CN115151048A - Method for preparing ceramic substrate and power module and corresponding equipment - Google Patents

Abstract

The invention provides a preparation method and corresponding equipment of a ceramic substrate and a power module, wherein the preparation method of the ceramic substrate comprises the following steps of S1, brushing a layer of silver colloid on a mounting surface of a ceramic substrate; s2, pasting a layer of copper foil on the silver adhesive, and then pressing the ceramic substrate and the copper foil; s3, pasting a photosensitive film on the pressed copper foil, and then sequentially carrying out development and first cleaning to remove the photosensitive film on the part of the copper foil which is not required to be reserved; s4, removing the part, which is not required to be reserved, of the copper foil through etching, and then tearing off the rest photosensitive film; and S5, removing the silver paste below the part, which is not required to be reserved, of the copper foil through secondary cleaning, so as to obtain the ceramic substrate. The preparation method of the ceramic substrate does not need sputtering equipment in the conventional production process, and compared with the sputtering process, the process is simpler and the cost is lower.

Description

Method for preparing ceramic substrate and power module and corresponding equipment

Technical Field

The invention relates to the technical field of electronic devices, in particular to a method for preparing a ceramic substrate and a power module and corresponding equipment.

Background

The Power device is a Modular Intelligent Power System (MIPS), which is a Power driving product combining Power electronics and integrated circuit technology, and the MIPS not only integrates a Power switch device and a driving circuit, but also is internally provided with fault detection circuits such as overvoltage, overcurrent and overheat, and the MIPS can send detection signals to a CPU or a DSP for interrupt processing. The MIPS mainly comprises a high-speed low-power-consumption tube core, an optimized gate-level driving circuit and a quick protection circuit, and even if a load accident or improper use occurs, the MIPS can be prevented from being damaged.

However, with the demand for energy saving and emission reduction and the progress of semiconductor technology, more and more power modules are applied to products such as household appliances and new energy vehicles. When the power module works, internal power components can generate high heat, so that the requirement on the heat dissipation performance of the module is high.

The MIPS module of less power encapsulates on aluminium base board, and aluminium has fine heat conductivility but aluminium is the conductor again simultaneously, consequently needs to be equipped with one deck insulating layer between aluminium base board and the circuit layer, and the insulating layer is because coefficient of heat conductivity is little, so can influence the heat conductivility of aluminium base board, therefore the insulating layer need be done very thinly, but this makes the power of module too big in order to avoid heavy current to damage the insulating layer thereby to lead to the short circuit again.

High-power MIPS module generally uses ceramic substrate, and alumina ceramics has fine heat conductivity and insulating material again, and the manufacture process of current ceramic substrate is through the mode of sputtering in order to make ceramic surface metallization, then at the etching of metallization surface and generate the circuit, electroplates at last and makes the circuit layer bodiness, and this kind of technology through sputtering prepares ceramic substrate, not only leads to the technology complicated, and its cost is still high, has seriously influenced ceramic substrate's popularization.

Disclosure of Invention

Aiming at the defects of the related technologies, the invention provides a preparation method of a ceramic substrate, which aims to solve the problems of complex process and high manufacturing cost caused by the preparation of the existing ceramic substrate through a sputtering process.

In order to solve the above technical problem, in a first aspect, the present invention provides a method for preparing a ceramic substrate, including the steps of:

s1, brushing a layer of silver colloid on a mounting surface of a ceramic substrate;

s2, pasting a layer of copper foil on the silver adhesive, and then pressing the ceramic substrate and the copper foil;

s3, pasting a photosensitive film on the pressed copper foil, and then sequentially carrying out development and first cleaning to remove the photosensitive film on the part of the copper foil which is not required to be reserved;

s4, removing the part, which is not required to be reserved, of the copper foil through etching, and then tearing off the rest photosensitive film;

and S5, removing the silver colloid under the part, which does not need to be reserved, of the copper foil through secondary cleaning, so as to obtain the ceramic substrate.

Preferably, in the step S1, the step of brushing a layer of silver paste on the mounting surface of the ceramic substrate includes: firstly, placing the ceramic substrate into a jig, then placing the ceramic substrate and the jig on an offset printing machine together, and finally brushing the silver colloid on the mounting frame of the ceramic foundation through the offset printing machine; wherein, the thickness of the silver colloid is 0.2mm.

Preferably, in the step S2, the step of attaching a layer of copper foil to the silver paste specifically includes: selecting the copper foil matched with the mounting surface of the ceramic substrate, then contacting one side of the copper foil with one side of the silver adhesive, and finally rolling on the surface of the copper foil through a roller so as to completely attach the copper foil to the silver adhesive.

Preferably, in the step S2, the step of laminating the ceramic substrate and the copper foil includes: firstly, placing the ceramic substrate and the copper foil together with the jig into a laminating machine, then starting the laminating machine for vacuumizing, and carrying out the press fit on the ceramic substrate and the copper foil; wherein the applied pressure of the laminator after vacuum pumping is 200psi, and the pressing process is kept for 1h at 175 ℃.

Preferably, in the step S3, the specific steps of sequentially performing development and first cleaning to remove the photosensitive film on the portion of the copper foil that does not need to be left are: irradiating the photosensitive film on the part of the copper foil needing to be reserved by adopting ultraviolet light, and then cleaning the photosensitive film for the first time by adopting alkaline solution to remove the photosensitive film on the part of the copper foil needing not to be reserved.

Preferably, in the step S4, the specific steps of removing the portion of the copper foil that does not need to be left by etching are: and carrying out the etching on the copper foil by using a strong alkaline solution so as to remove the part of the copper foil which does not need to be remained.

Preferably, in the step S5, the specific steps of removing the silver paste under the portion of the copper foil which does not need to be remained by the second cleaning are as follows: firstly, placing the etched ceramic substrate into an ultrasonic cleaning machine filled with acetone for chemical cleaning, and then placing the ceramic substrate after chemical cleaning into the ultrasonic cleaning machine filled with deionized water for clean cleaning, thereby removing the silver colloid under the part of the copper foil which is not required to be reserved; in the chemical cleaning process, the temperature of the acetone is 50 ℃, the cleaning time is 30 minutes, and in the clean cleaning process, the cleaning time is 5 minutes.

In a second aspect, the present invention provides a ceramic substrate produced by the method for producing a ceramic substrate as described above.

In a third aspect, the present invention provides a method for manufacturing a power module, including the following steps:

s6, respectively brushing solder paste with the melting point of 220 ℃ on a plurality of mounting positions of copper foil in the ceramic substrate to form a plurality of welding spots; the ceramic substrate used is the ceramic substrate according to claim 8;

s7, respectively mounting a plurality of pins on the copper foil;

s8, curing a plurality of components to the plurality of welding spots by adopting a reflow oven with the peak temperature of 230 ℃;

s9, respectively welding aluminum wires among a plurality of components and between the components and the welding spots so as to realize the electrical connection among the components and between the components and the copper foil;

s10, packaging the component and the exposed part of the copper foil in a plastic package material in an injection molding mode;

and S11, sequentially carrying out punching load and bending to manufacture the pins into the required shapes so as to obtain the power module.

In a fourth aspect, a power module is manufactured by the manufacturing method of the power module as described above.

Compared with the prior art, the preparation method of the ceramic substrate disclosed by the invention has the advantages that the copper foil is tightly attached to the surface of the ceramic substrate by using the silver colloid to prepare and form the ceramic substrate, so that sputtering equipment in the conventional production process is not needed, and the process is simpler and lower in cost compared with the sputtering process.

Drawings

The present invention will be described in detail below with reference to the accompanying drawings. The foregoing and other aspects of the invention will become more apparent and more readily appreciated from the following detailed description, taken in conjunction with the accompanying drawings. In the drawings:

FIG. 1 is a flow chart illustrating the steps of a method for manufacturing a ceramic substrate according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a ceramic substrate, silver paste and a copper foil provided in the embodiment of the present invention after lamination;

FIG. 3 is a schematic diagram of a structure of a photosensitive film on a portion of a copper foil that is not to be left by removing the photosensitive film according to an embodiment of the present invention;

FIG. 4 is a schematic structural view of a portion of a copper foil that is not to be left after removal according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a ceramic substrate according to an embodiment of the present invention;

FIG. 6 is a flowchart illustrating steps of a method for manufacturing a power module according to an embodiment of the present invention;

fig. 7 is a schematic cross-sectional view of a power module according to an embodiment of the present invention;

fig. 8 is a schematic perspective view of a power module according to an embodiment of the present invention.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

The embodiments/examples described herein are specific embodiments of the present invention, are intended to be illustrative of the concepts of the present invention, are intended to be illustrative and exemplary, and should not be construed as limiting the embodiments and scope of the invention. In addition to the embodiments described herein, those skilled in the art will be able to employ other technical solutions which are obvious based on the disclosure of the claims and the specification of the present application, and these technical solutions include those which make any obvious replacement or modification of the embodiments described herein, and all of which are within the scope of the present invention.

Example one

The embodiment of the invention provides a preparation method of a ceramic substrate, which comprises the following steps as shown in figure 1:

s1, brushing a layer of silver colloid on the mounting surface of the ceramic substrate.

Wherein, the installation face of the ceramic substrate is flat and smooth, and other faces can be designed into different shapes or structures according to actual requirements.

In this embodiment, in the step S1, the step of brushing a layer of silver paste on the mounting surface of the ceramic substrate specifically includes: firstly, the ceramic substrate is placed in a jig, then the ceramic substrate and the jig are placed on an offset printing machine together, and finally the silver colloid is brushed on the mounting frame of the ceramic foundation through the offset printing machine.

The thickness of the silver colloid is 0.2mm, and the silver colloid can be controlled by a printing screen plate in an offset printing machine.

After the ceramic substrate and the jig are placed on the offset printing machine together, the mounting surface of the ceramic substrate faces upwards and is kept in a horizontal state, so that the offset printing machine can brush the ceramic substrate conveniently.

S2, pasting a layer of copper foil on the silver paste, and then pressing the ceramic substrate and the copper foil.

Referring to fig. 2, fig. 2 is a schematic structural view of the ceramic substrate, the silver paste, and the copper foil after lamination, wherein 101 is a ceramic base, 102 is a pin, and 103 is a copper foil.

In this embodiment, in the step S2, the step of attaching a layer of copper foil to the silver paste specifically includes: selecting the copper foil matched with the mounting surface of the ceramic substrate, then contacting one side of the copper foil with one side of the silver adhesive, and finally rolling on the surface of the copper foil through a roller so as to completely attach the copper foil to the silver adhesive. Therefore, bubbles can be prevented from being generated between the copper foil and the ceramic substrate in the pasting process.

The thickness of the copper foil may be 61um, 70um, 86um, etc. according to actual requirements, and is not specifically limited herein.

In this embodiment, in the step S2, the step of pressing the ceramic substrate and the copper foil specifically includes: firstly, placing the ceramic substrate and the copper foil together with the jig into a laminating machine, then starting the laminating machine for vacuumizing and carrying out the press-fitting on the ceramic substrate and the copper foil; wherein the applied pressure of the laminator after vacuum pumping is 200psi, and the pressing process is kept for 1h at 175 ℃.

And S3, pasting a photosensitive film on the pressed copper foil, and then sequentially carrying out development and first cleaning to remove the photosensitive film on the part of the copper foil which is not required to be reserved.

Referring to fig. 3, fig. 3 is a schematic structural view of the photosensitive film on the portion of the copper foil that does not need to be remained after removing the copper foil, wherein 104 is the photosensitive film.

In this embodiment, in the step S3, the specific steps of sequentially performing development and first cleaning to remove the photosensitive film on the portion of the copper foil that does not need to be left are as follows: irradiating the photosensitive film on the part of the copper foil needing to be reserved by adopting ultraviolet light (UV light), and then cleaning the photosensitive film for the first time by adopting alkaline solution to remove the photosensitive film on the part of the copper foil needing not to be reserved.

The photosensitive film on the part of the copper foil which is not required to be reserved is not irradiated by ultraviolet light and is not cured on the copper foil, and the photosensitive film can be easily removed by cleaning with the alkaline solution to expose the part of the copper foil which is required to be removed.

And S4, removing the part of the copper foil which is not required to be remained by etching, and then tearing off the rest photosensitive film.

Fig. 4 is a schematic structural view of a portion of the copper foil that does not need to be left removed, as shown in fig. 4.

In this embodiment, in the step S4, the specific steps of removing the portion of the copper foil that does not need to be left by etching are as follows: and carrying out the etching on the copper foil by using a strong alkaline solution so as to remove the part of the copper foil, which does not need to be remained.

Since the portions of the copper foil that are not to be left are not provided with the photosensitive film, the portions can be easily etched away by the strongly alkaline solution to leave the portions of the copper foil that are to be left, thereby forming a circuit.

After the rest photosensitive film is torn off, the remained part of the copper foil can be used for mounting components.

And S5, removing the silver paste below the part, which is not required to be reserved, of the copper foil through secondary cleaning, so as to obtain the ceramic substrate.

Referring to fig. 5, fig. 5 is a schematic structural diagram of a ceramic substrate.

In this embodiment, in the step S5, the specific steps of removing the silver paste under the portion of the copper foil that does not need to be retained by the second cleaning include: firstly, placing the etched ceramic substrate into an ultrasonic cleaning machine filled with acetone for chemical cleaning, and then placing the ceramic substrate after chemical cleaning into the ultrasonic cleaning machine filled with deionized water for clean cleaning, thereby removing the silver colloid under the part of the copper foil which is not required to be reserved; in the chemical cleaning process, the temperature of the acetone is 50 ℃, the cleaning time is 30 minutes, and in the clean cleaning process, the cleaning time is 5 minutes.

Wherein, chemical cleaning with during clean cleaning, the ultrasonic cleaner who uses is same platform, of course, according to actual demand, also can use two different platforms.

Compared with the prior art, the preparation method of the ceramic substrate in the embodiment is used for tightly attaching the copper foil to the surface of the ceramic substrate by using the silver paste to prepare and form the ceramic substrate, so that sputtering equipment in the conventional production process is not needed, and compared with a sputtering process, the process is simpler, lower in cost and more convenient to popularize.

Example two

An embodiment of the present invention provides a ceramic substrate, as shown in fig. 5, the ceramic substrate is manufactured by the method for manufacturing a ceramic substrate according to the first embodiment.

Since the ceramic substrate in this embodiment is manufactured by the method for manufacturing a ceramic substrate in the first embodiment, the technical effect achieved by the method for manufacturing a ceramic substrate in the first embodiment can also be achieved, which is not described herein again.

EXAMPLE III

An embodiment of the present invention provides a method for manufacturing a power module, as shown in fig. 6, the method includes the following steps:

s6, respectively brushing solder paste with the melting point of 220 ℃ on a plurality of mounting positions of copper foil in the ceramic substrate to form a plurality of welding spots; the ceramic substrate used in example two was the ceramic substrate used in example two.

And S7, respectively mounting the plurality of pins on the copper foil.

And S8, curing the plurality of components to the plurality of welding spots by adopting a reflow oven with the peak temperature of 230 ℃.

And S9, respectively welding aluminum wires among the components and between the components and the welding points so as to realize the electric connection among the components and between the components and the copper foil.

And S10, packaging the component and the exposed part of the copper foil in a plastic package material in an injection molding mode.

And S11, manufacturing the pins into a required shape through punching and bending in sequence to obtain the power module.

In this embodiment, the plurality of components include a capacitor (chip capacitor) and a resistor (chip resistor) to which a heat sink is attached, a driver chip (driver IC), an Insulated Gate Bipolar Transistor (IGBT), a fast recovery diode, and the like.

The IGBT and the fast recovery diode are main heating devices inside the power module; the driving chip is used for receiving an external MCU signal to control the on-off of the power switch device; the pin is used for realizing the electric connection of the power module and the external electric control board.

Referring to fig. 7 and 8, wherein fig. 7 is a schematic cross-sectional view of a power module, fig. 8 is a schematic perspective view of the power module, 201 is an igbt, 202 is a driver chip, 203 is a chip capacitor, 204 is an aluminum wire, 205 is a pin, and 206 is a snapback diode. Of course, only some of the devices are labeled in fig. 7 and 8, and some of the devices are not labeled.

In this embodiment, a plurality of components are welded together through respective welding routes, that is, 20mil aluminum wires are welded at the drain electrode welding position of the igbt and the welding position of the snapback diode, and of course, according to actual requirements, the 20mil aluminum wires are further welded to the welding points at the welding positions of the two components.

In this embodiment, aluminum wires are respectively welded between the component and the solder joints, that is, 1.5mil of the aluminum wires are welded between the welding position of the driving chip and the solder joint, and between the welding position of the gate of the igbt and the solder joint.

In addition, between the step S10 and the step S11, a step of laser marking may be added, that is, product information is printed on the molding compound by laser.

Since the ceramic substrate in the second embodiment is used in the method for manufacturing a power module in this embodiment, the technical effect achieved by the ceramic substrate in the second embodiment can be achieved, and details are not described herein.

Example four

The embodiment of the invention provides a power module, which is manufactured by the manufacturing method of the power module in the third embodiment, as shown in fig. 7 and 8.

Since the power module in this embodiment is manufactured by the method for manufacturing a power module in the third embodiment, the technical effect achieved by the method for manufacturing a power module in the third embodiment can also be achieved, which is not described herein again.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (10)

1. A method for preparing a ceramic substrate is characterized by comprising the following steps:

s1, brushing a layer of silver colloid on a mounting surface of a ceramic substrate;

s2, pasting a layer of copper foil on the silver adhesive, and then pressing the ceramic substrate and the copper foil;

s3, pasting a photosensitive film on the pressed copper foil, and then sequentially carrying out development and first cleaning to remove the photosensitive film on the part of the copper foil which is not required to be reserved;

s4, removing the part, which is not required to be reserved, of the copper foil through etching, and then tearing off the rest photosensitive film;

and S5, removing the silver paste below the part, which is not required to be reserved, of the copper foil through secondary cleaning, so as to obtain the ceramic substrate.

2. The method for preparing a ceramic substrate according to claim 1, wherein in the step S1, the step of brushing a layer of silver paste on the mounting surface of the ceramic substrate comprises the following specific steps: firstly, placing the ceramic substrate into a jig, then placing the ceramic substrate and the jig on an offset printing machine together, and finally brushing the silver colloid on the mounting frame of the ceramic foundation through the offset printing machine; wherein the thickness of the silver colloid is 0.2mm.

3. The method for manufacturing a ceramic substrate according to claim 2, wherein in the step S2, the step of attaching a layer of copper foil to the silver paste specifically comprises: selecting the copper foil matched with the mounting surface of the ceramic substrate, then contacting one side of the copper foil with one side of the silver paste, and finally rolling on the surface of the copper foil through a roller so as to completely attach the copper foil to the silver paste.

4. The method for preparing a ceramic substrate according to claim 3, wherein in the step S2, the step of laminating the ceramic base material and the copper foil comprises: firstly, placing the ceramic substrate and the copper foil together with the jig into a laminating machine, then starting the laminating machine for vacuumizing and carrying out the press-fitting on the ceramic substrate and the copper foil; wherein the applied pressure of the laminator after vacuum pumping is 200psi, and the pressing process is kept for 1h at 175 ℃.

5. The method for preparing a ceramic substrate according to claim 1, wherein the step S3 of removing the photosensitive film on the portion of the copper foil that does not need to be left by sequentially performing the steps of developing and first cleaning comprises: irradiating the photosensitive film on the part of the copper foil needing to be reserved by adopting ultraviolet light, and then cleaning the photosensitive film for the first time by adopting alkaline solution to remove the photosensitive film on the part of the copper foil needing not to be reserved.

6. The method for preparing a ceramic substrate according to claim 1, wherein the step S4 of removing the portion of the copper foil not to be left by etching comprises the specific steps of: and carrying out the etching on the copper foil by using a strong alkaline solution so as to remove the part of the copper foil, which does not need to be remained.

7. The method for preparing the ceramic substrate according to claim 1, wherein in the step S5, the step of removing the silver paste under the portion of the copper foil which does not need to be remained by the second cleaning comprises the following specific steps: firstly, placing the etched ceramic substrate into an ultrasonic cleaning machine filled with acetone for chemical cleaning, and then placing the ceramic substrate after chemical cleaning into the ultrasonic cleaning machine filled with deionized water for clean cleaning, thereby removing the silver colloid under the part of the copper foil which is not required to be reserved; in the chemical cleaning process, the temperature of the acetone is 50 ℃, the cleaning time is 30 minutes, and in the cleaning process, the cleaning time is 5 minutes.

8. A ceramic substrate produced by the method for producing a ceramic substrate according to any one of claims 1 to 7.

9. A method of making a power module, comprising the steps of:

s6, respectively brushing solder paste with the melting point of 220 ℃ on a plurality of mounting positions of copper foil in the ceramic substrate to form a plurality of welding spots; the ceramic substrate according to claim 8 is used as the ceramic substrate;

s7, respectively mounting a plurality of pins on the copper foil;

s8, curing a plurality of components to the plurality of welding points by adopting a reflow oven with the peak temperature of 230 ℃;

s9, respectively welding aluminum wires among a plurality of components and between the components and the welding spots so as to realize the electrical connection among the components and between the components and the copper foil;

s10, packaging the component and the exposed part of the copper foil in a plastic package material in an injection molding mode;

and S11, manufacturing the pins into a required shape through punching and bending in sequence to obtain the power module.

10. A power module characterized by being produced by the production method for a power module according to claim 9.

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