Chip glue injection method and semiconductor structure

Abstract

This application discloses a chip encapsulation method and a semiconductor structure. The method includes: soldering a packaged chip with solder balls evenly arranged on its bottom to a circuit substrate; performing a first preheating treatment on the packaged chip; injecting a first amount of structural adhesive into the corners of the packaged chip; maintaining the temperature for a first predetermined time; and then performing a high-temperature curing treatment to form initial encapsulation areas corresponding to each corner; performing a second preheating treatment on the packaged chip; injecting a second amount of structural adhesive into the corners of the packaged chip; maintaining the temperature for a second predetermined time; and then performing a high-temperature curing treatment to form edge encapsulation areas corresponding to each corner. The second amount of structural adhesive and the second predetermined time of temperature maintenance ensure that the bonding strength and bonding area of ​​the edge encapsulation areas meet preset bonding strength and preset bonding area. This method avoids the air gap problem caused by using a fully or nearly fully filled encapsulation method, thereby ensuring the stability of the bonding performance of the packaged chip.

Description

Technical Field

[0001] This application relates to the field of semiconductor processing technology, specifically to a chip encapsulation method and a semiconductor structure. Background Technology

[0002] For large-size SOC chips used in automotive applications, Ball Grid Array Package (BGA) technology is adopted. BGA packaging is commonly used in high-performance integrated circuits such as motherboard control chipsets and memory. It is the best choice for high-density, high-performance, multi-functional and high-I / O pin packaging. Most existing high-pin-count chips (such as graphics chips and chipsets) use BGA packaging technology.

[0003] Existing technologies use a method of completely or almost completely filling the space between the packaged chip and the circuit board with structural adhesive. Due to the large area of ​​the adhesive, the flow direction of the structural adhesive is uncontrollable. For example, structural adhesives flowing in opposite directions may generate eddies due to convergence, which in turn can generate air bubbles (i.e., air bubbles), affecting the bonding stability.

[0004] Therefore, how to effectively implement structural adhesive injection for BAG-packaged chips such as large-size automotive SOC chips is a problem that needs to be solved. Summary of the Invention

[0005] The technical problem to be solved by this application is to provide a chip encapsulation method to solve the problem of affecting the bonding stability during the encapsulation process of existing BAG packaged chips.

[0006] According to one aspect of the present invention, a chip encapsulation method is provided, the method comprising:

[0007] After soldering the packaged chip with solder balls evenly arranged on the bottom to the circuit board, the packaged chip is subjected to a first preheating treatment. A first amount of structural adhesive is injected into the corner of the packaged chip, and after being kept at a temperature for a first predetermined time, a high-temperature curing treatment is performed to form an initial adhesive injection area corresponding to each corner. The first amount of structural adhesive and the first predetermined time of temperature keeping make the initial adhesive injection area reach a preset bonding range in the direction of the central region of the bonding surface of the packaged chip.

[0008] The packaged chip is subjected to a second preheating treatment, a second amount of structural adhesive is injected into the corner positions of the packaged chip, and after being kept at a temperature for a second predetermined time, a high-temperature curing treatment is performed to form an edge adhesive injection area corresponding to each of the corner positions. The second amount of structural adhesive and the second predetermined time of heat preservation make the bonding strength and bonding area of ​​the edge adhesive injection area meet the preset bonding strength and preset bonding area.

[0009] The initial glue injection area and the edge glue injection area form the target glue injection area, and the interval between any adjacent target glue injection areas is greater than a predetermined distance threshold.

[0010] In some embodiments, the initial injection area is adjacent to the edge injection area.

[0011] In some embodiments, injecting a first amount of structural adhesive at the corner of the packaged chip includes injecting 90±10 mm of structural adhesive at the corner of the packaged chip using an L-shaped injection method, wherein, for each corner, the length of the starting injection edge is less than the length of the ending injection edge, so that the amount of structural adhesive injected from the starting injection edge and the ending injection edge toward the center region is the same.

[0012] In some embodiments, the length of the starting injection edge is 10 mm to 11 mm, and the length of the ending injection edge is 12 mm to 13 mm.

[0013] In some embodiments, injecting a second amount of structural adhesive at the corner of the packaged chip includes injecting 6±2 mm of structural adhesive at the corner of the packaged chip using an L-shaped injection method, wherein the length of the two injection edges at the same corner is 3 mm to 5 mm.

[0014] In some embodiments, the first predetermined duration of heat preservation includes heat preservation for 3 ± 1 minutes, or the second predetermined duration of heat preservation includes heat preservation for 3 ± 1 minutes.

[0015] In some embodiments, the first preheating treatment of the packaged chip includes: preheating the packaged chip to 80°C to 90°C; or,

[0016] The second preheating treatment of the packaged chip includes: preheating the packaged chip to 80°C to 90°C.

[0017] In some embodiments, the high-temperature curing treatment after the first predetermined insulation time includes: after the first predetermined insulation time, performing a high-temperature curing treatment on the initial adhesive injection area at a temperature of 140°C to 160°C for 14 to 18 minutes; or...

[0018] The high-temperature curing process after the second predetermined insulation time includes: after the second predetermined insulation time, using a temperature of 140°C to 160°C and a duration of 14 to 18 minutes to perform high-temperature curing on the edge glue injection area.

[0019] In some embodiments, injecting a first amount of structural adhesive at the corners of the packaged chip includes injecting the first amount of structural adhesive at each corner of the packaged chip in a clockwise direction; or, injecting a second amount of structural adhesive at the corners of the packaged chip includes injecting the second amount of structural adhesive at each corner of the packaged chip in a clockwise direction.

[0020] In some implementations, the predetermined distance threshold includes the spacing between 5 to 20 solder balls.

[0021] According to another aspect of the present invention, a semiconductor structure is provided, including a packaged chip and a circuit substrate. Solder balls are uniformly arranged on the bottom of the packaged chip, and the packaged chip is soldered to the circuit substrate through the solder balls. Each corner region of the packaged chip and the circuit substrate includes a target injection region formed by injecting structural adhesive. The target injection region includes an initial injection region and an edge injection region. The initial injection region reaches a preset bonding range in the direction towards the central region of the bonding surface of the packaged chip. The bonding strength and bonding area of ​​the edge injection region satisfy the preset bonding strength and preset bonding area. The spacing between any adjacent target injection regions is greater than a predetermined distance threshold.

[0022] Compared with the prior art, this application has the following advantages:

[0023] The chip encapsulation method provided in this application includes: soldering a packaged chip with solder balls evenly arranged on the bottom to a circuit board; performing a first preheating treatment on the packaged chip; injecting a first amount of structural adhesive at the corners of the packaged chip; maintaining the temperature for a first predetermined time; and performing a high-temperature curing treatment to form an initial encapsulation area corresponding to each corner; the first amount of structural adhesive and the first predetermined time of maintaining the temperature cause the initial encapsulation area to reach a preset bonding range in the direction towards the center of the packaged chip; performing a second preheating treatment on the packaged chip; injecting a second amount of structural adhesive at the corners of the packaged chip; maintaining the temperature for a second predetermined time; and performing a high-temperature curing treatment to form an edge encapsulation area corresponding to each corner; the second amount of structural adhesive and the second predetermined time of maintaining the temperature cause the bonding strength and bonding area of ​​the edge encapsulation area to meet the preset bonding strength and preset bonding area; wherein the initial encapsulation area and the edge encapsulation area form a target encapsulation area, and the interval between any adjacent target encapsulation areas is greater than a predetermined distance threshold. In this method, the first gluing creates an initial gluing area that reaches a preset bonding range in the direction towards the center of the bonding surface. The second gluing creates edge gluing areas that meet preset bonding strength and preset bonding area at each corner. This can compensate for the insufficient amount of adhesive at the edges caused by the structural adhesive flowing towards the center of the chip during the first gluing. Through the first and second gluing, the bonding strength and bonding area (bonding area at the edges and bonding area towards the center of the packaged chip) are effectively guaranteed. Furthermore, the target gluing area formed by the initial gluing area and the edge gluing area can avoid the problem of air leakage caused by using a gluing method that completely or almost completely fills the chip due to its large size, thereby ensuring the stability of the bonding performance of the packaged chip.

[0024] The above description is merely an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0025] Figure 1 This is a process flow diagram of the chip encapsulation method provided in the embodiments of this application;

[0026] Figure 2 This is a schematic diagram of chip encapsulation provided in the embodiments of this application.

[0027] Attached image annotations:

[0028] 1. Packaged chip, 2. Circuit board, 3. Initial encapsulation area, 4. Edge encapsulation area. Detailed Implementation

[0029] Many specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application; therefore, this application is not limited to the specific embodiments disclosed below.

[0030] The terminology used in one or more embodiments of this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the one or more embodiments of this specification. The singular forms “a,” “described,” and “the” as used in one or more embodiments of this specification and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in one or more embodiments of this specification refers to and includes any or all possible combinations of one or more associated listed items.

[0031] It should be understood that although the terms first, second, etc., may be used to describe various information in one or more embodiments of this specification, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first may also be referred to as second without departing from the scope of one or more embodiments of this specification, and similarly, second may also be referred to as first. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0032] To address the issue of air pockets caused by completely or nearly completely filling the chip during the chip encapsulation process, this application provides a chip encapsulation method. Please refer to [link / reference]. Figures 1-2 Understanding this embodiment, Figure 1 This is a process flow diagram of the chip encapsulation method provided in this embodiment; Figure 2 This is a schematic diagram of chip encapsulation provided in the embodiments of this application.

[0033] Ball Grid Array Package (BGA) is a surface-mount packaging technology used in integrated circuits. BGA-packaged chips have metal solder balls arranged in a grid-like pattern on the bottom, connecting to pads on the circuit board (or printed circuit board, PCB). Compared to packages such as Dual In-line Package (DIP) or Quad Flat Package (Quad Flat Package), BGA packages can accommodate more pins, as all the solder balls on the bottom surface of the chip can be used as pins.

[0034] During BGA packaging, when the packaged chip is fixed to the circuit board using surface mount technology, the bottom solder balls are arranged to correspond to the positions of the copper foil on the circuit board. After the solder balls are melted, the surface tension will cause the molten solder balls to support the package point and align with the circuit board. With the correct spacing, after the solder balls cool and fix, the resulting solder joint can connect the packaged chip and the circuit board.

[0035] The chip encapsulation method provided in this embodiment is applied to the encapsulation process following the above-described process, such as... Figure 1 and Figure 2 As shown, the chip encapsulation method provided in this embodiment includes:

[0036] S1, after soldering the packaged chip 1 with solder balls evenly arranged on the bottom to the circuit board 2, the packaged chip 1 is subjected to a first preheating treatment, and a first amount of structural adhesive is injected into the corners of the packaged chip 1. After keeping it warm for a first predetermined time, a high-temperature curing treatment is performed to form an initial adhesive injection area 3 corresponding to each corner.

[0037] The aforementioned first quantity of structural adhesive and the first predetermined insulation time enable the initial adhesive injection area 3 to reach a predetermined bonding range in the direction towards the central region of the packaged chip 1. That is, the initial adhesive injection area can characterize the extension depth of the structural adhesive towards the center of the chip.

[0038] S2, perform a second preheating treatment on the packaged chip 1, inject a second amount of structural adhesive at the corners of the packaged chip 1, and perform a high-temperature curing treatment after keeping it warm for a second predetermined time to form an edge adhesive injection area 4 corresponding to each corner.

[0039] The aforementioned second quantity of structural adhesive and the second predetermined duration of thermal insulation ensure that the bonding strength and bonding area of ​​the edge adhesive injection area 4 meet the preset bonding strength and preset bonding area.

[0040] In this embodiment, the initial glue-filling area 3 and the edge glue-filling area 4 form the target glue-filling area. The distance between any adjacent target glue-filling areas is greater than or equal to a predetermined distance threshold. This is to prevent a single target glue-filling area from being too large, or to prevent target glue-filling areas formed at different corner positions from merging, which could lead to air pockets in the middle of the chip. In this embodiment, the predetermined distance threshold can be the spacing between 5 to 20 solder balls. In this embodiment, the initial glue-filling area and the edge glue-filling area are connected to form an overall target glue-filling area. That is, after the initial glue-filling area is formed by high-temperature curing, this initial glue-filling area can serve as a boundary barrier for the second glue-filling process. Based on this, the glue-filling amount and glue-filling area for the second glue-filling are determined, making the glue-filling amount and heat preservation time for the second glue-filling more accurate, thereby effectively ensuring the bonding performance of the edge glue-filling area after the second glue-filling.

[0041] In another embodiment, a certain gap may also be maintained between the initial glue-filling area and the edge glue-filling area, that is, the initial glue-filling area effectively bonds the area near the middle of the chip, and the edge glue-filling area effectively bonds the edge of the chip.

[0042] The purpose of performing the first or second preheating treatment on the packaged chip 1 is to bring the packaged chip 1 into a state suitable for glue injection. In this embodiment, for a large-size automotive SOC chip, during the first preheating treatment, the packaged chip can be preheated to 80°C to 90°C, for example, 85°C; similarly, during the second preheating treatment, the packaged chip can be preheated to 80°C to 90°C.

[0043] The aforementioned injection of a first quantity of structural adhesive at the corners of the packaged chip can refer to injecting a first quantity of structural adhesive at each corner of the packaged chip in a clockwise direction. For example, for a large-size automotive SOC chip, an L-shaped dispensing method is used to inject 90±10 mm of structural adhesive at each corner of the packaged chip. The dispensing needle continuously dispenses adhesive at each corner and along the L-shaped path, thereby injecting the structural adhesive into the gap between the solder balls on the soldering surface between the packaged chip and the circuit board. The length of the starting dispensing edge at each corner is less than the length of the ending dispensing edge, so that the amount of structural adhesive injected from the starting and ending dispensing edges towards the center area is the same. For example, the length of the starting dispensing edge is 10 mm to 11 mm, and the length of the ending dispensing edge is 12 mm to 13 mm.

[0044] The amount of adhesive injected and the duration of the heat treatment together determine the flow direction, velocity, and flow rate of the structural adhesive between the packaged chip 1 and the circuit board 2. The heat treatment duration characterizes the flow time of the structural adhesive, and it, along with the amount of adhesive injected, affects the bonding performance. With a fixed amount of adhesive injected, if the heat treatment duration is too long, the structural adhesive will flow towards the central region of the chip for too long, resulting in excessive flow. This can cause the structural adhesive flowing from the corner areas into the central region to converge, leading to eddies and air bubbles, thus affecting the bonding performance. Conversely, if the heat treatment duration is too short, the structural adhesive will flow towards the central region for too short a time, resulting in insufficient flow and inadequate bonding area, also affecting the bonding performance. In this embodiment, for a large-size automotive SOC chip, the aforementioned first predetermined heat treatment duration can be 3 ± 1 minutes.

[0045] For the second injection, the structural adhesive can be injected into each corner of the packaged chip in a clockwise direction. For example, for a large-size automotive SOC chip, an L-shaped injection method can be used to inject 6±2 mm of structural adhesive into the corner of the packaged chip. The length of the two injection edges at each corner can be 3 mm to 5 mm, such as 4 mm. Correspondingly, the second predetermined heat preservation time can be 3±1 minutes.

[0046] In this embodiment, for the large-size SOC chip for vehicle use, the above-mentioned high-temperature curing treatment after the first predetermined heat preservation time can specifically refer to: after the first predetermined heat preservation time, using a temperature of 140°C to 160°C for 14 to 18 minutes to perform high-temperature curing treatment on the initial glue injection area.

[0047] The above-mentioned high-temperature curing treatment after the second predetermined insulation time can specifically refer to: after the second predetermined insulation time, using a temperature of 140℃ to 160℃ for 14 minutes to 18 minutes to perform high-temperature curing treatment on the edge glue injection area.

[0048] The chip encapsulation method provided in this application includes: soldering a packaged chip with solder balls evenly arranged on the bottom to a circuit board; performing a first preheating treatment on the packaged chip; injecting a first amount of structural adhesive at the corners of the packaged chip; maintaining the temperature for a first predetermined time; and performing a high-temperature curing treatment to form an initial encapsulation area corresponding to each corner; the first amount of structural adhesive and the first predetermined time of maintaining the temperature cause the initial encapsulation area to reach a preset bonding range in the direction towards the center of the packaged chip; performing a second preheating treatment on the packaged chip; injecting a second amount of structural adhesive at the corners of the packaged chip; maintaining the temperature for a second predetermined time; and performing a high-temperature curing treatment to form an edge encapsulation area corresponding to each corner; the second amount of structural adhesive and the second predetermined time of maintaining the temperature cause the bonding strength and bonding area of ​​the edge encapsulation area to meet the preset bonding strength and preset bonding area; wherein the initial encapsulation area and the edge encapsulation area form a target encapsulation area, and the interval between any adjacent target encapsulation areas is greater than a predetermined distance threshold. In this method, the first gluing creates an initial gluing area that reaches a preset bonding range in the direction towards the center of the bonding surface. The second gluing creates edge gluing areas that meet preset bonding strength and preset bonding area at each corner. This can compensate for the insufficient amount of adhesive at the edges caused by the structural adhesive flowing towards the center of the chip during the first gluing. Through the first and second gluing, the bonding strength and bonding area (bonding area at the edges and bonding area towards the center of the packaged chip) are effectively guaranteed. Furthermore, the target gluing area formed by the initial gluing area and the edge gluing area can avoid the problem of air leakage caused by using a gluing method that completely or almost completely fills the chip due to its large size, thereby ensuring the stability of the bonding performance of the packaged chip.

[0049] Another embodiment of this application provides a semiconductor structure including a packaged chip and a circuit substrate. Solder balls are uniformly arranged on the bottom of the packaged chip, and the packaged chip is soldered to the circuit substrate through the solder balls. Each corner area of ​​the packaged chip and the circuit substrate includes a target injection area formed by injecting structural adhesive. The target injection area includes an initial injection area and an edge injection area. The initial injection area reaches a preset bonding range in the direction towards the center area of ​​the packaged chip. The bonding strength and bonding area of ​​the edge injection area meet the preset bonding strength and preset bonding area. The spacing between any adjacent target injection areas is greater than a predetermined distance threshold.

[0050] It should be noted that although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

Claims

1. A chip encapsulation method, characterized in that, The method includes: After soldering the packaged chip with solder balls evenly arranged on the bottom to the circuit board, the packaged chip is subjected to a first preheating treatment. A first amount of structural adhesive is injected into the corners of the packaged chip, and after being kept at a temperature for a first predetermined time, a high-temperature curing treatment is performed to form an initial injection area corresponding to each corner, which represents the extension depth of the structural adhesive toward the center of the chip. The first amount of structural adhesive and the first predetermined time of temperature keeping make the initial injection area reach a preset bonding range in the direction toward the center of the packaged chip. The packaged chip is subjected to a second preheating treatment, a second amount of structural adhesive is injected into the corner positions of the packaged chip, and after being kept at a temperature for a second predetermined time, a high-temperature curing treatment is performed to form an edge adhesive injection area corresponding to each of the corner positions. The second amount of structural adhesive and the second predetermined time of heat preservation make the bonding strength and bonding area of ​​the edge adhesive injection area meet the preset bonding strength and preset bonding area. The initial glue injection area is connected to the edge glue injection area, and the initial glue injection area and the edge glue injection area form a target glue injection area. The interval between any adjacent target glue injection areas is not less than a predetermined distance threshold.

2. The chip encapsulation method according to claim 1, characterized in that, Injecting a first amount of structural adhesive at the corner of the packaged chip includes: injecting 90±10 mm of structural adhesive at the corner of the packaged chip using an L-shaped injection method, wherein, for each corner, the length of the starting injection edge is less than the length of the ending injection edge, so that the amount of structural adhesive injected from the starting injection edge and the ending injection edge toward the center region is the same.

3. The chip encapsulation method according to claim 2, characterized in that, The length of the starting injection edge is 10 mm to 11 mm, and the length of the ending injection edge is 12 mm to 13 mm.

4. The chip encapsulation method according to claim 1, characterized in that, Injecting a second amount of structural adhesive at the corner of the packaged chip includes injecting 6±2 mm of structural adhesive at the corner of the packaged chip using an L-shaped injection method, wherein the length of the two injection edges at the same corner is 3 mm to 5 mm.

5. The chip encapsulation method according to claim 1, characterized in that, The first predetermined duration of heat preservation includes heat preservation for 3 ± 1 minutes, or the second predetermined duration of heat preservation includes heat preservation for 3 ± 1 minutes.

6. The chip encapsulation method according to claim 1, characterized in that, The first preheating treatment of the packaged chip includes: preheating the packaged chip to 80°C to 90°C; or, The second preheating treatment of the packaged chip includes: preheating the packaged chip to 80°C to 90°C.

7. The chip encapsulation method according to claim 1, characterized in that, The high-temperature curing treatment following the first predetermined insulation period includes: after the first predetermined insulation period, applying a high-temperature curing treatment to the initial adhesive-filled area at a temperature of 140°C to 160°C for 14 to 18 minutes; or... The high-temperature curing process after the second predetermined insulation time includes: after the second predetermined insulation time, using a temperature of 140°C to 160°C and a duration of 14 to 18 minutes to perform high-temperature curing on the edge glue injection area.

8. The chip encapsulation method according to claim 1, characterized in that, Injecting a first quantity of structural adhesive at the corners of the packaged chip includes: injecting the first quantity of structural adhesive at each corner of the packaged chip in a clockwise direction; or, Injecting a second amount of structural adhesive at the corners of the packaged chip includes injecting a second amount of structural adhesive at each corner of the packaged chip in a clockwise direction.

9. The chip encapsulation method according to claim 1, characterized in that, The predetermined distance threshold includes the spacing between 5 to 20 solder balls.

10. A semiconductor structure prepared using the chip encapsulation method according to any one of claims 1-9, characterized in that, The package includes a packaged chip and a circuit board. Solder balls are evenly arranged on the bottom of the packaged chip. The packaged chip is soldered to the circuit board through the solder balls. Each corner area of ​​the packaged chip and the circuit board includes a target injection area formed by injecting structural adhesive. The target injection area includes an initial injection area and an edge injection area that characterize the extension depth of the structural adhesive toward the center of the chip. The initial injection area is connected to the edge injection area. The initial injection area reaches a preset bonding range in the direction toward the center of the packaged chip. The bonding strength and bonding area of ​​the edge injection area meet the preset bonding strength and preset bonding area. The spacing between any adjacent target injection areas is not less than a predetermined distance threshold.

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