Preparation method of internal insulation packaging structure and internal insulation packaging structure

Abstract

The invention relates to a preparation method of an internal insulation packaging structure and the internal insulation packaging structure. The preparation method comprises the following steps: S1, feeding an upper frame and a lower frame into a printing machine to print solder; s2, sequentially fitting and assembling the printed lower frame, the insulating part and the printed upper frame; s3, putting the assembled product into a machine table for die bonding; s4, feeding a product subjected to die bonding into a welding furnace for welding; and S5, a welded finished product is cleaned. The preparation method of the internal insulation packaging structure and the internal insulation packaging structure have the following advantages that the welding flux of the upper frame and the lower frame is printed through a printing machine, so that the coverage range of the welding flux on the upper frame and the lower frame is accurate, the thickness is uniform, and after the welding flux is fed into a welding furnace to be welded, the welding flux is uniform; the insulating part is firmly combined with the upper frame and the lower frame and is not easy to separate, and the rate of finished products is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor packaging, and in particular to a preparation method of an internal insulation packaging structure and the internal insulation packaging structure. Background Art

[0002] In actual applications of power device products, in situations where heat dissipation requirements are high, a heat sink will be required to be mounted on the back of the discrete device. Then, in order to ensure the insulation performance of the power device in a high-voltage environment, it is necessary to use insulation measures to separate the lead frame from the heat sink during the manufacturing process. The prior art uses a sandwich insulation structure, that is, the plastic packaging material uses a two-layer copper frame, one layer for chip welding and one layer for back heat dissipation, and the two layers of copper frames are insulated and isolated with double-sided copper-clad ceramic sheets. This solution has high reliability and is easy to achieve mass production, but the solution has high requirements for welding, especially the placement and amount of solder, which makes the processing efficiency low and the preparation difficult. Summary of the invention

[0003] An object of the present application is to provide a method for preparing an internal insulation packaging structure and an internal insulation packaging structure, which can improve processing efficiency and reduce preparation difficulty.

[0004] The technical solution adopted in this application is: a method for preparing an internal insulation packaging structure, comprising the following steps:

[0005] S1, sending the upper frame and the lower frame into the printing machine to print solder;

[0006] S2, assembling the printed lower frame, insulating member and printed upper frame in sequence;

[0007] S3, put the assembled products into the machine for die bonding;

[0008] S4, the products after crystal bonding are sent to the welding furnace for welding;

[0009] S5. Clean the finished product after welding.

[0010] Compared with the prior art, the advantage of the present application is that the solder of the upper frame and the lower frame is printed by a printing machine, so that the coverage of the solder on the upper frame and the lower frame is accurate and the thickness is uniform. After being sent into the welding furnace for welding, the insulation parts are firmly combined with the upper frame and the lower frame, and are not easy to separate, and the yield rate is improved.

[0011] In some embodiments of the present application, step S1 includes step S11: before printing, placing the upper frame and the lower frame on a positioning plate, and sending the upper frame and the lower frame into a printing press through the positioning plate.

[0012] In some embodiments of the present application, screen printing is used in step S1; the solder in step S1 is solder paste; the screen printing in step S1 includes: printing holes with the same size as the chip on the upper frame, printing holes with the same size as the insulating part on the lower frame, and printing holes with the same size as the insulating part on the upper frame.

[0013] In some embodiments of the present application, step S2 includes step S21: before the printed lower frame and the insulating parts are assembled together, the printed lower frame is placed on the graphite welding plate; step S2 also includes step S22: before the insulating parts are assembled together, the insulating parts are arranged in an orderly manner.

[0014] Furthermore, the aligning of the insulating parts in step S22 is as follows: placing the insulating parts on a rocking plate and shaking the insulating parts so that the insulating parts enter the fixed grooves on the rocking plate; and the assembling of the insulating parts and the printed lower frame in step S2 is as follows: using a suction cup to absorb the aligned insulating parts and placing the insulating parts on the printed lower frame through the suction cup.

[0015] In some embodiments of the present application, in step S3, the wafer is placed on the upper frame and fixed.

[0016] In some embodiments of the present application, step S4 includes step S41: performing a first quality inspection on the product after crystal bonding before sending it into the welding furnace; step S4 also includes step S42: after welding, the finished product is sent out of the welding furnace for a second quality inspection.

[0017] In some embodiments of the present application, the welding furnace in step S4 is a vacuum sintering furnace; the welding temperature is 360° C.-380° C.; the welding time is 60 seconds; and the vacuum degree is 20 MPa.

[0018] In some embodiments of the present application, the cleaning in step S5 is performed using an ultrasonic cleaning machine.

[0019] An internal insulation packaging structure obtained by the present invention is prepared by the above-mentioned preparation method of an internal insulation packaging structure, and includes a lower frame, an upper frame and a chip. An insulating member for isolating the lower frame and the upper frame is provided between the lower frame and the upper frame. One side of the upper frame is connected to one side of the insulating member, the other side of the upper frame is connected to the chip, and the other side of the insulating member is connected to the lower frame.

[0020] In some embodiments of the present application, welding reinforcement areas are provided on both the front and back sides of the insulating member. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a flow chart of Embodiment 1 of the present invention;

[0022] Figure 2This is a schematic diagram of the structure of Embodiment 2 of the present invention.

[0023] Figure 3 It is a schematic structural diagram of the insulating component of Example 2 of the present invention.

[0024] In the figure: 1. upper frame; 2. lower frame; 3. insulating part; 4. chip; 5. welding reinforcement area. DETAILED DESCRIPTION

[0025] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0026] Embodiment 1:

[0027] This embodiment provides a method for preparing an internal insulation packaging structure, such as Figure 1 As shown, the following steps are included:

[0028] S1, sending the upper frame 1 and the lower frame 2 into the printing machine to print solder;

[0029] S2, assembling the printed lower frame 2, the insulating member 3 and the printed upper frame 1 in sequence;

[0030] S3, put the assembled products into the machine for die bonding;

[0031] S4, the products after crystal bonding are sent to the welding furnace for welding;

[0032] S5. Clean the finished product after welding.

[0033] The solder of the upper frame 1 and the lower frame 2 is printed by a printing machine, so that the coverage of the solder on the upper frame 1 and the lower frame 2 is accurate and the thickness is uniform. After being sent into the welding furnace for welding, the insulation part 3 is firmly bonded to the upper frame 1 and the lower frame 2, is not easy to separate, and the yield rate is improved.

[0034] The printed areas of the upper frame 1 and the lower frame 2 are metal areas connected to the insulating member 3 .

[0035] In order to facilitate printing, the step S1 includes step S11: before printing, the upper frame 1 and the lower frame 2 are placed on the positioning plate, and the upper frame 1 and the lower frame 2 are sent to the printing machine through the positioning plate. The upper frame 1 and the lower frame 2 are placed on the positioning plate so that the positions of the upper frame 1 and the lower frame 2 are fixed, which is convenient for the printing machine to accurately position and print, and to facilitate the batch feeding and removal of the upper frame 1 and the lower frame 2.

[0036] In order to ensure reliable printing, screen printing is used in step S1; the solder in step S1 is solder paste; the screen printing in step S1 includes: printing a printing hole with the same size as the chip 4 on the upper frame 1, printing a printing hole with the same size as the insulating member 3 on the lower frame 2, and printing a printing hole with the same size as the insulating member 3 on the upper frame 1. Screen printing has fast printing speed and good quality, and can accurately print the position of the printing hole with the same size as the chip 4 or the insulating member 3.

[0037] In order to facilitate subsequent welding, the step S2 includes step S21: before the printed lower frame 2 and the insulating member 3 are assembled together, the printed lower frame 2 is placed on the graphite welding plate; and step S2 also includes step S22: before the insulating member 3 is assembled together, the insulating member 3 is aligned. The graphite welding plate can withstand the high temperature of heating and welding in the vacuum sintering furnace. Placing the printed lower frame 2 on the graphite welding plate can minimize the movement of the lower frame 2 before the welding is completed, and reduce the risk of damaging the printed surface during movement; aligning the insulating member 3 can facilitate access to the insulating member 3.

[0038] In order to ensure that the insulating parts 3 are reliably aligned, the insulating parts 3 in step S22 are aligned as follows: the insulating parts 3 are placed on a rocking plate, and the insulating parts 3 are shaken to make them enter the fixed grooves on the rocking plate. The rocking plate can be used to simply and quickly arrange the insulating parts 3 in order, which is convenient for subsequent use of the insulating parts 3; the spacing between adjacent fixed grooves of the rocking plate is the same as the spacing between adjacent lower frames 2 placed on the graphite welding plate; in step S2, the insulating parts 3 and the printed lower frame 2 are fitted and assembled as follows: the aligned insulating parts 3 are adsorbed with a suction cup and the insulating parts 3 are placed on the printed lower frame 2 through the suction cup. The suction cup can adsorb the entire row of insulating parts 3 and then place them on the printed lower frame 2, and the fitting and assembly is fast and accurate.

[0039] In order to fix the wafer 4 , in step S3 , the wafer 4 is placed on the upper frame 1 and fixed.

[0040] In order to improve the yield rate, step S4 includes step S41: before the product after crystal bonding is sent into the welding furnace, it is subjected to a first quality inspection, and the first quality inspection is carried out by visual inspection; step S4 also includes step S42: after welding, the finished product is sent out of the welding furnace for a second quality inspection, and the second quality inspection is carried out by visual inspection.

[0041] In order to ensure reliable welding, the welding furnace in step S4 is a vacuum sintering furnace, and the material is heated after being sent into the vacuum sintering furnace to complete automatic welding; the welding temperature is 360°C-380°C; the welding time is 60S; and the vacuum degree is 20MPa.

[0042] In order to ensure reliable cleaning, an ultrasonic cleaning machine is used for cleaning in step S5, and the products are visually inspected and packaged before storage.

[0043] Embodiment 2:

[0044] This embodiment provides an internal insulation packaging structure, such as Figure 2 As shown, it is manufactured by the manufacturing method of an internal insulation packaging structure described in Example 1, comprising a lower frame 2, an upper frame 1 and a wafer 4, an insulating member 3 for isolating the lower frame 2 and the upper frame 1 is provided between the lower frame 2 and the upper frame 1, one side of the upper frame 1 is connected to one side of the insulating member 3, the other side of the upper frame 1 is connected to the wafer 4, and the other side of the insulating member 3 is connected to the lower frame 2. In this embodiment, the insulating member 3 is a ceramic sheet.

[0045] The traditional structure is a bare copper frame with no insulation function. It is used in low voltage scenarios and is suitable for scenarios less than or equal to 400V. The ceramic sheet has an insulation function, which can prevent the chip and the ground terminal from short-circuiting, improve reliability, and is suitable for scenarios greater than or equal to 800V.

[0046] like Figure 3 As shown, both the front and back sides of the insulating member 3 are provided with welding reinforcement areas 5, and the welding reinforcement areas 5 are used to enhance the contact strength with the solder. In this embodiment, the welding reinforcement areas 5 are arranged with mesh-like grooves or protrusions to enhance the welding strength.

[0047] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing an internal insulation packaging structure, characterized in that: The following steps are involved: S1, sending the upper frame and the lower frame into the printing machine to print solder; S2, assembling the printed lower frame, insulating member and printed upper frame in sequence; S3, put the assembled products into the machine for die bonding; S4, the products after crystal bonding are sent to the welding furnace for welding; S5. Clean the finished product after welding.

2. The method for preparing an internal insulation packaging structure according to claim 1, characterized in that: The step S1 includes step S11: before printing, placing the upper frame and the lower frame on the positioning plate, and sending the upper frame and the lower frame into the printing machine through the positioning plate.

3. The method for preparing an internal insulation packaging structure according to claim 1, characterized in that: In the step S1, screen printing is adopted; The solder in step S1 is solder paste; The screen printing in step S1 includes: printing holes with the same size as the wafer on the upper frame, printing holes with the same size as the insulating member on the lower frame, and printing holes with the same size as the insulating member on the upper frame.

4. The method for preparing an internal insulation packaging structure according to claim 1, characterized in that: The step S2 includes step S21: before the printed lower frame and the insulating member are assembled together, the printed lower frame is placed on the graphite welding plate; and step S2 also includes step S22: before the insulating member is assembled together, the insulating member is aligned.

5. The method for preparing an internal insulation packaging structure according to claim 4, characterized in that: The insulating parts are aligned in step S22 as follows: the insulating parts are placed on a rocking plate and shaken to make the insulating parts enter the fixed grooves on the rocking plate; the insulating parts and the printed lower frame are assembled in step S2 as follows: the aligned insulating parts are adsorbed with suction cups and the insulating parts are placed on the printed lower frame through the suction cups.

6. The method for preparing an internal insulation packaging structure according to claim 1, characterized in that: In step S3, the wafer is placed on the upper frame and fixed.

7. The method for preparing an internal insulation packaging structure according to claim 1, characterized in that: The step S4 includes step S41: before the product after crystal bonding is sent into the welding furnace, it is subjected to the first quality inspection; and step S4 also includes step S42: after welding, the finished product is sent out of the welding furnace for the second quality inspection.

8. The method for preparing an internal insulation packaging structure according to claim 1, characterized in that: In step S4, the welding furnace is a vacuum sintering furnace; the welding temperature is 360° C.-380° C.; the welding time is 60 seconds; and the vacuum degree is 20 MPa.

9. An internal insulation packaging structure, characterized in that: The method for preparing an internal insulation packaging structure according to any one of claims 1 to 8 is adopted, comprising a lower frame, an upper frame and a chip, an insulating member for isolating the lower frame and the upper frame is provided between the lower frame and the upper frame, one side of the upper frame is connected to one side of the insulating member, the other side of the upper frame is connected to the chip, and the other side of the insulating member is connected to the lower frame.

10. The inner insulation packaging structure according to claim 9, characterized in that: The front and back sides of the insulating member are both provided with welding reinforcement areas.

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