High-precision semiconductor base assembly and preparation method thereof

Abstract

The present invention discloses a base assembly for high-precision semiconductors and a preparation method thereof, comprising a plastic base, wherein the plastic base is embedded with a lead frame, a plurality of PIN pins are vertically arranged on the lead frame, and a plurality of welding parts are provided on the plastic base; the preparation method comprises: punching a substrate into required circuits; making a lead frame; injection molding to form the plastic base; dividing the injection-molded workpiece into single pieces; implanting an IC chip to form a semiconductor injection-molded part; the invention forms the plastic base by a one-time injection molding method, reserves a fitting site for the IC chip, and then implants the chip. When the product base is unqualified, the chip will not be damaged. Compared with the existing process, the qualified rate of the product is guaranteed, and the finished product rate can reach 98%, which greatly increases the yield rate.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor packaging, and in particular to a base assembly for a high-precision semiconductor and a preparation method thereof. Background Art

[0002] Existing voice coil motors typically include a base, a metal circuit embedded within the base, a lower reed electrically connected to the metal circuit, a coil, and a magnetic structure that interacts with the coil. With the increasing demand for miniaturization of electronic devices, the structure of miniature digital cameras has become increasingly smaller, placing increasing demands on the stability and reliability of voice coil motors. Conventional technology often uses a substrate as the base, embeds the chip, coil, etc. into the base, and then packages them through secondary injection molding. This is inefficient, and assembly of thin-film reeds is particularly difficult. For example, patent application CN105676407B discloses a lens drive device comprising a lower reed, with reed baffles disposed on the four edges of the base. The lower reed is clamped into the base via the baffles. However, the clamping method for securing the reed is prone to failure.

[0003] Because the reed is extremely fragile and easily damaged, it will increase the cost for parts manufacturers or camera manufacturers. In addition, due to the special characteristics of its thin structure, its fixing structure is also difficult to design. Simple fixing can easily cause the reed to fall off during use, causing the voice coil motor to fail, thus affecting the quality and service life of the camera assembly.

[0004] Another example is the invention patent application shown in the publication number CN112799260A, which discloses a lens drive mechanism, including an upper spring, and a plurality of frame mounting holes are provided on the outer ring of the upper spring, and the frame mounting holes are fixedly connected to the upper spring positioning column. Usually, the spring fixed by this fixing method needs to be fixed by melting the fixing column and fixing by gluing for subsequent fixing. However, first of all, because the positioning of the column holes at the four corners is difficult and auxiliary processes are required for reinforcement after positioning, the operation process and cost are increased. Moreover, even if multiple auxiliary processes are added, the fixed structure is still too fragile, and it is still impossible to avoid the spring from falling off relative to the plastic body during use. Finally, when the column hole matching fixing method is adopted, the welding of the fixed spring and the metal circuit injected into the plastic body is generally suitable for laser welding to achieve electrical conductivity. The laser welding area is small, and the glue point method is used for secondary reinforcement after welding. However, the welding structure of the laser welding method still has the problem of low strength, and whether it is welding or glue point, the operation in the plastic body also has operational limitations.

[0005] For example, the voice coil motor disclosed in publication number CN111555536A includes an upper reed and a lower reed. A positioning post is provided on the base. When installing the lower reed, a fixing post for the lower reed must be provided on one side of the positioning post and welded to the lower reed. This fixing method requires a space outside the fixing post for securing and welding the reed when the base is formed. This fixing and welding method is also not conducive to the miniaturization of the voice coil motor.

[0006] The existing method for preparing high-precision semiconductor injection molding devices uses a strip pulling method for injection molding, such as the patent publication number: CN 112738995 A, a base with a metal circuit, its production process and voice coil motor, and CN112737272 A disclosed substrate with electronic components welded thereto, its production process, and voice coil motor, has a complex process and low efficiency due to multiple injection molding operations. When the strip passes through a hot melt furnace for IC implantation, the strip is heated unevenly in some areas, causing deformation. This deformation of the strip can affect the flatness of the final product by more than 5 degrees, resulting in a high error rate in subsequent processing. Therefore, the existing technology often uses two injection molding processes. That is, after the first injection molding, the chip is attached, and then injection molding is performed again after exiting the hot melt furnace until the required injection thickness is reached. This reduces the thickness of the injection molded part entering the hot melt furnace and the deformation, thereby solving the above problems. However, the error rate of the injection molded parts themselves is high, with an error of about 5%. Therefore, after the two injection molding processes and chip attachment, there is an error rate of 2%-5%, and the overall production line error rate is about 15%, resulting in a low yield rate. In addition, due to the continuous feeding of the strip material, if a problem occurs in the first injection molding before chip attachment, it is impossible to remove the defective parts, and the chips will still be attached, resulting in chip waste and significantly increased costs. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the present invention proposes a base assembly for high-precision semiconductors, comprising a plastic base, wherein a lead frame is embedded in the plastic base, and the lead frame includes a support platform, and the support platform is provided with an outer frame around it, and the outer frame is integrally formed with the support platform through a connecting part; a plurality of welding parts are provided on the plastic base, and the welding parts are used for subsequent assembly and connection; a plurality of placement grooves are provided on the plastic base, and PAD points are provided in the placement grooves, and grooves are provided on the plastic base between the PAD points, and a plurality of floating material pinholes are provided on the plastic base.

[0008] Preferably, the welding portion includes a plurality of connecting grooves provided on the plastic base, a soldering platform is provided on one side of the connecting groove, and some of the soldering platforms are inlaid with soldering pieces.

[0009] Preferably, a plurality of PIN pins are vertically arranged on the outer frame of the lead frame, the PAD point and the outer frame of the lead frame are integrally formed, and the PIN pins protrude from the plastic base.

[0010] Preferably, a plurality of mark points are provided on the plastic base.

[0011] The present invention proposes a method for preparing a high-precision semiconductor injection molding device, comprising:

[0012] S1: providing a base material strip and punching the base material into a required lead frame, wherein the lead frame includes a PAD point;

[0013] S2: Bend the corners of the lead frame to form PIN pins, and use a spot plating wheel to electroplate the PIN pins.

[0014] S3: making the lead frame into a tape roll;

[0015] S4: Pull the material strip to feed the lead frame into the injection mold, and then perform injection molding to form a plastic base. After the injection molding is completed, the PIN pins are exposed from the plastic base. The plastic base covers the outer frame of the lead frame and reserves IC patch points and lead points. The support platform and the connection part of the lead frame support the plastic base;

[0016] S5: cutting the PIN pins and the plastic base, dividing the injection-molded workpiece into individual cut pieces to form a base assembly, and rotating the individual base assemblies;

[0017] S6: Chip implantation: Place the rotating tray into a hot melting furnace, implant the IC chip by soldering and melting the solder paste, seal the bonded IC chip with glue, bond the coil on the glue seal, and perform curing and drying to form a semiconductor injection molded part;

[0018] S7: inspecting the semiconductor injection molded part.

[0019] Preferably, when the plastic base is injected S4, the IC patch points and lead points are pressed tightly by inserts, thereby reserving the IC patch points and lead points during molding.

[0020] Preferably, the turnover method in S5 is to place the base assembly into the Tray, inspect and confirm that the appearance is correct, and then place the qualified base assembly into the turnover tray.

[0021] Preferably, the peripheral transfer plate is made of aluminum alloy, and is provided with a plurality of groups of contoured grooves, and the contoured grooves have the same shape as the bottom surface of the base assembly.

[0022] Preferably, during the cutting step S5 , part of the PIN pins are cut off so that the PIN pins are exposed from the plastic base, and the connecting portion is cut off at the same time.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention forms a plastic base through one-time injection molding, reserves a fitting site for the IC chip, and then implants the chip. When the product base processing is unqualified, the chip, coil and other parts will not be damaged. Compared with the existing two-time injection molding and string operation process, the chip implantation process is after injection molding, and the injection molding yield has no effect on the overall yield. Moreover, there is no need for string operation, which improves the utilization efficiency of the machine, shortens the process flow, simplifies the process, ensures the qualified rate of the product, and the finished product rate can reach 98%, which greatly increases the yield.

[0025] 2. In the present invention, in order to avoid deformation of the lead frame during injection molding, a support platform is provided at the center of the lead frame. This arrangement is more conducive to protecting the lead frame and making it less likely to deform, while saving the use of plastic. After the injection molding is completed, the support platform is removed.

[0026] 3. In the present invention, grooves are provided between each PAD point, thereby solving the problem of overflow of solder paste at the bottom when the IC chip is soldered. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments.

[0028] Figure 1 It is a schematic diagram of the process of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of the plastic base of the present invention;

[0030] Figure 3 for Figure 2 Enlarged view of point A in the middle;

[0031] Figure 4 This is a schematic diagram of the lead frame structure of the present invention;

[0032] Among them, 1. Plastic base; 101. PIN foot; 102. Storage groove; 103. PAD point; 104. Groove; 2. Lead frame; 201. Support platform; 202. Outer frame; 203. Connection part; 3. Welding part; 301. Connection groove; 302. Soldering station. DETAILED DESCRIPTION

[0033] In view of the shortcomings of the prior art, the present invention proposes a high-precision semiconductor base assembly, such as Figure 2As shown, it includes a plastic base 1, wherein the plastic base 1 is embedded with a lead frame 2, as shown in FIG. Figure 4 As shown, the lead frame 2 is vertically provided with a plurality of PIN pins 101 and PAD points 103. The PAD points 103 serve as a soldering platform for the IC chip. The PIN pins 101 protrude from the plastic base 1. The lead frame 2 is a required circuit frame arranged according to the product requirements and is not limited to a fixed shape. Its function is to conduct circuits with the IC chip.

[0034] like Figure 3 As shown, the plastic base 1 is provided with a plurality of welding parts 3, and the welding parts 3 include a plurality of connecting grooves 301 provided on the plastic base 1. A soldering platform 302 is provided on one side of the connecting groove 301, and some soldering platforms 302 are inlaid with soldering pieces. In this embodiment, the plastic base 1 is a square structure with a through hole provided in the center, and a group of welding parts 3 are provided at the four corners of the plastic base 1.

[0035] The plastic base 1 is provided with a plurality of placement grooves 102, the PAD points 103 are located in the placement grooves 102, and the plastic base 1 is provided with grooves 104 between the PAD points 103. The grooves 104 are used to prevent the solder paste at each PAD point 103 from overflowing and mixing when tinning. The plastic base 1 is provided with a plurality of floating pinholes and MARK points. The floating pinholes are used to press the lead frame 2 to prevent the lead frame 2 from shifting during injection molding. The MARK points are used for image recognition and positioning, and then the base component quality is detected by an industrial camera. In this embodiment, In the embodiment, four groups of storage grooves 102 are provided on the plastic base 1, and four groups of PAD points 103 are provided in each group of storage grooves 102. The lead frame 2 includes a support platform 201, and the support platform 201 is surrounded by an outer frame 202. The outer frame 202 is integrally formed with the support platform 201 through a connecting portion 203. The lead frame 2 can be changed according to processing requirements, but all lead frames 2 have a support platform 201, a connecting portion 203, an outer frame 202 and a PAD point 103 connected to the outer frame 202.

[0036] In view of the shortcomings of the prior art, the present invention proposes a method for preparing a high-precision semiconductor injection molding device. Figure 1 ,include

[0037] S1: Provide a base material strip, and punch the base material into the required lead frame 2, wherein the lead frame 2 includes a PAD point 103; as an embodiment: provide a copper base material coil, and use high-speed stamping and bending forming equipment to punch the copper base material into a lead frame 2, wherein the lead frame 2 includes the required circuit, a support platform 201, an outer frame 202 and a PAD point 103, the support platform 201 is circular, and a plurality of connecting parts 203 are arranged around the support platform 201, and the other end of the connecting part 203 is connected to the outer frame 202, and the support platform 201 is connected to the outer frame 202 through the connecting part 203, and these structures are on the same horizontal plane, and the support platform 201 is provided with evenly distributed fixing holes, and the support platform 201 is used to fix the outer frame 202 through the connecting part 203 during injection molding.

[0038] S2: Bend the corners of the lead frame 2 to form PIN pins 101, and use a spot plating wheel to electroplate the PIN pins 101. As a preferred embodiment, Ni / Au / Ag is used as the plating material during the electroplating.

[0039] As an embodiment, bending processing is performed on both sides of the outer frame to form PIN pins 101 that are perpendicular and protrude from the outer frame.

[0040] S3: making the lead frame 2 into a material strip roll;

[0041] S4: Pull the material strip to feed the lead frame 2 into the injection mold, and then perform injection molding to form a plastic base 1. In the injection molding machine, the engineering modified plastic is liquefied by heating, and then injection molding is performed. The plastic base 1 covers part of the outer frame, thereby being positioned on the outer frame and molded on the outer frame. The support platform 201 is placed in the through hole of the plastic base 1, and the plane where it is located is lower than the top surface of the plastic base 1 and the support platform 201 is not wrapped by the plastic. When the plastic wraps the part of the outer frame, the outer frame 202 is subjected to force, which often causes the outer frame 202 to deform. The support platform 201 supports the outer frame 202 through the connecting portion 203 when the outer frame 202 is about to deform, shares the force on the outer frame 202, and prevents the outer frame 202 from deforming;

[0042] After the injection molding is completed, the PIN pin 101 exposes the plastic base 1, and the plastic base 1 covers the outer frame of the lead frame 2 and is pressed against the IC patch point and the lead point through the insert, thereby reserving the IC patch point and the lead point during molding; as an embodiment: the shape inside the injection mold is triangular grooves are provided at the four corners, and the triangular grooves are used to cooperate with the subsequent assembly process to complete the embedded assembly, and the clockwise side of each groove has a soldering station higher than the bottom surface plane, and the soldering station is used to cooperate with the assembly process to complete the connection between components, and some soldering stations are inlaid with soldering pieces, and there is a rectangular groove on the counterclockwise side of the soldering station without soldering pieces, and the rectangular grooves are evenly arranged There are four PAD points 103, which serve as welding platforms for IC chips. Grooves 104 are provided between the PAD points 103. A number of floating pinholes are provided on the plastic base 1. The floating pinholes are formed by fixing the lead frame 2 with floating pins in the mold during injection molding, and are used to prevent the lead frame 2 from shifting during injection molding. A number of MARK points are provided on the plastic base 1, and the MARK points are used for image recognition and positioning, and then the product quality is detected by an industrial camera. The rectangular groove is used as an IC chip patch. Grooves 104 are provided between the four PAD points 103 to prevent the solder paste at each PAD point 103 from overflowing and mixing during tinning.

[0043] S5: Cut the PIN pin 101 and the support platform 201, and at the same time divide the continuous base assembly that has been injection molded into single base assemblies. Cutting the PIN pin 101 refers to cutting the exposed part of the PIN pin 101 to equal length. Cutting the support platform 201 refers to punching the connection part 203, cutting off the connection part 203, and then causing the support platform 201 to fall. Place the cut single base assembly into the Tray. Place the base assembly into the Tray before implanting the IC chip. After the appearance is inspected by manual observation or an industrial camera and is qualified, place the qualified base assembly into the peripheral transfer tray. As an embodiment, an automatic material picker can be used to place the single product in the Tray into the peripheral transfer tray.

[0044] The circumferential transfer plate is made of aluminum alloy and is provided with a plurality of groups of contoured grooves. The contoured grooves have the same shape as the base assembly. When the base assembly is in the contoured grooves, it is completely fitted with the contoured grooves.

[0045] The present application uses one-time injection molding. After injection molding, the base is placed in a peripheral transfer plate, and then placed in a hot melting furnace for IC chip implantation. The base assembly is supported by the contoured groove in the peripheral transfer plate. The peripheral transfer plate is made of aluminum alloy and fits perfectly with the bottom surface of the injection molded part. The heat contact is extremely uniform, and the hot melting furnace is equipped with a constant temperature system to ensure further stable heat distribution. Due to the design of the contoured groove, the deformation of the base assembly after heating is reduced, and the deformation can be reduced to less than 3 wires, solving the problem of deformation in the hot melting furnace. Therefore, only a single injection molding is required and a position for the chip is reserved. The error rate of one injection molding is much lower than the probability of two injection moldings. The unqualified rate of each injection molding process is often around 5%. Combined with the IC chip The rejection rate during chip implantation is often around 2%-3%, and the traditional pulling belt processing is a continuous operation, and the damaged base cannot be removed. Therefore, the qualification rate of traditional processing is around 85%. After the improvement, the qualified base is placed in the rotating tray for implantation after the single product is inspected and removed from the tray during IC chip implantation. Therefore, the yield rate can reach around 98%. At the same time, since the deformation of the product during injection molding in traditional processing will also cause the IC chip to be scrapped, the improvement can greatly reduce the scrap volume of IC chips, and the cost of IC chips is relatively high, so the processing cost is greatly reduced. At the same time, since there is no need to use the stringing method of pulling belt, the maximum production capacity of each machine can be brought into play, which increases work efficiency.

[0046] S6: Place the IC chip in the base assembly, implant the IC chip by soldering and melting the tin patch, seal the bonded IC chip with glue, and bond the coil on the IC chip glue package, and finally cure and dry it to form a semiconductor device.

[0047] As an embodiment, an automated production line is used to place the carrier into a machine, and solder is applied to the PAD points 103 on the bottom surface of the plastic base 1. The solder paste is inspected on the same machine. Then, an IC chip is implanted in the rectangular groove, and a coil is attached. The coil is a magnetic field induction wire that can form a stable magnetic field to meet the use requirements. The coil completely covers the bottom surface of the plastic base 1. A visual inspection is then performed. After the inspection, reflow soldering is performed, and the IC chip is encapsulated with glue. Finally, the process is cured and dried.

[0048] S7: Detecting the semiconductor device.

Claims

1. A method for preparing a high-precision semiconductor injection molding device, wherein a base assembly comprises a plastic base (1), wherein a lead frame (2) is embedded in the plastic base (1), wherein the lead frame (2) comprises a support platform (201), wherein an outer frame (202) is provided around the support platform (201), and the outer frame (202) is integrally formed with the support platform (201) via a connecting portion (203); the support platform (201) is not wrapped by plastic, and when the outer frame (202) is about to be deformed, the support platform (201) supports the outer frame (202) via the connecting portion (203), shares the force of the outer frame (202), prevents the outer frame (202) from being deformed, cuts off the connecting portion (203), and thereby causes the support platform (201) to fall; The plastic base (1) is provided with a plurality of welding portions (3), and the welding portions (3) are used for subsequent assembly and connection; The plastic base (1) is provided with a plurality of placement grooves (102), the placement grooves (102) are provided with PAD points (103), the plastic base (1) between the PAD points (103) is provided with grooves (104), and the plastic base (1) is provided with a plurality of floating material pinholes, characterized in that: The preparation method comprises: S1: providing a base material strip and punching the base material into a required lead frame, wherein the lead frame includes a PAD point; S2: bend the edge corners of the lead frame to form PIN pins, and use a spot plating wheel to electroplate the PIN pins; S3: making the lead frame into a material strip roll; S4: Pulling the material strip to feed the lead frame into the injection mold, and then performing a single injection molding to form a plastic base. After the injection molding is completed, the PIN pins are exposed from the plastic base. The plastic base covers the outer frame of the lead frame and reserves IC patch points and lead points. The support platform and the connection part of the lead frame support the plastic base; S5: cutting the PIN pins and the plastic base, dividing the injection-molded workpiece into individual cut pieces to form a base assembly, and transferring the individual base assemblies to a turnover tray; S6: Chip implantation: Place the rotating tray into a hot melt furnace, implant the IC chip by soldering and melting the solder paste, seal the bonded IC chip with glue, bond the coil on the glue seal, and perform curing and drying to form a semiconductor injection molded part; S7: Detecting the semiconductor injection molded part.

2. The method for preparing a high-precision semiconductor injection molded device according to claim 1, wherein: The welding portion (3) comprises a plurality of connecting grooves (301) provided on the plastic base (1), a welding platform (302) is provided on one side of the connecting groove (301), and welding pieces are embedded on some of the welding platforms (302).

3. The method for preparing a high-precision semiconductor injection molded device according to claim 1, wherein: A plurality of PIN pins (101) are vertically arranged on the outer frame (202) of the lead frame (2), the PAD point (103) and the outer frame (202) of the lead frame (2) are integrally formed, and the PIN pins (101) protrude from the plastic base (1).

4. The method for preparing a high-precision semiconductor injection molded device according to claim 1, wherein: Several mark points are provided on the plastic base (1).

5. The method for preparing a high-precision semiconductor injection molded device according to claim 1, wherein: When the plastic base is injected S4, the IC patch points and lead points are pressed tightly by the inserts, thereby reserving the IC patch points and lead points during molding.

6. The method for preparing a high-precision semiconductor injection molded device according to claim 1, wherein: The turnover method in S5 is to place the base assembly into the tray, inspect and confirm that the appearance is correct, and then place the qualified base assembly into the turnover tray.

7. The method for preparing a high-precision semiconductor injection molded device according to claim 1, wherein: The circumferential transfer plate is made of aluminum alloy and is provided with a plurality of groups of contoured grooves, and the contoured grooves have the same shape as the bottom surface of the base assembly.

8. The method for preparing a high-precision semiconductor injection molded device according to claim 1, wherein: During the S5 cutting, a portion of the PIN pins is cut off so that the PIN pins are exposed from the plastic base, and the connecting portion is cut off at the same time.

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