Electronic device and method for manufacturing an electronic device

Abstract

To enable mounting of components on a substrate with high density without causing electric failure.SOLUTION: An electronic device includes semiconductor chips 20 and 21, and a circuit plate 12 having a front surface covered with a plating film 12a and having the semiconductor chips 20 and 21 disposed through first and second solders 16a and 16b in a predetermined component region on the front surface. The electronic device includes a liquid-repellent part 14 along a side part of the component region on the circuit plate 12. Therefore, the spread of the first and second solders 16a and 16b can be suppressed by forming the liquid-repellent part 14 between the semiconductor chips 20 and 21 while shortening the distance between the semiconductor chips 20 and 21.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an electronic device in which components are soldered to a substrate and a method for manufacturing the electronic device.

Background Art

[0002] A semiconductor device, which is an example of an electronic device, includes a power device and is used as a power conversion device. The power device is, for example, a semiconductor chip including an IGBT (Insulated Gate Bipolar Transistor) or a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor). Such a semiconductor device includes the semiconductor chip and a ceramic circuit board on which the semiconductor chip is disposed via solder. The ceramic circuit board includes an insulating board and a plurality of circuit boards formed on the insulating board. The semiconductor chip is disposed via solder on any one of the plurality of circuit boards. Further, a slit may be formed around the component region of the semiconductor chip on the circuit board. Such a slit has functions such as alignment of the semiconductor chip and suppression of spread of solder.

[0003] In such semiconductor devices, a semiconductor chip is placed on a ceramic circuit board via solder, and the solder is melted and solidified to fix the semiconductor chip to the circuit board. However, the molten solder can flow out of the component area of ​​the semiconductor chip. Furthermore, the flowing solder can sometimes even pass through slits. Therefore, various technologies have been proposed to prevent solder leakage. For example, a linear solder flow prevention section made of oxide is formed on the circuit board along the semiconductor chip (see, for example, Patent Document 1). Alternatively, a plating is formed on the surface of the circuit board, and a solder-free area is formed around the component area of ​​the semiconductor chip in the plating (see, for example, Patent Document 2). In addition, a copper oxide film is formed on an insulating substrate in areas where a semiconductor chip is not placed (see, for example, Patent Document 3). Furthermore, a first region and a second region with lower solder wettability than the first region are formed around the semiconductor chip that is joined by solder on the mounting surface of the mounting member (see, for example, Patent Document 4). Furthermore, even when a ceramic circuit board is placed on a metal base plate via solder, a dam material is formed around the component area of ​​the ceramic circuit board (see, for example, Patent Documents 5 and 6). Also, a partition layer is formed around the component area of ​​the semiconductor chip on a mounting member on which the semiconductor chip is mounted via solder (see, for example, Patent Document 7). Moreover, laser irradiation is performed around the semiconductor chip on a lead on which the semiconductor chip is placed, forming a groove around it, and generating oxidation regions on both sides of the groove. The walls of the groove are composed of an oxidized base substrate and a portion of the oxidized plating material (see, for example, Patent Document 8).

[0004] Such semiconductor devices are further sealed by a sealing member, which encloses the semiconductor chip and the ceramic circuit board. In semiconductor devices, an anchor layer, which consists of groove-like recesses, is formed around the semiconductor chip on the circuit board to improve the adhesion between the sealing member and the ceramic circuit board (see, for example, Patent Document 9). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2013-247256 [Patent Document 2] Japanese Patent Publication No. 2008-177383 [Patent Document 3] Japanese Patent Application Publication No. 8-031848 [Patent Document 4] Japanese Patent Publication No. 2009-218280 [Patent Document 5] Japanese Patent Publication No. 2010-212723 [Patent Document 6] Japanese Patent Publication No. 2006-216729 [Patent Document 7] Japanese Patent Publication No. 2016-174053 [Patent Document 8] Japanese Patent Publication No. 2017-005149 [Patent Document 9] Japanese Patent Publication No. 2016-029676 [Overview of the project] [Problems that the invention aims to solve]

[0006] In recent years, there has been a demand for smaller and higher-capacity semiconductor devices. As a result, the mounting density of semiconductor chips has increased, and the spacing between them has narrowed. This makes it difficult to form materials to limit solder leakage between semiconductor chips. If the solder beneath a semiconductor chip melts, it can fuse with other semiconductor chips, increasing the likelihood of poor contact between them. This, in turn, reduces the reliability of the semiconductor device.

[0007] This invention has been made in view of the above points, and aims to provide an electronic device and a method for manufacturing an electronic device that can mount components on a substrate at high density without causing electrical defects. [Means for solving the problem]

[0008] According to one aspect of the present invention, the present invention comprises a first component which is a rectangular semiconductor chip in plan view, and a circuit board whose front surface is coated with a plating film, and in the first component region of the front surface the first component is arranged via a first solder, wherein the circuit board includes an oxide film formed by oxidation of the plating film along the side of the first component region of the circuit board, and a portion of the plating film remains beneath the oxide film. The aforementioned oxide film is An electronic device and a method for manufacturing an electronic device are provided, comprising a resist portion formed along the side of the first component region in a plan view and heat-affected zones formed along the resist portion on both sides of the resist portion, wherein the resist portion has a liquid-repellent portion formed at a distance of 300 μm or more from the first component, and the first component is arranged such that only the long side of the first component is parallel to the direction in which the liquid-repellent portion is formed and adjacent to the liquid-repellent portion, and the short side of the first component does not face the liquid-repellent portion. [Effects of the Invention]

[0009] According to the disclosed technology, it is possible to provide an electronic device and a method for manufacturing an electronic device in which components can be mounted on a substrate at high density without electrical failures, thereby suppressing a decrease in reliability. [Brief explanation of the drawing]

[0010] [Figure 1] This is a side view showing an electronic device according to an embodiment. [Figure 2] This is a plan view showing an electronic device according to an embodiment. [Figure 3] This is a plan view of a circuit board included in the electronic device of the embodiment. [Figure 4] This is a cross-sectional view of a circuit board included in the electronic device of the embodiment. [Figure 5] This diagram shows a flowchart of the manufacturing method for the electronic device according to the embodiment. [Figure 6] This is a plan view of a ceramic circuit board included in the electronic device of the embodiment. [Figure 7] This is a plan view showing the soldering process of the manufacturing method of the electronic device according to the embodiment. [Figure 8]This is a plan view (part 1) of the reflow soldering process in the method for manufacturing the electronic device of the embodiment. [Figure 9] This is a plan view (part 2) of the reflow soldering process in the method for manufacturing the electronic device of the embodiment. [Figure 10] This is a plan view (part 3) of the reflow soldering process in the method for manufacturing the electronic device of the embodiment. [Figure 11] This is a plan view (part 1) of the reflow soldering process in the method for manufacturing the electronic device of the reference example. [Figure 12] This is a plan view (part 2) of the reflow soldering process in the method for manufacturing the electronic device of the reference example. [Figure 13] This is a plan view (part 1) of an example of forming a liquid repellent portion formed on the ceramic circuit board of the electronic device of the embodiment. [Figure 14] This is a plan view (part 2) of an example of forming a liquid repellent portion formed on the ceramic circuit board of the electronic device of the embodiment.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments will be described with reference to the drawings. In the following description, "front surface" and "upper surface" refer to the surface facing upward in the electronic device 50 of FIG. 1. Similarly, "up" refers to the upward direction in the electronic device 50 of FIG. 1. "Back surface" and "lower surface" refer to the surface facing downward in the electronic device 50 of FIG. 1. Similarly, "down" refers to the downward direction in the electronic device 50 of FIG. 1. The same directionality is meant in other drawings as necessary. "Front surface", "upper surface", "up", "back surface", "lower surface", "down", "side surface" are merely convenient expressions for specifying relative positional relationships and do not limit the technical idea of the present invention. For example, "up" and "down" do not necessarily mean the vertical direction with respect to the ground. That is, the directions of "up" and "down" are not limited to the direction of gravity.

[0012] The electronic device of this embodiment will be described using Figures 1 and 2. Figure 1 is a side view showing the electronic device of this embodiment, and Figure 2 is a top view showing the electronic device of this embodiment. In this embodiment, the semiconductor device is used as an example for the description. In Figure 1, the sealing member is represented by a dashed line, and in Figure 2, the sealing member is not shown. In addition, the description of the case that houses the ceramic circuit board 10 etc. in the electronic device 50 is omitted. In this embodiment, multiple circuit boards 12, multiple semiconductor chips 20, 21, multiple contact components 30, multiple bonding wires 15, and multiple external connection terminals 40 are described without distinction, using the same reference numerals. Other components that are multiple are also described without distinction, using the same reference numerals.

[0013] As shown in Figures 1 and 2, the electronic device 50 has a ceramic circuit board 10 and semiconductor chips 20 and 21 bonded to the front surface of the ceramic circuit board 10. The electronic device 50 also has a contact component 30 bonded to the front surface of the ceramic circuit board 10. The semiconductor chips 20 and 21 and the contact component 30 are bonded to the front surface of the ceramic circuit board 10 via solder (not shown), which is a bonding member. The electronic device 50 also has a bonding wire 15 that electrically connects the front surface of the ceramic circuit board 10 to the main electrodes of the semiconductor chips 20 and 21. An external connection terminal 40 is press-fitted and attached to the contact component 30. Furthermore, the electronic device 50 is sealed by a sealing member 45 so that the tip of the external connection terminal 40 attached to the contact component 30 protrudes along with the semiconductor chips 20 and 21 on the front surface of the ceramic circuit board 10.

[0014] The ceramic circuit board 10 comprises an insulating plate 11, a plurality of circuit boards 12 formed on the front surface of the insulating plate 11, and a metal plate 13 formed on the back surface of the insulating plate 11. The insulating plate 11 is made of a material with excellent thermal conductivity. Such a material is a ceramic with high thermal conductivity. Examples of ceramics include aluminum oxide, aluminum nitride, and silicon nitride. The thickness of the insulating plate 11 is 0.5 mm or more and 2.0 mm or less. The plurality of circuit boards 12 are made of a base material with excellent conductivity. Examples of such materials include copper or copper alloys. A plating film 12a (see Figure 4) is formed on the surface of the circuit boards 12 by a plating process to improve corrosion resistance. Examples of plating materials used for the plating film are nickel or nickel alloys. Nickel-phosphorus alloys and nickel-boron alloys are preferred as nickel alloys. The metal plate 13 is made of a metal with excellent thermal conductivity. Such metals include, for example, aluminum, iron, silver, copper, or alloys containing at least one of these. The thickness of the metal plate 13 is 0.1 mm or more and 2.0 mm or less. To improve corrosion resistance, a plating film may be formed on the surface of the metal plate 13 by plating. Examples of plating materials used for the plating film include nickel, nickel-phosphorus alloy, and nickel-boron alloy. A cooling module (not shown) may also be attached to the back surface of the metal plate 13. The insulating plate 11 has a rectangular shape in plan view, for example. The metal plate 13 has a rectangular shape in plan view, with a smaller area than the insulating plate 11 and a larger area than the total area of ​​the circuit board 12. Therefore, the ceramic circuit board 10 has a rectangular shape, for example.

[0015] Liquid-repellent portions 14 are appropriately formed on the circuit board 12. The liquid-repellent portions 14 are formed in the gaps between the component areas on the circuit board 12 where the semiconductor chips 20 and 21 are arranged. They are also formed in the gaps between the semiconductor chip 20 and the contact components 30 (external connection terminals 40). Furthermore, they are formed in the gaps between the semiconductor chip 21 and the edges of the circuit board 12 (the areas where the bonding wires 15 are joined). Such liquid-repellent portions 14 are formed along the longitudinal or transverse direction of the ceramic circuit board 10. Note that the location and direction of formation of the liquid-repellent portions 14 are examples only, and they can be formed in locations and directions as needed. Details of the liquid-repellent portions 14 will be described later.

[0016] As the ceramic circuit board 10 having such a configuration, for example, a DCB (Direct Copper Bonding) substrate or an AMB (Active Metal Brazed) substrate can be used. Alternatively, a cooling module (not shown) may be attached to the back surface of the metal plate 13 of the ceramic circuit board 10 via a thermal conductive bonding material. This further improves the heat dissipation of the electronic device 50. The thermal conductive bonding material can be, for example, thermal grease, solder, or silver solder. Thermal grease can be, for example, silicone mixed with metal oxide fillers. The cooling module can be made of a metal with excellent thermal conductivity. Such metals can be, for example, aluminum, iron, silver, copper, or an alloy containing at least one of these. The cooling module can also be, for example, a heat sink with one or more fins and a cooling device using a liquid coolant.

[0017] The semiconductor chip 20 is made of silicon or silicon carbide and includes a switching element such as an IGBT or power MOSFET. Such a semiconductor chip 20 has a rectangular shape in plan view and, for example, has a drain electrode (or collector electrode) as the main electrode on its back surface, and a gate electrode and source electrode (or emitter electrode) as the control electrode and main electrode on its front surface. The gate electrode is located in the center of the short side of the front surface of the semiconductor chip 20. The semiconductor chip 21 also includes a diode. The diode is a FWD (Free Wheeling Diode) such as an SBD (Schottky Barrier Diode) or a PiN (P-intrinsic-N) diode. Such a semiconductor chip 21 has a cathode electrode as the main electrode on its back surface and an anode electrode as the main electrode on its front surface. The back sides of the above semiconductor chips 20 and 21 are bonded to a predetermined circuit board (not shown). The semiconductor chips 20 and 21 are joined to the circuit board 12 via solder (not shown). Solder will be described later. Although not shown, an RC (Reverse-Conducting)-IGBT, which combines the functions of IGBT and FWD, may be used instead of the semiconductor chips 20 and 21. An electronic component 22 is provided so as to span across the pair of circuit boards 12. The electronic component 22 is, for example, a thermistor or a current sensor. The thickness of such semiconductor chips 20 and 21 is, for example, 180 μm or more and 220 μm or less, with an average of about 200 μm.

[0018] The bonding wires 15 electrically connect the semiconductor chips 20, 21 to the circuit board 12, or to multiple semiconductor chips 20, 21 as appropriate. Such bonding wires 15 are made of a material with excellent conductivity. Such materials include, for example, gold, silver, copper, aluminum, or an alloy containing at least one of these. The diameter of the bonding wires 15 through which the control current flows is, for example, 110 μm or more and 200 μm or less. The diameter of the bonding wires 15 through which the main current flows may be, for example, 350 μm or more and 600 μm or less.

[0019] The contact component 30 comprises a main body with a cylindrical through-hole formed inside and flanges provided at the open ends of the main body. This through-hole may be cylindrical or polygonal prism-shaped. The contact component 30 is made of a metal with excellent conductivity. Such metals include, for example, silver, copper, nickel, or alloys containing at least one of these. To improve corrosion resistance, a plating film may be formed on the surface of the contact component 30 by plating. Examples of plating materials used for the plating film include nickel, nickel-phosphorus alloys, and nickel-boron alloys.

[0020] The external connection terminal 40 has a rod-shaped body and tapered tips formed at both ends of the body. The body is prismatic in shape. The length of the diagonal of the cross-section of the external connection terminal 40 is several percent longer than the diameter of the body of the contact component 30. Therefore, the external connection terminal 40 can be press-fitted into the contact component 30. The external connection terminal 40 is also made of a metal with excellent conductivity. Such metals include, for example, silver, copper, nickel, or an alloy containing at least one of these. To improve corrosion resistance, a plating film may be formed on the surface of the external connection terminal 40 by plating. The plating material used for the plating film is preferably nickel or an alloy containing nickel. Examples of nickel-containing alloys include nickel-phosphorus alloys and nickel-boron alloys.

[0021] Furthermore, the solder used to join the semiconductor chips 20, 21 and the contact components 30 to the circuit board 12 is based on lead-free solder. Lead-free solder mainly consists of at least one of the following alloys: an alloy of tin and silver, an alloy of tin and antimony, an alloy of tin and zinc, or an alloy of tin and copper. Additives may also be included in the solder. Examples of additives include copper, bismuth, indium, nickel, germanium, cobalt, or silicon. It is also preferable that the solder used to join the semiconductor chips 20, 21 and the solder used to join the contact components 30 have different solder compositions. In this case, the solder used to join the semiconductor chips 20, 21 is less prone to void formation and has high temperature resistance. For example, such solder is an alloy mainly composed of tin and antimony. The solder used to join wiring terminals such as the contact components 30 has a lower modulus of elasticity than the solder under the semiconductor chips 20, 21. The solder beneath the contact component 30 is, for example, an alloy mainly composed of tin and silver. Furthermore, the solder joining the semiconductor chips 20 and 21 can be thinner than the solder joining the contact component 30. The thickness of the solder beneath the semiconductor chips 20 and 21 is 0.05 mm or more and 0.25 mm or less. The thickness of the solder beneath the contact component 30 is 0.10 mm or more and 0.50 mm or less. Because the solder beneath the semiconductor chips 20 and 21 has a higher elastic modulus than the solder beneath the contact component 30, the thickness of the solder beneath the semiconductor chips 20 and 21 can be made thinner than the solder beneath the contact component 30. Therefore, the heat generated by the semiconductor chips 20 and 21 during the operation of the electronic device 50 can be dissipated effectively. As previously described, the solder beneath the contact component 30 is thick. Therefore, the solder beneath the contact component 30 can withstand the stress when the external connection terminal 40 is inserted into the through-hole of the contact component 30, and the occurrence of cracks and delamination in the solder can be suppressed. Therefore, damage to the electronic device 50 can be prevented.

[0022] The sealing member 45 may be, for example, a silicone gel. Alternatively, it may include, for example, a thermosetting resin such as epoxy resin, phenolic resin, or maleimide resin, and a filler contained in the thermosetting resin. As an example of such a sealing member 45, it may include epoxy resin and a filler such as silicon dioxide, aluminum oxide, boron nitride, or aluminum nitride as a filler in the epoxy resin.

[0023] Next, the liquid-repellent portion 14 formed on the circuit board 12 will be explained using Figures 3 and 4. Figure 3 is a plan view of the circuit board included in the electronic device of the embodiment, and Figure 4 is a cross-sectional view of the circuit board included in the electronic device of the embodiment. Note that Figure 3 shows an enlarged view of the dashed line area in the circuit board 12 of Figure 2. Also, Figure 4 is a cross-sectional view along the dashed line YY in Figure 3. Note that Figures 3 and 4 show the plating film 12a formed on the surface of the circuit board 12.

[0024] The liquid-repellent portion 14 shown in Figure 3 is formed linearly on the plating film 12a between a pair of semiconductor chips 20 and 21. In Figure 3, three pairs of semiconductor chips 20 and 21 are provided. The semiconductor chip 20 is positioned so that its long side aligns with the formation direction of the liquid-repellent portion 14, which will be described later. In this case, the semiconductor chip 20 is positioned so that the short side on which the gate electrode is located does not face the liquid-repellent portion 14. When the long side of the semiconductor chip 20 aligns with the formation direction of the liquid-repellent portion 14, the position of the solder edge is restricted over a longer distance compared to when the short side aligns with the formation direction of the liquid-repellent portion 14, making it easier to stabilize the position of the semiconductor chip 20. The semiconductor chip 20 should be positioned such that the side on which the gate electrode is located does not face the liquid-repellent portion 14, taking into consideration the wire placement. The liquid-repellent portion 14 can repel solder. Such a liquid-repellent portion 14 includes a resist portion 14a and a heat-affected zone 14b. The resist portion 14a is an oxide film. The oxide film is, for example, a nickel oxide film. Such a resist portion 14a is formed by oxidizing the plating film 12a by irradiating it with a laser. The laser irradiation can be performed using either a seam laser that continuously emits laser light or a spot laser that irradiates pulsed laser light. Figure 3 shows the case of laser irradiation using a seam laser. Therefore, in a plan view, the liquid-repellent portion 14 in Figure 3 is a linear (dotted line in the case of a spot laser) laser mark. Furthermore, as will be described later, the liquid-repellent portion 14 is formed by laser scanning during laser irradiation. In particular, the resist portion 14a is formed by multiple laser marks that are formed along each other with each laser scan, either touching or partially overlapping. The resist portion 14a formed in this way preferably has a thickness of 40 nm or more of the resist portion 14a (oxide film) before soldering. And it is preferable that the thickness of the resist portion 14a (oxide film) after soldering is 25 nm or more. The reason why the thickness of the resist portion 14a (oxide film) decreases before and after soldering is thought to be because the oxide film is partially reduced by the flux contained in the solder. Furthermore, the width of the resist portion 14a can be as low as 150 μm.

[0025] The heat-affected region 14b is an oxide film formed along the resist portion 14a. As previously described, laser scanning is performed on the plating film 12a by laser irradiation in order to form the resist portion 14a. At this time, as the resist portion 14a is formed, the plating film 12a on both sides of the resist portion 14a is affected by the heat of the laser. In this way, the heat-affected region 14b is formed on both sides of the resist portion 14a. Furthermore, the width of the heat-affected region 14b widens as the output of the laser used to form the resist portion 14a increases. Also, as the width of the resist portion 14a widens, the width of the heat-affected region 14b widens as well. However, when the width of the resist portion 14a exceeds a predetermined value, the width of the heat-affected region 14b becomes constant. As shown in Figure 4, the influence of laser heat on such a heat-affected region 14b decreases as it moves away from the resist portion 14a.

[0026] In the liquid-repellent portion 14 having such a configuration, the liquid-repellent ability is higher on the resist portion 14a than on the heat-affected zone 14b. Furthermore, the liquid-repellent ability of the heat-affected zone 14b is higher on the resist portion 14a side than on the outer side. Therefore, as shown in Figure 4, although the first and second solders 16a and 16b extend to some extent to the outside of the liquid-repellent portion 14, the first and second solders 16a and 16b cannot extend to the central part including the resist portion 14a. Also, since such a liquid-repellent portion 14 is formed by laser irradiation, there are areas where a part of the plating film 12a remains beneath the liquid-repellent portion 14. The total thickness of the liquid-repellent portion and the remaining part of the plating film is preferably 6 μm or more. The thickness of the remaining part of the plating film beneath the liquid-repellent portion is preferably 5 μm or more.

[0027] Note that the formation of the liquid-repellent portion 14 on the semiconductor chips 20 and 21 shown in Figure 3 is just one example. The resist portion 14a of the liquid-repellent portion 14 is formed on the plating film 12a under the following conditions. First, it is preferable that the resist portion 14a is at least 0.3 mm away from the semiconductor chips 20 and 21. Also, it is preferable that the resist portion 14a is at least 0.5 mm away from the edge of the circuit board 12. The width of the resist portion 14a is preferably 0.4 mm or more and 0.5 mm or less. However, if it is difficult to keep the resist portion 14a at least 0.3 mm away from the semiconductor chips 20 and 21, or at least 0.5 mm away from the edge of the circuit board 12, it is preferable that the width of the resist portion 14a be 0.15 mm or more. Furthermore, if the end of the resist portion 14a is at least 0.5 mm away from the edge of the circuit board 12, its length is preferably extended to a maximum of 1.0 mm from the end face of the semiconductor chips 20 and 21. Furthermore, it is preferable that the resist portion 14a is at least 0.3 mm away from the contact component 30. If a distance of 0.3 mm or more cannot be achieved, it is preferable that the width of the resist portion 14a be between 0.1 mm and 0.2 mm.

[0028] Next, the manufacturing method of such an electronic device 50 will be explained using Figures 6 to 10, which show each step, following the flowchart shown in Figure 5. Figure 5 is a flowchart of the manufacturing method of the electronic device according to the embodiment. Figure 6 is a plan view of the ceramic circuit board included in the electronic device according to the embodiment. Figure 7 is a plan view showing the soldering step of the manufacturing method of the electronic device according to the embodiment. Figures 8 to 10 are plan views of the reflow soldering step of the manufacturing method of the electronic device according to the embodiment, corresponding to the location in Figure 3.

[0029] The electronic device 50 is manufactured according to the following manufacturing process (flowchart). Each of the following manufacturing steps is performed manually or by manufacturing equipment as necessary.

[0030] [Step S10] Prepare semiconductor chips 20, 21, ceramic circuit board 10, and contact components 30. Not limited to these components, prepare in advance any other components necessary for the manufacture of the electronic device 50. The ceramic circuit board 10 has an insulating plate 11, a plurality of circuit boards 12 formed on the front surface of the insulating plate 11 (see Figure 6), and a metal plate 13 formed on the back surface of the insulating plate 11. In Figure 6, the rectangular dashed lines attached to the plurality of circuit boards 12 represent the component areas 20a, 21a of the semiconductor chips 20, 21. Although not shown in Figure 6, a plating film is formed on the surface of the circuit boards 12 by a plating process.

[0031] [Step S11] Liquid-repellent portions 14 are formed on the circuit board 12 of the ceramic circuit substrate 10 by laser irradiation, as shown in Figure 6. The laser irradiation is performed using, for example, a YAG laser or a YVO4 laser. Using such a laser device, a resist portion 14a is formed by repeatedly scanning a predetermined area with a seam laser or spot laser. The predetermined area is, for example, between the areas where semiconductor chips 20 and 21 are placed, or between the areas where semiconductor chips 20 and 21 and contact components 30 are placed (see Figure 2). If necessary, it may also be between the areas where multiple contact components 30 are placed. The width of the resist portion 14a can be appropriately controlled according to the number of laser scans. The width of the resist portion 14a shown in Figure 3 is an example. The width of the resist portion 14a can be made wider or narrower than the width of the resist portion 14a shown in Figure 3 by increasing or decreasing the number of laser scans compared to this case. The laser irradiation conditions can be appropriately set between a scanning speed of 1000 mm / second, a scanning interval of 40 μm, a spot variable of -10 or more and 10 or less, and a pulse frequency of 25 kHz or more and 60 kHz or less. In this case, the laser irradiation oxidizes the plating film 12a on the surface of the circuit board 12, and the laser scanning and laser output are set to such an extent that the base material portion of the circuit board 12 is not exposed. Furthermore, as the resist portion 14a is formed, a heat-affected zone 14b is formed on both sides of the resist portion 14a along the resist portion 14a. The width of the heat-affected zone 14b on one side formed in this way is, for example, 50 μm or more.

[0032] [Step S12] As shown in Figure 7, solder plates 31 are placed in the component areas 20a, 21a of the semiconductor chips 20, 21 and the installation area of ​​the contact component 30 on the circuit board 12 of the ceramic circuit board 10. Alternatively, solder may be applied to the circuit board 12 of the ceramic circuit board 10, for example, by dispensing. In Figure 7, the solder plates 31 for the semiconductor chips 20, 21 are shown as squares, and the solder plates 31 for the contact component 30 are shown as circles.

[0033] In this case, it is assumed that the solder board 31 is of the same quality. This solder board 31 is made of lead-free solder whose main component is at least one of the following alloys: a tin-silver-copper alloy, a tin-zinc-bismuth alloy, a tin-copper alloy, or a tin-silver-indium-bismuth alloy. In addition, it contains flux which has the function of removing oxides on the circuit board 12 (plating film 12a). The flux contains, for example, epoxy resin, carboxylic acid, rosin resin, activator, and solvent, and may also contain other components as needed. Furthermore, such a solder board 31 may contain additives such as nickel, germanium, cobalt, or silicon.

[0034] [Step S13] On the solder board 31 arranged in step S12, the semiconductor chips 20, 21 and contact components 30 are set using a mounting device (not shown). At this time, the electronic components 22 are also set in the same manner.

[0035] [Step S14] In step S12, the semiconductor chips 20, 21 and contact components 30 are set on the circuit board 12 of the ceramic circuit board 10 via the solder board 31 and then transported to the reflow oven. At this time, the semiconductor chips 20, 21 on the circuit board 12 (plating film 12a) are mounted on the solder board 31, for example, as shown in Figure 8. In this state, the inside of the oven is depressurized and heat treatment is performed at the reflow treatment temperature (reflow soldering process). The reflow treatment temperature is, for example, 250°C or higher and 300°C or lower. As a result, the solder board 31 between the plating film 12a and the semiconductor chips 20, 21 melts. The first and second solders 16a and 16b that have melted from the solder board 31 spread to the outside of the semiconductor chips 20, 21, as shown in Figure 9. At this time, the semiconductor chips 20, 21 may move on the spread first and second solders 16a and 16b. Furthermore, the spread first and second solders 16a and 16b extend onto the liquid-repellent portion 14. In some cases, the first and second solders 16a and 16b may even bond together on the liquid-repellent portion 14. Subsequently, the first and second solders 16a and 16b on the liquid-repellent portion 14 are repelled by the liquid-repellent portion 14, creating a predetermined gap between them. Consequently, as shown in Figure 10, the semiconductor chips 20 and 21 that had shifted position on the spread first and second solders 16a and 16b return to their predetermined positions. Then, the semiconductor chips 20 and 21 are joined to the circuit board 12 (plating film 12a) by the solidified first and second solders 16a and 16b (see Figure 4). The contact components 30 are similarly joined to the circuit board 12 (plating film 12a) by solder.

[0036] [Step S15] The ceramic circuit board 10, on which semiconductor chips 20, 21 and contact components 30 are bonded to each circuit board 12, is removed from the reflow oven. Then, using an ultrasonic bonding tool (not shown), predetermined areas of each circuit board 12 of the ceramic circuit board 10 and the semiconductor chips 20, 21 are electrically connected with bonding wires 15. After connecting the bonding wires 15 in this manner, external connection terminals (not shown) are press-fitted into each contact component 30.

[0037] [Step S16] The semiconductor chips 20, 21 and contact components 30 are bonded to each circuit board 12, and the ceramic circuit board 10, which is electrically connected by bonding wires 15, is set in a case and sealed with a sealing member 45. This completes the manufacture of the electronic device 50 shown in Figures 1 and 2.

[0038] Here, the reflow soldering in step S14 described above, when a slit is formed in the location where the liquid-repellent portion 14 is formed on the circuit board 12 without forming the liquid-repellent portion 14, will be explained using Figures 11 and 12. Figures 11 and 12 are plan views of the reflow soldering process in the manufacturing method of the reference example electronic device. The reference example electronic device has the same configuration as the electronic device 50, except for the slit 140 which is provided in place of the liquid-repellent portion 14, and the same reference numerals are used, so their explanations are omitted. Also, Figures 11 and 12 show cases corresponding to the states in Figures 8 and 10.

[0039] Semiconductor chips 20 and 21 are placed on the circuit board 12 (plating film 12a) of the ceramic circuit board 10, with slits 140 formed therein, via solder plates 31, and then transported to a reflow oven (see Figure 11). The slits 140 are concave grooves formed in the circuit board 12 (plating film 12a). In this state, when the oven is depressurized and heated at the reflow temperature, the solder plates 31 between the plating film 12a and the semiconductor chips 20 and 21 melt. The molten first and second solders 16a and 16b from the solder plates 31 spread to the outside of the semiconductor chips 20 and 21. As a result, for example, the semiconductor chip 20 on the circuit board 12 (in the middle of Figure 12) rotates in place or shifts position due to the spread first solder 16a. A portion of the rotated semiconductor chip 20 is positioned on the slits 140 via the first solder 16a. When the first solder 16a fills the slit 140, there is a risk of voids forming within the slit 140. If voids form in this way, the heat dissipation to the semiconductor chip 20 will decrease. This can also occur on the semiconductor chip 21 side.

[0040] Furthermore, on the circuit board 12 (left and right sides of Figure 12), the first and second solders 16a and 16b are joined together in the gap. In such cases, the semiconductor chips 20 and 21 become electrically connected, which can cause electrical malfunctions in the electronic device 50.

[0041] Therefore, the electronic device 50 includes semiconductor chips 20 and 21, which are components, and a circuit board 12 whose front surface is coated with a plating film 12a, and in a predetermined component area on the front surface, the semiconductor chips 20 and 21 are arranged via first and second solders 16a and 16b. The electronic device 50 has a liquid-repellent portion 14 formed along the side of the component area of ​​the circuit board 12, which includes an oxide film formed by the oxidation of the plating film 12a on the front surface, with a portion of the plating film 12a remaining beneath the oxide film. As a result, the first and second solders 16a and 16b are repelled by the liquid-repellent portion 14, and their spread is suppressed by the liquid-repellent portion 14. Furthermore, since the liquid-repellent portion 14 is formed by laser irradiation, it can be formed even in a narrow area. Therefore, it is possible to shorten the spacing between the semiconductor chips 20 and 21 while forming the liquid-repellent portion 14 between them to suppress the spread of the first and second solders 16a and 16b. Furthermore, it is not necessary to form slits in the circuit board 12 to suppress the spreading of the first and second solders 16a and 16b. Therefore, a decrease in the bending strength of the circuit board 12 can be prevented. Consequently, semiconductor chips 20 and 21 can be mounted at high density without electrical defects, and a decrease in the strength of the electronic device 50 can be suppressed, as can a decrease in the reliability of the electronic device 50.

[0042] Next, various examples of the formation of the liquid-repellent portion 14 formed on the circuit board (plating film) on which the semiconductor chips are arranged will be described based on Figures 13 and 14. Figures 13 and 14 are plan views of examples of the formation of the liquid-repellent portion formed on the ceramic circuit board of the electronic device of the embodiment. In Figures 13 and 14, a plating film 12a is formed on the surface of the circuit board 12. An example is shown in which semiconductor chips 23a, 23b, 23c, and 23d are joined to the plating film 12a by solder (not shown). Furthermore, in Figures 13 and 14, the semiconductor chips 23a, 23b, 23c, and 23d are arranged in two rows and two columns on the circuit board 12 (plating film 12a).

[0043] In Figure 13(A), the liquid-repellent portion 14 is formed continuously (in a cross shape) between the semiconductor chips 23a, 23b, 23c, and 23d. Furthermore, the liquid-repellent portion 14 is formed around the semiconductor chips 23a, 23b, 23c, and 23d. Note that the liquid-repellent portion 14 may also be formed continuously (in a cross shape) only between the semiconductor chips 23a, 23b, 23c, and 23d. Also, in Figure 13(B), the liquid-repellent portion 14 is formed intermittently as in Figure 13(A). Note that the intermittent liquid-repellent portion 14 in Figure 13(B) is just one example. The spacing may be narrowed to form more dotted lines. In Figure 13(C), the liquid-repellent portion 14 is also formed intermittently as in Figure 13(A). However, in Figure 13(C), the parts where the liquid-repellent portion 14 intersect are left untouched, and the remaining parts are formed intermittently.

[0044] In Figure 14(A), the liquid-repellent portion 14 is formed at the corners of the regions surrounding the semiconductor chips 23a, 23b, 23c, and 23d, compared to the case in Figure 13(C). In Figure 14(B), the liquid-repellent portion 14 is formed continuously at the boundaries of the semiconductor chips 23a, 23b, 23c, and 23d, compared to the case in Figure 13(C). In Figure 14(C), the liquid-repellent portion 14 is formed at the corners of the regions surrounding the semiconductor chips 23a, 23b, 23c, and 23d, compared to the case in Figure 14(B).

[0045] By forming the liquid-repellent portion 14 in this way, the spread of solder under the semiconductor chips 23a, 23b, 23c, and 23d can be prevented, and the placement positions of the semiconductor chips 23a, 23b, 23c, and 23d can be brought as close together as possible. The width of the liquid-repellent portion 14 in Figures 13 and 14 can be set as needed. Furthermore, the liquid-repellent portion 14 is not limited to the cases in Figures 13 and 14, but can be formed on the plating film 12a of semiconductor chips as appropriate. [Explanation of symbols]

[0046] 10 Ceramic circuit boards 11 Insulating board 12 Circuit board 12a Plating film 13 Metal plate 14 Liquid repellent part 14a Resist section 14b Heat affected zone 15 Bonding wires 16a First solder 16b Second solder 20, 21, 23a, 23b, 23c, 23d Semiconductor chips 20a, 21a Component area 22 Electronic Components 30 Contact parts 31 solder board 40 External connection terminals 45 Sealing member 50 Electronic equipment

Claims

1. The first component is a semiconductor chip that is rectangular in shape when viewed from above, A circuit board in which the front surface is coated with a plating film, and the first component is arranged in the first component area of ​​the front surface via a first solder, It has, The circuit board includes an oxide film formed by oxidation of the plating film on the front surface along the side of the first component region, with a portion of the plating film remaining beneath the oxide film, the oxide film including a resist portion formed along the side of the first component region in a plan view and heat-affected zones formed along the resist portion on both sides thereof, the resist portion having a liquid-repellent portion that is 300 μm or more away from the first component, The first component is positioned such that only its long side is parallel to the direction in which the liquid-repellent portion is formed and adjacent to the liquid-repellent portion, while its short side does not face the liquid-repellent portion. electronic equipment.

2. The width of the heat-affected region is 50 μm or more. The electronic device according to claim 1.

3. The thickness of the resist portion is 25 nm or more. The electronic device according to claim 1.

4. The width of the resist portion is 400 μm or more and 500 μm or less. The electronic device according to claim 1.

5. The total thickness of the liquid-repellent portion and the remaining portion of the plating film is 6 μm or more. The electronic device according to claim 1.

6. The thickness of the remaining portion of the plating film below the liquid-repellent area is 5 μm or more. The electronic device according to claim 1.

7. The circuit board is made of copper or a copper alloy. The aforementioned plating film is nickel or a nickel-containing alloy. The electronic device according to claim 1.

8. The liquid-repellent portion is linear or dotted in shape when viewed from above. The electronic device according to claim 1.

9. The oxide film contained in the liquid-repellent portion includes a first laser mark caused by laser light irradiated onto the plating film. The electronic device according to claim 8.

10. The oxide film includes the first laser trace and a second laser trace that is in contact with the first laser trace or partially overlaps with the first laser trace, The electronic device according to claim 9.

11. The semiconductor chip is provided with control electrodes on the sides of the front surface of the semiconductor chip that are not the long side facing the liquid-repellent portion. The electronic device according to claim 1.

12. It further has a second part, The circuit board has a second component region on its front surface adjacent to the first component region, where the second component is arranged via a second solder joint, and the liquid-repellent portion is formed in the gap between the first component region and the second component region. The electronic device according to any one of claims 1 to 11.

13. The first component region is provided near the edge of the circuit board. The liquid-repellent portion is formed along the side of the end portion of the first component region. The electronic device according to any one of claims 1 to 11.

14. It further has a conductive third component, The circuit board has a third component region on its front surface adjacent to the first component region where the third component is arranged, and the liquid-repellent portion is formed in the gap between the first component region and the third component region. The electronic device according to any one of claims 1 to 11.

15. A process of preparing a first component, which is a rectangular semiconductor chip in plan view, and a circuit board, in which the front surface of which the area of ​​the first component is set is coated with a plating film, The process involves irradiating the plated film adjacent to the first component region with laser light to form an oxide film on the surface of the plated film, wherein a portion of the plated film remains beneath the oxide film, and the oxide film includes a resist portion formed along the side of the first component region in a plan view, and heat-affected zones formed along the resist portion on both sides of the resist portion, wherein the resist portion is a liquid-repellent portion located at least 300 μm away from the first component region. A step of placing the first solder in the first component region of the plating film, The first step is to place the first component on the first solder such that only the long side of the first component is parallel to the direction of formation of the liquid-repellent portion and adjacent to the liquid-repellent portion, and the short side of the first component does not face the liquid-repellent portion. The first step of melting the solder, A method for manufacturing an electronic device having [a certain characteristic].

16. The thickness of the resist portion formed in the step of forming the liquid-repellent portion is 40 nm or more. A method for manufacturing an electronic device according to claim 15.

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