Manufacturing method of aluminum substrate with low expansion coefficient

Abstract

The invention discloses a manufacturing method of a low-expansion-coefficient aluminum substrate. The aluminum substrate is provided with an aluminum alloy base layer, an insulating layer and a copper foil layer. The insulating layer is arranged on the aluminum alloy base layer, and the copper foil layer is arranged on the insulating layer; the insulating layer is composed of multiple sub-insulating layers, the multiple sub-insulating layers are sequentially a transition layer, an aluminum oxide layer, a persimmon oxide layer and an aluminum oxide layer from the aluminum alloy base layer to the copper foil layer, the transition layer, the aluminum oxide layer, the persimmon oxide layer and the aluminum oxide layer are generated in a sputtering deposition mode, and the transition layer is a CrTiAlN film. According to the invention, the insulating layer is arranged into a four-layer structure, and the aluminum oxide film and the persimmon oxide film with low expansion coefficients are adopted, so that the aluminum substrate has a low thermal expansion coefficient, the influence of high temperature generated when an element works on the aluminum substrate is better ensured, and meanwhile, the influence of the aluminum substrate on the element and the whole circuit is also reduced; through reasonable proportioning, the thermal expansion coefficient of the insulating layer can be further reduced.

Description

Technical Field

[0001] The invention belongs to the field of circuit board production and manufacturing, relates to the production of an aluminum substrate, and specifically relates to a method for producing an aluminum substrate with a low expansion coefficient. Background Art

[0002] With the development of science and technology, electronic components are constantly developing towards miniaturization, high-end, lightweight, diversification and high working performance.

[0003] As the number of components per unit area increases, the heat generated per unit area is getting bigger and bigger, and the heat will affect the circuit board, and the impact on the circuit board will affect the components, and the two will affect each other. That is, the performance, reliability and service life of the components may be affected by the increase in temperature.

[0004] Aluminum substrates are widely used in circuit boards because of their good performance. Aluminum substrates are affected by the temperature of components, and the impact on components is getting more and more attention, because this is a key part of the circuit connection with high quality requirements. Therefore, when considering the heat dissipation of aluminum substrates, it is more necessary to pay attention to the influence of the thermal expansion coefficient of aluminum substrates.

[0005] In order to make the thermal expansion coefficient of the aluminum substrate relatively low, it is necessary to select and improve the materials of each layer of the aluminum substrate. Summary of the invention

[0006] In view of the above background, an object of the present invention is to provide a method for manufacturing a low expansion coefficient aluminum substrate to solve the problems in the prior art.

[0007] The specific scheme of the present invention is as follows:

[0008] A method for manufacturing a low expansion coefficient aluminum substrate, the aluminum substrate comprising an aluminum alloy base layer, an insulating layer and a copper foil layer; the insulating layer is arranged on the aluminum alloy base layer, and the copper foil layer is arranged on the insulating layer;

[0009] The insulating layer is composed of a plurality of sub-insulating layers, and the arrangement of the plurality of sub-insulating layers from the aluminum alloy base layer to the copper foil layer is a transition layer, an aluminum oxide layer, an aluminum oxide layer and an aluminum oxide layer in sequence. The transition layer, the aluminum oxide layer, the aluminum oxide layer and the aluminum oxide layer are respectively generated by sputtering deposition, and the transition layer is a CrTiAlN film.

[0010] Preferably,

[0011] Before performing sputtering deposition, the surface and side edges of the aluminum alloy base are cleaned, and the surface and side edges of the aluminum alloy base are first polished with sandpaper. After the surface and side edges are polished, a transition zone greater than the thickness value is polished at the edge of the bottom surface of the aluminum alloy base;

[0012] After polishing, the aluminum alloy substrate is placed in an acetone solution for ultrasonic cleaning for 25 minutes; after cleaning, the aluminum alloy substrate is blown dry using nitrogen.

[0013] Preferably,

[0014] The transition layer is deposited by unbalanced magnetron sputtering, and the targets are titanium target, aluminum target and chromium target respectively. The target sizes are The sputtering chamber was evacuated to a maximum vacuum of 2.0 × 10 - 3 Pa, argon and nitrogen are introduced to adjust the vacuum degree to about 0.5Pa, and the sputtering power is turned on to form a CrTiAlN film; the unbalanced magnetron sputtering deposition process parameters are: titanium target power 900W, aluminum target power 600W, chromium target power 300W, argon flow rate 0.03slm, nitrogen flow rate 0.02slm, deposition temperature 200°C, and deposition time 150min.

[0015] Preferably,

[0016] After the unbalanced magnetron sputtering deposition process completes the CrTiAlN film, the CrTiAlN film is heated at a temperature rise rate of 5°C / min to 1000°C and kept at this temperature for 5 hours; the temperature is lowered to 600°C at a rate of 5°C / min, and then high-purity oxygen is introduced at a flow rate of 0.06slm. The holding time at 600°C is set for 2 hours, and the thickness and generation rate of aluminum oxide are detected at the same time, and finally the temperature is lowered to room temperature.

[0017] Preferably,

[0018] When the thickness of the aluminum oxide reaches the set thickness, the temperature is reduced to room temperature at a rate of 20°C / min, at which time the thickness of the aluminum oxide film meets the requirement;

[0019] When the generation rate of the aluminum oxide is less than the required value, the difference between the current thickness of the aluminum oxide and the set thickness is calculated, and the time required for the current generation to reach the set thickness is calculated. When the time meets the requirement, the temperature is kept for the time, and then the temperature is reduced to room temperature at a rate of 5°C / min. At this time, the thickness of the aluminum oxide film meets the requirement;

[0020] If the time cannot meet the requirement or the aluminum oxide film has stopped growing before reaching the set thickness, the temperature is lowered to room temperature at a rate of 30°C / min. At this time, the thickness of the aluminum oxide film does not meet the requirement.

[0021] Preferably,

[0022] When the thickness of the aluminum oxide film does not meet the requirements, DC magnetron reactive sputtering is required to continue sputtering the aluminum oxide film. The target material is pure aluminum, the sputtering power is 100W, the sputtering pressure is 0.4Pa, the sputtering temperature is room temperature, the target spacing is 50mm, and the vacuum degree is 2.0×10 -4 Pa, the flow ratio of argon and oxygen is 20:1, and sputtering is stopped when the thickness requirement is met.

[0023] Preferably,

[0024] When the thickness of the aluminum oxide film meets the requirements, the persimmon oxide film is sputtered by DC magnetron reactive sputtering, and a pure persimmon target is selected, the sputtering power is 100W, the sputtering pressure is 0.4Pa, the sputtering temperature is room temperature, the target spacing is 50mm, and the vacuum degree is 2.0×10 -4 Pa, the flow ratio of argon and oxygen is 20:1, and sputtering is stopped when the thickness requirement is met.

[0025] Preferably,

[0026] After the persimmon oxide film is sputtered, DC magnetron reactive sputtering is required to continue sputtering the aluminum oxide film. The target material is pure aluminum, the sputtering power is 100W, the sputtering pressure is 0.4Pa, the sputtering temperature is room temperature, the target spacing is 50mm, and the vacuum degree is 2.0×10 - 4 Pa, the flow ratio of argon and oxygen is 20:1, and sputtering is stopped when the thickness requirement is met.

[0027] Preferably,

[0028] The film thickness ratio of the transition layer, the aluminum oxide layer, the persimmon oxide layer and the aluminum oxide layer is 10:1:0.5:1.

[0029] Preferably,

[0030] The film thickness ratio of the aluminum oxide layer, the persimmon oxide layer and the aluminum oxide layer is 2:1:2.

[0031] The beneficial effects of the present invention are:

[0032] The present invention sets the insulating layer into a four-layer structure, adopts aluminum oxide film and persimmon oxide film with low expansion coefficient, so that the aluminum substrate has a low thermal expansion coefficient, which further ensures the influence of high temperature generated by the component during operation on the aluminum substrate, and also reduces the influence of the aluminum substrate on the component and the entire circuit; through reasonable ratio, the thermal expansion coefficient of the insulating layer can be further reduced.

[0033] Specific real-time method

[0034] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0035] The present invention discloses a method for manufacturing an aluminum substrate with a low expansion coefficient. It can be further known that the present invention also discloses an aluminum substrate manufactured by using the manufacturing method.

[0036] In all embodiments of the present invention,

[0037] The aluminum substrate of the present invention comprises an aluminum alloy base layer, an insulating layer and a copper foil layer, which is the basic structure of a single-layer aluminum substrate. The insulating layer is arranged on the aluminum alloy base layer, and the copper foil layer is arranged on the insulating layer.

[0038] The method for manufacturing the low thermal expansion coefficient aluminum substrate of the present invention has the following multiple embodiments. Those skilled in the art can know that the contents described in the embodiments are mutually progressive or complementary.

[0039] Embodiment 1

[0040] The insulating layer of the low expansion coefficient aluminum substrate of the present invention is composed of multiple layers of sub-insulating layers, and the multiple layers of sub-insulating layers are arranged from the aluminum alloy base layer to the copper foil layer in the order of transition layer, aluminum oxide layer, persimmon oxide layer and aluminum oxide layer, and the transition layer, aluminum oxide layer, persimmon oxide layer and aluminum oxide layer are respectively generated by sputtering deposition.

[0041] In this embodiment, the preferred transition layer is a CrTiAlN film.

[0042] Embodiment 2

[0043] On the basis of Example 1, in order to improve the bonding strength between the surface of the aluminum alloy base plate and other layers, the surface and sides of the aluminum alloy base are cleaned before sputtering deposition. The present invention adds cleaning of the sides and bottom of the aluminum alloy base. Since there will be a deposition layer at a certain distance on the sides and bottom during sputtering, if cleaning is not performed, the bonding strength of the deposition layer on the sides will not be high, thereby reducing the bonding strength of the entire deposition layer and the aluminum alloy base.

[0044] The cleaning process of the present invention is different from the traditional cleaning method. First, the surface and side edges of the aluminum alloy base are polished with sandpaper. After the surface and side edges are polished, a transition zone greater than the thickness value is polished at the edge of the bottom surface of the aluminum alloy base.

[0045] After grinding, the aluminum alloy base is placed in an acetone solution for ultrasonic cleaning for 25 minutes. After cleaning, the aluminum alloy base is blown dry with nitrogen. The purpose of this step is to remove the tiny particles generated during the grinding process, and impurities can be further removed during the drying process.

[0046] The transition layer is produced by sputtering deposition, which is unbalanced magnetron sputtering. The target materials are titanium target, aluminum target and chromium target. The target sizes are The sputtering chamber was evacuated to a maximum vacuum of 2.0 × 10 -3 Pa, argon and nitrogen are introduced to adjust the vacuum degree to about 0.5Pa, and the sputtering power is turned on to form a CrTiAlN film; the unbalanced magnetron sputtering deposition process parameters are: titanium target power 900W, aluminum target power 600W, chromium target power 300W, argon flow rate 0.03slm, nitrogen flow rate 0.02slm, deposition temperature 200°C, and deposition time 150min.

[0047] After the unbalanced magnetron sputtering deposition process completes the CrTiAlN film, the CrTiAlN film is heated at a temperature rise rate of 5°C / min to 1000°C and kept at this temperature for 5 hours; the temperature is lowered to 600°C at a rate of 5°C / min, and then high-purity oxygen is introduced at a flow rate of 0.06slm. The holding time at 600°C is set for 2 hours, and the thickness and generation rate of aluminum oxide are detected at the same time, and finally the temperature is lowered to room temperature.

[0048] Embodiment 3

[0049] Based on the second embodiment, the third embodiment controls the thickness of the aluminum oxide film.

[0050] When the thickness of the aluminum oxide reaches the set thickness, it is cooled to room temperature at a rate of 20° C. / min. At this time, the thickness of the aluminum oxide film meets the requirement.

[0051] When the generation rate of aluminum oxide is lower than the required value, the difference between the current thickness of aluminum oxide and the set thickness is calculated, and the time required for the current generation to reach the set thickness is calculated. When the time meets the requirement, the temperature is kept warm for the time, and then cooled to room temperature at a rate of 5°C / min. At this time, the thickness of the aluminum oxide film meets the requirement.

[0052] If the time cannot meet the requirement or the aluminum oxide film has stopped growing before reaching the set thickness, the temperature is lowered to room temperature at a rate of 30°C / min. At this time, the thickness of the aluminum oxide film does not meet the requirement.

[0053] When the thickness of the aluminum oxide film does not meet the requirements, DC magnetron reactive sputtering is required to continue sputtering the aluminum oxide film. The target material is pure aluminum, the sputtering power is 100W, the sputtering pressure is 0.4Pa, the sputtering temperature is room temperature, the target spacing is 50mm, and the vacuum degree is 2.0×10 -4 Pa, the flow ratio of argon and oxygen is 20:1, and sputtering is stopped when the thickness requirement is met.

[0054] It can be seen from the above control method that the present invention monitors the production status of the aluminum oxide film and controls the generation status of the aluminum oxide film according to the monitoring results. Therefore, the generation of the aluminum oxide film can be controlled more accurately, the bonding strength is improved, and at the same time, a low thermal expansion coefficient layer can be provided, and a better quality substrate can be provided for the subsequent low thermal expansion layer.

[0055] When the thickness of the aluminum oxide film meets the requirements, the persimmon oxide film is sputtered by DC magnetron reactive sputtering, and a pure persimmon target is selected, the sputtering power is 100W, the sputtering pressure is 0.4Pa, the sputtering temperature is room temperature, the target spacing is 50mm, and the vacuum degree is 2.0×10 -4 Pa, the flow ratio of argon and oxygen is 20:1, and sputtering is stopped when the thickness requirement is met.

[0056] After the persimmon oxide film is sputtered, DC magnetron reactive sputtering is required to continue sputtering the aluminum oxide film. The target material is pure aluminum, the sputtering power is 100W, the sputtering pressure is 0.4Pa, the sputtering temperature is room temperature, the target spacing is 50mm, and the vacuum degree is 2.0×10 - 4 Pa, the flow ratio of argon and oxygen is 20:1, and sputtering is stopped when the thickness requirement is met.

[0057] The oxide film provides a low thermal expansion layer.

[0058] Embodiment 4

[0059] In order to make the low thermal expansion layer have a better thermal expansion ratio, on the basis of the third embodiment, the film thickness ratio of the transition layer, the aluminum oxide layer, the persimmon oxide layer and the aluminum oxide layer is 10:1:0.5:1.

[0060] Embodiment 5

[0061] In order to make the low thermal expansion layer have a better thermal expansion ratio, on the basis of Example 3, the film thickness ratio of the aluminum oxide layer, the persimmon oxide layer and the aluminum oxide layer is 2:1:2.

[0062] The beneficial effects of the present invention are:

[0063] The present invention sets the insulating layer into a four-layer structure, adopts aluminum oxide film and persimmon oxide film with low expansion coefficient, so that the aluminum substrate has a low thermal expansion coefficient, which further ensures the influence of high temperature generated by the component during operation on the aluminum substrate, and also reduces the influence of the aluminum substrate on the component and the entire circuit; through reasonable ratio, the thermal expansion coefficient of the insulating layer can be further reduced.

[0064] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for manufacturing a low expansion coefficient aluminum substrate, Features: The aluminum substrate comprises an aluminum alloy base layer, an insulating layer and a copper foil layer; the insulating layer is arranged on the aluminum alloy base layer, and the copper foil layer is arranged on the insulating layer; The insulating layer is composed of a plurality of sub-insulating layers, and the arrangement of the plurality of sub-insulating layers from the aluminum alloy base layer to the copper foil layer is a transition layer, an aluminum oxide layer, an aluminum oxide layer and an aluminum oxide layer in sequence. The transition layer, the aluminum oxide layer, the aluminum oxide layer and the aluminum oxide layer are respectively generated by sputtering deposition, and the transition layer is a CrTiAlN film.

2. The method for manufacturing a low expansion coefficient aluminum substrate according to claim 1, Features: Before performing sputtering deposition, the surface and side edges of the aluminum alloy base are cleaned, and the surface and side edges of the aluminum alloy base are first polished with sandpaper. After the surface and side edges are polished, a transition zone greater than the thickness value is polished at the edge of the bottom surface of the aluminum alloy base; After polishing, the aluminum alloy substrate is placed in an acetone solution for ultrasonic cleaning for 25 minutes; after cleaning, the aluminum alloy substrate is blown dry using nitrogen.

3. The method for manufacturing a low expansion coefficient aluminum substrate according to claim 2, Features: The transition layer is deposited by unbalanced magnetron sputtering, and the targets are titanium target, aluminum target and chromium target respectively. The target sizes are The sputtering chamber was evacuated to a maximum vacuum of 2.0 × 10 -3 Pa, argon and nitrogen are introduced to adjust the vacuum degree to about 0.5Pa, and the sputtering power is turned on to form a CrTiAlN film; the unbalanced magnetron sputtering deposition process parameters are: titanium target power 900W, aluminum target power 600W, chromium target power 300W, argon flow rate 0.03slm, nitrogen flow rate 0.02slm, deposition temperature 200°C, and deposition time 150min.

4. The method for manufacturing a low expansion coefficient aluminum substrate according to claim 3, Features: After the unbalanced magnetron sputtering deposition process completes the CrTiAlN film, the CrTiAlN film is heated at a temperature rise rate of 5°C / min to 1000°C and kept at this temperature for 5 hours; the temperature is lowered to 600°C at a rate of 5°C / min, and then high-purity oxygen is introduced at a flow rate of 0.06slm. The holding time at 600°C is set for 2 hours, and the thickness and generation rate of aluminum oxide are detected at the same time, and finally the temperature is lowered to room temperature.

5. The method for manufacturing a low expansion coefficient aluminum substrate according to claim 4, Features: When the thickness of the aluminum oxide reaches the set thickness, the temperature is reduced to room temperature at a rate of 20°C / min, at which time the thickness of the aluminum oxide film meets the requirement; When the generation rate of the aluminum oxide is less than the required value, the difference between the current thickness of the aluminum oxide and the set thickness is calculated, and the time required for the current generation to reach the set thickness is calculated. When the time meets the requirement, the temperature is kept for the time, and then the temperature is reduced to room temperature at a rate of 5°C / min. At this time, the thickness of the aluminum oxide film meets the requirement; If the time cannot meet the requirement or the aluminum oxide film has stopped growing before reaching the set thickness, the temperature is lowered to room temperature at a rate of 30°C / min. At this time, the thickness of the aluminum oxide film does not meet the requirement.

6. The method for manufacturing a low expansion coefficient aluminum substrate according to claim 5, Features: When the thickness of the aluminum oxide film does not meet the requirements, DC magnetron reactive sputtering is required to continue sputtering the aluminum oxide film. The target material is pure aluminum, the sputtering power is 100W, the sputtering pressure is 0.4Pa, the sputtering temperature is room temperature, the target spacing is 50mm, and the vacuum degree is 2.0×10 -4 Pa, the flow ratio of argon and oxygen is 20:1, and sputtering is stopped when the thickness requirement is met.

7. The method for manufacturing a low expansion coefficient aluminum substrate according to claim 6, Features: When the thickness of the aluminum oxide film meets the requirements, the persimmon oxide film is sputtered by DC magnetron reactive sputtering, and a pure persimmon target is selected, the sputtering power is 100W, the sputtering pressure is 0.4Pa, the sputtering temperature is room temperature, the target spacing is 50mm, and the vacuum degree is 2.0×10 -4 Pa, the flow ratio of argon and oxygen is 20:1, and sputtering is stopped when the thickness requirement is met.

8. The method for manufacturing a low expansion coefficient aluminum substrate according to claim 7, Features: After the persimmon oxide film is sputtered, DC magnetron reactive sputtering is required to continue sputtering the aluminum oxide film. The target material is pure aluminum, the sputtering power is 100W, the sputtering pressure is 0.4Pa, the sputtering temperature is room temperature, the target spacing is 50mm, and the vacuum degree is 2.0×10 -4 Pa, the flow ratio of argon and oxygen is 20:1, and sputtering is stopped when the thickness requirement is met.

9. The method for manufacturing a low expansion coefficient aluminum substrate according to claim 8, Features: The film thickness ratio of the transition layer, the aluminum oxide layer, the persimmon oxide layer and the aluminum oxide layer is 10:1:0.5:

1.

10. The method for manufacturing a low expansion coefficient aluminum substrate according to claim 8, Features: The film thickness ratio of the aluminum oxide layer, the persimmon oxide layer and the aluminum oxide layer is 2:1:2.