A power device package structure based on top heat dissipation

Abstract

The utility model discloses a kind of power device packaging structures based on top heat dissipation, comprising: lead frame, chip to be assembled, ceramic copper-clad plate, first bonding lead, second bonding lead and plastic package body;Lead frame includes base island, first pin and second pin;Base island includes oppositely arranged bearing surface and heat dissipation surface, ceramic copper-clad plate is composed of top circuit copper layer, middle insulating layer and bottom copper layer, bottom copper layer is set to be connected on bearing surface, chip to be assembled is welded on top circuit copper layer;The edge of middle insulating layer extends to the outside edge of top circuit copper layer and bottom copper layer, forms boss structure.The utility model technical scheme forms insulating state between chip to be assembled and radiator by ceramic copper-clad plate, need not be set on outside insulating film, avoid insulating film breakage shell electrification;The design of boss structure can increase with the improvement of withstand voltage value of chip to be assembled, play the role of increasing creepage distance.

Description

Technical Field

[0001] This utility model relates to the field of power device packaging, and in particular to a power device packaging structure based on top heat dissipation. Background Technology

[0002] Most power devices employ bottom heat dissipation (i.e., the soldering surface of the PCB board is the heat dissipation surface). To address the insufficient heat dissipation capacity of the PCB soldering surface, top heat dissipation packaging structures were developed. Top heat dissipation involves soldering the chip to be soldered onto the top, and the customer installs a heat sink on top during use, thereby improving heat dissipation capacity, reducing chip junction temperature, and extending product lifespan. However, the exposed surface of the top heat dissipation in existing technologies is also electrically charged and not insulated. When installing the heat sink, the customer needs to install a heat dissipation sheet with an insulating film between the heat sink and the power device's heat dissipation surface (which is electrically charged). This insulating film is typically a polyimide film, only a few tens of micrometers thick. Overly tight installation poses a risk of damage, which could result in the casing becoming electrically charged. Utility Model Content

[0003] The main purpose of this invention is to propose a power device packaging structure based on top heat dissipation, which aims to solve the risk of insulation failure caused by insulation film damage when non-insulated top heat dissipation products are used by customers.

[0004] To achieve the above objectives, the present invention proposes a power device packaging structure based on top heat dissipation, characterized in that it includes: a lead frame, a chip to be assembled, a ceramic copper-clad laminate, a first bonding lead, a second bonding lead, and a molding compound; the lead frame includes a base island, a first pin, and a second pin; the base island includes a carrier surface and a heat dissipation surface arranged opposite to each other, the ceramic copper-clad laminate is disposed on the carrier surface, the ceramic copper-clad laminate is integrally formed from a top circuit copper layer, an intermediate insulating layer, and a bottom copper layer, the bottom copper layer is disposed and connected to the carrier surface, and the chip to be assembled is soldered onto the top circuit copper layer; The first pin is connected to the top circuit copper layer via the first bonding lead, and the second pin is connected to the surface of the chip to be assembled via the second bonding lead; the edge of the intermediate insulating layer extends to the outer edge of the top circuit copper layer and the bottom copper layer, forming a boss structure; the chip to be assembled, the ceramic copper-clad laminate, the first bonding lead and the second bonding lead are all encapsulated in the plastic package, and the end of the first pin away from the top circuit copper layer, the end of the second pin away from the chip to be assembled and the heat dissipation surface of the base island are all exposed outside the plastic package.

[0005] Preferably, it further includes a heat dissipation pad, which is disposed on the heat dissipation surface.

[0006] Preferably, the power device package structure based on top heat dissipation is used for mounting on a printed circuit board and also includes a heat sink, which is mounted on the power device package structure by locking screws, and the heat sink is in close contact with the heat dissipation pad by the locking force of the locking screws.

[0007] Preferably, the height of the boss structure is set to 0.3-0.8mm.

[0008] Preferably, the edge of the bearing surface is provided with a V-shaped groove.

[0009] Preferably, the edge of the heat dissipation surface is provided with a locking groove.

[0010] Compared with the prior art, the beneficial effects of this utility model are: by forming an insulating state between the chip to be assembled and the heat sink through the ceramic copper-clad plate, there is no need to set an insulating film on the outside, avoiding the casing from becoming electrified when the insulating film is damaged. At the same time, the ceramic copper-clad plate can also effectively conduct away the heat of the chip to be assembled; the design of the boss structure can be increased as the withstand voltage value of the chip to be assembled increases, thereby increasing the creepage distance. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the power device packaging structure of this utility model; The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0013] The power device packaging structure based on top heat dissipation proposed in this embodiment, such as... Figure 1As shown, it includes: a lead frame 1, a chip to be assembled 2, a ceramic copper-clad laminate 3, a first bonding lead 41, a second bonding lead 42, and a molding compound 5; the lead frame 1 includes a base island 11, a first pin 12, and a second pin 13; the base island 11 includes a bearing surface 111 and a heat dissipation surface 112 arranged opposite to each other, the ceramic copper-clad laminate 3 is disposed on the bearing surface 111, the ceramic copper-clad laminate 3 is integrally formed by a top circuit copper layer 31, an intermediate insulating layer 32, and a bottom copper layer 33, the bottom copper layer 33 is soldered to the bearing surface 111 of the base island 11 by copper plate solder, the chip to be assembled 2 is soldered to the top circuit copper layer 31 by chip solder, the exposed surface of the top circuit copper layer 31 is the welding surface of the top circuit copper layer 31, and the welding surface of the top circuit copper layer 31 is... The chip to be assembled 2 is soldered with chip solder; the first pin 12 is connected to the top circuit copper layer 31 through the first bonding lead 41, and the second pin 13 is connected to the surface of the chip to be assembled 2 through the second bonding lead 42; the edge of the intermediate insulating layer 32 extends to the outer edge of the top circuit copper layer 31 and the bottom copper layer 33 to form a boss structure; the chip to be assembled 2, the ceramic copper-clad laminate 3, the first bonding lead 41 and the second bonding lead 42 are all wrapped in the plastic package 5 through the molding process, which isolates them from the external air and plays a protective role such as dustproof, moistureproof and physical damage prevention. The end of the first pin 12 away from the top circuit copper layer 31, the end of the second pin 13 away from the chip to be assembled 2 and the heat dissipation surface 112 of the base island 11 are all exposed outside the plastic package 5. The ceramic copper-clad laminate 3 forms an insulation state between the chip 2 to be assembled and the heat sink 6, eliminating the need for an external insulating film and preventing the casing from becoming electrified if the insulating film is damaged. At the same time, the ceramic copper-clad laminate 3 can also effectively conduct heat away from the chip 2 to be assembled. The design of the boss structure can be increased as the withstand voltage of the chip 2 to be assembled increases, thereby increasing the creepage distance.

[0014] Specifically, it also includes a heat dissipation pad 8, which is disposed on the heat dissipation surface 112. The heat dissipation pad 8 is used to fill the gap between the heat dissipation surface 112 and the external heat dissipation device. In the prior art, an insulating layer is provided between the chip to be assembled 2 and the heat sink 6 device, that is, a polyimide film, usually tens of micrometers thick, is covered on the heat dissipation pad 8. However, in this application, the ceramic copper-clad laminate 3 is designed to be internally insulated instead of externally insulated, which avoids the consequence of the insulating film being damaged during downstream customer assembly and surface mounting, causing the casing to become electrified.

[0015] Specifically, the top-heat-dissipating power device package structure is mounted on the printed circuit board 7 and includes a heat sink 6. The heat sink 6 is secured to the power device package structure by locking screws 9, and the heat sink 6 is in close contact with the thermal pad 8 through the tightening force of the locking screws 9. The heat sink 6 is stably mounted on the printed circuit board 7, making the entire package structure more robust, and the closer contact between the heat sink 6 and the thermal pad results in more efficient heat conduction. The heat sink 6 can adopt a fin-like or other structure that does not limit the expansion of the heat dissipation area.

[0016] Specifically, the edge of the middle insulating layer 32 of the ceramic copper-clad laminate 3 extends beyond the edges of the top circuit copper layer 31 and the bottom copper layer 33 to form a boss structure. This extension value is usually set to 0.3~0.8mm, which increases with the increase of the withstand voltage value of the chip 2 to be assembled, thereby increasing the creepage distance.

[0017] Specifically, a V-groove 111a is provided at the edge of the bearing surface 111. The V-groove 111a can prevent the solder of the ceramic copper-clad laminate 3 from overflowing from the bearing surface 111 and causing defects.

[0018] Specifically, a locking groove 112a is provided at the edge of the heat dissipation surface 112. This is used to increase the bonding force between the molding compound 5 and the base island 11.

[0019] Compared with the prior art, the beneficial effects of this utility model are: by forming an insulating state between the chip 2 to be assembled and the heat sink 6 through the ceramic copper-clad plate 3, there is no need to set an insulating film on the outside, avoiding the casing from becoming charged due to damage to the insulating film. At the same time, the ceramic copper-clad plate 3 can also effectively conduct away the heat of the chip 2 to be assembled; the design of the boss structure can be increased as the withstand voltage value of the chip 2 to be assembled increases, thereby increasing the creepage distance.

[0020] When using surface mount technology (SMT), the first pin 12 and the second pin 13 are soldered onto the soldering surface of the printed circuit board 7 using SMT. A thermal pad (i.e., thermal grease or thermal pad) is placed on the heat dissipation surface 112 to fill the microscopic gaps between the heat dissipation surface 112 and the heat sink 6, ensuring good tight contact. The heat sink 6 is placed on the thermal grease or thermal pad, and the heat sink 6 is in tight contact with the heat dissipation surface 112 through a locking force. This locking force is generated by the heat sink 6 being locked to the printed circuit board 7 by the locking screw 9. Since the base island 11 is in an insulated state from the chip 2 to be assembled, there is no need to place an insulating pad between the heat dissipation surface 112 and the heat sink 6, which is convenient for customers to install and use, and there is no need to worry about the heat sink 6 being electrified.

[0021] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the description and drawings of this utility model, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A power device packaging structure based on top heat dissipation, characterized in that, include: The assembly comprises a lead frame, a chip to be assembled, a ceramic copper-clad laminate, a first bonding lead, a second bonding lead, and a molding compound; the lead frame includes a base island, a first pin, and a second pin; the base island includes a support surface and a heat dissipation surface arranged opposite to each other; the ceramic copper-clad laminate is integrally formed from a top circuit copper layer, a middle insulating layer, and a bottom copper layer; the bottom copper layer is disposed and connected to the support surface; and the chip to be assembled is soldered onto the top circuit copper layer. The first pin is connected to the top circuit copper layer via the first bonding lead, and the second pin is connected to the surface of the chip to be assembled via the second bonding lead; the edge of the intermediate insulating layer extends to the outer edge of the top circuit copper layer and the bottom copper layer, forming a boss structure; the chip to be assembled, the ceramic copper-clad laminate, the first bonding lead and the second bonding lead are all encapsulated in the plastic package, and the end of the first pin away from the top circuit copper layer, the end of the second pin away from the chip to be assembled and the heat dissipation surface of the base island are all exposed outside the plastic package.

2. The power device packaging structure based on top heat dissipation as described in claim 1, for mounting on a printed circuit board, characterized in that, It also includes a heat sink, which is mounted on the power device package structure by a locking screw, and the heat sink is in close contact with the heat dissipation surface of the base island by the locking force of the locking screw.

3. The power device packaging structure based on top heat dissipation as described in claim 1, characterized in that, The height of the boss structure is set at 0.3-0.8mm.

4. The power device packaging structure based on top heat dissipation according to any one of claims 1 to 3, characterized in that, The edge of the bearing surface is provided with a V-shaped groove.

5. The power device packaging structure based on top heat dissipation as described in claim 4, characterized in that, The edge of the heat dissipation surface is provided with a locking groove.

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