Lead frame manufacturing method, lead frame manufacturing die, and lead frame

Abstract

Embodiments of the present invention provide a method for manufacturing a lead frame, a mold for manufacturing a lead frame, and a lead frame, which relate to the technical field of semiconductor packaging. In this method, the metal core frame is fixed by an upper mold and a lower mold, and then a plastic package body is formed between the upper mold and the lower mold, and the plastic package body is transversely sliced to obtain a plurality of substrate frames. Finally, the substrate frames are plated to obtain a plurality of lead frames. Compared with the prior art, the present invention avoids the use of etching and stamping processes, but uses plastic encapsulant to encapsulate metal profiles according to the arrangement to manufacture the frame, thus avoiding the process problems brought by the etching and stamping processes. Moreover, a large number of physical processing methods are adopted, improving the manufacturing efficiency of the lead frame. And the metal layer for arranging pins on the lead frame can be directly determined according to the metal profile, enabling more pins to be arranged under the same package size, thereby improving the packaging performance.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor packaging, and more particularly, to a method for manufacturing a lead frame, a mold for manufacturing a lead frame, and a lead frame. Background Art

[0002] A lead frame is a commonly used packaging substrate structure in the packaging technology. In the prior art, the lead frame is usually manufactured by an etching process or a stamping process. The stamping process is prone to generating burrs during the production process, and is also prone to deformation, with poor manufacturing accuracy, and also has the disadvantages of high cost and long cycle. Therefore, the etching process is usually used to manufacture the lead frame. However, the etching process is complex, with a long production time, high cost, and pollution. Summary of the Invention

[0003] The objectives of the present invention include, for example, providing a method for manufacturing a lead frame, a mold for manufacturing a lead frame, and a lead frame, which have simple and reliable process steps, short production cycles, low costs, and no pollution.

[0004] The embodiments of the present invention can be implemented as follows:

[0005] In a first aspect, the present invention provides a method for manufacturing a lead frame, including:

[0006] Installing a plurality of metal profiles on a lower mold, wherein the plurality of metal profiles extend upward to form a metal core frame;

[0007] Installing an upper mold on the top end of the metal core frame to fix the metal core frame between the lower mold and the upper mold;

[0008] Molding a plastic sealing body between the lower mold and the upper mold;

[0009] Cutting the plastic sealing body at intervals along a direction perpendicular to the extension direction of the metal profile to obtain a plurality of substrate frames;

[0010] Performing a plating treatment on the plurality of substrate frames to obtain a plurality of lead frames.

[0011] In an alternative embodiment, before the step of performing a plating treatment on the plurality of substrate frames, the method further includes:

[0012] Grinding the substrate frames to a preset thickness.

[0013] In an alternative embodiment, the step of performing a plating treatment on the plurality of substrate frames includes:

[0014] Performing a silver plating treatment on one surface of the substrate frames.

[0015] In an alternative embodiment, the plurality of metal profiles include metal columns and a plurality of metal rods. The step of installing the plurality of metal profiles on the lower mold includes:

[0016] Installing a metal column on the lower mold;

[0017] Installing a plurality of metal rods surrounding the metal column on the lower mold;

[0018] Wherein, column-shaped positioning holes for installing the metal column and rod-shaped positioning holes for installing the metal rods are formed on the lower mold.

[0019] In an alternative embodiment, the metal column is a copper column and the metal rod is a copper rod.

[0020] In an alternative embodiment, the step of encapsulating to form an encapsulation body between the lower mold and the upper mold includes:

[0021] Arranging a plurality of encapsulation templates between the upper mold and the lower mold to form an inner cavity between the upper mold and the lower mold;

[0022] Injecting encapsulation material into the inner cavity;

[0023] Removing the encapsulation templates after the encapsulation material is cured.

[0024] In an alternative embodiment, after the step of encapsulating to form an encapsulation body between the lower mold and the upper mold, the method further includes:

[0025] Removing the upper mold and the lower mold.

[0026] In an alternative embodiment, after the step of cutting the encapsulation body at intervals in a direction perpendicular to the extension direction of the metal profiles, the method further includes:

[0027] Removing the substrate frame at the top and the substrate frame at the bottom.

[0028] In a second aspect, the present invention provides a lead frame manufacturing mold applicable to the lead frame manufacturing method according to any one of the foregoing embodiments. The lead frame manufacturing mold includes:

[0029] A lower mold for installing a metal core frame formed by a plurality of upwardly extending metal profiles;

[0030] An upper mold for installing at the top of the metal core frame to fix the metal core frame between the lower mold and the upper mold;

[0031] A plastic encapsulation mold, which is used to be arranged between the upper mold and the lower mold and jointly form an inner cavity with the upper mold and the lower mold for injecting plastic encapsulation material;

[0032] A cutting mold, which is used to cut the plastic encapsulation body formed between the upper mold and the lower mold at intervals along a direction perpendicular to the extension direction of the metal profile to obtain a plurality of substrate frames.

[0033] In a third aspect, the present invention provides a lead frame, which is prepared by the lead frame preparation method according to any one of the foregoing embodiments.

[0034] The beneficial effects of the embodiments of the present invention include, for example:

[0035] The present invention provides a novel lead frame preparation method, mold and lead frame. It fixes the metal core frame formed by a plurality of metal profiles through the upper mold and the lower mold, then forms a plastic encapsulation body between the upper mold and the lower mold, and performs a transverse slicing process on the plastic encapsulation body to obtain a plurality of substrate frames. Finally, plating treatment is performed on the substrate frames to obtain a plurality of lead frames. Compared with the prior art, the present invention avoids using etching process and stamping process, but uses plastic encapsulation material to encapsulate the metal profiles according to the arrangement to make the frame, thus avoiding the process problems brought by the etching process and the stamping process. Moreover, a large number of physical processing methods are adopted, which improves the manufacturing efficiency of the lead frame. And the metal layer for arranging pins on the lead frame can be directly determined according to the metal profile, and more pins can be arranged under the same package size, thereby improving the packaging performance. Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as a limitation of the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0037] Figure 1 It is a step block diagram of the lead frame preparation method provided by the embodiment of the present invention;

[0038] Figures 2 to 6 It is a process flow diagram of the lead frame preparation method provided by the embodiment of the present invention;

[0039] Figure 7 It is a structural schematic diagram of the lead frame provided by the embodiment of the present invention.

[0040] Icons: 100 - lead frame; 110 - chip bonding area; 130 - pin soldering area; 200a - upper mold; 200b - lower mold; 210 - positioning hole; 300 - metal profile; 310 - metal column; 330 - metal rod; 400 - plastic package body. Detailed implementation mode

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the accompanying drawings here can be arranged and designed in various different configurations.

[0042] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0043] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0044] In the description of the present invention, it should be noted that if terms such as "upper", "lower", "inner", "outer", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the present invention is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 construed as a limitation of the present invention.

[0045] In addition, if terms such as "first", "second", etc. are used only for distinguishing descriptions, they cannot be understood as indicating or implying relative importance.

[0046] As disclosed in the background art, the prior art usually uses etching or stamping processes to prepare lead frames. Specifically, for ordinary etched frame products, copper is etched away chemically, the process is extremely complex, time-consuming in production, and the quantity produced at one time is small. For stamping frame products, a stamping die needs to be customized for each frame product, resulting in high costs and the problem of stamping burrs.

[0047] For example, the conventional etching process is as follows:

[0048] 1. Press the photoresist tightly on both sides of the copper material;

[0049] 2. Expose and develop the photoresist to transfer the designed pattern onto the photoresist by exposure. Under the irradiation of ultraviolet light, the black part of the light irradiation is not transmissive, and part of the photoresist does not react with the ultraviolet light;

[0050] 3. Use the developer to clean the unexposed photoresist, leaving the part that has undergone the optical reaction and exposing the copper material to be etched;

[0051] 4. Etch the exposed copper material with the etching solution;

[0052] 5. Use the stripping agent to remove the photoresist film covering the copper material to obtain the bare copper material;

[0053] 6. Electroplate the metal on the specific area.

[0054] Using the above etching process, the process is complex, the production requirements are high, the production cycle is long, and the quantity produced at one time is small. However, in the present application, the new preparation method adopted tries to use a reasonable method to encapsulate, cut, and grind the materials, greatly shortening the process of frame manufacturing. And several frames can be produced after each encapsulation, resulting in a great improvement in efficiency.

[0055] At the same time, aiming at the problems brought by the stamping process, the encapsulation mold and cutting mold of the present invention can be mutually universal, and only the upper and lower positioning molds during encapsulation need to be customized, greatly reducing the production and manufacturing cycle and cost of the molds.

[0056] In addition, for traditional WB wire bonding frame products, connection bars need to be designed between the pins and heat sinks during design, and connection bars and connecting ribs are also required for the inner extension of the FC flip-chip frame. These connection bars and connecting ribs will occupy a large amount of space, resulting in a maximum of two rows of pins can be placed on the four sides of the WB wire bonding. That is to say, under the same package size, the number of pins that can be accommodated is less. However, the internal design of the present invention abandons the traditional frame connection structure, and more pins can be easily arranged by placing two more rows of metal profiles on the four sides, increasing the number of transmitted signals and improving the packaging quality. And when the frame is cut into individual ones during the subsequent packaging process, the copper material does not need to be cut, which can reduce the loss of the cutting tool. When performing the front silver plating process, since the whole frame is already a plane, there is no risk of copper leakage to the back, which can improve the bonding force with the encapsulant during subsequent packaging.

[0057] To solve a series of problems brought by the existing process, the present invention provides a new method for preparing a lead frame, a mold, and a lead frame. It should be noted that, without conflict, the features in the embodiments of the present invention can be combined with each other. Specific embodiments

[0059] See Figure 1 , this embodiment provides a method for manufacturing a lead frame for manufacturing the lead frame 100 ( Figure 7 shown). Compared with the conventional method, the process steps are simple and reliable, the production cycle is short, the cost is low, and there is no pollution.

[0060] Combined with Figure 7 , the lead frame 100 provided in this embodiment includes a chip bonding area 110 located in the middle area and a pin welding area 130 located around the chip bonding area 110. Both the chip bonding area 110 and the pin welding area 130 are made of metal materials, and the remaining positions are made of non-metal materials such as resin.

[0061] The method for manufacturing the lead frame provided in this embodiment specifically includes the following steps:

[0062] S1: Install a plurality of metal profiles 300 on the lower mold 200b.

[0063] Combined with reference to Figure 2 and Figure 3 , specifically, wherein the plurality of metal profiles 300 extend upward to form a metal core frame, and the tops of the metal core frame are kept flush. Among them, the lower mold 200b can be customized according to the shapes and quantities of the chip bonding area 110 and the pin welding area 130 on the lead frame 100 to be manufactured. For example, in this embodiment, the lower mold 200b is provided with positioning holes 210 for fixing a plurality of metal profiles 300. When actually performing step S1, the plurality of metal profiles 300 are installed in the positioning holes 210 of the lower mold 200b.

[0064] In the actual implementation process, before performing step S1, the upper mold 200a ( Figure 4 shown) and the lower mold 200b can be selected or manufactured first according to the lead frame 100 to be manufactured. Both the upper mold 200a and the lower mold 200b are provided with positioning holes 210 for fixing a plurality of metal profiles 300, and the structural shapes of the upper mold 200a and the lower mold 200b are the same.

[0065] It should be noted that in this embodiment, the multiple metal profiles 300 include metal columns 310 and multiple metal rods 330. When installing the multiple metal profiles 300 on the lower mold 200b, first install the metal column 310 on the lower mold 200b, and then install the multiple metal rods 330 arranged around the metal column 310 on the lower mold 200b. Among them, columnar positioning holes for installing the metal column 310 and rod-shaped positioning holes for installing the metal rod 330 are provided on the lower mold 200b. Moreover, since multiple metal rods 330 are used for installation, more metal rods 330 can be formed around the metal column 310, increasing the number of pin welding areas 130, enabling the lead frame 100 to transmit more signals.

[0066] In this embodiment, the metal column 310 is in the shape of a rectangular block, and the multiple metal rods 330 are arranged around the metal column 310. Preferably, the metal column 310 is a copper column and the metal rod 330 is a copper rod. Using copper to form the metal core frame has good electrical connection performance. Of course, other conductive metal materials such as aluminum or gold can also be used for the metal rod 330 and the metal column 310 here.

[0067] S2: Install the upper mold 200a on the top of the metal core frame.

[0068] Combined with reference to Figure 4 , specifically, by setting the upper mold 200a, the metal core frame is fixed between the lower mold 200b and the upper mold 200a. The two ends of the metal column 310 and the multiple metal rods 330 are respectively correspondingly adapted to the positioning holes 210 of the upper mold 200a and the lower mold 200b, thereby realizing the fixation of the metal column 310 and the multiple metal rods 330.

[0069] It should be noted that in this embodiment, the upper mold 200a and the lower mold 200b are arranged opposite to each other and parallel, and the shapes of the upper mold 200a and the lower mold 200b are the same here, improving their versatility.

[0070] S3: Mold a molding compound 400 between the lower mold 200b and the upper mold 200a.

[0071] Combined with reference to Figure 5 , specifically, in actual molding, a molding die can be used. The molding die includes at least multiple molding templates. When actually performing step S3, multiple molding templates can be set between the upper mold 200a and the lower mold 200b to form an inner cavity between the upper mold 200a and the lower mold 200b, and then molding compound is injected into the inner cavity. Finally, the molding templates are removed after the molding compound is cured. The molding compound 400 can be in the shape of a rectangular column and cover both the metal column 310 and the multiple metal rods 330. Preferably, the size of the molding compound 400 is adapted to the sizes of the upper mold 200a and the lower mold 200b.

[0072] After forming the plastic package 400, it is also necessary to remove the upper mold 200a and the lower mold 200b so that the upper mold 200a and the lower mold 200b can be reused.

[0073] S4: Perform spaced cutting on the plastic package 400 along a direction perpendicular to the extension direction of the metal profile 300.

[0074] Refer to Figure 6 , specifically, through the spaced cutting process, a plurality of substrate frames can be obtained, and each substrate frame is in a sheet shape.

[0075] After the cutting is completed, since the substrate frames at the top and bottom are close to the upper mold 200a and the lower mold 200b, their uniformity cannot be guaranteed. Therefore, it is necessary to remove the substrate frames at the top and the substrate frames at the bottom, and continue the subsequent process with the substrate frames in the middle part.

[0076] S5: Grind the substrate frame to a preset thickness.

[0077] Specifically, using the grinding process, grind the substrate frame to a preset thickness. During actual grinding, grinding can be performed simultaneously from the upper and lower sides of the substrate frame to ensure that both sides are in a smooth state.

[0078] S6: Perform plating treatment on a plurality of substrate frames.

[0079] Refer to Figure 7 , specifically, after grinding the substrate frame to a preset thickness, perform silver plating on one surface of the substrate frame. After silver plating, the lead frame 100 is obtained. The plating treatment can be achieved by electroplating or electroless plating, and the specific process of the plating treatment is not limited herein. Of course, the plating layer can also be changed according to actual situations, such as gold plating or zinc plating, etc., which is not specifically limited herein.

[0080] During actual silver plating, for example, on the front surface of the substrate frame, the cut surfaces of a plurality of metal rods 330 and the cut edges of the metal posts 310 can be silver plated, so that only the copper layer is exposed at the center position of the metal posts 310 on the front surface of the substrate frame, and at the same time, the back surface of the substrate frame is not silver plated, and the standard lead frame 100 is obtained.

[0081] In this embodiment, since silver plating is performed on the front surface of the substrate frame, and at this time the substrate frame is already a complete planar structure, there is no risk of silver leaking to the back surface, and silver plating can improve the bonding force between the lead frame 100 and the plastic encapsulant during subsequent encapsulation, improving the reliability.

[0082] It should be noted that the above steps are only operations performed by a single upper mold 200a and a single lower mold 200b. During actual production, multiple lower molds 200b and multiple upper molds 200a can be set up simultaneously to prepare the encapsulation body 400 at the same time, and perform cutting operations on multiple encapsulation bodies 400 at the same time, doubling the preparation efficiency of the lead frame 100, obtaining multiple lead frames 100 in a plate shape to form a frame plate structure, and finally performing a cutting operation on the frame plate structure to obtain a single lead frame 100.

[0083] In this embodiment, since the process of encapsulating after installing the metal rod 330 and the metal column 310 is adopted, there is no copper layer connection between adjacent two lead frames 100 on the finally formed frame plate structure. Therefore, the copper layer will not be cut during cutting, undoubtedly improving the service life of the cutting mold.

[0084] This embodiment also provides a lead frame preparation mold applicable to the foregoing lead frame preparation method. The lead frame preparation mold includes a lower mold 200b, an upper mold 200a, an encapsulation mold (not shown in the figure), and a cutting mold (not shown in the figure). Among them, the lower mold 200b is used to install a metal core frame formed by a plurality of upwardly extending metal profiles 300, and the upper mold 200a is used to be installed at the top of the metal core frame so that the metal core frame is fixed between the lower mold 200b and the upper mold 200a. And a plurality of positioning holes 210 are opened on the upper mold 200a and the lower mold 200b. The plurality of positioning holes 210 are adapted to the metal profiles 300 and can realize the fixing action of the metal profiles 300. The encapsulation mold is used to be arranged between the upper mold 200a and the lower mold 200b and jointly form an inner cavity for injecting encapsulation material with the upper mold 200a and the lower mold 200b. The cutting mold is used to cut the encapsulation body 400 formed between the upper mold 200a and the lower mold 200b at intervals along the direction perpendicular to the extension direction of the metal profiles 300 to obtain a plurality of substrate frames.

[0085] In this embodiment, only the upper mold 200a and the lower mold 200b are directly adapted to the shape and specifications of the lead frame 100. No matter what specifications of the lead frame 100 are prepared, the encapsulation mold and the cutting mold can be universal. Only the upper mold 200a and the lower mold 200b need to be customized, which undoubtedly greatly reduces the mold production and manufacturing cycle and cost.

[0086] Please continue to refer to Figure 7, this embodiment also provides a lead frame 100, which includes a chip bonding area 110 located in the middle region and a pin soldering area 130 located around the chip bonding area 110. Both the chip bonding area 110 and the pin soldering area 130 are made of metal materials, and the remaining positions are made of non-metal materials such as resin. Both the chip bonding area 110 and the pin soldering area 130 are copper layers, and a plating layer is provided on one side surface thereof. The plating layer is silver, which can improve the bonding force between the lead frame 100 and the encapsulant during subsequent encapsulation and improve the reliability.

[0087] For the lead frame 100 provided in this embodiment, since there is no need to design a connecting rod structure, multiple pin soldering areas 130 can be directly formed by arranging multiple metal rods 330. Undoubtedly, the number of pin soldering areas 130 is increased, so that more pins can be placed under the same size, the number of transmitted signals is increased, and the performance of the final product is improved.

[0088] This embodiment provides a method for manufacturing a lead frame, a mold and a lead frame 100. The metal core frame formed by multiple metal profiles 300 is fixed by an upper mold 200a and a lower mold 200b, and then an encapsulant 400 is formed between the upper mold 200a and the lower mold 200b. The encapsulant 400 is transversely sliced to obtain multiple substrate frames, and finally the substrate frames are plated to obtain multiple lead frames 100. This embodiment avoids the use of etching process and stamping process, but uses the encapsulant to encapsulate the metal profiles 300 according to the arrangement to make the frame, thus avoiding the process problems brought by the etching process and stamping process, and a large number of physical processing methods are adopted, which improves the manufacturing efficiency of the lead frame 100. And the metal layer for arranging pins on the lead frame 100 can be directly determined according to the metal profiles 300, and more pins can be arranged under the same package size, thereby improving the packaging performance.

[0089] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for manufacturing a lead frame, characterized in that, Comprising: Install a plurality of metal profiles in the positioning holes of the lower mold, wherein the plurality of metal profiles extend upward to form a metal core framework; Install an upper mold at the top of the metal core framework to fix the metal core framework between the lower mold and the upper mold; Encapsulate between the lower mold and the upper mold to form an encapsulation body; Perform spaced cutting on the encapsulation body along a direction perpendicular to the extension direction of the metal profile to obtain a plurality of substrate frameworks; Perform plating treatment on the plurality of substrate frameworks to obtain a plurality of lead frames; Wherein, positioning holes for fixing the metal profiles are formed on the lower mold and the upper mold, and the shape of the positioning holes is adapted to the shape of the metal profiles; The step of encapsulating between the lower mold and the upper mold to form an encapsulation body includes: Arrange a plurality of encapsulation templates between the upper mold and the lower mold to form an inner cavity between the upper mold and the lower mold; Inject encapsulation material into the inner cavity; Remove the encapsulation templates after the encapsulation material is cured.

2. The method for manufacturing a lead frame according to claim 1, wherein Before the step of performing plating treatment on the plurality of substrate frameworks, the method further includes: Grind the substrate frameworks to a preset thickness.

3. The method for preparing a lead frame according to claim 1, wherein The step of performing plating treatment on the plurality of substrate frameworks includes: Perform silver plating on one side surface of the substrate frameworks.

4. The method for manufacturing a lead frame according to claim 1, wherein the plurality of metal profiles include metal columns and a plurality of metal rods, characterized in that, The step of installing a plurality of metal profiles on the lower mold includes: Install metal posts on the lower mold; Install a plurality of metal rods surrounding the metal posts on the lower mold; Wherein, column-shaped positioning holes for installing the metal posts and rod-shaped positioning holes for installing the metal rods are formed on the lower mold.

5. The method for manufacturing a lead frame according to claim 4, wherein, The metal posts are copper posts, and the metal rods are copper rods.

6. The method for manufacturing a lead frame according to claim 1, characterized in that, After the step of encapsulating between the lower mold and the upper mold to form an encapsulation body, the method further includes: Remove the upper mold and the lower mold.

7. The method for manufacturing a lead frame according to claim 1, wherein After the step of performing spaced cutting on the encapsulation body along a direction perpendicular to the extension direction of the metal profile, the method further includes: Remove the substrate frameworks at the top and the substrate frameworks at the bottom.

8. A lead frame manufacturing die, applicable to the lead frame manufacturing method described in any one of claims 1-7, characterized in that, The lead frame preparation mold includes: A lower mold for installing a metal core framework formed by a plurality of upward-extending metal profiles; An upper mold for installing at the top of the metal core framework to fix the metal core framework between the lower mold and the upper mold; An encapsulation mold for being arranged between the upper mold and the lower mold and jointly forming an inner cavity for injecting encapsulation material with the upper mold and the lower mold; A cutting mold for performing spaced cutting on the encapsulation body formed by the encapsulation material between the upper mold and the lower mold along a direction perpendicular to the extension direction of the metal profile to obtain a plurality of substrate frameworks.

9. A lead frame, characterized in that, It is prepared by the lead frame preparation method according to any one of claims 1-7.

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