Chip packaging substrate via hole structure

Abstract

The invention provides a chip packaging substrate via hole structure, which comprises a substrate and a via hole formed in the substrate, and is characterized in that the via hole comprises a memory metal outer layer, a copper wall layer and a phase change fluid channel; the memory metal outer layer is located on the outermost layer of the via hole, the memory metal outer layer is made of memory metal, the memory metal can deform while absorbing heat, and the shape of the memory metal can be recovered after the temperature is reduced; the copper wall layer is made of a metal heat conduction material; the phase change fluid channel is filled with phase change fluid, the phase change fluid is vaporized after absorbing heat, and the phase change fluid is liquefied when releasing heat. According to the invention, the risk of mismatching of thermal expansion coefficients among materials of the substrate is effectively reduced while the heat exchange capability of the via holes is enhanced, compared with an existing via hole heat dissipation mode, the temperature performance can be further optimized, and meanwhile, the packaging warping level can be effectively controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of chip packaging, and in particular to a chip packaging substrate via structure. Background Art

[0002] Chip packaging is the process of processing the chip and its peripheral devices, materials and connecting lines into modular components to facilitate interface, fixation and communication with the external environment. Chip packaging involves the physical connection and electrical characteristics of the chip with the outside world, which has an important impact on the performance and application of the chip. The packaging determines the structure, size, power consumption, operating temperature and accuracy of the chip. At the same time, the choice of packaging method will also affect the cost, reliability, heat dissipation, substrate connection and other aspects of the chip. Therefore, the exploration and improvement of chip packaging will help improve packaging quality, accelerate process flow and reduce costs.

[0003] The power density of current chip packages is getting higher and higher, and the package size is getting larger and larger. It has become an urgent problem to be solved on the packaging side to quickly achieve chip heat conduction while effectively reducing the risk of warping. The current solution is to increase the via aperture to enhance heat dissipation on the substrate side and increase the substrate thickness to reduce the risk of warping and cracking. However, the disadvantage is that after the substrate reaches a certain thickness, only mechanical drilling similar to copper rings can be used, resulting in a small area of ​​the via, which cannot play a significant role in heat dissipation optimization. In addition, the thicker the substrate, the higher the material cost and process difficulty. Summary of the invention

[0004] The purpose of the present invention is to provide a solution for filling phase change fluid to dissipate heat so as to improve the heat dissipation performance and the level of package warping in view of the shortcomings of the above-mentioned background technology.

[0005] In order to achieve the above-mentioned object, the present invention provides a chip packaging substrate via structure, comprising a substrate and a via opened on the substrate, characterized in that the via comprises a memory metal outer layer, a copper wall layer and a phase change fluid channel;

[0006] The memory metal outer layer is located at the outermost layer of the via hole, and the memory metal outer layer is made of memory metal. The memory metal can deform while absorbing heat, and can restore its shape after the temperature drops.

[0007] The copper wall layer is made of metal heat-conducting material;

[0008] The phase change fluid channel is filled with a phase change fluid, and the phase change fluid vaporizes after absorbing heat and liquefies when releasing heat.

[0009] Furthermore, the surface of the copper wall layer is plated with a capillary structure of sintered copper powder, so that the liquefied phase-change fluid flows into the heat source position by capillary action to fully absorb heat.

[0010] Furthermore, the memory metal is a copper-zinc-aluminum alloy or a nickel-titanium alloy or other copper-based alloys.

[0011] Furthermore, the copper wall layer is extended into the phase-change fluid channel.

[0012] Furthermore, the phase change fluid channel runs through the entire thickness of the substrate.

[0013] Furthermore, the phase-change fluid is integrally cast into each of the phase-change fluid channels and encapsulated.

[0014] Furthermore, the phase change fluid is integrally cast through a fluid casting jig, the fluid casting jig is provided with a plurality of casting holes, a funnel-shaped drainage portion is provided at the bottom of the casting holes, and the casting holes and the funnel-shaped drainage portion are arranged in one-to-one correspondence with the vias on the substrate.

[0015] Furthermore, the via holes on the substrate and the pouring holes are arranged in a rectangular array.

[0016] The above scheme of the present invention has the following beneficial effects:

[0017] The chip package substrate via structure provided by the present invention absorbs heat and absorbs a certain amount of deformation of the substrate by deforming itself through the memory metal or similar material with high thermal conductivity and capable of deformation recovery within a certain temperature range coated on the outer layer of the via. After the temperature drops to a certain temperature, the memory metal will restore its shape, thereby enhancing the heat exchange capacity of the via and effectively reducing the risk of mismatching thermal expansion coefficients between the various materials of the substrate; the heat exchange efficiency is further improved through the capillary structure of the sintered copper powder on the surface of the copper wall layer; the phase change fluid filled in the phase change fluid channel can absorb the heat generated by the substrate and undergo a phase change, thereby transferring the heat from the substrate to the inside of the phase change fluid, significantly improving the overall heat exchange efficiency, and when the substrate no longer generates heat and cools, the phase change fluid will undergo a reverse phase change process, releasing the heat, and then absorbing heat again to cool the substrate, which can further optimize the temperature performance compared to the existing via heat dissipation method, and the package warping level can be effectively controlled;

[0018] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a cross-sectional view of the overall structure of the present invention;

[0020] Figure 2 It is a schematic diagram of the fluid casting jig of the present invention;

[0021] Figure 3 It is a schematic diagram of the fluid casting jig of the present invention;

[0022] Figure 4 1 and 1 are isotherm cloud diagrams of simulation analysis in the embodiments of the present invention, wherein (a) is a conventional solution and (b) is this solution.

[0023] [Description of Reference Numerals]

[0024] 10-substrate; 11-dielectric layer; 12-copper layer; 20-via; 21-memory metal outer layer; 22-copper wall layer; 23-phase change fluid channel; 30-fluid pouring fixture; 31-pouring hole; 32-funnel-shaped drainage part. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a locking connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] like Figure 1As shown, an embodiment of the present invention provides a chip package substrate via structure, wherein a substrate 10 is composed of a dielectric layer 11 and a copper layer 12 stacked in sequence, and a via 20 passing through the dielectric layer 11 and the copper layer 12 is provided on the substrate 10. The via 20 includes a memory metal outer layer 21, a copper wall layer 22, and a phase change fluid channel 23.

[0029] In this embodiment, the memory metal outer layer 21 is located at the outermost layer of the via 20, and it can produce a certain amount of deformation while absorbing heat. After the temperature drops to a certain temperature, the memory metal will restore its shape. The surface of the copper wall layer 22 is plated with a capillary structure of sintered copper powder, so that the liquefied phase change fluid flows into the heat source position by capillary action to fully absorb heat, thereby improving the heat exchange efficiency and ensuring the cooling effect. Among them, the heat source position is the position with high temperature near the via.

[0030] The phase change fluid channel 23 is filled with a phase change fluid. It should be noted that phase change is a physical state transformation process of a substance under different temperature and pressure conditions. The phase change process is accompanied by the absorption or release of energy. For example, the vaporization process of the liquid-gas phase change absorbs a large amount of heat. Therefore, through the setting of the phase change fluid, it can absorb the heat generated by the substrate 10 and undergo a phase change, thereby transferring the heat from the substrate 10 to the inside of the phase change fluid. In contrast, the thermal conductivity of the metal copper, a heat-conducting material in the original mechanical copper ring, is 385W / mK. After being replaced with a phase change fluid to absorb heat, due to the phase change, the thermal conductivity can be increased to about 10000W / mK, which is about 25 times that of metal copper, so the overall heat exchange efficiency will be greatly improved. When the substrate 10 no longer generates heat and cools, the phase change fluid will undergo a gas-liquid phase change liquefaction process, release the heat, and then absorb heat again to cool the substrate 10.

[0031] It should be noted that the setting of the memory metal outer layer 21 in this embodiment enables the phase change fluid in the phase change fluid channel 23 to absorb heat until the phase change temperature point is reached when the temperature of the substrate 10 is high, absorbing a large amount of latent heat while maintaining a constant temperature. Since there is a large difference in the thermal expansion coefficients of copper and dielectric materials on the substrate 10, the memory metal absorbs a certain amount of deformation of the substrate 10 by deforming itself while absorbing heat. After the temperature drops to a certain temperature, the memory metal will restore its shape, thereby enhancing the heat exchange capacity of the via 20 while effectively reducing the risk of mismatching thermal expansion coefficients between the materials of the substrate 10.

[0032] In this embodiment, the memory metal can be: copper-zinc-aluminum alloy (Cu-Zn-Al), which has good shape memory effect and good thermal conductivity. The working temperature range is usually between room temperature and 200 degrees Celsius; nickel-titanium alloy (Ni-Ti), nickel-titanium alloy is one of the most widely used memory materials, with excellent shape memory effect and superelasticity, and performs well in a wide temperature range, usually from room temperature to above 100 degrees Celsius, its thermal conductivity is relatively good; copper-based alloys, other copper-based alloys besides Cu-Zn-Al, such as Cu-Al-Ni alloy, also show shape memory effect and good thermal conductivity. These materials can restore their preset shape after being heated due to their special crystal structure and phase change characteristics, so they can be used in this solution. Of course, in other embodiments, it can also be replaced with similar materials with high thermal conductivity and deformation recovery within a certain temperature range.

[0033] In this embodiment, the phase change fluid uses a liquid (gas) with high specific heat capacity and high latent heat to ensure that it has a good effect of absorbing heat and cooling the substrate 10, thereby improving the power density of the chip package. At the same time, the phase change fluid channel 23 is set through the entire thickness of the substrate 10. Considering that some substrates 10 adopt the form of double-sided packaging chips, the heat generated on both sides can be fully absorbed by the phase change fluid. In addition, the via structure provided in this embodiment is not only applicable to the substrate 10, but also to other structures in the chip package that need heat dissipation.

[0034] The phase change fluid is poured into each via hole 20 and encapsulated by integral pouring. Of course, other similar pouring methods can also be used. When the phase change fluid is poured into each via hole 20 by integral pouring, the phase change fluid is encapsulated by integral pouring. Figure 2 , Figure 3 The fluid casting fixture 30 is shown. The fluid casting fixture 30 is provided with a plurality of casting holes 31, and a funnel-shaped drainage portion 32 is provided at the bottom of the casting hole 31. The casting holes 31 and the funnel-shaped drainage portion 32 are arranged one-to-one with the via holes 20 on the substrate 10, so that each via hole 20 on the substrate 10 (i.e., in the phase change fluid channel 23) can be cast as a whole, which improves the convenience of the process and the casting quality.

[0035] It should be noted that the via holes 20 and the pouring holes 31 shown in the figure are arranged in a rectangular array. For different arrangements of the via holes 20 on different substrates 10, a fluid pouring fixture 30 with corresponding arrangements of the pouring holes 31 can be used for the pouring process.

[0036] In summary, the chip package substrate via structure provided in this embodiment is adopted. The memory metal or similar material with high thermal conductivity and capable of deformation recovery within a certain temperature range coated on the outer layer of the via 20 absorbs heat and absorbs a certain amount of deformation of the substrate 10 by its own deformation. After the temperature drops to a certain temperature, the memory metal will restore its shape, thereby enhancing the heat exchange capacity of the via 20 while effectively reducing the risk of mismatch in thermal expansion coefficients between the materials of the substrate 10. The heat exchange efficiency is improved by increasing the heat exchange area through the capillary structure of the sintered copper powder on the surface of the copper wall layer 22. The phase change fluid filled in the phase change fluid channel 23 can absorb the heat generated by the substrate 10 and undergo a phase change, thereby transferring the heat from the substrate 10 to the interior of the phase change fluid, significantly improving the overall heat exchange efficiency. When the substrate 10 no longer generates heat and cools, the phase change fluid will undergo a reverse phase change process, releasing heat, and then absorbing heat again to cool the substrate 10. Through simulation analysis, taking the 15mm*15mm FCBGA package as an example, the chip power consumption is 6W, and the simulation analysis at room temperature shows that the junction temperature is from 51.34℃ to 48.5℃, and the optimization ratio is about 5.5%. Figure 4 The isothermal contours of the two solutions are shown. Therefore, this solution can optimize the temperature performance based on the existing solution, and the package warpage level can be effectively controlled.

[0037] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0038] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A chip packaging substrate via structure, comprising a substrate and a via opening on the substrate, characterized in that: The via comprises a memory metal outer layer, a copper wall layer and a phase change fluid channel; The memory metal outer layer is located at the outermost layer of the via hole, and the memory metal outer layer is made of memory metal. The memory metal can deform while absorbing heat, and can restore its shape after the temperature drops. The copper wall layer is made of metal heat-conducting material; The phase change fluid channel is filled with a phase change fluid, and the phase change fluid vaporizes after absorbing heat and liquefies when releasing heat.

2. The chip package substrate via structure according to claim 1, characterized in that: The surface of the copper wall layer is plated with a capillary structure of sintered copper powder, so that the liquefied phase change fluid flows into the heat source position by capillary action to fully absorb heat.

3. The chip package substrate via structure according to claim 1, characterized in that: The memory metal is a copper-zinc-aluminum alloy or a nickel-titanium alloy or other copper-based alloys.

4. The chip package substrate via structure according to claim 1, characterized in that: The copper wall layer is extended into the phase-change fluid channel.

5. The chip package substrate via structure according to claim 1, characterized in that: The phase change fluid channel is arranged to penetrate the entire thickness of the substrate.

6. The chip package substrate via structure according to claim 1, characterized in that: The phase-change fluid is integrally poured into each of the phase-change fluid channels and encapsulated.

7. The chip package substrate via structure according to claim 6, characterized in that: The phase change fluid is integrally cast through a fluid casting jig, the fluid casting jig is provided with a plurality of casting holes, the bottom of the casting holes is provided with a funnel-shaped drainage portion, and the casting holes and the funnel-shaped drainage portion are arranged in one-to-one correspondence with the vias on the substrate.

8. The chip package substrate via structure according to claim 7, characterized in that: The via holes on the substrate and the pouring holes are arranged in a rectangular array.

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