CN115863279A - A high overload capacity power module based on the metal block design on the top of the chip - Google Patents

Abstract

The invention relates to a high overload capacity power module designed based on a metal block at the top of a chip, which comprises a substrate, a second solder layer, a lower copper layer of a ceramic copper-clad plate, a ceramic layer of the ceramic copper-clad plate, an upper copper layer of the ceramic copper-clad plate, a first solder layer and the chip which are sequentially arranged from bottom to top; the welding of third solder layer has the metal block that promotes the heat capacity and can strengthen power module overload capacity in the top of chip, and the metal block welds on the copper layer on the ceramic copper-clad plate through first solder layer simultaneously, is provided with the space that is used for filling insulating material in the both sides of chip, and the metal material that has high specific heat capacity is filled to the metal block, through the produced heat of metal material short-term overload of chip of quick absorption, strengthen power module's overload capacity. The invention improves the overload capacity of the power module, the realization method is simple and only needs vacuum welding, and the temperature response speed is higher and no additional thermal resistance is added to the power module because the added structure is close to the upper part of the chip.

Description

A high overload capacity power module based on the metal block design on the top of the chip

technical field

The invention relates to the technical field of semiconductor devices, in particular to a power module with high overload capability designed based on a metal block on the top of a chip.

Background technique

In power electronic systems, there are short-term overload conditions. For example, in the black start mode of the power grid system, the inrush current is three times the rated current and lasts for 4.4s; when the electric vehicle starts at full load and accelerates uphill, the motor output torque is large during the acceleration uphill phase, in order to ensure the dynamic performance of the motor Performance, the motor controller may be directly in a short-term overload state of 1.5 times for 10s or even longer; when the power system relay protection operates, the fault current is twice the rated current for 0.12s.

The total loss of power devices is mainly composed of switching loss and conduction loss: P _tot ＝P _sw +P _dc ＝(E _on +E _off )*f _sw +D*V*I, where P _tot is the total power chip loss; P _sw is switching loss; P _dc is conduction loss; E _on is turn-on loss; E _off is turn-off loss; f _sw is switching frequency; D is duty cycle; V is conduction voltage drop; I is conduction Pass current. On the one hand, the larger the conduction current, the greater the conduction voltage drop, and the greater the conduction loss; on the other hand, the larger the conduction current, the greater the turn-on loss and turn-off loss, and the greater the switching loss. When the power electronic system is in an overload state, the current that the device bears is several times the rated current, the loss increases rapidly, and the junction temperature rises rapidly, which poses a huge challenge to the reliability of the power device. Therefore, improving the short-term overload capability of power devices is of great significance to the safe and reliable operation of power electronic systems.

The short-term overload capability of power devices is related to chip structure, package structure and gate drive state. According to the Cauer thermal network model of the power module, as shown in Figure 1, during the operation of the power module, the junction temperature is determined by the product of the power loss and the junction-to-case thermal resistance, and the junction-to-case thermal resistance of the power module is determined by the RC thermal network of each layer of material Model composition:

Where Z _thjc is the junction-to-case impedance of the power module; R _i is the thermal resistance of the i-th layer; C _i is the heat capacity of the i-th layer. Therefore, at the packaging level, there are two basic methods to improve the short-term overload capability of power devices: one is to reduce the thermal resistance of the packaging structure; the other is to increase the thermal capacity of the packaging structure.

Chongqing University proposed to improve its short-term overload capability by filling phase-change materials in traditional power modules. As shown in Figure 2, the power module includes a substrate, a ceramic copper-clad laminate, a phase-change module and power terminals; the upper surface of the substrate is rectangular , a plurality of ceramic copper clad laminates are arranged on the substrate respectively, and the ceramic copper clad laminates are connected by copper bars; the phase change module is arranged on the ceramic copper clad laminate, and a plurality of power terminals are arranged on the power terminal installation end; the phase change module includes heat transfer The reinforced frame and the sealed cover are filled with phase change materials inside the heat transfer enhanced frame; the outer surface of the sealed cover is also welded with power semiconductor chips. This technology suppresses the junction temperature of the power module under overload conditions by increasing the instantaneous heat capacity of the power module. However, traditional power modules have low equivalent thermal capacity, large equivalent transient thermal resistance, insufficient short-term overload capability, and are difficult to meet the actual application requirements of power electronic systems, and are prone to thermal failures that cause system crashes and other safety issues. Moreover, the above-mentioned phase-change power module fills the phase-change material between the chip and the ceramic copper-clad laminate, which increases the thermal resistance of the power module during normal operation. When the temperature of the heat transfer enhancement frame rises, thermal stress will be generated between the chip and the chip, which may damage the chip. Moreover, the process is difficult to realize, the cost of the required phase change material is relatively high, and the cost of production and implementation is high.

It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to those of ordinary skill in the art.

Contents of the invention

The purpose of the present invention is to overcome the disadvantages of the prior art, provide a high overload capacity power module based on the metal block design on the top of the chip, and solve the problems existing in the traditional power module.

The purpose of the present invention is achieved through the following technical solutions: a high overload capacity power module designed based on the metal block on the top of the chip, which includes a substrate, a second solder layer, a lower copper layer of a ceramic copper clad laminate, and a ceramic The ceramic layer of the copper clad laminate, the copper layer of the ceramic copper clad laminate, the first solder layer and the chip;

On the top of the chip, a metal block that improves the heat capacity to enhance the overload capacity of the power module is welded through the third solder layer, and at the same time, the metal block is welded to the copper layer of the ceramic copper-clad board through the first solder layer, and is arranged on both sides of the chip There are gaps for filling insulating materials to prevent the power module from being broken down by high electric fields. The metal block is filled with metal materials with high specific heat capacity, and the metal materials can quickly absorb the heat generated by the chip when it is overloaded for a short time, and enhance the overload capacity of the power module. .

The metal block includes a middle protruding part that welds the metal block to the chip via the third solder layer by vacuum reflow soldering technology, and the middle protruding part goes upwards to the left and right sides of the chip with an arc of radius r Extend, then extend horizontally for a distance d, and then extend vertically downward for a distance h to obtain a left bulge and a right bulge, and between the left bulge and the middle bulge and the right bulge and the middle bulge A gap for filling insulating material is formed between the protrusions to prevent the power module from being broken down by a high electric field, and the middle protrusion is filled with a metal material with a high specific heat capacity;

The left protruding part and the right protruding part are soldered to the copper layer on the ceramic copper clad laminate through the first solder layer.

The middle protrusion is soldered to the active area located in the middle of the chip through the third solder layer, and the bottom surface area of the middle protrusion is smaller than the area of the active area, and does not contact with the terminal area located on the periphery of the chip, providing a pre-wired connection for the bonding wire. Leave space to ensure the electrical connection between the chip and the outside world.

The distance between the middle protrusion and the left protrusion and the right protrusion is 5 mm to 20 mm, and the radius r is 1 mm to 5 mm, so as to ensure insulation and fill enough metal material in the middle protrusion; d The size of h is 1mm to 5mm, and the height of h is greater than the height of one chip of radius r.

The metal block includes a middle protrusion that welds the metal block to the chip via a third solder layer by vacuum reflow technology, and the middle protrusion is respectively extended to the left and right sides of the chip by an arc with a radius of _r1 . Extend upwards, then extend laterally for a distance d, and then extend downwards in an arc of radius r ₂ to get the left and right bulges, and the left and middle bulges and the right A gap for filling insulating material is formed between the protruding part and the middle protruding part to prevent the power module from being broken down by a high electric field, and the middle protruding part is filled with a metal material with high specific heat capacity;

The left protruding part and the right protruding part are soldered to the copper layer on the ceramic copper clad laminate through the first solder layer.

Both sides of the metal block extend out of the bracket, and a round hole is arranged in the center of the bracket, and the round hole is connected with other chips or terminals through bolts to realize electrical connection.

The size of the radius r ₂ is 1 mm to 5 mm to ensure insulation and fill enough metal material in the middle protrusion; the size of the radius r ₂ is longer than the size of the radius r ₁ by the length of a chip, and the size of d is 1 mm to 5 mm.

The edge of the metal block is uniformly coated with single-layer graphene to increase thermal conductivity to achieve uniformity and heat conduction; the insulating material includes silica gel, and the metal material includes molybdenum or copper or silver materials.

The present invention has the following advantages: a power module with high overload capacity designed based on the metal block on the top of the chip, which improves the overload capacity of the power module, the cost of the material used is low, and the realization method is simple and only needs vacuum welding. The structure is close to the top of the chip so its temperature response is faster and does not add additional thermal resistance to the power module.

Description of drawings

Fig. 1 is a schematic diagram of a Cauer model of a traditional power module;

FIG. 2 is a schematic structural diagram of a traditional phase-change power module;

3 is a schematic structural diagram of Embodiment 1 of the present invention;

Fig. 4 is a schematic structural diagram of a void in Embodiment 1 of the present invention;

FIG. 5 is a schematic structural diagram of Embodiment 2 of the present invention;

FIG. 6 is a schematic structural diagram of a void in Embodiment 2 of the present invention;

7 is a top view of Embodiment 2 of the present invention;

In the figure: 1-substrate, 2-second solder layer, 3-under copper layer of ceramic copper clad laminate, 4-ceramic layer of ceramic copper clad laminate, 5-copper layer of ceramic copper clad laminate, 6-first solder layer, 7-chip , 8-third solder layer, 9-metal block, 91-left protrusion, 92-right protrusion, 93-middle protrusion, 10-bracket, 11-round hole.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only It is a part of the embodiments of this application, not all of them. The components of the embodiments of the application generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the application provided in conjunction with the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of the present application. The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 3, the present invention specifically relates to a high overload capacity power module based on the design of the metal block on the top of the chip, wherein a real-time mode includes a substrate 1, a second solder layer 2, a copper layer 3 under a ceramic copper clad laminate, a ceramic clad Copper ceramic layer 4 , copper layer 5 on ceramic copper clad laminate, first solder layer 6 and chip 7 . The power module chip uses lead-free solder reflow soldering technology to connect the semiconductor chip, ceramic copper-clad laminate, and substrate together. In order to effectively enhance the overload capacity of the power module and avoid adding additional thermal resistance to the power module, the chip 7 The third solder layer 8 and the metal block 9 are added above, wherein the connection part between the metal block and the chip is called the middle protrusion 93 of the metal block 9, and the connection parts on both sides of the metal block 9 and the copper layer 5 on the ceramic copper clad laminate are respectively called The left protruding portion 91 of the metal block 9 and the right protruding portion 92 of the metal block 9 .

Further, the middle protruding portion 93 of the metal block 9 is soldered to the chip 7 via the third solder layer 8 by vacuum reflow soldering technology. Considering the problem of thermal adaptation of the power module, the selection of the solder material on the chip is consistent with that of the chip. For materials with similar thermal expansion coefficients, such as molybdenum, other metal materials such as copper and aluminum can also be selected if cost and other factors are considered. The area of the bottom surface of the middle protrusion 9 of the metal block 9 is smaller than the area of the chip 7, and the metal block 9 is welded to the active area of the chip 7 without contacting the terminal area of the chip 7, and a certain margin is required for the bonding wires to be prepared. Leave space to ensure the electrical connection between the chip and the outside world.

The middle protrusion 93 of the metal block 9 extends upward with a certain arc to fill more metal material, and then extends laterally out of the left protrusion 91 and right protrusion 92 of the metal block 9 through the first solder layer 6 Welded on the copper layer 5 of the ceramic copper clad laminate, the lateral extension length is 5 mm to 20 mm, that is, the middle protrusion 92 of the metal block 9 and the left protrusion 91 or right protrusion of the metal block 9 The distance between 93 is 5 mm to 20 mm to ensure the electrical connection between the chip 7 and the outside. When the power module works normally, there is an electric field in the gaps of the metal block 9, so it is necessary to fill the gaps with insulating materials, such as silica gel, to ensure that the device is not broken down by a high electric field, as shown in Figure 4. Since the breakdown voltage of the silicone material is 20-25kV/mm, the arc radius of the middle protrusion 93 of the metal block 9, that is, r in Fig. 4, must be greater than 1 mm to ensure insulation, and must be less than 5 mm Fill enough metal material, the length h of the protrusions on both sides is higher than the height of the middle protrusion 93 by one chip, usually the length is 0.1 mm to 2 mm, and the distance d between the arc and the protrusions on both sides is 1 mm to 5 mm. In addition, the gap can reserve space for the volume expansion of the metal block 9 after the temperature rises, and the edge of the metal block 9 can be evenly coated with a single layer of graphene to increase the thermal conductivity, so as to achieve the effect of uniform temperature and heat conduction.

As shown in Figure 5, another embodiment of the present invention comprises a substrate 1, a second solder layer 2, a lower copper layer 3 of a ceramic copper clad laminate, a ceramic layer 4 of a ceramic copper clad laminate, a copper layer 5 of a ceramic copper clad laminate, a first solder Layer 6 and chip 7. The power module chip uses lead-free solder reflow soldering technology to connect the semiconductor chip, ceramic copper-clad laminate, and substrate together. In order to effectively enhance the overload capacity of the power module and avoid adding additional thermal resistance to the power module, the chip 7 The third solder layer 8 and the metal block 9 are added above, wherein the connection part between the metal block and the chip is called the middle protrusion 93 of the metal block 9, and the connection parts on both sides of the metal block 9 and the copper layer 5 on the ceramic copper clad laminate are respectively called The left protruding portion 91 of the metal block 9 and the right protruding portion 92 of the metal block 9 .

Furthermore, as shown in Figure 6, a certain arc is set at the corner of the metal block 9 added to the high overload capacity power module to increase the metal material added, and the gaps of the metal block 9 are filled with insulating materials such as silica gel. The breakdown voltage is 20-25kV/mm, so the arc radius of the protruding part 93 in the middle of the metal block 9 needs to be larger than 1 mm to ensure insulation, and it needs to be smaller than 5 mm to fill enough metal material, which is shown by r ₁ in Figure 6 , the arc radius r ₂ of the protruding part on both sides is longer than r ₁ by the height of the chip 7, usually the length of the protruding part is 0.1 mm to 2 mm, and the arc distance between the central protruding part 93 and the protruding parts on both sides is d 1 mm to 5 mm. As shown in Figure 7, the high overload capacity power chip does not use bonding wires to achieve electrical connection, the metal block 9 can be extended out of the bracket 10, the center of the bracket 10 is a round hole 11, and the round hole 11 can be connected to other devices with bolts. The chips 7 or terminals of the circular holes 11 are connected to realize electrical connection, which avoids the use of bonding wires and prevents the aging failure of the bonding wires from causing the power module to fail.

The above descriptions are only preferred embodiments of the present invention, and it should be understood that the present invention is not limited to the forms disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and Modifications can be made within the scope of the ideas described herein, by virtue of the above teachings or skill or knowledge in the relevant art. However, changes and changes made by those skilled in the art do not depart from the spirit and scope of the present invention, and should all be within the protection scope of the appended claims of the present invention.

Claims (8)

1. A high overload capacity power module based on chip top metal block design which characterized in that: the soldering flux comprises a substrate (1), a second soldering flux layer (2), a lower copper layer (3) of a ceramic copper-clad plate, a ceramic layer (4) of the ceramic copper-clad plate, an upper copper layer (5) of the ceramic copper-clad plate, a first soldering flux layer (6) and a chip (7) which are arranged in sequence from bottom to top;

the top of chip (7) has metal block (9) of promotion heat capacity in order to strengthen power module overload capacity through third solder layer (8) welding, metal block (9) weld on copper layer (5) on the ceramic copper-clad plate through first solder layer (6) simultaneously, both sides in chip (7) are provided with the space that is used for filling insulating material, prevent that power module from being punctured by high electric field, metal material that is filled with high specific heat capacity in metal block (9), produced heat when transshipping in the short-term through metal material quick absorption chip (7), strengthen power module's overload capacity.

2. The high overload capacity power module based on the design of the metal block on the top of the chip as claimed in claim 1, wherein: the metal block (9) comprises a middle bulge (93) which is formed by welding the metal block (9) on the chip (7) through a third solder layer (8) by a vacuum reflow soldering technology, the middle bulge (93) extends upwards to the left side and the right side of the chip (7) by an arc with the radius of r respectively, then extends for a distance d transversely, and then extends for a distance h vertically downwards to obtain a left bulge (91) and a right bulge (92), gaps for filling insulating materials are formed between the left bulge (91) and the middle bulge (93) and between the right bulge (92) and the middle bulge (93), the power module is prevented from being broken through by a high electric field, and the middle bulge (93) is filled with a metal material with high specific heat capacity;

the left convex part (91) and the right convex part (2) are welded on the copper layer (5) on the ceramic copper-clad plate through a first solder layer (6).

3. The high overload capacity power module based on the design of the metal block on the top of the chip as claimed in claim 2, wherein: the middle protruding portion (93) is welded in an active area located in the middle of the chip (7) through a third solder layer (8), the area of the bottom face of the middle protruding portion (93) is smaller than that of the active area, the middle protruding portion does not contact with a terminal area located on the periphery of the chip (7), a space is reserved for a bonding wire, and the chip (7) is guaranteed to be electrically connected with the outside.

4. The high overload capacity power module based on the design of the metal block on the top of the chip as claimed in claim 2, wherein: the distance between the middle convex part (93) and the left convex part (91) and the distance between the middle convex part (93) and the right convex part (92) are 5mm to 20mm, the radius r is 1mm to 5mm, so that insulation is ensured, and enough metal material is filled in the middle convex part (93); d is 1mm to 5mm, and the height of h is greater than the height of one chip (7) with radius r.

5. The high overload capacity power module based on the design of the metal block on the top of the chip as claimed in claim 1, wherein: the metal block (9) comprises a middle bulge part (93) which is welded on the chip (7) through a third solder layer (8) by a vacuum reflow soldering technology, and the middle bulge part (93) respectively uses the radius r to the left side and the right side of the chip (7) ₁ Extend upwards, then extend transversely a distance d, and then with a radius r ₂ The arc of the power module extends downwards to obtain a left convex part (91) and a right convex part (92), gaps for filling insulating materials are formed between the left convex part (91) and a middle convex part (93) and between the right convex part (92) and the middle convex part (93), the power module is prevented from being broken down by a high electric field, and the middle convex part (93) is filled with a metal material with high specific heat capacity;

the left convex part (91) and the right convex part (2) are welded on the copper layer (5) on the ceramic copper-clad plate through a first solder layer (6).

6. The high overload capacity power module based on the design of the metal block on the top of the chip as claimed in claim 5, wherein: the support (10) extends out of two sides of the metal block (9), a round hole (11) is formed in the center of the support (10), and the round hole (11) is connected with other chips or terminals in a bolt mode to achieve electrical connection.

7. The high overload capacity power module based on the design of the metal block on the top of the chip as claimed in claim 4, wherein: radius r ₂ Is 1mm to 5mm to ensure insulation and sufficient metal material is filled in the middle protruding part (93); radius r ₂ Radius of (d) to radius r ₁ Is longer by the length of one chip (7), and d is 1mm to 5mm.

8. The high overload capability power module based on the design of the metal block on the top of the chip according to any one of the claims 1 to 7, wherein: the edge of the metal block (9) is uniformly coated with single-layer graphene so as to increase the heat conductivity and achieve the purposes of uniform temperature and heat conduction; the insulating material comprises silica gel, and the metal material comprises molybdenum or copper or silver material.

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