Method for solving poor insulativity between DCB copper islands

Abstract

The invention relates to the technical field of copper-clad ceramic substrate processing, in particular to a method for solving poor insulativity between DCB copper islands. Comprising the following process: placing a DCB ceramic substrate with poor insulativity after pattern transfer in an oxygen-containing atmosphere or a non-oxygen-containing atmosphere for processing to obtain a finished product. The method has the beneficial effects that the method is a remedial treatment method for confirming a product with poor insulation, treatment under an oxygen-containing atmosphere or treatment under a non-oxygen-containing atmosphere is added to a DCB ceramic substrate with poor insulation after pattern transfer, and conductive components in an interface product and by-products after decomposition of the conductive components are effectively removed; the resistivity of the DCB copper island is increased, the insulativity is enhanced, and overlarge leakage current generated when high voltage is applied between the islands is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of copper-clad ceramic substrate processing, in particular to a method for solving poor insulation between DCB copper islands. Background Art

[0002] Direct Copper Bonding is a special process of direct copper bonding (DCB process), which is mainly to directly bond copper foil to the surface of ceramic substrate, and is a key process for preparing ceramic copper-clad substrates. The ceramic copper-clad substrates prepared by this process have excellent reliability, thermal conductivity and electrical properties, and are widely used in the manufacturing fields of electronic products and electrical appliances.

[0003] Among them, the bonding process of the DCB process is based on the principle that oxygen elements are introduced between the copper foil and the ceramic substrate to form a Cu-O eutectic liquid under temperature control, thereby utilizing the wettability of the eutectic liquid to the copper foil and the ceramic substrate to produce an interface effect, so that after cooling to room temperature, the two form a strong bonding force to bond the two. In the prior art, during the pretreatment and sintering of the copper sheet, the interface phase produced is generally CuAlO2 with a hexagonal crystal structure, which will cause the p-type semiconductor CuAlO2 to be turned on when a voltage is applied when the finished product is used, resulting in a significant reduction or loss of insulation between the copper islands; affecting the reliability and other performance of the finished product.

[0004] In summary, in order to solve the above problems, the present invention provides a method for solving the problem of poor insulation between DCB copper islands. Summary of the invention

[0005] The object of the present invention is to provide a method for solving the problem of poor insulation between DCB copper islands, so as to solve the problems raised in the above background technology.

[0006] A method for solving the problem of poor insulation between DCB copper islands, comprising the following processes:

[0007] The DCB ceramic substrate with poor insulation after pattern transfer is placed in an oxygen-containing atmosphere or a non-oxygen-containing atmosphere for treatment to obtain a finished product.

[0008] Among them, after the pattern is transferred, the ceramic substrate presents a specific distribution of copper blocks (copper islands), and the copper islands are separated; and when the finished product is used, the separated copper islands should be insulated. If there is a need for conduction, the copper islands are connected by bonding; if the insulation between the copper islands cannot be met, the air may be broken down to generate electric sparks.

[0009] However, in common processes, if the interface products are all CuAlO2, when voltage is applied, the p-type semiconductor CuAlO2 may be turned on, resulting in loss of insulation between copper islands. In general methods, the interface products of the reaction are related to the degree of pre-oxidation of the copper sheet, the temperature and atmosphere of sintering of copper and ceramic sheets. Interface products are not easy to observe, and methods such as XRD to characterize interface products cannot be applied in mass production; insulation can only be detected by applying voltage between copper islands after the pattern is transferred. At this time, the interface products have been generated, and CuAlO2 is not easy to react and cannot be removed by simple chemical treatment.

[0010] Therefore, in the present application, a process treatment (oxygen-containing atmosphere treatment or non-oxygen-containing atmosphere treatment) is added to the DCB ceramic substrate having poor insulation after pattern transfer to solve the existing drawbacks.

[0011] More optimally: the process of oxygen-containing atmosphere treatment includes the following steps:

[0012] S1: placing the DCB ceramic substrate with poor insulation after pattern transfer in a vacuum furnace, heating it to 700-980°C, performing the first stage of heat preservation, and then heating it to 1070-1080°C, performing the second stage of heat preservation, and cooling it to room temperature with the furnace to obtain a heat-treated DCB ceramic substrate;

[0013] S2: placing the heat-treated DCB ceramic substrate in an up-and-down spray-type horizontal transmission cleaning device, cleaning it with sulfuric acid, and drying it to obtain a finished product.

[0014] More optimally: the vacuum degree of the vacuum furnace is ≤10 -2 Pa; the heating rate is 15-20°C / min; the concentration of sulfuric acid is 3-7%.

[0015] More optimally: the first stage of heat preservation lasts for 2-5 minutes; the second stage of heat preservation lasts for 2-5 minutes.

[0016] During the process of this method, CuAlO2 in the interface product of the DCB ceramic substrate will decompose in an oxygen-containing atmosphere: 4CuAlO2+O2→(high temperature, oxygen-containing gas atmosphere)2CuAl2O4+2CuO, and the decomposition products CuAl2O4 and CuO will further decompose under high temperature and acidic conditions:

[0017] (1)CuAl2O4→(>1000℃)CuO+Al2O3

[0018] (2)CuAl2O4+8H + →Cu + +2Al 3+ +4H2O

[0019] (3)2CuO+4H + →2Cu 2+ +2H2O

[0020] More optimally: the process of the non-oxygen atmosphere treatment comprises the following steps:

[0021] S1: In a nitrogen atmosphere, a DCB ceramic substrate with poor insulation after pattern transfer is placed in a tunnel furnace for heating, and cooled along with the furnace to obtain a heat-treated DCB ceramic substrate;

[0022] S2: putting the heat-treated DCB ceramic substrate into a sulfuric acid solution, cleaning for 60-120 seconds, washing and drying to obtain a finished product.

[0023] More optimally, the specific parameters of the heating are: peak temperature of 700-1080°C, insulation time of 2-5 minutes, and whole process time of 15-45 minutes.

[0024] More optimally: the oxygen content in the nitrogen atmosphere is less than 100 ppm.

[0025] More optimally: the concentration of the sulfuric acid solution is 3-7%.

[0026] During this method, CuAlO2 in the interface product of the DCB ceramic substrate will decompose in a non-oxygen atmosphere: 2CuAlO2→(high temperature, inert gas atmosphere)CuAl2O4+Cu, where the decomposition product CuAl2O4 will further decompose under high temperature and acidic conditions:

[0027] (1)CuAl2O4→(>1000℃)CuO+Al2O3

[0028] (2)CuAl2O4+8H + →Cu + +2Al 3+ +4H2O

[0029] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present application is a remedial treatment method for products with poor insulation; it is not a process of conventional preparation process. Therefore, for products with poor insulation, firstly, by adding process treatment (oxygen atmosphere treatment or non-oxygen atmosphere treatment), CuAlO2 is decomposed to form CuAl2O4, CuO, etc., so as to promote subsequent pickling and remove the decomposition products between the grooves; thereby, the conductive components in the interface products and the byproducts after the decomposition of the conductive components are effectively removed; the resistivity of the DCB copper island is increased, the insulation is enhanced, and excessive leakage current is avoided when a high voltage is applied between the islands. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0031] Figure 1 The XRD characterization results of the present invention for normal insulation, abnormal insulation and the original ceramic chip interface product;

[0032] Figure 2 This is the XRD characterization result of the interface product of the product with good insulation obtained in Example 1;

[0033] Figure 3 This is the XRD characterization result of the interface product of the poorly insulated product obtained in Comparative Example 1. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that there is no special restriction on the purchasing manufacturers of all the raw materials involved in the present invention, and they are all common and general raw materials and can be purchased directly.

[0036] Embodiment 1: A method for solving the problem of poor insulation between DCB copper islands:

[0037] Step 1: Pre-oxidation of copper sheet: The cleaned copper sheet passes through various temperature zones of the tunnel furnace, where the peak temperature of the oxidation zone is 810°C, the oxygen flow rate is 100mL / min, and the mesh belt conveying speed is 175mm / min;

[0038] Step 2: Sintering of copper ceramic sheets: The pre-oxidized copper sheets are passed through a tunnel furnace and sintered at 1070°C in an oxygen atmosphere of 100 ppm to combine them with the ceramic sheets to obtain a copper-clad ceramic substrate.

[0039] Step 3: Pattern transfer: The copper-clad ceramic substrate is passed through a copper etching solution to obtain a circuit pattern to obtain a DCB ceramic substrate; wherein the anti-corrosion film is a dry film, the concentration of hydrochloric acid is 2.5 mol / L, the concentration of copper ions is 120 g / L, and the Ph value is 1.4;

[0040] Step 4: Treatment in an oxygen-containing atmosphere: (1) Place the DCB ceramic substrate after pattern transfer in a vacuum furnace, heat it to 980°C, carry out the first stage of heat preservation, continue to heat it to 1075°C, carry out the second stage of heat preservation, and cool it to room temperature with the furnace to obtain a heat-treated DCB ceramic substrate; (2) Place the heat-treated DCB ceramic substrate in an upper and lower spray-type horizontal transmission cleaning equipment, use sulfuric acid to clean it, and dry it to obtain a finished product.

[0041] Comparative Example 1: Compared with Example 1, the treatment process in an oxygen-containing atmosphere after pattern transfer is missing, and the details are as follows:

[0042] Step 1: Pre-oxidation of copper sheet: The cleaned copper sheet passes through various temperature zones of the tunnel furnace, where the peak temperature of the oxidation zone is 810°C, the oxygen flow rate is 100mL / min, and the mesh belt conveying speed is 175mm / min;

[0043] Step 2: Sintering of copper ceramic sheets: The pre-oxidized copper sheets are passed through a tunnel furnace and sintered at 1070°C in an oxygen atmosphere of 100 ppm to combine them with the ceramic sheets to obtain a copper-clad ceramic substrate.

[0044] Step 3: Pattern transfer: The copper-clad ceramic substrate is passed through a copper etching solution to obtain a circuit pattern to obtain a DCB ceramic substrate; wherein the anti-corrosion film is a dry film, the concentration of hydrochloric acid is 2.5 mol / L, the copper ion concentration is 120 g / L, and the Ph value is 1.4.

[0045] Test experiment 1: 18 motherboards were prepared with the same process as in Example 1, and 5 different positions in the motherboard were tested. A voltage of 1000V was applied between two copper islands separated from each other, and the current passing between the two test leads was the inter-island leakage current, and the converted resistance was the surface insulation resistance. The measured data are shown in the following table:

[0046]

[0047]

[0048] Table 1

[0049] Test experiment 2: 18 motherboards were prepared with the same process as in comparative example 1, and 5 different positions in the motherboard were tested. A voltage of 1000V was applied between two copper islands separated from each other, and the current passing between the two test leads was the inter-island leakage current, and the converted resistance was the surface insulation resistance. The measured data are shown in the following table:

[0050]

[0051]

[0052] Table 2

[0053] Conclusion: Example 1 is a remedial treatment method for products that have been confirmed to have poor insulation (Comparative Example 1), that is, on the basis of Comparative Example 1, a treatment process under an oxygen-containing atmosphere is added to improve the insulation of the product. Figure 3 The XRD characterization results show that the interface products are Al2O3, ZrO2, and CuAlO2. CuAlO2 is a p-type semiconductor, so the insulation between the copper islands is reduced. Example 1 is processed after the pattern transfer. Figure 2 ,XRD characterization results show that the interface products are only Al2O3 and ZrO2, and the insulation between copper islands is improved.

[0054] Finally, it should be noted that the above description is only a preferred example 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, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for solving the problem of poor insulation between DCB copper islands, characterized by: The method comprises the following process: placing a DCB ceramic substrate with poor insulation after pattern transfer in an oxygen-containing atmosphere or a non-oxygen-containing atmosphere for treatment to obtain a finished product.

2. A method for solving the problem of poor insulation between DCB copper islands according to claim 1, characterized in that: The process of treating in an oxygen-containing atmosphere includes the following steps: S1: placing the DCB ceramic substrate with poor insulation after pattern transfer in a vacuum furnace, heating it to 700-980°C, performing the first stage of heat preservation, and then heating it to 1070-1080°C, performing the second stage of heat preservation, and cooling it to room temperature with the furnace to obtain a heat-treated DCB ceramic substrate; S2: placing the heat-treated DCB ceramic substrate in an up-and-down spray-type horizontal transmission cleaning device, cleaning it with sulfuric acid, and drying it to obtain a finished product.

3. A method for solving the problem of poor insulation between DCB copper islands according to claim 2, characterized in that: The vacuum degree of the vacuum furnace is ≤10 -2 Pa; the heating rate is 15-20°C / min; the concentration of sulfuric acid is 3-7%.

4. A method for solving the problem of poor insulation between DCB copper islands according to claim 2, characterized in that: The first stage of heat preservation lasts for 2-5 minutes; the second stage of heat preservation lasts for 2-5 minutes.

5. A method for solving the problem of poor insulation between DCB copper islands according to claim 1, characterized in that: The process of the non-oxygen atmosphere treatment comprises the following steps: S1: In a nitrogen atmosphere, a DCB ceramic substrate with poor insulation after pattern transfer is placed in a tunnel furnace for heating, and cooled along with the furnace to obtain a heat-treated DCB ceramic substrate; S2: putting the heat-treated DCB ceramic substrate into a sulfuric acid solution, cleaning for 60-120 seconds, washing and drying to obtain a finished product.

6. A method for solving the problem of poor insulation between DCB copper islands according to claim 5, characterized in that: The specific parameters of the heating are: peak temperature of 700-1080°C, insulation time of 2-5 minutes, and whole process time of 15-45 minutes.

7. A method for solving the problem of poor insulation between DCB copper islands according to claim 5, characterized in that: The oxygen content in the nitrogen atmosphere is less than 100 ppm.

8. A method for solving the problem of poor insulation between DCB copper islands according to claim 5, characterized in that: The concentration of the sulfuric acid solution is 3-7%.

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