Method for bonding electronic components using pneumatic pressure

Abstract

The present invention provides a method for bonding electronic components using pneumatic pressure, wherein a process of bonding electronic components can be performed as a batch process in a pneumatic chamber to greatly increase productivity, and location-specific pressure differences of bonding portions can be minimized to improve bonding quality. The present invention is characterized in that a temporarily bonded assembly in which a semiconductor chip and a substrate are temporarily bonded by a conductive bonding member is introduced into a pneumatic chamber and positioned so as not to be in contact with a heated heat conduction plate, and then, when the internal pressure of the pneumatic chamber increases and reaches a set pressure, is brought into contact with the heat conduction plate and thereby pressed and sintered for a predetermined time.

Description

Method for joining electronic components using pneumatic pressure

[0001] The present invention relates to a method for joining electronic components using pneumatic pressure, which can join electronic components with excellent joining quality in a batch process using pneumatic pressure.

[0002] Typically, a heat sink is installed to quickly dissipate heat generated from heat-generating components such as power semiconductor chips to the outside.

[0003] Conventional bonding between power semiconductor chips and heat sink substrates typically involves the use of conductive bonding paste or bonding film. Specifically, the primary method employed is a pressure-sintering process that involves interposing conductive bonding paste or conductive bonding film between the power semiconductor chip and the heat sink substrate and applying pressure using a press under high temperature and high pressure.

[0004] However, this conventional bonding method had a problem in that the number of power semiconductor chips and heat sink substrates that could be bonded at one time was limited depending on the area of ​​the press used in the bonding process.

[0005] In addition, since the mechanical pressure of the press is used to pressurize and bond the power semiconductor chip and the heat dissipation substrate, there was a problem that it was difficult to secure process reproducibility because there was a possibility of pressure deviation depending on the location of the bonding area.

[0006] The matters described in the background art above are intended to help understand the background of the invention and may include matters that are not publicly disclosed prior art.

[0007] The technical problem to be solved by the present invention is to provide a method for joining electronic components using pneumatic pressure, which can increase productivity by performing the joining between a power semiconductor chip and a heat dissipation substrate in a batch process using pneumatic pressure, and can improve the joining quality by reducing the occurrence of pressure deviation according to the position of the joining part.

[0008] A method for joining electronic components using pneumatics according to the present invention for solving the above-described problem comprises the steps of: preparing a joint in which a semiconductor chip and a substrate are joined by a joint member; introducing the joint into a pneumatic chamber and arranging the joint at a position not in direct contact with a heat-conducting plate heated to a certain temperature; increasing the internal pressure of the pneumatic chamber into which the joint is introduced to a set pressure; and, when the internal pressure of the pneumatic chamber reaches the set pressure, bringing the joint into contact with the heat-conducting plate and pressurizing and sintering the joint for a certain period of time in a high-temperature and high-pressure environment within the pneumatic chamber.

[0009] The above-mentioned joining member may be composed of a metallic material having electrical conductivity and thermal conductivity.

[0010] In this case, the bonding member may be made of a conductive paste or conductive film containing Ag.

[0011] In the step of preparing the above-mentioned joint, a joint can be prepared by interposing a joint member between a semiconductor chip and a substrate on which an Au plating layer is formed on the lower surface.

[0012] Before introducing the above-mentioned joint into the pneumatic chamber, the heat conducting plate can be maintained at a temperature of 350°C using a temperature control device.

[0013] In the step of increasing the internal pressure of the above pneumatic chamber to the set pressure, the pressure control device is operated to circulate and move the air inside the pneumatic chamber, and the internal pressure can be increased to the set pressure at which the pressure sintering of the joint is possible.

[0014] At this time, the internal pressure of the pneumatic chamber can be increased to a maximum of 1 MPa using the pressure control device.

[0015] As one embodiment, in the step of placing a joint inside the pneumatic chamber, a heat-insulating member may be interposed between the joint and the heat-conducting plate so that the joint does not come into direct contact with the heat-conducting plate.

[0016] And, in the step of pressurizing and sintering the joint, when the internal pressure of the pneumatic chamber reaches the set pressure, the heat-insulating member arranged between the heat-conducting plate and the joint can be removed to bring the substrate of the joint into contact with the heat-conducting plate.

[0017] As another embodiment, in the step of placing the joint inside the pneumatic chamber, the joint may be placed on a jig placed at an upper position spaced apart from the heat-conducting plate so as not to come into direct contact with the heat-conducting plate.

[0018] And, in the step of pressurizing and sintering the above-mentioned joint, when the internal pressure of the pneumatic chamber reaches the set pressure, the joint on the jig can be lowered to bring the substrate of the joint into contact with the heat conducting plate.

[0019] According to the present invention, productivity can be greatly increased by performing the bonding process between a semiconductor chip and a heat dissipation substrate as a batch process in a pneumatic chamber.

[0020] Furthermore, the present invention utilizes pneumatic pressure generated within a pneumatic chamber rather than the mechanical pressure of a conventional press to bond under pressure sintering in a high-pressure, high-temperature environment, thereby preventing pressure variations at different locations in the bonding area and forming a high-quality, robust bonding layer with virtually no voids. This provides the advantage of ensuring excellent bonding process reproducibility between semiconductor chips and heat-dissipating substrates and yielding products with uniform bonding quality.

[0021] Figure 1 is a schematic diagram showing a pneumatic chamber applied to a method for joining electronic components using pneumatic pressure according to the present invention.

[0022] Figure 2 is a real photograph showing the internal structure of a pneumatic chamber with a heat conduction plate installed.

[0023] Figure 3 is a graph showing the relationship between pressure and temperature increase within a pneumatic chamber.

[0024] Figure 4 is a process diagram showing a bonding process of a semiconductor chip and a heat dissipation substrate using a conventional press.

[0025] Figure 5 is a process diagram showing a process of bonding a semiconductor chip and a heat dissipation substrate using pneumatic pressure according to the present invention.

[0026] Figure 6 is a flowchart sequentially explaining a method for joining electronic components using pneumatic pressure according to the present invention.

[0027] Figure 7 is a drawing showing the test results and image photographs of a specimen sintered under pressure using a method for joining electronic components using pneumatic pressure according to the present invention.

[0028] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0029] Fig. 1 shows the internal structure of a pneumatic chamber used in a method for joining electronic components using pneumatic pressure according to the present invention, and Fig. 2 shows the internal structure of a pneumatic chamber in which a heat-conducting plate is installed.

[0030] Referring to FIGS. 1 and 2, an embodiment of the present invention will be described as an example of a method for joining two electronic components, a power semiconductor chip (10) and a heat dissipation substrate (40), using pneumatic pressure.

[0031] In the method for bonding electronic components using pneumatic pressure according to the present invention, a bonded body (50) in which a power semiconductor chip (10) and a heat dissipation substrate (40) are bonded with a conductive bonding member (30) is introduced into a pneumatic chamber (100) and pressure sintered under a high temperature and high pressure environment, thereby manufacturing a product having excellent bonding quality.

[0032] The joint (50) that is introduced into the pneumatic chamber (100) may be a joint (50) formed by laminating a conductive joint (30) on a heat dissipation substrate (40) and then laminating a power semiconductor chip (10) on the conductive joint (30).

[0033] In this case, a conductive paste or conductive film containing Ag can be used as the conductive bonding member (30).

[0034] Inside the pneumatic chamber (100) into which the joint body (50) in which the power semiconductor chip (10) is jointed with a conductive joint member (30) on a heat sink (40) is introduced, a heat conducting plate (110), a temperature control device (120), and a pressure control device (130) are provided.

[0035] The heat-conducting plate (110) is located inside the pneumatic chamber (100) into which the joint (50) is initially introduced, and the joint (50) introduced into the pneumatic chamber (100) is placed on the heat-conducting plate (110) in a pre-heated state, so that it can be heated to a certain temperature within a short period of time through the heat-conducting plate (110).

[0036] In this case, the heat-conducting plate (110) is continuously maintained in a state of being preheated to a temperature of 350°C through the temperature control device (120) before the joint (50) is introduced into the pneumatic chamber (100), so that when the joint (50) introduced into the pneumatic chamber (100) comes into contact with the heat-conducting plate (110), the joint (50) can be heated in a short period of time. However, the temperature at which the heat-conducting plate (110) is heated is not necessarily limited to the above-mentioned 350°C temperature.

[0037] The pressure control device (130) can maintain the inside of the pneumatic chamber (100) at a high temperature and high pressure environment that allows for pressure sintering of the joint (50) by continuously circulating air inside the pneumatic chamber (100) and increasing the inside of the pneumatic chamber (100) to a set pressure (for example, up to 1 MPa).

[0038] For reference, the graph illustrated in FIG. 3 shows the relationship between temperature and pressure increase when a high temperature and high pressure environment is created inside the pneumatic chamber (100) through a temperature control device (120) and a pressure control device (130).

[0039] Meanwhile, Fig. 4 shows a process for bonding a semiconductor chip and a heat dissipation substrate using a conventional press. As shown in Fig. 4, a conductive paste is first applied or a conductive film is transferred on a heat dissipation substrate (3) to form a conductive bonding layer (4), and a power semiconductor chip (1) having a plating layer (2, for example, an Au plating layer) formed on the lower surface is placed on the conductive bonding layer (4), and the power semiconductor chip (1) is pressed downward by a press in a constant temperature environment to bond the power semiconductor chip.

[0040] However, the conventional bonding method using a press has a disadvantage in that the number of power semiconductor chips and heat dissipation substrates that can be bonded at one time is limited depending on the press's pressing area. In addition, since the bonding between the power semiconductor chip (1) and the heat dissipation substrate (3) is performed using the mechanical pressure of the press, there is a possibility of pressure deviation depending on the position of the conductive bonding layer (4), which makes it difficult to ensure reproducibility of the process.

[0041] For this reason, in the present invention, rather than using a conventional mechanical pressurization method using a press, the power semiconductor chip, the heat dissipation substrate, and the conductive bonding layer are uniformly pressurized from all sides by utilizing the pneumatic pressure acting inside the pneumatic chamber (100), thereby enabling the power semiconductor chip and the heat dissipation substrate to be firmly bonded with excellent bonding quality without causing a pressure deviation depending on the position of the bonding area between them.

[0042] Figure 5 is a process diagram showing a process of bonding a semiconductor chip and a heat dissipation substrate using pneumatic pressure according to the present invention.

[0043] As shown in FIG. 5, a conductive bonding member (30) is laminated and formed on a heat dissipation substrate (40), and a power semiconductor chip (11) having a plating layer (20, for example, an Au plating layer) formed on the lower surface of the conductive bonding member (30) is mounted to prepare a joint (50), and then the joint (50) is introduced into a pneumatic chamber (100), and when the inside of the pneumatic chamber (100) reaches a certain pressure, the heat dissipation substrate (40) of the joint (50) is brought into contact with a pre-heated heat-conducting plate (110) so that the temperature quickly rises to a set temperature, thereby causing the joint (50) to be pressure-sintered by pressure applied in all directions under a high temperature and high pressure environment created inside the pneumatic chamber (100), thereby obtaining a power semiconductor and heat dissipation substrate joint that is firmly joined with excellent quality without causing a pressure deviation depending on the position of the joining part.

[0044] Figure 6 is a flowchart sequentially explaining a method for joining electronic components using pneumatic pressure according to the present invention.

[0045] Referring to FIG. 6, a method for bonding a power semiconductor chip and a heat dissipation substrate according to an embodiment of the present invention first prepares a bonded body (50) in which a power semiconductor chip (10) and a heat dissipation substrate (40) are bonded by a conductive bonding member (30) (S10).

[0046] Then, the joint (50) is introduced into the pneumatic chamber (100) and the joint (50) is placed at a position that does not directly contact the heat conducting plate (110) heated to a certain temperature (S20).

[0047] In this case, the heat conducting plate (110) inside the pneumatic chamber (100) can be maintained in a heated state at a temperature of 350°C through a temperature control device (120) prior to the initial introduction of the joint (50) into the pneumatic chamber (100).

[0048] Here, if the joint (50) introduced into the pneumatic chamber (100) comes into direct contact with the heat-conducting plate (110) heated to a high temperature of 350°C, a problem may occur in which the inside of the pneumatic chamber (100) is sintered before the set pressure is reached. Therefore, it is necessary to prevent the pneumatic chamber (100) from coming into contact with the heat-conducting plate (110) until the set pressure (e.g., 1 MPa) is reached.

[0049] Accordingly, in order to prevent the joint (50) initially introduced into the pneumatic chamber (100) from making direct contact with the heat-conducting plate (110), the space between the joint (50) and the heat-conducting plate (110) is covered with a heat-blocking member (not shown), or the joint (50) is placed on a separate jig so that it is positioned at a position spaced apart from the upper portion of the heat-conducting plate (110), thereby temporarily blocking heat from being directly transferred from the heat-conducting plate (110) to the joint (50).

[0050] In this way, various methods other than the above-mentioned method can be used as long as heat transfer between the heat conduction plate (110) and the joint (50) can be temporarily blocked until the inside of the pneumatic chamber (100) reaches the set pressure.

[0051] As in the above step S20, after the initial joint (50) is placed inside the pneumatic chamber (100) at a position that does not directly contact the heat conducting plate (110), the internal pressure of the pneumatic chamber (100) into which the joint (50) is placed is increased to a set pressure (e.g., 1 MPa) using a pressure control device (130) (S30).

[0052] Then, when the internal pressure of the pneumatic chamber (100) reaches the set pressure, the heat-insulating member covering the space between the heat-conducting plate (110) and the joint (50) is removed, or the joint (50) mounted on the jig is lowered so that the heat-radiating plate (40) portion of the joint (50) touches the heat-conducting plate (110), and then the joint (50) is pressurized and sintered for a certain period of time under a high-temperature and high-pressure environment within the pneumatic chamber (100) (S40).

[0053] When the joint (50) comes into contact with the high-temperature heat-conducting plate (110), the temperature of the joint (50) rises instantaneously due to heat conduction transmitted from the heat-conducting plate (110), and the joint (50) is pressurized and sintered for a certain period of time in a high-temperature and high-pressure environment, thereby firmly bonding the power semiconductor chip (10) and the heat-dissipating substrate (40).

[0054] As described above, the bonding process between the power semiconductor chip (10) and the heat dissipation substrate (40) is performed as a batch process under a high temperature and high pressure environment created within a pneumatic chamber (100), so that productivity can be greatly increased since it is not limited by the pressing area of ​​the press as in the bonding method using a conventional press.

[0055] In addition, by using high-temperature heat transferred in a short period of time by the contact of the pneumatic pressure and the heat conducting plate (110) created in the pneumatic chamber (100) rather than the mechanical pressure using the existing press, the bonding is performed by pressure sintering in a high-pressure, high-temperature environment, so that no pressure deviation occurs at each position of the bonding portion, and an overall uniform, high-quality, and strong bonding structure with almost no void generation can be formed. Accordingly, there is an advantage in that the reproducibility of the bonding process between the power semiconductor chip (10) and the heat dissipation substrate (40) is excellent, and a product with uniform bonding quality can be obtained.

[0056] For reference, Fig. 7 shows the test results and image photographs of a specimen pressure-sintered using the electronic component joining method using pneumatic pressure according to the present invention.

[0057] In the test of Fig. 7, a 50 μm thick Ag film was used as a conductive bonding member, the lower plate (heat dissipation substrate) was formed at a temperature environment of 350°C, the upper plate (power semiconductor chip) was formed at 80°C, and the sintering pressure was formed at a pressure environment of 1 MPa. In addition, the upper plate (power semiconductor chip) used a 5×5 mm specimen whose lower surface was plated with Au.

[0058] As confirmed from the sintering test results in Fig. 7, the post-sintering image of the pressure-sintered specimen in the pneumatic chamber (sintering equipment) is as shown in the photo on the right, and as confirmed from the graph on the left, the shear strength test results of the sintered specimen also confirmed that the bonding strength (shear strength in the graph) between the power semiconductor chip and the heat dissipation substrate increased to a very excellent value depending on the sintering time.

[0059] The above description is merely an example of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention.

Claims

1. A step of preparing a temporary joint by temporarily joining a semiconductor chip and a substrate using a bonding member; A step of introducing a joint into a pneumatic chamber and placing the joint at a position that does not directly contact a heat-conducting plate heated to a certain temperature; A step of increasing the internal pressure of the pneumatic chamber into which the adhesive is inserted to the set pressure; A step of bringing the joint into contact with a heat conducting plate when the internal pressure of the pneumatic chamber reaches a set pressure and pressurizing and sintering the joint for a certain period of time in a high temperature and high pressure environment within the pneumatic chamber; A method for joining electronic components using pneumatic pressure, including:

2. In paragraph 1, A method for joining electronic components using pneumatic pressure, wherein the above-mentioned joining member is composed of a metal material having electrical conductivity and thermal conductivity.

3. In paragraph 2, A method for joining electronic components using pneumatic pressure, wherein the above-mentioned joining member is made of a conductive paste or conductive film containing Ag.

4. In paragraph 1, In the step of preparing the above-mentioned joint, A method for joining electronic components using pneumatic pressure, which prepares a temporary joint by interposing a joining member between a semiconductor chip and a substrate on which an Au plating layer has been formed on the lower surface.

5. In paragraph 1, A method for joining electronic components using pneumatic pressure, wherein the heat-conducting plate is maintained at a temperature of 350°C using a temperature control device before introducing the above-mentioned joint into the pneumatic chamber.

6. In paragraph 1, In the step of increasing the internal pressure of the above pneumatic chamber to the set pressure, A method for joining electronic components using pneumatic pressure, which operates a pressure control device to circulate air inside a pneumatic chamber and increase the internal pressure to a set pressure that allows for pressure sintering of a joint.

7. In paragraph 6, A method for joining electronic components using pneumatic pressure, which increases the internal pressure of a pneumatic chamber to a maximum of 1 MPa using the above pressure regulating device.

8. In paragraph 1, In the step of placing the joint inside the above pneumatic chamber, A method for joining electronic components using pneumatic pressure, in which a heat-insulating member is interposed between the joint and the heat-conducting plate, and the joint is positioned so that the joint and the heat-conducting plate do not come into direct contact.

9. In paragraph 8, In the step of pressure sintering the above-mentioned joint, A method for joining electronic components using pneumatic pressure, wherein when the internal pressure of the pneumatic chamber reaches the set pressure, a heat-insulating member placed between the heat-conducting plate and the joint is removed to bring the substrate of the joint into contact with the heat-conducting plate.

10. In paragraph 1, In the step of placing the joint inside the above pneumatic chamber, A method for joining electronic components using pneumatic pressure, in which a joint is placed on a jig positioned at an upper position away from a heat-conducting plate so as not to come into direct contact with the heat-conducting plate.

11. In paragraph 10, In the step of pressure sintering the above-mentioned joint, A method for joining electronic components using pneumatic pressure, in which when the internal pressure of the pneumatic chamber reaches the set pressure, the joint on the jig is lowered to bring the substrate of the joint into contact with the heat conducting plate.

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