Power device packaging method and semiconductor power device

Abstract

The invention discloses a packaging method of a power device and a semiconductor power device, relates to the technical field of semiconductor device packaging, and can solve the problem of incomplete coverage of chip bonding glue so as to improve the product yield and reliability of the semiconductor power device. According to the specific scheme, the method comprises the steps that a plurality of substrate structures are obtained, each substrate structure comprises a frame carrier and a ceramic substrate arranged on the frame carrier, and the frame carrier and the ceramic substrate are bonded through soft solder; for the ceramic substrate in each substrate structure, acquiring the current height of the current ceramic substrate, and taking the current height as the reference height for generating the chip adhesive on the current ceramic substrate; and after chip bonding glue is generated on the ceramic substrate according to the reference height, the chip is fixed on the ceramic substrate by using the chip bonding glue.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor device packaging, and in particular to a packaging method for a power device and a semiconductor power device. Background Art

[0002] With the accelerated replacement of semiconductor devices and the increasing use of power semiconductors in automotive applications, higher demands are being placed on device reliability. During the chip packaging process for power devices, die bonding material not only secures the chip to the lead frame but also provides electrical conductivity and heat dissipation. Therefore, die bonding material plays a crucial role between the chip and the lead frame.

[0003] Currently, the standard height for measuring glue dispensing in normal packaging is the height of the first chip on the measurement frame, and subsequent products are also dispensed according to this standard height. However, for multi-chip packaging products using soft solder to bond a DPC substrate, further bonding is required. Since soft solder bonds the die at high temperatures, solder reflow at high temperatures can affect the flatness of the substrate after bonding, resulting in varying degrees of difference. During the process of applying glue or dispensing on the substrate, due to the difference in substrate flatness, the glue application or dispensing pattern may be incomplete, or the dispensing head may be damaged by impact. This results in incomplete adhesive coverage after bonding, thus affecting product yield and reliability. Summary of the Invention

[0004] The present application provides a packaging method for a power device and a semiconductor power device, which can solve the problem of incomplete chip adhesive coverage, thereby improving the product yield and reliability of the semiconductor power device.

[0005] To achieve the above objectives, this application adopts the following technical solutions:

[0006] In a first aspect of an embodiment of the present application, a method for packaging a power device is provided, the method comprising:

[0007] Obtain a plurality of substrate structures, each of the substrate structures comprising: a frame carrier and a ceramic substrate disposed on the frame carrier, wherein the frame carrier and the ceramic substrate are bonded together by soft solder;

[0008] For each ceramic substrate in the substrate structure, obtaining a current height of the current ceramic substrate, and using the current height as a reference height for generating a die-bonding adhesive on the current ceramic substrate;

[0009] After die bonding adhesive is generated on the ceramic substrate according to the reference height, the chip is fixed on the ceramic substrate using the die bonding adhesive.

[0010] As a possible implementation manner, obtaining the current height of the current ceramic substrate includes:

[0011] After the dispensing head is lowered to contact the first surface of the ceramic substrate, a contact sensor integrated in the dispensing head is used to obtain a current height of the first surface.

[0012] As a possible implementation manner, the step of generating a die-bonding adhesive on the ceramic substrate according to the reference height includes:

[0013] After the dispensing head is raised a first distance on the reference height, the dispensing head is used to apply glue on the first surface of the ceramic substrate to generate the die-bonding glue.

[0014] As a possible implementation manner, the first distance is: 100-150 um.

[0015] As a possible implementation manner, the adhesive is conductive silver glue, insulating glue or liquid glue.

[0016] As a possible implementation, after obtaining the current height of the ceramic substrate using the contact sensor integrated in the dispensing head, the method further includes:

[0017] determining a contact height according to the current height;

[0018] For the next ceramic substrate, when the dispensing head descends to the contact height, it continues to descend at a preset contact speed until it contacts the first surface of the ceramic substrate.

[0019] As a possible implementation manner, the contact height is 100-400 um on the first surface, and the contact speed is 10-40 um / ms.

[0020] As a possible implementation manner, after the chip is fixed on the ceramic substrate by using the die bonding adhesive, the method further includes:

[0021] The die bonding adhesive is cured according to a preset baking process temperature curve to obtain a cured structure.

[0022] As a possible implementation manner, after obtaining the solidified structure, the method further includes:

[0023] The solidified structure is sequentially subjected to plasma cleaning, wiring, plastic sealing, tinning and rib cutting processes.

[0024] According to a second aspect of the embodiments of the present application, a semiconductor power device is provided. The semiconductor power device is prepared by using the packaging of a power device according to the first aspect of the embodiments of the present application.

[0025] The beneficial effects of the technical solutions provided in the embodiments of the present application include at least:

[0026] The power device packaging method provided in an embodiment of the present application obtains multiple substrate structures, each substrate structure comprising: a frame carrier and a ceramic substrate disposed on the frame carrier, the frame carrier and the ceramic substrate being bonded together by soft solder. For each ceramic substrate in the substrate structure, the current height of the ceramic substrate is obtained, and the current height is used as a reference height for generating die bonding adhesive on the current ceramic substrate. After generating die bonding adhesive on the ceramic substrate based on the reference height, the chip is secured to the ceramic substrate using the die bonding adhesive. The power device packaging method provided in the present application measures the reference height of the adhesive dispensed on each solder-bonded ceramic substrate before applying the adhesive. This method can effectively prevent incomplete die bonding adhesive coverage of the upper chip caused by inconsistent die bonding adhesive heights on the ceramic substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A flowchart of a power device packaging method provided in an embodiment of the present application;

[0028] Figure 2 This is a front view of a sheet after bonding provided in an embodiment of the present application;

[0029] Figure 3 A top view of a wafer after bonding provided in an embodiment of the present application;

[0030] Figure 4 A schematic diagram of dispensing glue on a DPC substrate on the first substrate structure provided in an embodiment of the present application;

[0031] Figure 5 A schematic diagram of dispensing glue on a DPC substrate on a second substrate structure provided in an embodiment of the present application;

[0032] Figure 6 This is a schematic diagram of a normal glue drawing after measuring the reference height on the DPC provided in an embodiment of the present application;

[0033] Figure 7 This is a schematic diagram of a normal adhesive bond after the reference height is measured on the DPC provided in an embodiment of the present application;

[0034] Figure 8 A schematic diagram of an abnormality of glue drawing without measuring the reference height on the DPC provided in an embodiment of the present application;

[0035] Figure 9 This is a schematic diagram of incomplete adhesive coverage after the adhesive is abnormally adhered to the DPC without measuring the reference height provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0037] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

[0038] Additionally, the use of “based on” or “according to” is intended to be open and inclusive, in that a process, step, calculation, or other action “based on” or “according to” one or more conditions or values ​​may, in practice, be based on additional conditions or beyond values.

[0039] With the accelerated replacement of semiconductor devices and the increasing use of power semiconductors in automotive applications, higher demands are being placed on device reliability. During the chip packaging process for power devices, die bonding material not only secures the chip to the lead frame but also provides electrical conductivity and heat dissipation. Therefore, die bonding material plays a crucial role between the chip and the lead frame.

[0040] Usually, different bonding materials may be used for each chip in a power semiconductor multi-chip package. Some chips are bonded with soft solder, some with conductive silver glue, and some with insulating glue or DAF insulating film. Bonding materials play a vital role in the connection between the chip and the lead frame in the power device semiconductor packaging process. They not only fix the chip on the frame, but also conduct electricity and dissipate heat. Soft solder is a high-temperature bonding material and needs to be melted at above 200 degrees Celsius before bonding. Ordinary silver paste is bonded at room temperature, and DAF insulating film needs to be bonded at a temperature of about 130 degrees Celsius. Soft solder and DAF insulating film do not need to be baked and cured after bonding. The bonding glue used for bonding at room temperature needs to be baked and cured at a certain temperature after bonding.

[0041] Currently, the standard height for measuring glue dispensing in normal packaging is the height of the first chip on the measurement frame, and subsequent products are also dispensed according to this standard height. However, for multi-chip packaging products using soft solder to bond a DPC substrate, further bonding is required. Since soft solder bonds the die at high temperatures, solder reflow at high temperatures can affect the flatness of the substrate after bonding, resulting in varying degrees of difference. During the process of applying glue or dispensing on the substrate, due to the difference in substrate flatness, the glue application or dispensing pattern may be incomplete, or the dispensing head may be damaged by impact. This results in incomplete adhesive coverage after bonding, thus affecting product yield and reliability.

[0042] In order to solve the above problems, the present invention provides a packaging method for a power device. Figure 1 As shown, the method includes the following steps:

[0043] Step 101: Acquire multiple substrate structures, each of the substrate structures comprising: a frame carrier and a ceramic substrate disposed on the frame carrier, wherein the frame carrier and the ceramic substrate are bonded together by soft solder;

[0044] The ceramic substrate may be a DPC substrate. The bonding material used between the DPC substrate and the frame carrier is soft solder with a melting point above 200 degrees Celsius, and the bonding material used between the chip and the DPC substrate is insulating glue or liquid glue. Figure 2 This is the main view after gluing. Figure 3 It is a top view after the chips are bonded. Figure 2 and Figure 3 In the figure, 1 is the frame carrier, 2 is the soft solder, 3 is the DPC ceramic substrate, 4 is the adhesive, and 5 is the chip.

[0045] Step 102: for each ceramic substrate in the substrate structure, obtaining a current height of the current ceramic substrate, and using the current height as a reference height for generating a die bonding adhesive on the current ceramic substrate;

[0046] Optionally, obtaining the current height of the current ceramic substrate includes: lowering the dispensing head until it contacts the first surface of the ceramic substrate, and then using the contact sensor integrated in the dispensing head to obtain the current height of the first surface. The delay when the dispensing head descends can be 10 to 30 ms. Figure 4 As shown in FIG. 1 , it is a schematic diagram of dispensing glue on the DPC substrate on the first substrate structure. Figure 5 The figure shows the dispensing diagram of the DPC substrate on the second substrate structure. Figure 4 and Figure 5 The number 6 in the middle mark is the contact sensor, and the number 7 is the dispensing head.

[0047] Step 103 : After forming a die-bonding adhesive on the ceramic substrate according to the reference height, the chip is fixed on the ceramic substrate using the die-bonding adhesive.

[0048] Optionally, generating a die-bonding adhesive on the ceramic substrate according to the reference height includes:

[0049] After the dispensing head is raised a first distance on the reference height, the dispensing head is used to apply glue on the first surface of the ceramic substrate to generate the die-bonding glue.

[0050] The first distance may be 100-150 μm, and the adhesive may be conductive silver glue, insulating glue or liquid glue. The liquid glue may be liquid glue. Figure 6 The following is a normal diagram of glue drawing after measuring the reference height on DPC. Figure 7 This is a schematic diagram of normal adhesive coverage after the benchmark height is measured on the DPC and the adhesive is normally applied to the film; Figure 8 This is a schematic diagram of the glue anomaly on the DPC due to unmeasured reference height. Figure 9 This is a schematic diagram showing incomplete adhesive coverage after the adhesive is abnormally bonded without measuring the reference height on the DPC.

[0051] Optionally, after obtaining the current height of the ceramic substrate using a contact sensor integrated in the dispensing head, the method further includes:

[0052] A contact height is determined based on the current height. For the next ceramic substrate, when the dispensing head descends to the contact height, the dispensing head continues to descend at a preset contact speed until it contacts the first surface of the ceramic substrate. The contact height may be 100 to 400 μm above the first surface, and the contact speed may be 10 to 40 μm / ms.

[0053] It is understandable that during the descent of the dispensing head, it first descends at a faster speed, and then descends at a slower contact speed when it reaches the contact height, so as to avoid the dispensing head from descending too quickly and damaging the dispensing head.

[0054] Optionally, after the chip is fixed on the ceramic substrate by using the die bonding adhesive, the method further includes:

[0055] The die bonding adhesive is cured according to a preset baking process temperature curve to obtain a cured structure.

[0056] Optionally, after obtaining the solidified structure, the method further comprises:

[0057] The solidified structure is sequentially subjected to plasma cleaning, wiring, plastic sealing, tinning and rib cutting processes.

[0058] During the actual implementation process, when the first substrate structure moves to the dispensing position, the dispensing head measures the height on the DPC surface at a certain descending speed. The height measurement uses a contact sensor. When the contact sensor detects that the dispensing head contacts the DPC surface, the current height is recorded. The equipment records the dispensing reference height of the first substrate structure and raises it 100-150um at this height to apply glue. After the glue is applied, the first substrate structure continues to move forward. When the second substrate structure moves to the dispensing position, the dispensing head also measures the height from the dispensing head to the DPC surface in the second substrate structure according to the parameters of the first one. After the measurement is completed, the equipment will overwrite the previous reference height and raise it 100-150um according to the currently measured reference height for glue application. After the glue is applied, the substrate structure continues to move forward, and so on. The subsequent carriers follow the same method. Each time they reach a substrate structure, the dispensing reference height is measured and the measurement value of the previous one is overwritten. The glue is raised 100-150um at this height for glue application. After the glue is applied, the adhesive can be 100% covered.

[0059] The power device packaging method provided in an embodiment of the present application obtains multiple substrate structures, each substrate structure comprising: a frame carrier and a ceramic substrate disposed on the frame carrier, the frame carrier and the ceramic substrate being bonded together by soft solder. For each ceramic substrate in the substrate structure, the current height of the ceramic substrate is obtained, and the current height is used as a reference height for generating die bonding adhesive on the current ceramic substrate. After generating die bonding adhesive on the ceramic substrate based on the reference height, the chip is secured to the ceramic substrate using the die bonding adhesive. The power device packaging method provided in the present application measures the reference height of the adhesive dispensed on each solder-bonded ceramic substrate before applying the adhesive. This method can effectively prevent incomplete die bonding adhesive coverage of the upper chip caused by inconsistent die bonding adhesive heights on the ceramic substrate.

[0060] In addition, this application also provides a specific embodiment, which is as follows:

[0061] This example uses die bonding on a DPC ceramic substrate as an example. The frame carrier utilizes a nickel-plated frame made of TOLL pins. The DPC and frame carrier are bonded using Pb95.5Sn2Ag2.5 soft solder for high-temperature bonding. The DPC and the chip on top of it are bonded at room temperature using ATROX 800HT2V-P1 adhesive. The die bonding process described below involves bonding the chip to the first surface of the DPC substrate.

[0062] During the specific implementation process, the DPC bonding program is first debugged in the equipment. When the DPC ceramic substrate is placed on the core as required, the core is debugged by selecting the nozzle, ejector, die head and other consumables as required; the track temperature of the tin dropping area, die area and welding area is set within 340±40℃, and the process parameters are adjusted for DPC soft solder bonding. The solder thickness is controlled at 25-75um, and the solder voids are controlled at ≤5% for a single one and ≤10% for the whole.

[0063] After the DPC soft solder bonding is completed, the DPC upper chip bonding is debugged. ATROX 800HT2V-P1 bonding adhesive is used to bond the chips. After the product is loaded on the machine, the nozzle, ejector, dispensing head and the reheated bonding adhesive are selected as required. After replacing the bonding adhesive, the search contact sensor function is turned on, the dispensing head descending delay is set to 10ms, the search contact speed is set to 20um / ms, the search contact height is set to 200um, and the glue drawing height is set to be 100um higher than the base height.

[0064] When the first substrate structure moves to the dispensing position, the dispensing head measures the height on the DPC surface at a certain descending speed. The height measurement uses a contact sensor. When the contact sensor detects that the dispensing head contacts the DPC surface, it records the current height. The equipment records the dispensing reference height of the first substrate structure and raises it 100-150um at this height to apply glue. After the application of glue is completed, the first substrate structure continues to move forward. When the second substrate structure moves to the dispensing position, the dispensing head also measures the height from the dispensing head to the DPC surface in the second substrate structure according to the parameters of the first one. After the measurement is completed, the equipment will overwrite the previous reference height and raise it 100-150um according to the currently measured reference height for application of glue. After the application of glue is completed, the substrate structure continues to move forward, and so on. The subsequent carriers follow the same method. Each time they reach a substrate structure, they will measure the dispensing reference height and overwrite the measurement value of the previous one. They will raise it 100-150um according to this height for application of glue.

[0065] After the glue is applied, the die is bonded according to the set process parameters. After bonding, the adhesive is cured in an oven according to a fixed baking process temperature curve. After curing, the post-process plasma cleaning, wiring, plastic sealing, tinning and rib cutting are carried out to complete the packaging.

[0066] The present invention also provides a semiconductor power device, which is manufactured using a power device packaging method provided in the present invention. The power device packaging method includes:

[0067] Obtain a plurality of substrate structures, each of the substrate structures comprising: a frame carrier and a ceramic substrate disposed on the frame carrier, wherein the frame carrier and the ceramic substrate are bonded together by soft solder;

[0068] For each ceramic substrate in the substrate structure, obtaining a current height of the current ceramic substrate, and using the current height as a reference height for generating a die-bonding adhesive on the current ceramic substrate;

[0069] After die bonding adhesive is generated on the ceramic substrate according to the reference height, the chip is fixed on the ceramic substrate using the die bonding adhesive.

[0070] In one embodiment, obtaining the current height of the ceramic substrate includes:

[0071] After the dispensing head is lowered to contact the first surface of the ceramic substrate, a contact sensor integrated in the dispensing head is used to obtain a current height of the first surface.

[0072] In one embodiment, the step of generating a die-bonding adhesive on the ceramic substrate according to the reference height includes:

[0073] After the dispensing head is raised a first distance on the reference height, the dispensing head is used to apply glue on the first surface of the ceramic substrate to generate the die-bonding glue.

[0074] In one embodiment, the first distance is 100-150 um.

[0075] In one embodiment, the adhesive is conductive silver glue, insulating glue or liquid glue.

[0076] In one embodiment, after obtaining the current height of the ceramic substrate using the contact sensor integrated in the dispensing head, the method further includes:

[0077] determining a contact height according to the current height;

[0078] For the next ceramic substrate, when the dispensing head descends to the contact height, it continues to descend at a preset contact speed until it contacts the first surface of the ceramic substrate.

[0079] In one embodiment, the contact height is 100-400 um on the first surface, and the contact speed is 10-40 um / ms.

[0080] In one embodiment, after the chip is fixed on the ceramic substrate using the die bonding adhesive, the method further includes:

[0081] The die bonding adhesive is cured according to a preset baking process temperature curve to obtain a cured structure.

[0082] In one embodiment, after obtaining the solidified structure, the method further comprises:

[0083] The solidified structure is sequentially subjected to plasma cleaning, wiring, plastic sealing, tinning and rib cutting processes.

[0084] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The above embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for packaging a power device, characterized in that: The method comprises: Acquire a plurality of substrate structures, each of the substrate structures comprising: a frame carrier and a ceramic substrate disposed on the frame carrier, wherein the frame carrier and the ceramic substrate are bonded by soft solder; For each ceramic substrate in the substrate structure, obtaining a current height of the current ceramic substrate, and using the current height as a reference height for generating a die bonding adhesive on the current ceramic substrate; After die-bonding adhesive is generated on the ceramic substrate according to the reference height, the chip is fixed on the ceramic substrate by using the die-bonding adhesive.

2. The method according to claim 1, characterized in that The obtaining of the current height of the current ceramic substrate comprises: After the dispensing head is lowered to contact with the first surface of the ceramic substrate, a contact sensor integrated in the dispensing head is used to obtain a current height of the first surface.

3. The method according to claim 2, characterized in that The step of generating a bonding adhesive on the ceramic substrate according to the reference height includes: After the dispensing head is raised by a first distance on the reference height, the dispensing head is used to apply glue on the first surface of the ceramic substrate to generate the bonding glue.

4. The method according to claim 3, characterized in that: The first distance is 100-150 um.

5. The method according to claim 3, characterized in that: The adhesive is conductive silver glue, insulating glue or liquid glue.

6. The method according to claim 2, characterized in that After obtaining the current height of the current ceramic substrate using the contact sensor integrated in the dispensing head, the method further includes: Determining a contact height according to the current height; For the next ceramic substrate, when the dispensing head descends to the contact height, it continues to descend at a preset contact speed until it contacts the first surface of the ceramic substrate.

7. The method according to claim 6, characterized in that The contact height is 100-400 um on the first surface, and the contact speed is 10-40 um / ms.

8. The method according to claim 1, characterized in that After the chip is fixed on the ceramic substrate by using the die bonding adhesive, the method further includes: The die bonding adhesive is cured according to a preset baking process temperature curve to obtain a cured structure.

9. The method according to claim 8, characterized in that After obtaining the solidified structure, the method further comprises: The solidified structure is sequentially subjected to plasma cleaning, wiring, plastic sealing, tinning and rib cutting treatments.

10. A semiconductor power device, characterized in that: The semiconductor power device is prepared by packaging a power device according to any one of claims 1 to 9.

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