Chip packaging structure

Abstract

The embodiment of the invention aims to provide a chip packaging structure. The circuit board comprises a chip assembly, a substrate and an electrical connection structure between the chip assembly and the substrate. Wherein the electrical connection structure comprises a conductive adhesive, and the conductive adhesive is arranged between the chip assembly and the substrate and is respectively connected with electrical contact points of the chip assembly and the substrate; wherein the phase change material and the conductive adhesive intersect to form a heat dissipation structure. By using the conductive adhesive as a connection means between the chip and the PCB, the embodiment of the invention can realize a thinner connection layer, thereby significantly shortening a signal transmission path, reducing connection impedance, and improving the quality and speed of signal transmission. And moreover, the phase-change material is introduced to optimize heat dissipation, so that heat can be quickly absorbed and released in a local high-heat-flux area, and the temperature peak value in the package is reduced.

Description

Technical Field

[0001] Various embodiments of the present disclosure relate to the field of semiconductor technology, and in particular to a chip packaging structure. Background Art

[0002] With the continuous improvement of chip integration and the gradual increase in operating frequency, higher requirements are placed on the electrical performance, heat dissipation management and signal integrity of chip packaging.

[0003] 1. High-density integration and miniaturization: Modern electronic devices pursue miniaturization and high performance. The chip size is reduced and the integration is continuously improved, which makes the signal transmission path inside the package more complicated. How to achieve reliable electrical connection and efficient heat dissipation in a limited space has become a major challenge.

[0004] 2. High-speed signal transmission: As the operating frequency increases, high-speed signal transmission faces greater loss, reflection and electromagnetic interference problems. Traditional packaging methods, such as bump balls or wire bonding, may cause signal distortion or delay due to impedance and capacitance effects in high-speed signal transmission.

[0005] Traditional solder ball bump technology is used to connect chips to PCBs (Printed Circuit Boards). Although it can achieve good mechanical and electrical performance, its size and geometric structure limit the possibility of further shortening the signal transmission path. In addition, due to the fixed electrical characteristics of solder ball bumps, it is difficult to adapt to the impedance matching requirements of high-speed signal transmission.

[0006] 3. Thermal management: High-performance chips usually generate a lot of heat. If the heat cannot be dissipated in time, it will lead to performance degradation or even chip damage. The thermal management problem inside the package, especially the local high heat flux density area, has become more and more prominent.

[0007] In addition, conductive adhesive has been widely used as a connecting material in flexible electronic devices, but in the field of high-density and high-frequency chip packaging, the electrical properties and thermal management capabilities of conductive adhesive still need to be further optimized. Summary of the invention

[0008] An object of various embodiments of the present disclosure is to provide a chip packaging structure.

[0009] According to one aspect of the present disclosure, there is provided a chip packaging structure, comprising a chip component, a substrate, and an electrical connection structure between the chip component and the substrate; Wherein, the electrical connection structure comprises a conductive adhesive, and the conductive adhesive is arranged between the chip component and the substrate to respectively connect the electrical contact points of the chip component and the substrate; Wherein, the phase change material intersects with the conductive adhesive to form a heat dissipation structure of the chip packaging structure.

[0010] The various embodiments of the present disclosure improve the high-speed signal transmission and thermal management issues in modern chip packaging technology. Existing solder ball bump technology and conductive adhesive applications have certain limitations in meeting high-speed and high-density packaging requirements. By using conductive adhesive as a means of connection between a chip and a PCB, the embodiments of the present disclosure can achieve a thinner connection layer, thereby significantly shortening the signal transmission path, reducing the connection impedance, and improving the quality and speed of signal transmission. In addition, while providing electrical connection, the conductive adhesive material also has good adhesion properties, enhances the mechanical stability of the connection, is suitable for high-density packaging environments, and avoids the risk of traditional solder balls breaking in high temperature or high stress environments.

[0011] The embodiments of the present disclosure replace solder ball bumps with conductive glue and introduce phase change materials to optimize heat dissipation, which can quickly absorb and release heat in local high heat flux density areas, thereby achieving effective heat dissipation management. This heat dissipation solution can reduce the temperature peak inside the package, extend the service life of the chip and improve performance stability.

[0012] Therefore, the present disclosure improves the electrical and thermal management performance in existing packaging solutions, helps to solve key problems existing in current high-speed chip packaging technology, and promotes chip packaging to develop in a more efficient and intelligent direction.

[0013] Local temperature control: By optimizing the distribution design of the phase change material, the temperature of the local area can be controlled more accurately to ensure the optimal thermal management performance of the package under different working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Other features, objects and advantages of the present disclosure will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 A schematic diagram of a chip packaging structure according to an embodiment of the present disclosure is shown.

[0015] The same or similar reference numerals in the drawings represent the same or similar components. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0017] See also Figure 1 , which shows a schematic diagram of a chip packaging structure according to an embodiment of the present disclosure.

[0018] like Figure 1 As shown, the chip packaging structure includes a chip component 10 , a substrate 20 and an electrical connection structure 30 .

[0019] The electrical connection structure 30 includes a conductive adhesive, which is arranged between the chip assembly 10 and the substrate 20 to respectively connect the electrical contact points of the chip assembly 10 and the substrate 20 , so that the chip assembly 10 and the substrate 20 are electrically connected.

[0020] In the present disclosure, the chip assembly 10 and the substrate 20 are a set of relative concepts, which refer to different things according to different specific application scenarios, and may include at least the following three situations: 1) The chip component 10 is a bare chip, and the substrate 20 is a chip substrate. This is a first-level packaging of the bare chip, and a packaged chip is obtained after packaging. In this structure, a bare chip is directly mounted on the chip substrate, and the chip substrate acts as an intermediary, through which the chip signal and power supply are led out to a larger system, such as a PCB or system package. The chip substrate is usually made of multi-layer organic materials (such as BT resin (Bismaleimide Triazine Resin)) or ceramic materials, with fine wiring and multiple through holes for signal transmission and distribution. The bare chip and the chip substrate can also be packaged by a protective packaging material (i.e., a shell); 2) The chip assembly 10 is a packaged chip, and the substrate 20 is a PCB. In this case, the chip assembly is actually a chip that has completed the first-level packaging. The packaged chip includes a bare die, a chip substrate and a protective packaging material, and also includes an external connection interface for electrical connection with the PCB. The packaged chip realizes signal transmission, power distribution and integration with other electronic components through the PCB. The packaged chip and the PCB can also be further packaged by an external shell; 3) The chip component 10 is a bare chip, and the substrate 20 is a PCB. In this case, the signal of the bare chip is directly distributed and transmitted through the wiring of the PCB. The substrate (PCB) directly serves as the carrier of the bare chip. In addition to providing an electrical connection path and mechanical support, it may also provide environmental protection and stress buffering for the bare chip through a covering layer, such as a bottom filling material or a protective film. This method is usually used in certain application scenarios with low cost or high performance requirements. For example, in a system-level packaging scenario, multiple functional modules, such as processors, memories, sensors, etc., are integrated in one package, and the PCB can be used as a direct carrier. The bare chip is also integrated in the package as part of the functional module, and is directly connected to the PCB to achieve electrical and functional integration.

[0021] In each embodiment of the present disclosure, the electrical connection structure 30 between the chip assembly 10 and the substrate 20 uses conductive adhesive. Compared with the traditional solder ball bump connection, the use of conductive adhesive material as the electrical connection means between the chip assembly 10 and the substrate 20 has high conductivity and adhesion, and forms a thin and efficient connection layer.

[0022] Conductive adhesive is an adhesive material with conductive properties, usually composed of base polymer and conductive filler. The base polymer is usually a polymer material such as epoxy resin, acrylic resin or silicone rubber, which is responsible for providing adhesion and structural support. The choice of base polymer affects the mechanical strength, temperature resistance and chemical resistance of the conductive adhesive. Conductive fillers are usually metal particles (such as silver, copper, gold, aluminum, etc.), carbon black or carbon nanotubes. The quality and distribution of conductive fillers are critical to the electrical performance of conductive adhesives, as they provide a conductive path for current.

[0023] Conductive adhesive materials can be designed as composite structures containing multiple components to optimize performance. For example, conductive particles (such as silver or copper nanoparticles) can be combined with highly conductive polymers to improve conductivity while maintaining adhesion.

[0024] Some exemplary conductive adhesive materials are shown below: 1) Silver-based conductive adhesive (silver powder filled) Material composition: silver powder (usually high-purity silver powder), resin matrix (such as epoxy resin, polyurethane, etc.), toughening agent; Electrical conductivity: Suitable for applications requiring high electrical conductivity; Application: Commonly used in high-frequency electronic equipment, microelectronic packaging, solar panel connection, etc.; Working temperature: Generally, the working temperature range of silver-based conductive adhesive is -50°C to 150°C. Some high-temperature silver adhesives can reach 200°C, but too high a temperature will affect its conductivity and adhesion.

[0025] 2) Copper-based conductive adhesive (copper powder filled) Material composition: copper powder, resin matrix (epoxy resin, etc.); Conductivity: Copper's conductivity is not as good as silver, but it is still very conductive and cheaper than silver; Application: Used in low to medium frequency electrical appliances such as power electronic equipment; Working temperature: The working temperature is usually -40°C to 125°C. For high temperature applications, it is necessary to specially select high temperature resistant substrates and toughening agents.

[0026] 3) Carbon-based conductive adhesive (carbon black or graphite filled) Material composition: carbon black or graphite, resin matrix; Conductivity: Relatively low, but has advantages in cost and weight control. It is often used in applications requiring lower conductivity; Application: Widely used in low-power, low-frequency electronic equipment and static elimination applications; Working temperature: The working temperature range is wide, and it can work between -40°C and 150°C.

[0027] 4) Silver-copper alloy conductive adhesive (silver-copper alloy powder filling) Material composition: silver-copper alloy powder, epoxy resin, etc. Conductivity: Between the conductivity of silver and copper, suitable for applications requiring medium conductivity; Application: power modules, LED drive circuits, some high-temperature transmission lines, etc. Operating temperature: Typically -40°C to 180°C.

[0028] According to one example, flexible reinforcing fibers may also be added to the conductive adhesive to improve mechanical strength and durability. Flexible reinforcing fibers refer to fiber materials with a certain degree of flexibility, which are generally used to enhance the mechanical strength, durability and tensile strength of composite materials or adhesives. Adding flexible reinforcing fibers to the conductive adhesive can effectively improve its performance, especially when subjected to external forces and temperature changes, and can improve its stability and durability.

[0029] Applicable flexible reinforcing fibers include glass fiber, carbon fiber, aramid fiber (such as Kevlar), polyester fiber or nylon fiber. Adding flexible reinforcing fibers to conductive adhesive can significantly improve its mechanical strength and durability, especially for applications requiring high strength, high temperature resistance or long-term stable operation. This improvement can enable the conductive adhesive to maintain its electrical connection function and physical stability in more demanding working environments.

[0030] The electrical connection structure 30 uses conductive glue as the main connection material, and the conductive glue is arranged between the chip component 10 and the substrate 20. The function of the conductive glue is to achieve reliable electrical connection between the chip component 10 and the substrate 20. The conductive glue forms a conductive path with the electrical contact points on the chip component 10 and the substrate 20 respectively through the distribution and continuity of its conductive particles, thereby electrically connecting the two.

[0031] According to an example, between the chip assembly 10 and the substrate 20 , the conductive adhesive is usually evenly coated between the electrical contact points (such as pads, pins) of the chip assembly 10 and the corresponding electrical contact points (such as pads, contact points) of the substrate 20 .

[0032] For example, the conductive adhesive can be evenly coated on the contact area between the chip component 10 and the substrate 20. The base polymer in the conductive adhesive provides mechanical support and flexibility, while the conductive particles (such as silver, copper or carbon nanotubes, etc.) dispersed therein form a conductive network to ensure that the electrical signal can be smoothly transmitted from the chip component 10 to the substrate 20, while ensuring the stability and reliability of the contact.

[0033] This connection method effectively fills the gap that may exist between the chip component 10 and the substrate 20 through the adhesiveness of the conductive adhesive, avoiding poor connection caused by surface unevenness or dimensional tolerance. In addition, the conductive adhesive can also absorb part of the stress caused by thermal expansion, thereby enhancing the mechanical stability of the overall structure, especially under conditions of multiple thermal cycles or long-term use.

[0034] Through this arrangement, the electrical connection between the chip assembly 10 and the substrate 20 is completed, achieving reliable transmission of signals and power, and supporting the normal operation of the chip.

[0035] According to various embodiments of the present disclosure, the conductive adhesive includes at least the following arrangements to achieve electrical connection between the chip assembly 10 and the substrate 20: 1. Even coating: The conductive adhesive may be evenly coated on the surface where the electrical contact points (such as pads, pins) of the chip component 10 are located and the surface where the corresponding contact points (such as pads, contact points) of the substrate 20 are located, so as to form a stable electrical connection layer between the chip component 10 and the substrate 20 by bonding the two together; 2. Glue dispensing (glue dripping) method: The conductive glue may be applied to specific contact points of the chip component 10 and the substrate 20 by dispensing technology, rather than covering the entire contact surface. This method is suitable for high-precision electrical connection requirements; The chip packaging structure further introduces phase change material (PCM), which intersects with the conductive adhesive to form a heat dissipation structure. Here, "intersection" means, for example, that the phase change material is coated on the conductive adhesive or that the phase change material is embedded in the conductive adhesive. The heat dissipation structure, especially the phase change material, can conduct heat by being close to or directly contacting a heating element (such as a power element on a chip or substrate), or it can indirectly conduct heat for the chip assembly 10 and the substrate 20 electrically connected to the conductive adhesive by dissipating heat for the intersecting conductive adhesive. Phase change material is a material with phase change properties that changes state within a specific temperature range, such as from solid to liquid, or from liquid to solid. Phase change materials are commonly used for thermal management and can absorb or release heat to help dissipate heat.

[0036] Some exemplary phase change materials are shown below: 1) Paraffin-based phase change materials Material composition: Paraffin is one of the most common organic phase change materials and is usually mixed with appropriate amounts of additives (such as wax or fatty acid) to improve its thermal conductivity and phase change properties; Melting point range: usually between 40°C and 70°C; Application: Widely used in low to medium temperature thermal management applications, such as computer chip cooling, LED cooling, etc.

[0037] 2) Fatty Acids-based Phase Change Materials Material composition: such as stearic acid, palmitic acid, etc.; Melting point range: usually 50°C to 90°C, with good thermal stability and long service life; Application: used in electronic products, building insulation, heat conduction systems, etc.

[0038] 3) Inorganic salt (salt) based phase change materials Material composition: Inorganic salts, such as sodium chloride, calcium chloride, etc.; Melting point range: usually high, 70°C to 300°C; Application: Suitable for applications requiring higher temperature range, such as industrial thermal management, battery thermal management, high temperature equipment, etc.

[0039] 4) Metal alloy-based phase change materials Material composition: Metal alloys, such as sodium-calcium alloys, are often used in high-temperature applications; Melting point range: adjustable, usually 200°C to 800°C; Application: Suitable for high temperature environments, especially in areas that require high temperature thermal management, such as high temperature equipment thermal management, electronic equipment heat dissipation, battery thermal management, etc.

[0040] For the heat dissipation structure formed by the intersection of phase change material and conductive adhesive, some exemplary combinations of phase change material and conductive adhesive are as follows: For low to medium temperature electronic devices, you can choose a combination of silver-based or copper-based conductive adhesive and paraffin phase change material. Paraffin can start to melt at about 50°C, absorb a lot of heat, and keep the temperature of the device stable. This combination is particularly suitable for devices such as LED driver power supplies and power modules that require high conductivity and good thermal management. The proportion of phase change material is between 30%-50%, and the rest is conductive adhesive matrix and filler.

[0041] For high-temperature applications, you can choose to combine conductive adhesives (such as silver-based conductive adhesives) with inorganic salt phase change materials. Inorganic salts can provide a higher melting point (such as calcium chloride melting point of about 772 ° C), suitable for high-power, high-temperature equipment. This combination ratio requires a higher content of inorganic phase change materials, usually the proportion of phase change materials can reach 60%-70%, to provide sufficient heat capacity to absorb heat.

[0042] In some embodiments, coating the phase change material on the conductive adhesive means that the phase change material covers the outer surface of the conductive adhesive to form a coating layer with heat dissipation function. The phase change material layer can be fully covered or partially covered with respect to the conductive adhesive.

[0043] Full coverage means that the phase change material is evenly coated on the entire external surface of the conductive adhesive to provide comprehensive heat dissipation capabilities. The phase change material covers the entire external surface of the conductive adhesive, providing uniform heat dissipation support for all contact areas, which is suitable for chip packaging needs with a wide heat distribution.

[0044] According to one example, the PCM is coated on the outer surface of the conductive adhesive by spraying, brushing or screen printing to ensure uniform thickness.

[0045] Partial coverage, only applied to the local area of ​​the conductive glue, optimize the heat dissipation performance of the specific area. The phase change material only covers the specific area of ​​the conductive glue, such as the surface close to the heat source or the contact surface of the chip with a large heat load, to solve the local heat dissipation problem in a targeted manner.

[0046] According to one example, based on the distribution of heat sources in the chip, PCM is targetedly coated in areas with greater heat load to reduce material waste in unnecessary areas.

[0047] Phase change material coating can directly absorb and quickly transfer heat to the external environment, thereby reducing the operating temperature of the chip / conductive adhesive. In addition, the coating method is flexible and suitable for conductive adhesive application scenarios of different shapes and sizes.

[0048] Phase change material is coated on the conductive adhesive, that is, the conductive adhesive is partially or completely wrapped with phase change material. The thermal management characteristics of phase change material are fully utilized to optimize the heat dissipation effect by absorbing the heat generated during the operation of the chip, while ensuring that the electrical connection performance of the conductive adhesive is not affected.

[0049] As a coating method of conductive adhesive, dispensing focuses on applying conductive adhesive to the required position rather than covering the entire surface. It can be used for connection and bonding of electrical contact points, small pads or specific areas. Dispensing can achieve material arrangement in linear, dot or other complex tracks, and adapt to irregular surfaces or complex layouts.

[0050] According to one example, conductive glue is applied in the form of small dots on the electrical contact points of the chip and the substrate to form a high-precision electrical connection between the two.

[0051] Return to Reference Figure 1 In the electrical connection structure 30, the phase change material (red part) can form a ring-shaped package around the dot-shaped conductive glue (yellow part), which optimizes thermal management without affecting the electrical connection and can achieve targeted heat dissipation. It is suitable for high-precision electrical connections, while meeting the needs of local heat loads, saving the use of phase change materials and reducing costs.

[0052] In order to further optimize local heat dissipation, the phase change material can only wrap part of the dot-shaped conductive glue. For example, only the dot-shaped conductive glue in the area near the heat-generating chip or in the area with high heat flux density can be wrapped with the phase change material, while the dot-shaped conductive glue in other areas can dissipate heat by itself.

[0053] In addition, the phase change temperature can be used to trigger the phase change of the phase change material by heating, such as changing from solid to liquid, so that the liquid phase change material can be wrapped around the outside of the conductive glue.

[0054] Heating can trigger the phase change behavior of the phase change material. Specifically, the phase change material will change from solid to liquid within its specific temperature range. At this time, the volume of the phase change material will change and the density will decrease. This volume change will enable the phase change material to be wrapped around the conductive glue.

[0055] When the heating stops and the temperature drops, the phase change material will return from liquid to solid and shrink in volume. At this point, it will firmly wrap around the conductive glue, fix its position, and continue to provide thermal management functions in its solid state.

[0056] Due to the different densities of the conductive glue and the phase change material, during the heating process, the volume expansion or flow of the phase change material will cause it to form a layer of wrapping on the surface of the conductive glue. If the phase change material becomes thinner during the phase change, it will be able to fill the tiny gaps between the conductive glue and enhance its ability to absorb heat.

[0057] In some embodiments, the phase change material is embedded in the conductive adhesive, which means that the phase change material is distributed inside the conductive adhesive as a functional particle or a local embedding object to form a composite conductive heat dissipation structure. The phase change material can be uniformly embedded in the conductive adhesive or partially embedded in the conductive adhesive. Uniform embedding means that the phase change material particles are uniformly dispersed in the matrix of the conductive adhesive, and play a role in heat conduction and heat dissipation at the same time. Local embedding means that the phase change material is only embedded in the conductive adhesive near the high heat load area to form an enhanced local heat dissipation point.

[0058] According to one example, the phase change material can be dispersed in a specific area of ​​the conductive adhesive, such as inside the conductive adhesive, the phase change material is dispersed in a high heat flux density area close to the electronic components or the conductive path, so that once the heat is generated, it can be quickly absorbed and stored by the phase change material. This design enables the phase change material to play an effective temperature control role at the local high temperature point to avoid overheating.

[0059] Furthermore, the phase change material can be designed in layers, with each layer using phase change materials with different thermal conductivity and phase change temperature. The phase change material of each layer is designed according to the specific working environment and dispersed inside the conductive glue, so that it exhibits different conductive properties and adhesion properties in different temperature ranges, thereby automatically adjusting to adapt to temperature changes in the chip working environment.

[0060] According to another example, the phase change material is embedded in a specific location of the conductive adhesive, such as a location close to a heat-generating chip or power component, so that the heat is absorbed by the phase change material before reaching the conductive adhesive and spreading over a large area. This distribution design allows heat to be quickly absorbed by the phase change material in areas with high heat flux density, thereby effectively managing local temperature.

[0061] The embedded phase change material does not take up additional space when absorbing heat, which can effectively improve the overall thermal conductivity of the conductive adhesive. This avoids the problem of loose structure that may be caused by using phase change material alone, and enhances mechanical strength and thermal management capabilities.

[0062] For those skilled in the art, it is obvious that the embodiments of the present disclosure are not limited to the details of the above exemplary embodiments, and the embodiments of the present disclosure can be implemented in other specific forms without departing from the spirit or basic features of the embodiments of the present disclosure. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the embodiments of the present disclosure is limited by the attached claims rather than the above description, so it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the embodiments of the present disclosure. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it is obvious that the word "including" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units or devices stated in the system claim can also be implemented by one unit or device through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any specific order.

Claims

1. A chip packaging structure, comprising a chip component, a substrate, and an electrical connection structure between the chip component and the substrate; in, The electrical connection structure includes a conductive adhesive, which is arranged between the chip component and the substrate to connect the electrical contact points of the chip component and the substrate respectively; The phase change material intersects with the conductive adhesive to form a heat dissipation structure of the chip packaging structure, and the heat dissipation structure is arranged between the chip component and the substrate.

2. The chip packaging structure according to claim 1, wherein: The phase change material and the conductive adhesive intersect each other, comprising: The phase change material is coated on the conductive adhesive.

3. The chip packaging structure according to claim 2, wherein: The phase change material is coated on the conductive adhesive and comprises: The phase change material wraps a portion of the conductive adhesive.

4. The chip packaging structure according to claim 1, wherein: The phase change material and the conductive adhesive intersect each other, comprising: The phase change material is embedded in the conductive paste.

5. The chip packaging structure according to claim 4, wherein: The phase change material is embedded in the conductive adhesive and comprises: The phase change material is dispersed inside the conductive adhesive.

6. The chip packaging structure according to claim 5, wherein: The phase change material adopts a layered design, and each layer adopts a phase change material with different thermal conductivity and phase change temperature and is dispersed inside the conductive glue.

7. The chip packaging structure according to claim 4, wherein: The phase change material is embedded in the conductive adhesive and comprises: The phase change material is embedded in a specific position of the conductive adhesive.

8. The chip packaging structure according to claim 1, wherein: The conductive glue is respectively connected to the chip component and the electrical contact points of the substrate in a dispensing manner.

9. The chip packaging structure according to claim 1, wherein: The combination of the conductive adhesive and the phase change material is a combination of a silver-based or copper-based conductive adhesive and a paraffin phase change material.

10. The chip packaging structure according to claim 1, wherein: The combination of the conductive adhesive and the phase change material is a combination of a silver-based conductive adhesive and an inorganic salt phase change material.

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