Manufacturing method of ceramic copper-clad carrier plate for lead-free soldering paste, ceramic copper-clad carrier plate and electronic equipment

Abstract

The invention discloses a manufacturing method of a ceramic copper-clad carrier plate for lead-free soldering paste, the ceramic copper-clad carrier plate and application of the ceramic copper-clad carrier plate, and belongs to the field of integrated circuit manufacturing. S2, film pasting, exposure, development, etching, film stripping and surface treatment are sequentially carried out on the ceramic copper-clad carrier substrate, a pattern circuit is formed on the ceramic copper-clad carrier substrate, the ceramic copper-clad carrier is formed, the pattern circuit comprises at least one bonding pad used for being welded to an electronic element, and the pattern circuit comprises a copper layer and a protective film covering the copper layer; the surface treatment liquid medicine comprises the following components in parts by volume: 4-120 parts of benzotriazole stock solution; formic acid; and 1-60 parts by volume of water. According to the method, formic acid is added into the benzotriazole stock solution, so that the problem of copper surface oxidation of the ceramic copper-clad carrier plate when the ceramic copper-clad carrier plate is welded by lead-free soldering paste at a client side is solved.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuit manufacturing, and particularly relates to a manufacturing method of a ceramic copper-clad carrier for lead-free solder paste, a ceramic copper-clad carrier, and its application. Background Art

[0002] The ceramic copper-clad carrier is an important component of high-voltage high-power IGBT modules. It has the characteristics of high thermal conductivity, high electrical insulation, and relatively high mechanical strength of ceramics, as well as high electrical conductivity and excellent welding performance of oxygen-free copper. It can also be made into various patterns, and is a packaging material suitable for SIC chips, high-power IGBT modules, and semiconductor refrigeration and heating devices.

[0003] The ceramic copper-clad carrier is to manufacture a graphic circuit with at least one pad on the ceramic copper-clad carrier substrate. The ceramic copper-clad carrier substrate is slightly smaller than the PCB substrate, with a thickness of about 0.2 mm. Among them, the copper thickness is 250 - 600 um (the copper thickness of the PCB substrate is 25 - 105 um).

[0004] On the client side of the ceramic copper-clad carrier, the pads of the ceramic copper-clad carrier and electronic components are welded through solder paste. The welding is carried out at a high temperature (about 280 °C). The length of the furnace for welding on the client side of the ceramic copper-clad carrier is about 10 meters. The quality of the welding can only be identified when the welded product comes out of the furnace.

[0005] Due to its high welding strength, good electrical conductivity, ability to maintain the welding effect for a long time, wide application range, suitability for various different welding substrates and processes, and relatively low price and high cost performance, leaded solder paste has become the traditionally used solder paste when welding ceramic copper-clad carriers and electronic components.

[0006] With the development of society and science, since leaded solder paste contains harmful substances such as lead and has a large lead content, which has a greater negative impact on human health and the environment, lead-free solder paste has become the trend of technological development. The client side of the ceramic copper-clad carrier has also successfully developed lead-free solder paste and applied it to the welding of ceramic copper-clad carriers and electronic components.

[0007] However, when the client side of the ceramic copper-clad carrier applies lead-free solder paste to the welding of ceramic copper-clad carriers and electronic components, the products coming out of the furnace after welding have Figure 1 the problem that the copper surface of the ceramic copper-clad carrier has varying degrees of oxidation.

[0008] The above background art is for the convenience of understanding the present invention and is not prior art that has been publicly known to the general public before applying for the present invention. Summary of the Invention

[0009] In view of the above defects, the present invention provides a method for manufacturing a ceramic copper-clad carrier for lead-free solder paste, which solves the problem of copper surface oxidation during lead-free solder paste welding of the ceramic copper-clad carrier at the client side by adding formic acid to the benzotriazole-based stock solution.

[0010] The technical solution is as follows: A method for manufacturing a ceramic copper-clad carrier for lead-free solder paste, comprising the following steps: Step S1, pretreatment of the ceramic copper-clad carrier substrate, where the ceramic copper-clad carrier substrate is a plate with a copper layer covered on the front side and / or the back side of the ceramic; Step S2, sequentially laminating a film, exposing, developing, etching, stripping the film, and surface-treating on the ceramic copper-clad carrier substrate to form a graphic circuit on the ceramic copper-clad carrier substrate, thereby becoming a ceramic copper-clad carrier. The graphic circuit includes at least one pad for welding with an electronic component, and the graphic circuit includes a copper layer and a protective film covering the copper layer; In step S2, the surface treatment liquid medicine is: Benzotriazole-based stock solution, 4 to 120 parts by volume; Formic acid; and Water 1 to 60 parts by volume Wherein, the amount of formic acid is such that the pH value of the surface treatment liquid medicine after adding formic acid to the benzotriazole-based stock solution is 3 to 4; The part by volume is one of cubic meters, cubic decimeters, cubic centimeters, cubic millimeters, liters, and milliliters.

[0011] Further, the pH of the benzotriazole-based stock solution is 5.5 to 6.5.

[0012] Further, the benzotriazole-based stock solution is CBR-80, purchased from Hangzhou Heyun Technology Co., Ltd.

[0013] Further, in step S2, the running speed of the ceramic copper-clad carrier substrate is: 1 to 2 minutes, the temperature of the surface treatment liquid medicine is: 30 to 40 °C, and the nozzle spraying speed is: 40 to 80 L / Min.

[0014] Further, the benzotriazole-based stock solution is 60 to 100 parts by volume, and water is 20 to 40 parts by volume.

[0015] Further, the ceramic is one of alumina, aluminum nitride, and zirconia.

[0016] Further, the thickness of the copper layer is 250 - 600 μm, and the thickness of the protective film is 5 - 10 nm.

[0017] The present invention also provides a ceramic copper-clad carrier.

[0018] A ceramic copper-clad carrier board, which is prepared by the method for manufacturing a ceramic copper-clad carrier board for lead-free solder paste as described above.

[0019] The present invention also provides an application of a ceramic copper-clad carrier board.

[0020] An application of the above-mentioned ceramic copper-clad carrier board, characterized in that the ceramic copper-clad carrier board is welded with electronic components through lead-free solder paste to form an electronic device.

[0021] Furthermore, the welding conditions for the welding are: welding temperature 220 - 350 °C, nitrogen protection, reflow soldering, and the running speed of the tunnel furnace track is 0.003 - 0.005 m / s.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: By adding formic acid to the benzotriazole-based stock solution, the present invention solves the problem of copper surface oxidation that occurs during lead-free solder paste welding of the ceramic copper-clad carrier board at the client side. Description of the Drawings

[0023] Figure 1 It is a schematic diagram showing different degrees of oxidation on the copper surface in the background art of the present invention; Figure 2 It is a schematic diagram of the pad position in Embodiment 1 of the present invention; Figure 3 It is a schematic cross-sectional view of the ceramic copper-clad carrier board in Embodiment 1 of the present invention; Figure 4 It is a schematic cross-sectional view of the ceramic copper-clad carrier board in Comparative Example 4 of the present invention; In the figure: 1, pad; 2, substrate of the ceramic copper-clad carrier board; 3, protective film; 4, copper layer. Detailed Embodiments

[0024] The technical solutions of the present invention will be described in detail below with specific embodiments. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention rather than limiting the claims of the present invention.

[0025] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inner", "outer", "front", "rear", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use. It is 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 should not be construed as a limitation to the present invention.

[0026] In the description of the present invention, it should also be noted that, unless otherwise clearly specified and defined, the terms "set", "provided with", "installed", "connected", and "communicated" should be understood in a broad sense. For example, it can be fixedly connected, detachably connected, or integrally connected; it can be directly communicated, or indirectly communicated through an intermediate medium, and can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0027] In the present invention, unless otherwise specified, all are prior arts.

[0028] In order to solve the oxidation problems of different degrees that occur when the ceramic copper-clad substrate client uses lead-free solder paste in the background art, the inventor team carried out the following examples and comparative examples to find a solution to the copper surface oxidation problem.

[0029] In the prior art, the ceramic copper-clad substrate is made through the following steps: Step S1, pre-treatment of the ceramic copper-clad substrate. The ceramic copper-clad substrate is a board with a copper layer covered on the front and / or back of the ceramic. Step S2, sequentially laminating, exposing, developing, etching, stripping, and surface treatment on the ceramic copper-clad substrate; forming a graphic circuit on the ceramic copper-clad substrate to become a ceramic copper-clad substrate. The graphic circuit includes at least one pad functional area for welding with electronic components, and the graphic circuit is composed of a copper layer and a protective film covering the copper layer.

[0030] In the prior art, the surface treatment process in the preparation of the ceramic copper-clad substrate is as follows: after the ceramic copper-clad substrate is stripped, it enters the surface treatment process. At this time, the ceramic copper-clad substrate runs forward at a certain speed, and the surface treatment liquid medicine covers the copper surface of the ceramic copper-clad substrate by spraying or soaking. The purpose of this protective film is to prevent the copper surface under it from oxidizing in the subsequent client (especially during welding, because the welding temperature is relatively high and gas will overflow during the welding process, and the molecular activity is stronger at high temperatures).

[0031] In the prior art, there are various types of surface treatment liquid medicines for the copper surface, such as benzotriazole series, methacrylate and benzimidazole series, etc., and there are also copper passivators, copper and alloy protectors, copper plating protectors, etc. The benzotriazole series has good corrosion inhibition and scale inhibition effects, and can effectively protect the copper surface from corrosion and pollution. Therefore, it is used as a surface treatment agent in the preparation of the ceramic copper-clad substrate. When the ceramic copper-clad substrate is used together with leaded solder paste, no oxidation phenomenon occurs on the copper surface after coming out of the welding furnace.

[0032] Example 1 A manufacturing method of a ceramic copper-clad substrate includes the following steps: Step S1, pretreatment of the ceramic copper-clad substrate. The ceramic copper-clad substrate is a sheet with a copper layer covered on the front side or / and the back side of the ceramic. Among them, the thickness of the copper layer is about 500um; Step S2, sequentially film pasting, exposure, development, etching, stripping, and surface treatment on the ceramic copper-clad substrate; forming a graphic circuit on the ceramic copper-clad substrate to become a ceramic copper-clad carrier. This graphic circuit includes at least one pad 1 for soldering with electronic components (such as Figure 2 ), and this graphic circuit is composed of a copper layer and a protective film covering the copper layer (such as Figure 3 ). Figure 2 In, pad 1 is located in the pad area of the graphic circuit. Figure 3 What is shown is that there are graphic layers on both the front and back sides of the ceramic. Among them, the ceramic copper-clad substrate 2 is located in the middle, and copper layers 4 are covered on both its front and back sides, and a protective film 3 is covered on the other side of the copper layer 4. The thickness of the protective film 3 is about 8nm; In step S2, the surface treatment process is: The surface treatment liquid medicine is: Benzotriazole-based stock solution purchased from the market (CBR-80, purchased from Hangzhou Heyun Technology Co., Ltd.), PH5.5 - 6.5, 100L Formic acid Among them, the amount of formic acid is such that the PH value of the surface treatment liquid medicine after adding formic acid to the benzotriazole-based stock solution is about 3.

[0033] Control of the running speed of the ceramic copper-clad substrate: 1.25m / min Control of the temperature of the surface treatment liquid medicine: 35°C Control of the spraying speed of the nozzle: 60L / Min The protective film 3 formed in this embodiment contains a benzotriazole-based surface treatment agent and formic acid.

[0034] Example 2 The difference between this embodiment and Example 1 is that: In step S2, the surface treatment liquid medicine is: Benzotriazole-based stock solution purchased from the market (CBR-80, purchased from Hangzhou Heyun Technology Co., Ltd.), PH5.5 - 6.5, 100L Formic acid Among them, the amount of formic acid is such that the PH value of the surface treatment liquid medicine after adding formic acid to the benzotriazole-based stock solution is about 4.

[0035] The protective film 3 formed in this embodiment contains a benzotriazole-based surface treatment agent and formic acid.

[0036] Example 3 The difference between this embodiment and Example 1 is that: In step S2, the surface treatment liquid medicine is as follows: Benzotriazole-based stock solution purchased from the market (CBR-80, purchased from Hangzhou Heyun Technology Co., Ltd.), pH 5.5 - 6.5, 60 L Formic acid Water 40 L Among them, the amount of formic acid is such that the pH value of the surface treatment liquid medicine is about 4 after adding formic acid to the benzotriazole-based stock solution.

[0037] The protective film 3 formed in this embodiment contains a benzotriazole-based surface treatment agent and formic acid.

[0038] Example 4 The difference between this example and Example 1 is that: In step S2, the surface treatment liquid medicine is as follows: Benzotriazole-based stock solution purchased from the market (CBR-80, purchased from Hangzhou Heyun Technology Co., Ltd.), pH 5.5 - 6.5, 80 L Formic acid Water 20 L Among them, the amount of formic acid is such that the pH value of the surface treatment liquid medicine is about 4 after adding formic acid to the benzotriazole-based stock solution.

[0039] The protective film 3 formed in this embodiment contains a benzotriazole-based surface treatment agent and formic acid.

[0040] Comparative Example 1 The difference between this comparative example and Example 1 is that: In step S2, the surface treatment liquid medicine is as follows: Benzotriazole-based stock solution purchased from the market (CBR-80, purchased from Hangzhou Heyun Technology Co., Ltd.), pH 5.5 - 6.5, 100 L.

[0041] The protective film 3 formed in this comparative example is a protective film in the prior art.

[0042] Comparative Example 2 The difference between this comparative example and Example 1 is that: In step S2, the surface treatment liquid medicine is as follows: Benzotriazole-based stock solution purchased from the market (CBR-80, purchased from Hangzhou Heyun Technology Co., Ltd.), pH 5.5 - 6.5, 100 L Benzoic acid Among them, the amount of benzoic acid is such that the pH value of the surface treatment liquid medicine is about 3 after adding benzoic acid to the benzotriazole-based stock solution.

[0043] The protective film 3 formed in this comparative example contains a benzotriazole-based surface treatment agent and benzoic acid.

[0044] Comparative Example 3 The difference between this comparative example and Example 1 is as follows: In step S2, the surface treatment liquid medicine is: Benzotriazole-based stock solution purchased from the market (CBR-80, purchased from Hangzhou Heyun Technology Co., Ltd.), pH 5.5 - 6.5, 100 L Glacial acetic acid Among them, the amount of glacial acetic acid is such that the pH value of the surface treatment liquid medicine after adding glacial acetic acid to the benzotriazole-based stock solution is about 3.

[0045] The protective film 3 formed in this comparative example contains a benzotriazole-based surface treatment agent and glacial acetic acid.

[0046] Comparative Example 4 The difference between this comparative example and Example 1 is as follows: In step S2, the surface treatment liquid medicine is: Benzotriazole-based stock solution purchased from the market (CBR-80, purchased from Hangzhou Heyun Technology Co., Ltd.), pH 5.5 - 6.5, 100 L Hydrochloric acid (36 - 38 wt%), purchased from the market Among them, the amount of hydrochloric acid is such that the pH value of the surface treatment liquid medicine after adding hydrochloric acid to the benzotriazole-based stock solution is about 3.

[0047] In this comparative example, during the surface treatment process in step S2, no film was formed after the surface treatment liquid medicine was sprayed onto the ceramic copper-clad carrier board substrate. Therefore, the graphic circuit consists only of a copper layer (as Figure 4 ).

[0048] Comparative Example 5 The difference between this comparative example and Example 1 is as follows: In step S2, the surface treatment liquid medicine is: Benzotriazole-based stock solution purchased from the market (CBR-80, purchased from Hangzhou Heyun Technology Co., Ltd.), pH 5.5 - 6.5, 100 L Sodium hydroxide solution (5 wt%), prepared Among them, the amount of sodium hydroxide solution is such that the pH value of the surface treatment liquid medicine after adding sodium hydroxide solution to the benzotriazole-based stock solution is about 8.

[0049] In this comparative example, during the surface treatment process in step S2, although a film was formed after the surface treatment liquid medicine was sprayed onto the ceramic copper-clad carrier board substrate, the formed film dissolved again. Therefore, the graphic circuit after surface treatment also only has Figure 4 a copper layer.

[0050] Example 5 The ceramic copper-clad substrates prepared in Examples 1-4 and Comparative Examples 1-3 were sent to the client of the ceramic copper-clad substrate for welding. Among them, the ceramic copper-clad substrate prepared in Comparative Example 1 was welded with leaded solder and lead-free solder, and the remaining ceramic copper-clad substrates were only welded with lead-free solder. The welding conditions are shown in Table 1 below: Table 1 Welding Parameters The copper surface of the ceramic copper-clad substrate after being welded in the welding furnace was inspected, and the results are shown in Table 2 below: Table 2 Results of the Copper Surface after Welding It can be seen from the results in Table 2 that when formic acid was added during surface treatment, the formed protective film 3 did not show oxidation on the copper surface after welding when the customer used lead-free solder paste for welding. This indicates that after the addition of formic acid, not only the acidity of the entire liquid medicine was adjusted, but it also participated in the film-forming process of the benzotriazole-based stock solution, modified the protective film 3, and enabled the modified protective film 3 to adapt to the welding with lead-free solder paste.

[0051] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for making a ceramic copper-clad substrate for lead-free solder paste, characterized in that: The following steps are involved: Step S1, pre-treatment of a ceramic copper-clad carrier substrate, the ceramic copper-clad carrier substrate being a plate having a copper layer coated on the front and / or back of the ceramic; Step S2, sequentially laminating, exposing, developing, etching, stripping, and surface treating on the ceramic copper-clad carrier substrate, forming a graphic circuit on the ceramic copper-clad carrier substrate to become a ceramic copper-clad carrier, the graphic circuit comprising at least one pad for soldering with an electronic component, the graphic circuit comprising a copper layer and a protective film covering the copper layer; In step S2, the surface treatment solution is: Benzotriazole stock solution, 4 to 120 parts by volume; Formic acid; as well as Water 1~ 60 parts by volume Wherein, the amount of formic acid is such that the pH value of the surface treatment solution after formic acid is added to the benzotriazole stock solution is 3 to 4; The volume unit is one of cubic meter, cubic decimeter, cubic centimeter, cubic millimeter, liter, and milliliter.

2. The method for manufacturing a ceramic copper-clad substrate for lead-free solder paste according to claim 1, characterized in that: The benzotriazole stock solution has a pH of 5.5 to 6.

5.

3. The method for manufacturing a ceramic copper-clad substrate for lead-free solder paste according to claim 2, characterized in that: The benzotriazole stock solution is CBR-80, purchased from Hangzhou Heyun Technology Co., Ltd.

4. The method for manufacturing a ceramic copper-clad substrate for lead-free solder paste according to any one of claims 1 to 3, characterized in that: In step S2, the operation speed of the ceramic copper-clad carrier substrate is: 1 ~ 2min, the surface treatment liquid temperature is: 30 ~ 40°C, and the nozzle spray speed is: 40~80L / Min.

5. The method for manufacturing a ceramic copper-clad substrate for lead-free solder paste according to any one of claims 1 to 3, characterized in that: The benzotriazole stock solution comprises 60 to 100 parts by volume and water comprises 20 to 40 parts by volume.

6. The method for manufacturing a ceramic copper-clad substrate for lead-free solder paste according to any one of claims 1 to 3, characterized in that: The ceramic is one of aluminum oxide, aluminum nitride and zirconium oxide.

7. The method for manufacturing a ceramic copper-clad substrate for lead-free solder paste according to any one of claims 1 to 3, characterized in that: The copper layer has a thickness of 250-600um, and the protective film has a thickness of 5-10nm.

8. A ceramic copper-clad substrate, characterized in that: The ceramic copper-clad substrate is prepared by the method for preparing a ceramic copper-clad substrate for lead-free solder paste according to any one of claims 1 to 7.

9. An application of the ceramic copper-clad substrate according to claim 8, characterized in that: The ceramic copper-clad carrier board is soldered with electronic components through lead-free solder paste to form an electronic device.

10. The use of the ceramic copper-clad substrate according to claim 9, characterized in that: The welding conditions of the welding are: welding temperature 220-350°C, nitrogen protection, reflow soldering, and the running speed of the tunnel furnace crawler is 0.003-0.005m / s.

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