Chip carrier lead frame pier structure and process method thereof

Abstract

The present invention discloses a chip carrier lead frame pier structure and a process method thereof, comprising a chip carrier lead frame, wherein fixed piers are arranged above a base island of the chip carrier lead frame and in an area covered by a plastic package, an adhesive material is arranged on the upper surface of the base island area in the chip carrier lead frame, the adhesive material contains a pier structure, and the chip is located above the piers and the adhesive material. In the present invention, piers are arranged on the base island of the chip carrier lead frame, and when the adhesive material is coated on an area containing the fixed piers, due to the cohesive force characteristics of the adhesive material, the adhesive material on the base island of the chip carrier lead frame containing the piers will move toward the fixed piers instead of diffusing outwards, thereby fully mastering the area and position accuracy of the adhesive material, and avoiding contamination of the area of ​​non-adhesive material due to diffusion.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor packaging, and in particular to a chip carrier lead frame pier structure and a process method thereof. Background Art

[0002] The system terminal products developed by modern technology are basically oriented towards light weight, small size, multi-function, fast communication speed, fast charging speed, low power consumption, long standby time, etc., especially the terminal system products that can be portable and mobile, such as communication smartphones, tablet computers, laptops, consumer electronics and wearable electronics.

[0003] Semiconductor chip packaging technology is particularly critical in electronic devices. It is responsible for the light, thin, short and small appearance of the package volume. In addition to the above-mentioned scope, it also bears the requirements of high power, multiple functions, anti-interference, high density, high durability and reliability. Therefore, the recent packaging technology has developed silicon through-hole via technology (TSV), silicon through-hole chip stacking technology (TSV Stacking), silicon chip line rewiring technology (RDL), fan out (FO) or fan in (FI), metal pier (Metal Bump), metal pier stacking technology (Metal Bump Stacking), metal pier under metal layer (Under Bump Metallization) to connect metal piers or subsequent process technologies.

[0004] Whether it is traditional packaging technology structure or advanced packaging technology and structure, there are potential reliability issues that need to be alleviated or resolved, especially tiny cracks or delamination between two or more substances and bonding substances in homogeneous or heterogeneous substances. These are defects that often occur in semiconductor packaging structures and are also very difficult to resolve reliability defects. Summary of the invention

[0005] The purpose of the present invention is to provide a chip carrier lead frame pier structure and a process method thereof. By setting a fixed and immovable pier on the surface of the chip carrier lead frame base island, the distance between the chip and the chip carrier lead frame base island is effectively controlled, thereby effectively solving the production problems, product reliability problems, the release of adhesive materials, and the separation of glue and conductive materials in the adhesive materials caused by traditional packaging structures and process methods.

[0006] The technical problems solved by the present invention are:

[0007] (1) How to solve the pollution and bridge short circuit defects caused by the diffusion of adhesive materials during coating;

[0008] (2) How to solve the defects of delamination and cracking between the chip carrier lead frame base island and the adhesive material and the chip;

[0009] (3) How to prevent the adhesive from being released from the periphery of the chip carrier lead frame base island during high-temperature baking, causing the adhesive to be lost and contaminated;

[0010] (4) How to solve the defects caused by adding tiny conductive or non-conductive micro-spherical bodies to the adhesive material? Since the micro-spherical bodies are in an unfixed free state, when the micro-spherical bodies are added to the conductive or non-conductive adhesive material and coated on the top of the metal base island, it is difficult to evenly distribute the micro-spherical bodies in the adhesive material, resulting in a tilt between the chip and the chip carrier lead frame base island after the chip is installed;

[0011] (5) How to solve the problem that the chip size is larger than the chip carrier lead frame base island size.

[0012] The purpose of the present invention can be achieved by the following technical solutions:

[0013] A chip carrier lead frame pier structure comprises a chip carrier lead frame, wherein piers are fixedly arranged above a base island of the chip carrier lead frame and in an area covered by a plastic package;

[0014] A chip is connected in a plastic sealing area of ​​the chip carrier lead frame via an adhesive material, and the chip is located above the bridge pier.

[0015] As a further embodiment of the present invention: the bonding material includes epoxy resin or soft solder;

[0016] The epoxy resin includes conductive epoxy resin and non-conductive epoxy resin;

[0017] The soft solder includes solder paste and lead paste, or any material that is both conductive and has bonding ability.

[0018] As a further solution of the present invention: comprising the following steps:

[0019] Step 1: Prepare the bridge piers

[0020] A plurality of bridge piers are formed by stamping a die on the surface of the base island of the chip carrier lead frame, and then the surfaces of the plurality of bridge piers are flattened by a flattening die to complete the adjustment of the overall height of the bridge piers. The material of the bridge piers can be made into conductive or non-conductive materials according to the functional characteristics of the chip;

[0021] Step 2: Apply adhesive

[0022] Injecting adhesive material into the plastic sealing area of ​​the base island of the chip carrier lead frame and located at the plurality of bridge piers, and making the adhesive material completely cover the bridge piers;

[0023] Step 3: Chip Installation

[0024] The chip is placed on the adhesive material containing the bridge pier in step 2, and the water in the adhesive material is evaporated by a fixed high-temperature oven or a temperature-programmable oven, so that the adhesive material completely fixes the base island and the chip to solidify;

[0025] Step 4: Bonding Wire

[0026] The metal wire bonding equipment is used to bond the chip to the inner pins, and the chip is packaged on the chip carrier lead frame through plastic sealing, baking, laser printing, rib cutting, metal surface electroplating, and outer pin forming.

[0027] As a further solution of the present invention: the bridge pier in step 1 is a cylinder, a triangular prism or a polygon.

[0028] As a further solution of the present invention: the bridge pier is vertically or obliquely arranged on the chip carrier lead frame.

[0029] Beneficial effects of the present invention:

[0030] (1) In the present invention, bridge piers are arranged on the base island of the chip carrier lead frame. When the adhesive material is coated on the area containing the fixed bridge piers, due to the cohesive force characteristics of the material, the adhesive material on the base island of the chip carrier lead frame containing the bridge piers will move toward the fixed bridge piers instead of spreading outwards, so that the area of ​​the adhesive material is fully filled with the adhesive material, avoiding contamination of the area without the adhesive material due to diffusion;

[0031] (2) When the chip is precisely placed on the adhesive material containing the bridge piers in the present invention, a vacuum is formed and the adhesive material firmly adsorbs the chip, so that the chip, the adhesive material and the chip carrier lead frame base island maintain a precise position and height, which can effectively prevent the position of the chip from drifting randomly, thereby making the production process smoother, reducing the downtime rate, reducing the maintenance rate, increasing efficiency, and increasing the reliability of the packaging structure, thereby reducing internal friction such as material cost, production cost, management cost and quality cost;

[0032] (3) The adhesive material in the present invention uses a non-conductive adhesive material. By controlling the height of the bridge pier, the distance between the chip and the chip carrier lead frame base island can be effectively controlled. When the product requires the use of a non-conductive adhesive material, the current or voltage on the chip will not cause the chip to be too close to the base island due to the chip installation pressure, thereby effectively avoiding leakage or short circuit between the chip and the chip carrier lead frame base island;

[0033] (4) The adhesive material used in the present invention is a conductive adhesive material. By controlling the height of the bridge pier, the distance between the chip and the chip carrier lead frame base island can be effectively controlled. When the product requires the use of a conductive adhesive material, the adhesive and the conductive material in the conductive adhesive material will not be separated due to the chip installation pressure. The original good ratio between the adhesive and the conductive material can be fully maintained, thereby ensuring that the adhesive material can fully bond the metal base island and the chip without cracking or delamination. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be further described below in conjunction with the accompanying drawings.

[0035] Figure 1 It is a schematic diagram of the process flow of the chip carrier lead frame pier structure of the present invention.

[0036] Figure 2 It is a structural schematic diagram of the chip carrier lead frame in the present invention for preparing bridge piers.

[0037] Figure 3 It is a schematic diagram of the chip carrier lead frame and inner pins preparing bridge piers in the present invention.

[0038] Figure 4 The present invention is a schematic diagram of a chip carrier lead frame structure in the prior art.

[0039] Figure 5 It is a schematic diagram of the structure of non-conductive microspheres in the bonding material of the present invention.

[0040] In the figure: 1. chip carrier lead frame; 2. bridge pier; 3. chip. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] See also Figure 1-Figure 5 As shown, the present invention is a chip carrier lead frame pier structure, a pier 2 is fixedly arranged above the base island of the chip carrier lead frame 1 and in the area covered by the plastic packaging body, a chip 3 is connected to the plastic packaging area of ​​the chip carrier lead frame 1 via an adhesive material, and the chip 3 is located above the pier 2.

[0043] When in use, a fixed and immovable bridge pier 2 is set on the surface of the base island of the chip carrier lead frame 1 to effectively control the distance between the chip 3 and the base island of the chip carrier lead frame 1, thereby effectively solving the production problems, product reliability problems, the release of adhesive materials, and the separation of glue and conductive materials in the adhesive materials caused by traditional packaging structures and process methods.

[0044] The adhesive material includes epoxy resin or soft solder, the epoxy resin includes conductive epoxy resin and non-conductive epoxy resin, and the soft solder includes solder paste, lead paste or any material that is conductive and has adhesive properties.

[0045] A process for a chip carrier lead frame pier structure, comprising the following steps:

[0046] Step 1: Prepare the bridge piers

[0047] A plurality of bridge piers 2 are formed on the surface of the base island of the chip carrier lead frame 1 by die stamping, and then the surfaces of the plurality of bridge piers 2 are flattened by a flattening die to complete the overall height adjustment of the bridge piers 2;

[0048] Step 2: Apply adhesive

[0049] Injecting adhesive material into the plastic sealing area of ​​the base island of the chip carrier lead frame 1 and located in the plurality of bridge piers 2, and making the adhesive material completely cover the bridge piers 2;

[0050] Step 3: Chip Installation

[0051] The chip 3 is placed on the adhesive material containing the bridge pier 2 in step 2, and the water in the adhesive material is evaporated by a fixed high-temperature oven or a temperature-programmable oven, so that the adhesive material completely fixes the base island and the chip 3 to solidify;

[0052] Step 4: Bonding Wire

[0053] The metal wire bonding equipment is used to bond the chip 3 to the inner pins, and the chip 3 is packaged on the chip carrier lead frame 1 through plastic sealing, baking, laser printing, rib cutting, electroplating the metal surface, and forming the outer pins.

[0054] In step 1, the bridge pier 2 is manufactured by using a mold with needle-shaped protrusions to impact the surface of the chip carrier lead frame 1, so that the bridge pier 2 is extruded around the surface of the chip carrier lead frame 1 due to the impact. If the height needs to be controlled, the extruded bridge pier 2 is pressed to the actual required height by a flattening mold;

[0055] The height requirement of the bridge pier 2 depends on the product characteristics and application, and the height of the bridge pier 2 is controlled by adjusting the depth of the needle-shaped protrusion mold and the pressing depth of the flattening mold;

[0056] The needle-shaped protrusion mold may impact the chip carrier lead frame 1 vertically up and down to obtain the bridge pier 2, or may impact at an angle to obtain the bridge pier 2 with a unidirectional arc structure.

[0057] As long as the convex structure is exposed on the surface of the chip carrier lead frame 1 or the surface of the organic substrate carrier, no matter what shape or structure it is, it falls within this category, including whether the convex structure is a single point, multiple points, a line segment or an area.

[0058] Among them, in step three, for the bonding of the chip 3 to the chip carrier lead frame 1, first, a bridge pier 2 of non-conductive material is made, and traditional dispensing technology is used and the moisture is evaporated by baking to solidify it, or 3D printing technology is used to point out a certain amount of non-conductive material at the position where it needs to be fixed, and then distribute it to the required position of the base island of the chip carrier lead frame 1.

[0059] The height of the pier 2 can be controlled by leveling the pier 2 at a limited pressure or by rotating a tool at high speed to perform shearing, grinding or chemical corrosion.

[0060] The bridge pier 2 in step 1 is a cylinder, a triangular prism or a polygon.

[0061] The bridge pier 2 is vertically or obliquely arranged on the chip carrier lead frame 1 .

[0062] Among them, the bridge piers 2 on the chip carrier lead frame 1 can be arranged in a rectangular array or a circular array, and the shapes of adjacent bridge piers 2 on the chip carrier lead frame 1 can be the same or different. At the same time, the sizes of adjacent bridge piers 2 on the chip carrier lead frame 1 can be the same or different. Through the adaptive arrangement of the bridge piers 2, the adhesive material can be more firmly attached to the chip carrier lead frame, and the area of ​​the adhesive material can be fully filled with the adhesive material to avoid contamination in the area of ​​the non-adhesive material due to diffusion, thereby enhancing the adhesion of the bridge piers 2 to the adhesive material.

[0063] Among them, when the void bubbles that need to be close to zero are enclosed in the adhesive material, a vacuum can be used to form a negative pressure during the high-temperature evaporation of water to extract the gas in the adhesive material out of the adhesive material.

[0064] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A process for a chip carrier lead frame pier structure, the pier structure comprising a chip carrier lead frame (1), characterized in that: A fixed bridge pier (2) is provided above the base island of the chip carrier lead frame (1) and in the area covered by the plastic package; A chip (3) is connected to the base island region of the chip carrier lead frame (1) via an adhesive material, and the chip (3) is located above the bridge pier (2); Adhesive materials include epoxy resin or soft solder; The soft solder includes solder paste and lead paste; The preparation method of the pier structure comprises the following steps: Step 1: Prepare the bridge piers A plurality of bridge piers (2) are formed on the surface of the base island of the chip carrier lead frame (1) by means of a die stamping, and then the surfaces of the plurality of bridge piers (2) are flattened by means of a flattening die to complete the overall height adjustment of the bridge piers (2); Step 2: Apply adhesive Injecting an adhesive material onto the base island of the chip carrier lead frame (1) and in the plastic sealing area of ​​the plurality of bridge piers (2), and allowing the adhesive material to completely cover the bridge piers (2); Step 3: Chip Installation Placing the chip (3) on the adhesive material containing the bridge pier (2) in step 2, and evaporating the water in the adhesive material by using a fixed high-temperature oven or a temperature-programmable oven to completely solidify the adhesive material; Step 4: Bonding Wire The metal wire is bonded to the chip (3) and the inner pins by a metal wire bonding device, and the chip (3) is packaged on the chip carrier lead frame (1) by plastic sealing with plastic resin, baking, laser printing, rib cutting, metal surface electroplating, and outer pin forming.

2. A process for a chip carrier lead frame pier structure according to claim 1, characterized in that: The bridge pier (2) in step 1 is a cylinder, a triangular prism or a polygon.

3. A process for a chip carrier lead frame pier structure according to claim 2, characterized in that: The bridge pier (2) is arranged vertically or obliquely on the chip carrier lead frame (1).

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