Semiconductor packaging mold and packaging process

Abstract

The invention discloses a semiconductor packaging mold and packaging technology, and belongs to the technical field of semiconductor packaging, the semiconductor packaging mold comprises an upper mold plate and a lower mold plate, and the lower surface of the upper mold plate is provided with at least one mold cavity; a high-temperature-resistant layer is embedded into the lower die groove of the lower die plate and is slightly higher than the upper surface of the lower die plate, the upper surface of the high-temperature-resistant layer is covered with a sheet, and a PCB is placed between the upper die plate and the lower die plate. The die structure is simplified, the die manufacturing cost is reduced, and waste materials are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor packaging, and in particular to a semiconductor packaging mold and a packaging process. Background Art

[0002] The existing semiconductor products packaged with PCB boards are all made by using solid epoxy resin and large hydraulic equipment packaging technology. The general process is as follows: after the PCB board is placed in the mold, the upper and lower molds are closed by strong pressure, and the solid epoxy resin is converted into liquid epoxy resin by pressure under heat. Then, the extruder rod of the hydraulic equipment is squeezed into each product cavity through the mold runner. After heating for several minutes, the liquid epoxy resin is solidified to obtain the desired product. The defect of the current molding method is that it is necessary to use molding equipment to provide strong pressure to close the two templates above, so that the PCB board and the template surface are completely fitted, which is inefficient, has high requirements for the mold surface flatness accuracy, and has high equipment and mold manufacturing costs. In addition, the mold internal runner is long, and the epoxy resin runner after curing has no secondary utilization value, which causes a large amount of material waste and environmental damage. Summary of the invention

[0003] The purpose of the present invention is to provide a packaging mold and packaging process for semiconductor products that replace the existing PCB board packaging in order to address the defects of the prior art. Qualified semiconductor products can be produced through a very simple process.

[0004] The technical problem to be solved by the present invention can be implemented through the following technical solutions.

[0005] A semiconductor packaging mold comprises an upper mold plate and a lower mold plate, wherein at least one mold cavity is formed on the lower surface of the upper mold plate, and the upper surface of the upper mold plate comprises at least one glue inlet and an exhaust port; a lower mold groove is formed on the upper surface of the lower mold plate, a high temperature resistant layer is embedded in the lower mold groove of the lower mold plate and is slightly higher than the upper surface of the lower mold plate, and the high temperature resistant layer is made of an elastomeric material; a PCB board is placed between the upper mold plate and the lower mold plate, and the PCB board corresponds to the mold cavity of the upper mold plate.

[0006] In the above technical solution, preferably, the upper surface of the high temperature resistant layer is covered with a thin sheet, and the thin sheet is a material with high hardness and high toughness.

[0007] In the above technical solution, preferably, the glue inlet and the exhaust port constitute a glue injection and exhaust structure, wherein the glue is injected vertically downward and exhausted upward, and the glue inlet and the exhaust port are used as an ejection mechanism for ejecting the product.

[0008] In the above technical solution, preferably, the high temperature resistant layer can be silicone or rubber.

[0009] In the above technical solution, preferably, the PCB board can be a stamped lead frame or a PCB etching part, and at least one of the front and back sides has a solder pad.

[0010] In the above technical solution, preferably, the high temperature resistant layer is completely surrounded by the lower mold groove and fixed on the upper surface of the lower mold plate.

[0011] The packaging process of any of the above-mentioned semiconductor packaging molds is characterized by comprising the following steps: Step 1: Assemble the lower mold body, place the high temperature resistant layer in the groove of the lower mold, and place a thin sheet on the upper surface of the high temperature resistant layer or no thin sheet; Step 2: After heating the upper mold plate to the required temperature, spray the release agent on the lower surface of the upper mold plate and the upper surface of the lower mold plate, and then place the PCB board on the surface of the lower mold assembly and position it; Step 3: Use external force to apply pressure to close the mold and lock it. The back of the PCB board corresponds to and fits with the high temperature resistant layer of the lower template or the thin sheet of the lower template, and the front of the PCB board corresponds to and fits completely with the mold cavity surface of the upper template, so that the liquid epoxy resin or liquid silicone rubber, or thermosetting plastic injected into the mold is completely sealed in the mold cavity and cannot overflow to the pad area on the front and back sides of the PCB board; Step 4: Use the glue injection equipment to inject liquid epoxy resin or liquid silicone rubber, or thermosetting plastic, into the mold cavity from the glue inlet under pressure, and exhaust the air from the exhaust port until the entire mold is filled; Step 5: Place the mold in a baking oven for baking and curing; Step 6: Eject the cured product.

[0012] The beneficial effects of the present invention are: 1. The present invention utilizes the principle and characteristics of the elastic material that the volume is incompressible, it is very easy to deform and has good resilience, and the thin sheet has high yield strength and low tensile strength, so as to force the thin sheet to be completely and evenly pressed on the front and back surfaces of the PCB board that are not completely flat. Only a small pressure is required to fit the non-completely flat surface, and only a small pressure is required to completely prevent the liquid epoxy resin or liquid silicone rubber or thermoplastic material from overflowing to the PCB board pad.

[0013] 2. The present invention utilizes the glue inlet and the exhaust port as the ejection mechanism for ejecting the product, which can simplify the mold structure, reduce the mold manufacturing cost, and can also achieve the effect of cleaning the mold by removing the dirt remaining inside the glue inlet and the exhaust port during ejection by the ejector pin.

[0014] 3. The device and process provided by the present invention will not have a long internal runner, which reduces waste generation. Low-cost liquid ring resin or silicone rubber or thermosetting plastic is used for production, which reduces production costs and improves product quality reliability, and is suitable for large-scale automated production. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is an exploded side view of the final assembly mold of the present invention; Figure 2 It is a schematic diagram of the upper surface of the upper template of the present invention; Figure 3 It is a schematic diagram of the lower surface of the upper template of the present invention; Figure 4 Schematic diagram of the upper surface of the lower template of the present invention Figure 5 This is an assembly diagram of the lower mold body of the present invention; Figure 6 It is a schematic diagram of the PCB board structure; Explanation of the markings in the attached drawings: 1-upper template, 2-lower template, 3-high temperature resistant layer, 4-PCB board, 5-thin sheet, 6-glue inlet, 7-exhaust port, 8-mold cavity, 9-lower mold groove, 10-PCB front pad, 11-PCB back pad. Implementation

[0016] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Example

[0017] like Figure 1-5 As shown, a semiconductor packaging mold disclosed in the present invention includes an upper template 1, a lower template 2, a high temperature resistant layer 3, a PCB board 4, a thin sheet 5, at least one glue inlet 6, at least one exhaust port 7, at least one mold cavity 8, and a lower mold groove 9. The glue inlet 6 and the exhaust port 7 are opened on the upper surface of the upper template 1, the mold cavity 8 is opened on the lower surface of the upper template 1, and the lower mold groove 9 is opened on the upper surface of the lower template 2; the high temperature resistant layer 3 is an elastomeric material, which can be silicone or rubber; the thin sheet 5 is a material with high hardness and high toughness.

[0018] The lower mold plate 2 and the high temperature resistant layer 3 are assembled into a lower mold body, the high temperature resistant layer 3 is placed at the lower mold groove 9, and the high temperature resistant layer 3 is inserted into the lower mold groove 9. The lower mold groove 9 completely surrounds the high temperature resistant layer 3 and fixes it on the upper surface of the lower mold plate 2, and is slightly higher than the upper surface of the lower mold plate 2. The PCB board 4 is placed on the surface of the lower mold body, and after positioning, it corresponds to the mold cavity 8 of the upper mold plate 1. The PCB board 4 can be a stamped lead frame or a PCB etching part, with a pad on the front or the back, or with pads on both the front and back, such as Figure 6 As shown, a PCB board having solder pads on both sides is used in this embodiment.

[0019] The glue inlet 6 and the exhaust port 7 constitute not only the glue injection exhaust structure, but also the ejection mechanism for ejecting the product. When used as a glue injection exhaust structure, the glue is fed vertically downward and the exhaust is upward; when used as an ejection mechanism, the ejector pin can also be used to eject the dirt remaining inside the glue inlet and the exhaust port to achieve the effect of cleaning the mold.

[0020] After the lower mold is assembled, place the PCB board 4 on top of the lower mold, close the upper mold plate 1 and the lower mold plate 2, and apply external force to the upper and lower surfaces of the entire mold. Since the high temperature resistant layer 3 is an elastomeric material, the principle and characteristics of the elastomeric material are that the volume is incompressible, it is very easy to deform and has good resilience, and only a small pressure is required to fit the surface of the PCB board that is not completely flat, as follows: The volume of the high temperature resistant layer 3 is constrained in the lower mold groove 9. When subjected to force, its volume cannot overflow or overflows very little. By utilizing the characteristics of elastomer molecules and volume that are difficult to compress, after the high temperature resistant layer 3 is compressed, the concentrated stress is converted into deformation energy. After the volume is compressed to the limit, it is converted into uniform downward pressure. By utilizing the principle that the high temperature resistant layer 3 material is very easy to deform and rebound after being subjected to pressure, the stress is gently and evenly dispersed on the entire mold surface. The mold surface is evenly stressed and there will be no local uneven stress phenomenon, so that the high temperature resistant layer 3 can be completely and evenly pressed on the front and back surfaces of the uneven PCB board 4 pads, and fully pressed and completely fit with the side surface of the mold cavity 8. Only a small pressure needs to be applied to completely prevent liquid epoxy resin or liquid silicone glue or thermoplastic material from overflowing to the front and back pads of the PCB board 4.

[0021] When the packaging pressure required for product packaging is relatively high, the thin sheet 5 is placed on the upper surface of the high temperature resistant layer 3 so that the thin sheet 5 completely covers the high temperature resistant layer 3. When the uniform pressure of the high temperature resistant layer 3 is transmitted to the entire thin sheet 5, after the thin sheet 5 is stressed, due to the high yield strength and low tensile strength of the material with high toughness and high hardness, the thin sheet 5 is forced to be completely and evenly pressed on the front and back surfaces of the uneven PCB board 4 pads, and fully pressed and completely fitted with the side surface of the mold cavity 8, and as long as a small pressure is applied, the liquid epoxy resin or liquid silicone rubber or thermoplastic material can be completely prevented from overflowing to the front and back pads of the PCB board 4.

[0022] The present invention uses a very simple process to produce qualified semiconductor products. The high temperature resistant layer 3 and the thin sheet 5 can be used repeatedly, and this structure is also suitable for semiconductor products such as PCB boards with traditional mold packaging. Example

[0023] According to the semiconductor packaging mold disclosed in Embodiment 1, the present invention further discloses a semiconductor packaging process, comprising the following steps: Step 1: Assemble the lower mold body, place the high temperature resistant layer 3 on the lower mold groove 9, and place the sheet 5 on the upper surface of the high temperature resistant elastic body; Step 2: After heating the upper mold plate 1, spray a release agent on the lower surface of the upper mold plate 1 and the upper surface of the lower mold plate 2, and then place the PCB board 4 on the surface of the lower mold assembly and position it; Step 3: Use external force to apply pressure to close the mold and lock it, so that the back pad 11 of the PCB board 4 corresponds to and fits with the thin sheet 5, and the front pad 10 of the PCB board 4 completely fits with the surface of the mold cavity 8 of the upper model plate 1, so that the liquid epoxy resin or liquid silicone rubber, or thermosetting plastic injected into the mold is completely sealed in the mold cavity 8 and cannot overflow to the front and back pad areas of the PCB board; Step 4: Use the glue injection equipment to inject liquid epoxy resin or liquid silicone rubber, or thermosetting plastic, into the mold cavity 8 from the glue inlet 6 under pressure, and exhaust the air from the exhaust port 7 until the entire mold is filled; Step 5: Place the mold in a baking oven for baking and curing; Step 6: Eject the cured product.

[0024] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several changes and substitutions without departing from the principle of the present invention. These changes and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A semiconductor packaging mold, comprising an upper mold plate (1) and a lower mold plate (2), wherein the lower surface of the upper mold plate (1) has at least one mold cavity (8), It is characterized in that The upper surface of the upper template (1) is provided with at least one glue inlet (6) and an exhaust port (7); the upper surface of the lower template (2) is provided with a lower mold groove (9), a high temperature resistant layer (3) is embedded in the lower mold groove (9) of the lower template (2) and is slightly higher than the upper surface of the lower template (2), and the high temperature resistant layer (3) is made of an elastomeric material; a PCB board (4) is placed between the upper template (1) and the lower template (2), and the PCB board (4) corresponds to the mold cavity (8) of the upper template (1).

2. The semiconductor packaging mold according to claim 1, It is characterized in that The upper surface of the high temperature resistant layer (3) is covered with a thin sheet (5), and the thin sheet (5) is a material with high hardness and high toughness.

3. The semiconductor packaging mold according to claim 1, It is characterized in that The glue inlet (6) and the exhaust port (7) constitute a glue injection and exhaust structure, wherein the glue is injected vertically downward and the exhaust is exhausted upward, and the glue inlet and the exhaust port are used as an ejection mechanism for ejecting the product.

4. The semiconductor packaging mold according to claim 1, It is characterized in that The high temperature resistant layer (3) may be silicone or rubber.

5. The semiconductor packaging mold according to claim 1, It is characterized in that The PCB board (4) may be a stamped lead frame or a PCB etching part, and at least one of the front and back sides has a solder pad.

6. The semiconductor packaging mold according to claim 1, It is characterized in that The high temperature resistant layer (3) is completely surrounded by the lower die groove (9) and fixed on the upper surface of the lower die plate (2).

7. The packaging process of the semiconductor packaging mold according to any one of claims 1 to 5, It is characterized in that The following steps are involved: Step 1: Assemble the lower mold body, place the high temperature resistant layer (3) on the lower mold groove (9), and place a thin sheet (5) on the upper surface of the high temperature resistant layer (3) or no thin sheet (5); Step 2: After the upper mold plate (1) is heated to a desired temperature, a release agent is sprayed on the lower surface of the upper mold plate (1) and the upper surface of the lower mold plate (2), and then the PCB board (4) is placed on the surface of the lower mold assembly and positioned; Step 3: Use external force to apply pressure to close the mold and lock it, so that the back side of the PCB board (4) corresponds to and fits with the high temperature resistant layer (3) of the lower mold plate (2) or the thin sheet (5) of the lower mold plate (2), and the front side of the PCB board (4) corresponds to and fits completely with the surface of the mold cavity (8) of the upper mold plate (1), so that the liquid epoxy resin or liquid silicone rubber, or thermosetting plastic injected into the mold is completely sealed in the mold cavity (8) and cannot overflow to the pad area on the front and back sides of the PCB board; Step 4: Using a glue injection device, liquid epoxy resin or liquid silicone rubber, or thermosetting plastic, is injected into the mold cavity (8) from the glue inlet (6) under pressure, and air is discharged from the exhaust port (7) until the entire mold is filled; Step 5: Place the mold in a baking oven for baking and curing; Step 6: Eject the cured product.

Images