avoid cutting through the exposed pads or internal substrate at the bottom of the package structure, and at the same time reduce defects such as chipping and burrs on the package edge, ensuring the flatness of the pins and pads, and avoiding affecting the yield of subsequent surface mount soldering.

[0037] The pins of QFN products are metal solder pads on the bottom side edge, with no protruding pins. Blade cutting will not cause bending, deformation or other damage to the pins. Compared with the heat-affected zone that may be generated by laser cutting, blade cutting is a cold processing method, which will not cause oxidation, warping or damage to the internal chip of the encapsulation material, metal solder pads and other packaging materials due to high temperature.

[0038] The parameters of the first cutting blade, such as its rotational speed, feed rate, and cutting depth, are easily standardized, making it suitable for mass production. The blade can be re-sharpened and reused, resulting in lower equipment maintenance costs compared to laser cutting equipment.

[0039] In some embodiments, the blade width of the first cutting blade is slightly larger than the width of the cutting groove 12, which is beneficial for the formation of the cutting groove. The movement trajectory of the first cutting blade can be strictly executed along the centerline of the cutting groove 12, avoiding cutting deviation that could cause misalignment of the concave and convex structures, thus improving the accuracy of cutting.

[0040] In some embodiments, the molding structure may be partially cut along the cutting path 12 using a first cutting blade, including: A first cutting blade is used to partially cut the plastic-encapsulated structure along the cutting path at a target feed rate. The target feed rate of the first cutting blade ranges from 20 mm / s to 40 mm / s, for example, 20 mm / s, 25 mm / s, 30 mm / s, 35 mm / s, or 40 mm / s. This allows the blade to cut the cutting path 12 with appropriate impact force and contact time, precisely removing the plastic-encapsulated layer 122 on the bottom wall 21 while preserving a certain thickness of the plastic-encapsulated layer 122 structure, and minimizing damage to the metal substrate layer 121 and the plastic-encapsulated unit 11 caused by cutting stress.

[0041] A lower speed limit of 20mm / s can ensure the basic efficiency of single-batch cutting and avoid a decrease in production capacity due to excessively slow speed, while an upper speed limit of 40mm / s can improve processing efficiency without sacrificing structural accuracy.

[0042] If the feed rate is less than 20 mm / s, the contact time between the blade and the material of the cutting groove 12 will be too long, which will intensify the extrusion of the tool on the molding layer 122 and the friction on the metal substrate layer 121. This will not only cause the metal substrate layer 121 to deform, but also easily generate a large amount of copper shavings that adhere to the cutting groove, affecting the operation of subsequent processes.

[0043] If the feed rate exceeds 40 mm / s, the cutting impact force of the blade will increase sharply, exceeding the bonding strength tolerance range between the molding layer 122 and the metal substrate. This can easily cause the molding layer 122 in the protrusion 22 to break and fall off, and burrs to appear on the bottom wall 21, thus destroying the structure of "the bottom wall 21 exposing the metal substrate layer 121 and the protrusion 22 retaining part of the molding layer 122". It can also cause the risk of pin warping of adjacent molding units 11.

[0044] In some embodiments, the molding structure may be partially cut along the cutting path 12 using a first cutting blade, including: The plastic-encapsulated structure is partially cut along the 12 cutting paths using a diamond blade.

[0045] Here, the cutting groove 12 is composed of a molding compound 122 and a metal substrate layer 121. The molding compound 122 is hard and brittle, while the metal substrate layer 121 has a certain degree of ductility. Traditional carbide inserts are prone to blade wear and cutting force attenuation during cutting, making it difficult to accurately control the cutting depth and path. Diamond inserts, on the other hand, have higher hardness and can stably maintain blade sharpness. During cutting, they wear down, which helps to form a protrusion 22 in the cutting groove that retains part of the molding compound 122, and allows the molding compound 122 in the bottom wall 21 area to be completely removed, exposing the metal substrate layer 121.

[0046] The small pin pitch and tight bonding between the pads and the substrate in the molding compound unit 11 mean that excessive cutting stress during the semi-cutting process can lead to pin warping and pad delamination. Diamond inserts, with their high cutting edge smoothness and low coefficient of friction with the cutting groove material 12, generate significantly lower cutting stress during cutting compared to traditional tools. This effectively reduces the extrusion deformation of the metal substrate layer 121 and the chipping damage to the molding compound layer 122. Furthermore, the low-friction cutting characteristics reduce copper shavings production, preventing them from adhering to the cutting groove and affecting the accuracy of subsequent tin plating processes, thus ensuring the structural integrity of intermediate products.

[0047] The hardness of diamond cutting tools is affected by factors such as the diamond grains, the bonding agent, and the grain size distribution. In diamond tools, grain size is a key indicator of abrasive particle size, directly impacting the tool's cutting performance and machining accuracy. Mesh count (mesh#), a specialized unit in the sieving field, represents the number of holes per square inch of screen, and its value is inversely proportional to the particle size.

[0048] The grit size of diamond abrasives follows relevant industry standards (such as national standard GB / T6406 and international standard ISO6106). Commonly used standard grit sizes are distributed in a geometric or approximately geometrical manner. For example, the medium-fine grit size range includes 120#, 150#, 180#, 220#, 240#, and 280# (in micrometers). Excluding binder and concentration, the larger the grit size, the finer the particles and the harder the cutting tool. The smaller the grit size, the larger the particles, resulting in higher cutting efficiency but easier wear.

[0049] In some embodiments, the first dicing blade has a grit size of 180#. Blades with this grit size are relatively soft and wear down faster, which is beneficial for quickly forming a textured groove. Using a 180# first dicing blade for a partial cut allows the blade to wear down along the cutting path 12, forming a textured groove. This ensures the stepped depth of the molding compound structure 1 while reducing the amount of metal substrate layer 121 exposed in the groove. Consequently, during subsequent tin plating, the amount of tin in the groove is significantly reduced, which helps prevent the blade from moving the tin during a full cut, thus avoiding bridging in the semiconductor package structure.

[0050] In some embodiments, the surface of the cutting channel 12 can be flush with the surface of the molding unit 11. In the cutting channel 12, the thickness of the molding layer 122 is in the range of 0.1mm-0.12mm, for example, 0.1mm, 0.11mm, 0.115mm, 0.118mm, 0.12mm, etc., and the thickness of the metal substrate layer 121 is in the range of 0.08mm-0.09mm, for example, 0.08mm, 0.082mm, 0.084mm, 0.086mm, 0.088mm, 0.09mm, etc.

[0051] Here, the design of the cutting groove 12 surface being flush with the surface of the molding unit 11 helps to ensure a stable blade feed path during half-cutting, avoiding cutting depth deviations caused by surface height differences. This allows for precise control over the structure of the bottom wall 21 of the cutting groove exposing the metal substrate layer 121 and the protrusion 22 retaining part of the molding layer 122. At the same time, the flush surface reduces the flow deviation of molten solder during tin plating, preventing additional adhesion of molten solder to non-target areas.

[0052] The thickness of the molding layer 122 ranges from 0.1mm to 0.12mm. This thickness is sufficient to protect the metal substrate layer 121 from external interference. If the molding layer 122 is too thin, a stable protective structure cannot be formed. If it is too thick, it will increase the difficulty and cost of cutting.

[0053] The thickness of the metal substrate layer 121 ranges from 0.08mm to 0.09mm. The thickness of the metal substrate layer 121 and the thickness of the molding layer 122 form a reasonable ratio, which can meet the bonding strength requirements of the side pads, bottom heat dissipation pads and the substrate in the molding structure. Furthermore, by controlling the thickness of the metal substrate layer 121, the amount of tin layer deposition during tin plating can be further limited, reducing the risk of tin whisker formation.

[0054] See Figure 3 , Figure 3 The mid-distance 'a' represents the thickness of the molding compound 122 in the protrusion 22. In some embodiments, the thickness of the molding compound 122 in the cutting channel 12 can be 0.12 mm, the thickness of the metal substrate layer 121 can be 0.08 mm, and the thickness of the molding compound 122 in the protrusion 22 can range from 0.035 mm to 0.045 mm, for example, 0.035 mm, 0.036 mm, 0.038 mm, 0.04 mm, 0.042 mm, 0.045 mm, etc.

[0055] Here, before the half-cut, the 0.12mm thickness of the molding layer 122 can meet the structural support requirements of the molding structure 1, and also provides a reasonable thickness margin for the molding layer 122 during the half-cut. The 0.08mm thickness of the metal substrate layer 121 can ensure the connection strength between the molding unit 11 and the metal substrate layer 121.

[0056] The thickness of the molding compound 122 in the protrusion 22 ranges from 0.035mm to 0.045mm, which can form a stable raised barrier structure within the dicing groove without affecting subsequent full-cutting processes due to excessive thickness of the molding compound 122. The molding compound 122 in the protrusion 22 can physically separate exposed metal areas during the subsequent tin plating stage, limiting the adhesion range of molten solder. During the full-cutting stage, the protrusion structure can prevent large-area direct contact between the high-speed blade and the solder layer, avoiding solder dust being scraped or squeezed onto the pin area. Simultaneously, the minimal thickness of the molding compound 122 does not add additional cutting stress, ensuring the structural integrity of the package unit.

[0057] See Figure 3 , Figure 3 The mid-distance b represents the distance from the bottom wall 21 to the surface of the molding unit 11 in a direction perpendicular to the surface of the molding unit 11. In some embodiments, in the cutting channel 12, the thickness of the molding layer 122 is 0.12 mm, the thickness of the metal substrate layer 121 is 0.08 mm, and the distance from the bottom wall 21 to the surface of the molding unit 11 in a direction perpendicular to the surface of the molding unit 11 ranges from 0.12 mm to 0.15 mm, for example, it can be 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, etc.

[0058] The lower limit of the distance from the bottom wall 21 to the surface of the molding unit 11 is equal to the thickness of the molding layer 122, ensuring that the molding layer 122 in the area of ​​the bottom wall 21 is completely removed and the metal substrate layer 121 is exposed. The upper limit is slightly higher than the thickness of the molding layer 122, allowing for further optimization of stress release by micro-cutting the surface of the metal substrate layer 121 without damaging the overall structure of the metal substrate layer 121. In other words, the thickness of the metal substrate layer 121 in the recess of the cutting groove is in the range of 0.05mm-0.08mm, ensuring that the metal substrate layer 121 is not cut through.

[0059] In some embodiments, after step S200, where the molding compound 1 is half-cut along the dicing groove 12 to obtain an intermediate product with a semiconductor package structure having dicing grooves, the process may further include: Step S300: Form a plating layer 31 in the cutting groove; In step S400, a second cutting blade is used to make a full cut at the cutting groove between two adjacent molding units, removing the protrusion 22 and a portion of the metal substrate layer 121 on both sides of the protrusion 22, thereby separating the adjacent molding units from each other and obtaining a semiconductor packaging structure.

[0060] In step S300, after the semi-cutting is completed, the cutting groove of the intermediate product has an uneven structure, with the bottom wall 21 exposing the metal substrate layer 121, and the protrusion 22 retaining part of the molding compound layer 122. At this time, the cutting groove is electroplated, and the electroplating solution can only deposit to form a plating layer 31 on the surface of the exposed metal substrate layer 121. The molding compound layer 122 of the protrusion 22 does not have the conditions for metal adhesion, so a plating layer 31 will not form.

[0061] In this embodiment, a plating layer 31 is formed within the cutting groove after the half-cut. The plating layer 31 adheres only to the exposed metal area of ​​the bottom wall 21 and does not diffuse to the molding compound layer 122 of the protrusion 22 or the pins of the adjacent molding compound unit 11, thus avoiding the problems of excessive tin plating and tin whisker growth in conventional processes. Furthermore, the plating layer 31 enhances the machinability of the metal substrate layer 121, reduces the scratching damage to the metal substrate layer 121 by the blade during the full cut, reduces the generation of metal debris, and forms a physical isolation layer to prevent the high temperature generated by the direct contact between the metal substrate layer 121 and the blade during the full cut from causing the tin layer to melt and diffuse.

[0062] In some embodiments, the plating layer 31 is a tin layer or nickel layer, etc., that can protect the metal substrate layer 121. Compared to the indiscriminate tin plating method in conventional processes, the plating layer 31 formed in the cutting groove after half-cutting only covers the metal area that needs protection, which can reduce the consumption of plating layer 31 material and also help to avoid short circuits caused by the diffusion of tin shavings during subsequent full-cutting. In addition, the plating layer 31 can fill the tiny burrs on the surface of the metal substrate layer 121 during half-cutting, improve the flatness of the bottom wall 21, and facilitate subsequent full-cutting.

[0063] In step S400, after the plating layer 31 is formed, a second cutting blade is used to perform full cutting along the cutting groove. During cutting, the blade feeds along the preset path of the cutting groove to remove the plastic encapsulation layer 122, plating layer 31, and metal substrate layer 121 of the protrusion 22, as well as a portion of the metal substrate layer 121 on both sides of the protrusion 22, thereby achieving complete separation of adjacent plastic encapsulation units 11.

[0064] In some embodiments, the width of the second dicing blade is smaller than the width of the first dicing blade; that is, the width of a full cut is smaller than the width of a half cut. Thus, the side surface of the semiconductor package structure obtained after full cutting has a stepped structure. See also... Figure 4 The two semiconductor package structures after separation each form a stepped structure. Specifically, the semiconductor package structure includes a molding unit 11 and a stepped structure located around the molding unit 11. The stepped structure includes a metal substrate layer 121 and a plating layer 31 covering the surface of the metal substrate layer 121.

[0065] During the cutting process, the plating layer 31 can effectively reduce the coefficient of friction between the second cutting blade and the metal substrate layer 121, thereby reducing cutting stress. At the same time, the physical barrier effect of the plating layer 31, combined with the concave-convex structure of the cutting groove, can constrain the small amount of metal debris and plating layer 31 debris generated during cutting at the bottom wall 21, preventing them from being carried by the blade to the pin area of ​​the molding unit 11, thus reducing the risk of short circuits and improving the reliability of the semiconductor packaging structure.

[0066] This application embodiment also provides an intermediate product of a semiconductor packaging structure, which is prepared using the above-described semiconductor packaging structure preparation method. The intermediate product includes molding compound units 11 and dicing grooves. Multiple molding compound units 11 are arranged at intervals. A dicing groove is disposed between two adjacent molding compound units 11. The dicing groove includes a bottom wall 21 and a protrusion 22 protruding from the bottom wall 21. The bottom wall 21 exposes a metal substrate layer 121, and the protrusion 22 includes the metal substrate layer 121 and a portion of the molding compound layer 122 remaining thereon.

[0067] This application embodiment forms a concave-convex cutting groove structure between adjacent molding units 11, where the bottom wall 21 exposes the metal substrate layer 121 and the protrusion 22 retains part of the molding layer 122. This reduces metal chips and the exposed area of ​​the metal substrate layer 121 after half-cutting, thereby reducing the amount of tin plating during subsequent tin plating and preventing short circuits caused by the tin being squeezed to the pin area by the second cutting blade during full cutting, thus improving product reliability.

[0068] The cutting groove can release the stress of the molding compound structure 1 in advance, avoiding the cutting stress of the high-speed tool during the subsequent full cut from directly acting on the molding compound unit 11, thereby reducing the possibility of damage to the molding compound unit 11. The bottom wall 21 of the cutting groove exposes the metal substrate layer 121, providing a precise metal adhesion site for the subsequent electroplating process. This avoids the problem of a large amount of tin and tin whiskers being present during the subsequent tin plating process due to the complete exposure of the metal substrate in the traditional half-cut process. During the subsequent full cut, the tin is squeezed by the blade or carried to the pin.

[0069] The protrusion 22 is composed of a metal substrate layer 121 and a remaining portion of the plastic encapsulation layer 122, which can form a physical barrier structure. This not only limits the adhesion range of the plating layer 31 and reduces the consumption of electroplating materials and the generation of tin whiskers, but also prevents the blade from directly contacting the plating layer 31 over a large area in the subsequent full-cutting process, thus preventing electroplating debris from being scraped to the pin area and causing a short circuit.

[0070] This intermediate product, processed in the electroplating process, has a concave-convex grooving structure that spatially constrains the plating layer 31. The electroplating solution can only be deposited on the surface of the exposed metal substrate layer 121. The molding compound 122 of the protrusion 22 does not have the conditions for metal adhesion and therefore will not adhere to the plating layer 31. Compared to the intermediate product with fully exposed metal in conventional processes, the intermediate product in this embodiment helps reduce the amount of tin plating in the subsequent grooving, thereby preventing the blade from moving the tin during subsequent full cuts and thus reducing tin bridging.

[0071] This application also provides a semiconductor packaging structure, which is prepared using the above-described semiconductor packaging structure preparation method.

[0072] In the semiconductor packaging structure of this application embodiment, during the manufacturing process, the dicing channel 12 is partially cut to form a concave-convex dicing groove. By retaining the molding compound 122 in the protrusion 22, metal chips can be reduced and the exposed area of ​​the metal substrate layer 121 after the partial cut can be reduced. This helps to reduce the amount of tin plating during subsequent tin plating and avoids short circuits caused by the tin being squeezed to the pin area by the second dicing blade during full cut, thereby improving the reliability of the semiconductor packaging structure.

[0073] It should be noted that some embodiments of this application have been described above. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims can be performed in a different order than that shown in the above embodiments and still achieve the desired result. In addition, the processes depicted in the drawings do not necessarily require the specific order or sequential order shown to achieve the desired result.

[0074] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this application (including the claims) is limited to these examples; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the above embodiments of this application, which are not provided in detail for the sake of brevity.

[0075] The embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included within the protection scope of this application.

Claims

1. A method for fabricating a semiconductor packaging structure, characterized in that, include: A molding structure is provided; wherein the molding structure includes a plurality of spaced molding units, and two adjacent molding units are connected by a slit, the slit including a metal substrate layer and a molding layer covering the surface of the metal substrate layer; The molding structure is partially cut along the cutting groove to obtain an intermediate product with a cutting groove; wherein the cutting groove includes a bottom wall and a protrusion protruding from the bottom wall, the bottom wall exposes the metal substrate layer, and the protrusion includes the metal substrate layer and a portion of the molding layer remaining.

2. The method for fabricating a semiconductor packaging structure according to claim 1, characterized in that, The step of partially cutting the molding structure along the cutting groove to obtain an intermediate product with a cutting groove includes: The molding structure is partially cut along the cutting groove using a first cutting blade to obtain an intermediate product with a cutting groove.

3. The method for preparing a semiconductor packaging structure according to claim 2, characterized in that, The step of using a first cutting blade to partially cut the plastic-encapsulated structure along the cutting path includes: The molding structure is partially cut along the cutting path using a first cutting blade at a target feed rate; wherein the target feed rate is in the range of 20mm / s-40mm / s.

4. The method for preparing a semiconductor packaging structure according to claim 2, characterized in that, The step of using a first cutting blade to partially cut the plastic-encapsulated structure along the cutting path includes: The encapsulated structure is partially cut along the cutting path using a diamond blade.

5. The method for fabricating a semiconductor packaging structure according to claim 1, characterized in that, The surface of the cutting channel is flush with the surface of the molding unit; in the cutting channel, the thickness of the molding layer ranges from 0.1mm to 0.12mm, and the thickness of the metal substrate layer ranges from 0.08mm to 0.09mm.

6. The method for fabricating a semiconductor packaging structure according to claim 5, characterized in that, In the cutting channel, the thickness of the molding layer is 0.12 mm, and the thickness of the metal substrate layer is 0.08 mm; the thickness of the molding layer in the protrusion ranges from 0.035 mm to 0.045 mm.

7. The method for fabricating a semiconductor packaging structure according to claim 5, characterized in that, In the cutting channel, the thickness of the molding layer is 0.12 mm, and the thickness of the metal substrate layer is 0.08 mm; in the direction perpendicular to the surface of the molding unit, the distance from the bottom wall to the surface of the molding unit ranges from 0.12 mm to 0.15 mm.

8. The method for preparing a semiconductor packaging structure according to any one of claims 1-7, characterized in that, After partially cutting the molding compound along the dicing groove to obtain an intermediate product of the semiconductor package structure with dicing grooves, the process further includes: A coating is formed within the cutting groove; A second cutting blade is used to make a full cut at the cutting groove between two adjacent molding units, removing the protrusion and parts of the metal substrate layer on both sides of the protrusion, thereby separating the adjacent molding units from each other to obtain a semiconductor package structure.

9. An intermediate product of a semiconductor packaging structure, characterized in that, The intermediate product is prepared using the method for preparing a semiconductor packaging structure as described in any one of claims 1-7, wherein the intermediate product comprises: Multiple encapsulation units, wherein the multiple encapsulation units are arranged at intervals; A cutting groove is disposed between two adjacent molding units. The cutting groove includes a bottom wall and a protrusion protruding from the bottom wall. The protrusion includes a metal substrate layer and a molding layer.

10. A semiconductor packaging structure, characterized in that, It is prepared using the semiconductor packaging structure preparation method as described in claim 8.

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