Heat transfer device for an electronic device

Abstract

The invention relates to a heat transfer device (100) for an electronic device (200). The heat transfer device (100) is configured to be arranged between an electronic heat source (210) and a heat dissipation device (220) of the electronic device (200) for heat transfer from the electronic heat source (210) to the heat dissipation device (220). The heat transfer device (100) comprises at least one TIM layer (110), and the TIM layer (110) comprises a first side (112) and a second side (114) arranged opposite to the first side (112), wherein the first side (112) and / or the second side (114) is covered by a coating (116, 116´) for improved heat transfer. Furthermore, embodiments of the invention also relate to an electronic device (200) comprising such a heat transfer device (100).

Description

[0001] HEAT TRANSFER DEVICE FOR AN ELECTRONIC DEVICE

[0002] TECHNICAL FIELD

[0003] Embodiments of invention relate to a heat transfer device for an electronic device. Furthermore, embodiments of the invention also relate to an electronic device comprising such a heat transfer device.

[0004] BACKGROUND

[0005] In recent years, with the continuous miniaturization and high-power density of electronic devices effective thermal management has become increasingly important.

[0006] Excessive heat generated by electronic components can lead to reduced performance, reliability, and even failure of electronic devices. Thermal interface materials (TIMs) play an important role in reducing thermal resistance and improving heat dissipation performance of electronic devices.

[0007] SUMMARY

[0008] An objective of embodiments of the invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions.

[0009] The above and further objectives are solved by the subject matter of the independent claims. Further embodiments of the invention can be found in the dependent claims.

[0010] According to a first aspect of the invention, the above mentioned and other objectives are achieved with a heat transfer device for an electronic device, the heat transfer device being configured to be arranged between an electronic heat source and a heat dissipation device of the electronic device for heat transfer from the electronic heat source to the heat dissipation device, the heat transfer device comprising: at least one thermal interface material, TIM, layer, the TIM layer comprising a first side and a second side arranged opposite to the first side, wherein the first side and / or the second side is covered by a coating for improved heat transfer.

[0011] An advantage of the heat transfer device according to the first aspect is that the coating can effectively fill the micro gaps of the TIM layer surface thus increase the thermal transfer surface area and improve the contact with the electronic heat source and / or the heat dissipation device. Thereby, the interfacial thermal resistance is reduced resulting in improved heat transfer. In an implementation form of a heat transfer device according to the first aspect, the TIM layer comprises a solid core.

[0012] An advantage with this implementation form is that the solid core TIM is easy to use and has better leakage properties compared to other types of TIMs.

[0013] In an implementation form of a heat transfer device according to the first aspect, the solid core comprises a material in a group comprising: a carbon-based material, a metal-based material, and alloys.

[0014] An advantage with this implementation form is that these materials have high thermal conductivity.

[0015] In an implementation form of a heat transfer device according to the first aspect, the heat transfer device comprises a buffer layer arranged between the solid core and the coating.

[0016] An advantage with this implementation form is that the buffer layer improves the bonding and contact between the coating and the solid core TIM thereby providing a more stable and reliable interface therebetween.

[0017] In an implementation form of a heat transfer device according to the first aspect, the buffer layer comprises a material in a group comprising: a polymer, a metal, a ceramic, a conductive adhesive, a composite material of a polymer, and a graphene functionalization process.

[0018] An advantage with this implementation form is that these materials all have suitable properties for the functions of the buffer layer.

[0019] In an implementation form of a heat transfer device according to the first aspect, a thickness of the buffer layer is less than 30% of a thickness of the coating.

[0020] An advantage with this implementation form is that this ratio in thickness between the buffe layer and the coating result in high thermal performance.

[0021] In an implementation form of a heat transfer device according to the first aspect, the coating is a wettability coating. An advantage with this implementation form is that the wettability coating effectively fills the micro gaps for improved heat transfer.

[0022] In an implementation form of a heat transfer device according to the first aspect, the wettability coating comprises a material in a group comprising: a liquid metal, a phase change material, a conductive adhesive, a silicone grease, a silicone oil with a filler, and a polymer with a filler.

[0023] An advantage with this implementation form is that these materials possess good wetting properties, which can enhance compatibility with the surface of the TIM layer, resulting in tighter and more stable contact between the TIM layer and other materials.

[0024] In an implementation form of a heat transfer device according to the first aspect, the filler comprises a high thermal conductive non-metallic compound.

[0025] In an implementation form of a heat transfer device according to the first aspect, heat transfer device comprises: an additional TIM layer; and a packaging layer arranged between the TIM layer and the additional TIM layer.

[0026] In an implementation form of a heat transfer device according to the first aspect, the first side is arranged to be attached to the electronic heat source and the second side is arranged to be attached to the heat dissipation device in use, or vice versa.

[0027] According to a second aspect of the invention, the above mentioned and other objectives are achieved with an electronic device comprising: an electronic heat source; a heat dissipation device; and a heat transfer device according to any one of the preceding claims, wherein the heat transfer device is arranged between the electronic heat source and the heat dissipation device and attached thereto for heat transfer from the electronic heat source to the heat dissipation device.

[0028] In an implementation form of an electronic device according to the second aspect, the electronic heat source is an integrated circuit. In an implementation form of an electronic device according to the second aspect, the heat dissipation device is a heat sink.

[0029] Further applications and advantages of embodiments of the invention will be apparent from the following detailed description.

[0030] BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The appended drawings are intended to clarify and explain different embodiments of the invention, in which:

[0032] - Fig. 1 shows heat transfer devices according to embodiments of the invention;

[0033] - Fig. 2 shows a heat transfer device comprising a buffer layer according to embodiments of the invention; and

[0034] - Fig. 3 to 5 show a heat transfer device arranged in an electronic device according to embodiments of the invention.

[0035] DETAILED DESCRIPTION

[0036] As aforementioned TIMs are used in electronic devices for heat control. In this respect solid TIMs have attracted significant attention due to its convenience and ease of use, high thermal conductivity, better leakage properties among other things. The drawback of solid TIMs lies in the contact resistance. Despite the exceptional thermal conductivity of solid TIMs, the actual heat transfer performance at the interface between the TIM and a heat source or a heat sink is limited by the contact resistance. This contact resistance occurs due to the imperfect and limited contact between the solid surface and the adjacent material(s).

[0037] Due to the poor compressibility of solid TIM and the poor infiltration between solid and solid, there will still be small air gaps between the interfaces of different layers when using solid TIM. Therefore, it is herein disclosed a heat transfer device for improved heat transfer between a heat source and a heat dissipation device, e.g., in electronic devices, compared to conventional solutions. The herein disclosed heat transfer device comprises at least one TIM layer having a coating for achieving the improved heat transfer. The coating can among other things effectively fill the micro gaps between different layers and thus increase the thermal transfer surface area and form better contact at the interfaces, thereby reducing the interfacial thermal resistance.

[0038] Fig. 1 shows a heat transfer device 100 according to embodiments of the invention. The heat transfer device 100 is configured to be arranged between an electronic heat source 210 and a heat dissipation device 220 of the electronic device 200 for heat transfer from the electronic heat source 210 to the heat dissipation device 220.

[0039] The heat transfer device 100 comprises at least one TIM layer 110 for improved heat transfer. The TIM layer 110 comprises a first side 112 and a second side 114 arranged opposite to the first side 112. The first side 112 and / or the second side 114 is covered by a coating 116, 116' for improved heat transfer.

[0040] Thus, it is herein disclosed a heat transfer device 100 for improved thermal management of electronic devices such as consumer electronics. This is achieved by reducing the contact thermal resistance between the TIM layer 110 and chip / heatsink by covering the TIM layer 110 with a coating 116 for improved heat transfer. The heat transfer device 100 may be employed in any suitable electronic devices having components generating heat. It can be used for consumer electronics including smartphones, tablets, PCs, 2in1 , notebooks, etc.

[0041] Furthermore, it should be realized that the present heat transfer device 100 may comprises one or more TIM layers 110, 110'. When the heat transfer device 100 only comprises one TIM layer 110 the first side 112 may be arranged to be attached to the electronic heat source 210 and the second side 114 may be arranged to be attached to the heat dissipation device 220 in use, or vice versa. However, if the heat transfer device 100 comprises two or more TIM layers 110, 110' and possibly other intermediate layers, the upper side of the heat transfer device 100 is configured to be attached to the electronic heat source 210 and the underside of the heat transfer device 100 is configured to be attached to the heat dissipation device 220 in use, or vice versa. The heat transfer device 100 may be attached to the heat transfer device 100 and the heat dissipation device 220 with mechanical means such as fasteners or other mechanical attachment means. Other example is the use of adhesives for attachment.

[0042] Further, that each TIM layer 110 may have the coating 116 on one side only or on both sides depends on application and heat transfer requirements. Fig. 1a shows the example when the underside 112 of the TIM layer 110 is covered by a coating while Fig. 1 b shows the example when the upper side 114 of the TIM layer 110 is covered by a coating 116'. Finally, Fig. 1c shows the example when both the upper side 114 and the underside 112 of the TIM layer 110 are covered by the coating 116, 116'.

[0043] In embodiments of the invention, the coating 116, 116' is a wettability coating which will increase the thermal contact in the interface between the TIM layer 110 and the heat source or heat dissipation device further. Generally, when selecting the coating 116 the wetting properties, thermal conductivity, and compatibility with the underlying materials may be considered among other things. When the coating material possess good wetting properties, the compatibility with the solid core of the TIM layer can be enhanced, resulting in tighter and more stable contact between the graphene and other materials and further reducing the interfacial thermal resistance.

[0044] The wettability coating may comprise a material in a group comprising: a liquid metal, a phase change material, a conductive adhesive, a silicone grease, a silicone oil with a filler, and a polymer with a filler. The filler may comprise a high thermal conductive non-metallic compound. Non-limiting examples of such fillers are oxide such as AI2O3, SiO2, BeO; Nitrides (BN), and carbides (SiC).

[0045] A number of different fabrication techniques may be used for producing the coating 116 on the TIM layer 110 such as spin coating, dip coating, or spray coating. The coating 116 may also be dispensed on the TIM layer 110 by using inkjet printing or micro-pipetting. Vacuum-assisted impregnation on the TIM layer 110 may also be employed. Yet another technique is solid-state diffusion which mean that coating materials can be mixed together with the solid core on the atomic level.

[0046] Furthermore, Fig. 2 shows a heat transfer device 100 comprising buffer layers according to embodiments of the invention. In Fig. 2 the heat transfer device 100 comprises two buffer layers 120, 120' but the heat transfer device 100 may comprise only one buffer layer 120. The buffer layer 120, 120' may in embodiments of the invention be arranged between a solid core 118 of the TIM layer 110 and the coating 116. The function of the buffer layer 120 is to address the imperfect contact or bonding between the TIM layer 110 and the coating layer 116. Thereby, a more stable and reliable interface is provided between the TIM layer 110 and the coating layer 116 further reducing the thermal resistance.

[0047] The buffer layer 120 can be made of various materials, depending on the requirement and need of the application. Including but not limited are materials such as polymers, metal, ceramic particles, nanoparticles and thermal conductive adhesives and composite materials consisting of a combination of polymers, ceramics or metals. More specifically, the buffer layer 120, 120' comprise a material in a group comprising: a polymer, a metal, a ceramic, a thermal conductive adhesive, a composite material of a polymer, and a graphene functionalization process. The relation between the buffer layer 120 and the coating 116 in regards of the thickness may in embodiments of the invention be such that a thickness of the buffer layer 120 is less than 30% of a thickness of the coating 116. In further embodiments of the invention, the thickness of the buffer layer 120 is less than 20% of a thickness of the coating 116, or the thickness of the buffer layer 120 is less than 15% of a thickness of the coating 116. It should be noted that in this discussion the two layers, i.e., the buffer layer 120 and the coating layer 116, are strongly distinguished but these two layers can be more or less mixed together. In absolute values for some general applications, the thickness of buffer layer 120 may be in the interval 10-200nm while the thickness of the coating 116 may be in the interval 2-1 Oum.

[0048] As for the solid core 118 of the TIM layer 110, the solid core 118 may be made of a material in a group comprising: a carbon-based material, a metal-based material, and alloys. For example, the solid core 118 may be composed of vertically aligned graphene forming a horizontal layer in a stacked sandwich structure.

[0049] Moreover, Fig. 3 to 5 show a heat transfer device 100 arranged in an electronic device 200 according to embodiments of the invention. With reference to Fig. 3, the disclosed electronic device 200 comprises an electronic heat source 210, a heat dissipation device 220, and a heat transfer device 100 according to embodiments of the invention. As shown in Fig. 3 the heat transfer device 100 is arranged between the electronic heat source 210 and the heat dissipation device 220 and attached thereto for heat transfer from the electronic heat source 210 to the heat dissipation device 220.

[0050] Fig. 4 shows embodiments of the invention when the heat transfer device 100 comprises more than one TIM layer 110, 110'. In such cases one or more intermediate layers may be arranged between the plural TIM layers 110, 110'of the heat transfer device 100. One such intermediate layer is a so-called packaging layer 130 which is arranged between a TIM layer 110 and an additional TIM layer 110'. The packaging layer 130 has among other things the function of fixing, sealing and protecting the chip and also enhancing the electrical and thermal properties of the chip.

[0051] Fig. 5 shows a further embodiment of an electronic device 200 according to the invention. As shown in Fig. 5 the electronic heat source 210 may be an integrated circuit (IC) while the heat dissipation device 220 may be a heat sink. The IC may be arranged on and being supported by a printed circuit board (PCB). Further, a packaging layer 130 may be arranged between the two TIM layers 110, 110' and the packaging layer 130 may have one or more ridges or flanges 132 that are supported by the PCB. The packaging layer 130 may be arranged relative to the heat source 210, e.g., arranged over the heat source 210, such that the TIM layer 110’ is sandwiched between the packaging layer 130 and the heat source 210, where the TIM 110’ layer is pressed against the heat source 210. The heat source 210 may include one or more heat producing components or devices, e.g., a CPU, a chip within the bottom fill, a semiconductor device, a flip-flop device, an image processor (GPU), a digital signal processor (DSP), a multi-processor system, an integrated circuit, a multi-core processor, etc. The packaging layer 130 may include a peripheral ridge or flange 132 surrounding a generally flat portion. Adhesive may be applied along the peripheral ridge 132 for attaching the packaging layer 130 to the PCB. The peripheral ridge 132 may thus protrude outward sufficiently to extend around the electronic components mounted on the PCB and thereby allow the adhesive on the peripheral ridge 132 to contact the PCB.

[0052] Alternate embodiments may include other ways and means of attaching the heat sink 220 or the package layer 130 to the PCB. For example, the adhesive may not be provided on all edges of the periphery of the package layer 130. Alternatively, the package layer 130may be a flat surface without any peripheral ridges or side walls. In this case, the adhesive itself can connect the gap between the legs of the package layer 130 and the PCB.

[0053] Finally, it should be understood that the invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.

Claims

CLAIMS1. A heat transfer device (100) for an electronic device (200), the heat transfer device (100) being configured to be arranged between an electronic heat source (210) and a heat dissipation device (220) of the electronic device (200) for heat transfer from the electronic heat source (210) to the heat dissipation device (220), the heat transfer device (100) comprising: at least one thermal interface material, TIM, layer (110), the TIM layer (110) comprising a first side (112) and a second side (114) arranged opposite to the first side (112), wherein the first side (112) and / or the second side (114) is covered by a coating (116, 116') for improved heat transfer.

2. The heat transfer device (100) according to claim 1 , wherein the TIM layer (110) comprises a solid core (118).

3. The heat transfer device (100) according to claim 2, wherein the solid core (118) comprises a material in a group comprising: a carbon-based material, a metal-based material, and alloys.

4. The heat transfer device (100) according to claim 2 or 3, further comprising a buffer layer (120, 120') arranged between the solid core (118) and the coating (116, 116').

5. The heat transfer device (100) according to claim 4, wherein the buffer layer (120, 120') comprises a material in a group comprising: a polymer, a metal, a ceramic, a conductive adhesive, a composite material of a polymer, and a graphene functionalization process.

6. The heat transfer device (100) according to claim 4 or 5, wherein a thickness of the buffer layer (120, 120') is less than 30% of a thickness of the coating (116, 116').

7. The heat transfer device (100) according to any one of the preceding claims, wherein the coating (116, 116') is a wettability coating.

8. The heat transfer device (100) according to claim 7, wherein the wettability coating comprises a material in a group comprising: a liquid metal, a phase change material, a conductive adhesive, a silicone grease, a silicone oil with a filler, and a polymer with a filler.

9. The heat transfer device (100) according to claim 8, wherein the filler comprises a high thermal conductive non-metallic compound.

10. The heat transfer device (100) according to any one of the preceding claims, further comprising: an additional TIM layer (110'); and a packaging layer (130) arranged between the TIM layer (110) and the additional TIM layer (110').

11. The heat transfer device (100) according to any one of the preceding claims, wherein the first side (112) is arranged to be attached to the electronic heat source (210) and / or the second side (114) is arranged to be attached to the heat dissipation device (220) in use, or vice versa.

12. An electronic device (200) comprising: an electronic heat source (210); a heat dissipation device (220); and a heat transfer device (100) according to any one of the preceding claims, wherein the heat transfer device (100) is arranged between the electronic heat source (210) and the heat dissipation device (220) and attached thereto for heat transfer from the electronic heat source (210) to the heat dissipation device (220).

13. The electronic device (200) according to claim 12, wherein the electronic heat source (210) is an integrated circuit.

14. The electronic device (200) according to claim 12 or 13, wherein the heat dissipation device (220) is a heat sink.

Images