Lead frame structure for enhancing plastic packaging binding force and manufacturing method thereof

Abstract

The invention provides a lead frame structure capable of enhancing plastic packaging binding force and a manufacturing method thereof, the lead frame structure comprises a plurality of lead frame units, each lead frame unit comprises a square base island and a plurality of pins arranged at the periphery of the base island, the base island is provided with a chip loading area used for loading a chip, and the chip loading area is provided with a plurality of pins arranged at the periphery of the base island. At least one side of the periphery of the chip loading area on the base island is provided with two adjacent grooves, the two adjacent grooves are separated by a connecting rib, the side wall of the connecting rib is provided with a through hole communicated with the two grooves, during packaging, a chip is adhered to the chip loading area and is connected with the pins through leads, and the chip loading area is provided with a plurality of through holes communicated with the two grooves. A plastic packaging material covers the base island, wraps the chip, is poured into the two grooves, and fills the through holes of the connecting ribs. By adopting the lead frame structure provided by the invention, the plastic packaging binding force can be enhanced, and the packaging reliability can be improved.

Description

Technical Field

[0001] The invention relates to the field of integrated circuit packaging, and in particular to a lead frame structure for enhancing plastic packaging bonding force and a manufacturing method thereof. Background Art

[0002] The lead frame of an integrated circuit is usually composed of multiple lead frame units. As shown in Figure 1 (a), each lead frame unit includes a base island and multiple pins, and its cross-sectional view is shown in Figure 1 (b). As shown in Figure 2 (a), when packaging an integrated circuit, the chip with the package is usually bonded and fixed on the base island of the lead frame, and then the chip and the pins are connected through internal leads. Finally, the lead frame unit is covered with plastic encapsulation material, and the pins are exposed. Its cross-sectional view is shown in Figure 2 (b).

[0003] As shown in FIG. 1 (b) and FIG. 2 (b), in the lead frame of the prior art, the base island is usually a complete plane, and the molding material and the base island are completely combined by the molecular attraction between the molding material and the base island. There may be insufficient bonding force, resulting in delamination problems between the molding material and the base island. Summary of the invention

[0004] The object of the present invention is to provide a lead frame structure with enhanced plastic packaging bonding force and a manufacturing method thereof.

[0005] In an embodiment of the present invention, a lead frame structure for enhancing the bonding force of plastic packaging is provided, which includes a plurality of lead frame units, each of which includes a square base island and a plurality of pins arranged on the periphery of the base island, the base island has a chip loading area for loading chips, and at least one side of the periphery of the chip loading area on the base island is provided with two adjacent grooves, the two adjacent grooves are separated by a connecting rib, and the side wall of the connecting rib is provided with a through hole connecting the two grooves. During packaging, the chip is bonded to the chip loading area and connected to the pins through leads, and the plastic packaging material covers the base island, encapsulates the chip and is poured into the two grooves, and fills the through hole of the connecting rib.

[0006] In the embodiment of the present invention, two adjacent grooves are arranged on each side around the periphery of the chip loading area on the base island.

[0007] In the embodiment of the present invention, the groove is in a rectangular shape.

[0008] In the embodiment of the present invention, the through hole is rectangular.

[0009] In the embodiment of the present invention, the bottom of the through hole is flush with the bottom of the groove.

[0010] In an embodiment of the present invention, a method for manufacturing the lead frame structure with enhanced plastic packaging bonding strength is also provided, which comprises: Step 1: attaching a mask on the surface of the lead frame plate, wherein the mask has a pattern corresponding to the groove; Step 2: Expose and develop to reveal the positions of two adjacent grooves on the surface of the plate that need to be etched, and cover the surface of the plate that does not need to be etched with a mask; Process 3: Etch the exposed surface of the plate to form two adjacent grooves, and then continue etching using the remaining solution in the two grooves to etch through the material below the middle connecting rib to form a through hole connecting the two grooves; Step 4: Remove the mask still attached to the surface of the plate after etching to obtain the final lead frame structure.

[0011] In an embodiment of the present invention, another method for manufacturing the lead frame structure with enhanced plastic packaging bonding strength is provided, which comprises: Step 1: attaching a mask on the surface of the lead frame plate, wherein the mask has a pattern corresponding to the groove; Step 2: Expose and develop to reveal the positions of two adjacent grooves on the surface of the plate that need to be etched, and cover the surface of the plate that does not need to be etched with a mask; Step 3: Etching the exposed surface of the plate to form two adjacent grooves, and then stopping etching; Step 4: removing the mask still attached to the surface of the plate after etching, and obtaining a lead frame with two grooves; Step 5: Paste a mask on the surface of the lead frame material obtained by the first etching; Step 6: Expose and develop the surface of the rib sidewall material that needs to be etched, and cover the surface of the plate that does not need to be etched with a mask; Step 7: etching away the exposed surface of the connecting rib side wall material to form a through hole connecting the two grooves; Step 8: Remove the mask still attached to the surface of the plate after etching to obtain the final lead frame structure.

[0012] Compared with the prior art, the lead frame structure for enhancing the plastic encapsulation bonding force of the present invention is adopted, at least one side of the periphery of the chip loading area on the base island is provided with two adjacent grooves, the two adjacent grooves are separated by a connecting rib, and the side wall of the connecting rib is provided with a through hole connecting the two grooves. During packaging, the chip is bonded to the chip loading area and connected to the pin through a lead wire, the plastic encapsulation material covers the base island, encapsulates the chip and is poured into the two grooves, and fills the through hole of the connecting rib, the plastic encapsulation material forms an interlocking state with the groove and the connecting rib structure, and the bonding force of the plastic encapsulation material and the base island is enhanced, so that it is not easy to delaminate from the base island; in addition, when the bonding material between the chip and the base island is glue, this design also increases the creeping distance of the glue and reduces the creeping distance of the glue on the chip, and at the same time increases the area on the base island where the wire can be welded, so as to avoid the glue overflowing from the base island and falling onto the back of the frame, the glue creeping too high onto the chip surface, and the problem of insufficient space for welding wires occurs, and at the same time, the product size can be designed to be smaller. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1( a ) is a schematic plan view of a lead frame structure in the prior art.

[0014] FIG. 1( b ) is a cross-sectional schematic diagram of a lead frame structure in the prior art.

[0015] FIG. 2( a ) is a plan view of a lead frame structure after packaging in the prior art.

[0016] FIG. 2( b ) is a cross-sectional schematic diagram of a lead frame structure after packaging in the prior art.

[0017] FIG. 3( a ) is a schematic plan view of a lead frame structure according to an embodiment of the present invention.

[0018] FIG3( b ) is a schematic cross-sectional view of a lead frame structure according to an embodiment of the present invention.

[0019] FIG. 4( a ) is a plan view of a lead frame structure after packaging according to an embodiment of the present invention.

[0020] FIG4( b ) is a schematic cross-sectional view of the lead frame structure after packaging according to an embodiment of the present invention.

[0021] Figure 5 It is a schematic diagram of a process of manufacturing a lead frame structure according to an embodiment of the present invention.

[0022] Figure 6 It is a schematic diagram of the second stage of another manufacturing process of the lead frame structure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] The implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0025] As shown in FIG. 3 (a) and FIG. 3 (b), in an embodiment of the present invention, a lead frame structure for enhancing the bonding force of plastic packaging is provided, which includes a plurality of lead frame units, each of which includes a base island and a plurality of pins arranged on the periphery of the base island. The base island is square, and has a chip loading area for loading chips on the base island. It should be noted that in the lead frame, the function of the base island is to load the chip, the area of ​​the base island is usually larger than the area of ​​the chip, and the chip is installed in the central area of ​​the base island. Therefore, the chip loading area is usually the central area of ​​the chip. Two adjacent grooves are provided on at least one side of the periphery of the chip loading area on the base island, and the two adjacent grooves are separated by a connecting rib, and the side wall of the connecting rib is provided with a through hole connecting the two grooves.

[0026] In an embodiment of the present invention, two adjacent grooves are arranged on each side of the periphery of the chip loading area on the base island. The shape of the groove is rectangular. The through hole is rectangular to facilitate manufacturing and molding. The bottom of the through hole is flush with the bottom of the groove. It should be noted that the number, position and shape of the grooves can also be adjusted according to actual needs, and the size of the through hole can also be set according to actual needs, and the present invention does not limit this.

[0027] As shown in FIG. 4 (a) and FIG. 4 (b), during packaging, the chip is bonded to the chip loading area and connected to the pins through leads. The plastic encapsulation material covers the base island, encapsulates the chip and is poured into the two grooves, and fills the through holes of the connecting ribs. The plastic encapsulation material, the grooves and the connecting rib structure form an interlocking state, which enhances the bonding strength between the plastic encapsulation material and the base island, making it difficult for the plastic encapsulation material to delaminate from the base island. In addition, when the bonding material between the chip and the base island is glue, this design can also allow excess glue to flow into the groove, increasing the glue creeping distance and reducing the glue creeping distance on the chip. At the same time, it increases the solderable wire area on the base island, avoiding the glue overflowing from the base island and falling onto the back of the frame, the glue creeping too high onto the chip surface, and the insufficient soldering wire space. At the same time, the product size can be designed to be smaller.

[0028] Furthermore, if Figure 5 As shown, in an embodiment of the present invention, a method for manufacturing the lead frame structure with enhanced plastic packaging bonding strength is also provided, which includes: Step 1: attaching a mask on the surface of the lead frame plate, wherein the mask has a pattern corresponding to the groove; Step 2: Expose and develop to reveal the positions of two adjacent grooves on the surface of the plate that need to be etched, and cover the surface of the plate that does not need to be etched with a mask; Process 3: Etch the exposed surface of the plate to form two adjacent grooves, and then continue etching using the remaining solution in the two grooves to etch through the material below the middle connecting rib to form a through hole connecting the two grooves; Step 4: Remove the mask still attached to the surface of the plate after etching to obtain the final lead frame structure.

[0029] The above-mentioned manufacturing method is used to make an embedded glue-locking structural frame that is etched and formed once. The requirement for the width of the connecting rib between two adjacent grooves is very high. If the width of the connecting rib is too wide, the material below cannot be etched through and a through hole cannot be formed. If the width of the connecting rib is too small, the connecting rib is easily etched away and two adjacent grooves cannot be formed.

[0030] To improve the above problems, Figure 6 As shown, in an embodiment of the present invention, another method for manufacturing the lead frame structure with enhanced plastic packaging bonding strength is provided, which includes: Step 1: attaching a mask on the surface of the lead frame plate, wherein the mask has a pattern corresponding to the groove; Step 2: Expose and develop to reveal the positions of two adjacent grooves on the surface of the plate that need to be etched, and cover the surface of the plate that does not need to be etched with a mask; Step 3: Etching the exposed surface of the plate to form two adjacent grooves, and then stopping etching; Step 4: removing the mask still attached to the surface of the plate after etching, and obtaining a lead frame with two grooves; Step 5: Paste a mask on the surface of the lead frame material obtained by the first etching; Step 6: Expose and develop the surface of the rib sidewall material that needs to be etched, and cover the surface of the plate that does not need to be etched with a mask; Step 7: etching away the exposed surface of the connecting rib side wall material to form a through hole connecting the two grooves; Step 8: Remove the mask still attached to the surface of the plate after etching to obtain the final lead frame structure.

[0031] In summary, the lead frame structure for enhancing the plastic encapsulation bonding force of the present invention is adopted, at least one side of the periphery of the chip loading area on the base island is provided with two adjacent grooves, the two adjacent grooves are separated by a connecting rib, and the side wall of the connecting rib is provided with a through hole connecting the two grooves. During packaging, the chip is bonded to the chip loading area and connected to the pin through a lead wire, and the plastic encapsulation material covers the base island, encapsulates the chip and is poured into the two grooves, and fills the through hole of the connecting rib. The plastic encapsulation material forms an interlocking state with the grooves and the connecting rib structure, thereby enhancing the bonding force between the plastic encapsulation material and the base island, making it difficult for the plastic encapsulation material and the base island to be delaminated. In addition, when the bonding material between the chip and the base island is glue, this design also increases the creeping distance of the glue and reduces the creeping distance of the glue on the chip, and at the same time increases the solderable wire area on the base island, thereby avoiding the occurrence of glue overflowing outside the base island and falling onto the back of the frame, glue creeping too high onto the chip surface, insufficient soldering wire space, and other problems, and at the same time, the product size can be designed to be smaller.

[0032] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A lead frame structure for enhancing plastic packaging bonding strength, characterized in that: It comprises a plurality of lead frame units, each of which comprises a square base island and a plurality of pins arranged on the periphery of the base island, the base island having a chip loading area for loading chips, at least one side of the periphery of the chip loading area on the base island being provided with two adjacent grooves, the two adjacent grooves being separated by a connecting rib, the side wall of the connecting rib being provided with a through hole connecting the two grooves, during packaging, the chip is bonded to the chip loading area and connected to the pins through leads, the plastic encapsulation material covers the base island, encapsulates the chip and is poured into the two grooves, and fills the through hole of the connecting rib.

2. The lead frame structure for enhancing plastic packaging bonding strength according to claim 1, characterized in that: Two adjacent grooves are arranged on each side around the periphery of the chip loading area on the base island.

3. The lead frame structure for enhancing plastic packaging bonding strength according to claim 1, characterized in that: The groove is in the shape of a rectangle.

4. The lead frame structure for enhancing plastic packaging bonding strength according to claim 1, characterized in that: The through hole is rectangular.

5. The lead frame structure for enhancing plastic packaging bonding strength according to claim 1, characterized in that: The bottom of the through hole is flush with the bottom of the groove.

6. A method for manufacturing a lead frame structure with enhanced plastic packaging bonding strength as claimed in any one of claims 1 to 5, characterized in that: include: Step 1: attaching a mask on the surface of the lead frame plate, wherein the mask has a pattern corresponding to the groove; Step 2: Expose and develop to reveal the positions of two adjacent grooves on the surface of the plate that need to be etched, and cover the surface of the plate that does not need to be etched with a mask; Process 3: Etch the exposed surface of the plate to form two adjacent grooves, and then continue etching using the remaining solution in the two grooves to etch through the material below the middle connecting rib to form a through hole connecting the two grooves; Step 4: Remove the mask still attached to the surface of the plate after etching to obtain the final lead frame structure.

7. A method for manufacturing a lead frame structure with enhanced plastic packaging bonding strength as claimed in any one of claims 1 to 5, characterized in that: include: Step 1: attaching a mask on the surface of the lead frame plate, wherein the mask has a pattern corresponding to the groove; Step 2: Expose and develop to reveal the positions of two adjacent grooves on the surface of the plate that need to be etched, and cover the surface of the plate that does not need to be etched with a mask; Step 3: Etching the exposed surface of the plate to form two adjacent grooves, and then stopping etching; Step 4: removing the mask still attached to the surface of the plate after etching, and obtaining a lead frame with two grooves; Step 5: Paste a mask on the surface of the lead frame material obtained by the first etching; Step 6: Expose and develop the surface of the rib sidewall material that needs to be etched, and cover the surface of the plate that does not need to be etched with a mask; Step 7: etching away the exposed surface of the connecting rib side wall material to form a through hole connecting the two grooves; Step 8: Remove the mask still attached to the surface of the plate after etching to obtain the final lead frame structure.

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