Electronic module

Abstract

This electronic module comprises: a circuit board; a terminal electrode connected to a first main surface of the circuit board and having a second main surface on the opposite side to the first main surface; and an insulator covering the first main surface and at least a portion of the terminal electrode. The second main surface is exposed from the insulator and has a first step portion at least in a part thereof.

Description

Electronic Module

[0001] The present invention relates to an electronic module.

[0002] The ceramic circuit board described in Patent Document 1 includes a ceramic insulating substrate, a metal circuit, a metal circuit forming surface which is a bonding interface between the ceramic insulating substrate and the metal circuit, and a ceramic exposed surface on which no metal circuit is formed. The metal circuit forming surface is formed so as to be higher than the ceramic exposed surface.

[0003] Japanese Patent Application Laid-Open No. 2001-274545

[0004] An object of the present invention is to improve the strength of the joint when soldered.

[0005] An electronic module according to one aspect of the present invention comprises: a circuit board; a terminal electrode connected to a first main surface of the circuit board and having a second main surface opposite the first main surface; and an insulator covering at least a portion of the terminal electrode and the first main surface, wherein the second main surface is exposed from the insulator and has a first step portion on at least a portion of the second main surface.

[0006] According to the electronic module of the present invention, the strength of the joints during solder mounting can be improved.

[0007] 15 is a bottom view of a radio frequency module according to a first embodiment of the present invention; FIG. 16 is a cross-sectional view showing a cut surface including line A-A of the radio frequency module of FIG. 1; FIG. 17 is a bottom view of a radio frequency module according to a second embodiment of the present invention; FIG. 18 is a cross-sectional view showing a cut surface including line B-B of the radio frequency module of FIG. 3; FIG. 19 is a bottom view of a radio frequency module according to a third embodiment of the present invention; FIG. 19 is a cross-sectional view showing a cut surface including line A-A of the radio frequency module of FIG. 5; FIG. 20 is a cross-sectional view of a radio frequency module according to a modification of the third embodiment of the present invention; FIG. 21 is a cross-sectional view showing a cut surface including line A-A of the radio frequency module of FIG. 7; FIG. 22 is a bottom view of a radio frequency module according to a fourth embodiment of the present invention; FIG. 23 is a cross-sectional view of a radio frequency module according to a first modification; FIG. 24 is a bottom view of a radio frequency module according to a second modification; FIG. 25 is a cross-sectional view showing a cut surface including line A-A of the radio frequency module of FIG. 11; FIG. 26 is a bottom view of a radio frequency module according to a third modification; FIG. 27 is a bottom view of a radio frequency module according to a fourth modification; FIG. 28 is a bottom view of a radio frequency module according to a fifth modification; FIG. 29 is a perspective view showing terminal electrodes of the radio frequency module of FIG. 15;

[0008] Hereinafter, embodiments will be described with reference to the accompanying drawings as appropriate. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters or redundant descriptions of substantially identical configurations may be omitted.

[0009] 1. First Embodiment 1-1. Configuration A high-frequency module 1 according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. The high-frequency module 1 is an example of an electronic module according to the present disclosure. FIG. 1 is a bottom view of the high-frequency module 1 according to the first embodiment, and FIG. 2 is a cross-sectional view (end view) of the high-frequency module 1 of FIG. 1 taken along line A-A. FIG. 2 shows a partially enlarged view of a terminal electrode 4 and its surrounding configuration. For ease of explanation, FIGS. 1 and 2 show an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other. The Z-axis indicates the vertical direction.

[0010] 1 and 2 , the high-frequency module 1 according to the first embodiment includes a circuit board 2, a terminal electrode 4, and an insulator layer 3. The terminal electrode 4 is connected to a lower surface 22 (an example of a first main surface) of the circuit board 2, and has a bottom surface 41 (an example of a second main surface) on the opposite side to the lower surface 22.

[0011] The circuit board 2 includes a plurality of laminated insulating layers formed of, for example, low-temperature co-fired ceramic, high-temperature co-fired ceramic, glass epoxy resin, or the like. Various internal wiring electrodes (not shown) are formed between adjacent insulating layers. Furthermore, a plurality of via conductors (not shown) are formed inside the circuit board 2 to connect the internal wiring electrodes. For example, the internal wiring electrodes are formed of a metal commonly used for wiring electrodes, such as Cu, Ag, or Al. Furthermore, each via conductor is formed of a metal such as Ag or Cu. The circuit board 2 may also be a single metal layer.

[0012] As shown in FIG. 2 , mounting electrodes 5 for mounting may be provided on the upper surface 21 of the circuit board 2. The mounting electrodes 5 are formed of a metal such as Cu, Ag, or Al, similar to the internal wiring electrodes. The mounting electrodes 5 electrically connect the electronic components 6 to the circuit board 2. The electronic components 6 are formed of chip components such as chip inductors, chip capacitors, and chip resistors. The electronic components 6 may also be semiconductor elements such as ICs and PAs (power amplifiers). The electronic components 6 may also be devices such as analog high-frequency circuits and surface acoustic wave filters. For example, the electronic components 6 are mounted using a common surface mounting technique such as solder bonding.

[0013] The insulator layer 3 covers at least a portion of the terminal electrode 4 and the lower surface 22 of the circuit board 2. For example, as shown in Fig. 2, the insulator layer 3 covers the upper surface 21 of the circuit board 2 and the lower surface 22 of the circuit board 2 that faces the upper surface 21 in the thickness direction of the circuit board 2 (a direction parallel to the Z axis; hereinafter, also referred to as the "Z direction") The insulator layer 3 may also cover at least a portion of the mounting electrodes 5 and the electronic components 6. The insulator layer 3 is formed of an insulating material, for example, a glass material or an epoxy resin in which silica or the like is dispersed as a filler.

[0014] The terminal electrode 4 is provided on the lower surface 22 of the circuit board 2 and is electrically connected to the circuit board 2. In the illustrated example, a bottom surface 41 of the terminal electrode 4 is exposed from the insulator layer 3. A substrate such as a motherboard is connected to the terminal electrode 4 via solder. Like the internal wiring electrodes, the terminal electrode 4 is formed of a metal commonly used for wiring electrodes, such as Cu, Ag, or Al. In the illustrated example, the terminal electrode 4 has a cylindrical shape. However, the shape of the terminal electrode 4 is not limited to the illustrated example and may be an elliptical cylinder, a rectangular cylinder, or a truncated cone.

[0015] A step portion 40 is provided on at least a portion of the bottom surface 41 of the terminal electrode 4. The step portion 40 is formed so that the entire outer periphery 42 of the terminal electrode 4 is within the step portion 40 when viewed from the thickness direction (Z direction). In the example of FIG. 1 , the step portion 40 is a circular groove provided on the edge of the bottom surface 41 of the terminal electrode 4 when viewed from the bottom. Such a step portion 40 is formed, for example, by cutting out the edge of the cylindrical terminal electrode 4 with a laser. Before the step portion 40 is formed, the surface of the high-frequency module 1, i.e., the bottom surfaces of the terminal electrodes 4 and the insulator layer 3, are substantially flush with each other.

[0016] 1 and 2 , in the first embodiment, a step portion 30 may be provided on the lower surface of the insulator layer 3. In the example of FIG. 1 , the step portion 30 is a circular groove surrounding the terminal electrode 4 when viewed from the bottom. In the first embodiment, the step portion 40 of the terminal electrode 4 and the step portion 30 of the insulator layer 3 are connected and integrated to form a step portion 50. Such a step portion 50 is formed, for example, by cutting out both the edge of the cylindrical terminal electrode 4 and the insulator layer 3 around the edge of the terminal electrode 4 using a laser.

[0017] 2 , the bottom surface 41 of the terminal electrode 4 includes a first surface 411 and a second surface 412. The distance in the thickness direction between the first surface 411 and the lower surface 22 of the circuit board 2 is different from the distance in the thickness direction between the second surface 412 and the lower surface 22 of the circuit board 2. In the high-frequency module 1 according to the first embodiment, the distance in the thickness direction from the lower surface 22 to the first surface 411 is longer than the distance from the lower surface 22 to the second surface 412.

[0018] For example, the distance from the lower surface 22 to the first surface 411 in the thickness direction (terminal height or terminal thickness) is 100 μm, but is not limited to this. For example, the distance from the first surface 411 to the second surface 412 in the thickness direction (cutting depth or height of the step portion 40) is 10 μm or more and less than 100 μm, but is not limited to this. For example, the distance from the first surface 411 to the second surface 412 in the thickness direction (cutting depth or height of the step portion 40) may be shorter than the distance between the second surface 412 and the lower surface 22 of the circuit board 2, but is not limited to this.

[0019] For example, the diameter (terminal width) of the terminal electrode 4 is 190 μm to 250 μm, but is not limited to this. Here, the diameter of the terminal electrode 4 refers to the length of the longest part of the terminal electrode 4 in the X direction or Y direction.

[0020] For example, the distance from the first surface 411 to the second surface 412 in the thickness direction (cutting depth) is, but is not limited to, 1 / 25 or more of the diameter (terminal width) of the terminal electrode 4. Due to the presence of the cut depth, when the terminal electrode 4 is soldered to the motherboard, the boundary between the first surface 411 of the terminal electrode 4 and the solder is covered with solder, making it possible to suppress the occurrence of cracks starting from the boundary.

[0021] In the high-frequency module 1 according to the first embodiment, the insulator layer 3 has a third surface 31 that is flush with the second surface 412. For example, the longest length in the X direction of the region including the second surface 412 and the third surface 31, i.e., the maximum width of the step portion 50, is 20 μm or more, but is not limited to this.

[0022] For example, the maximum length in the X direction of the second surface 412 of the terminal electrode 4, i.e., the maximum width of the step portion 40, is 10 μm or more, but is not limited to this. For example, the maximum length in the X direction of the third surface 31 of the insulator layer 3, i.e., the maximum width of the step portion 30, is 10 μm or more, but is not limited to this.

[0023] In the radio-frequency module 1 according to the first embodiment, the bottom surface 41 includes the columnar terminal electrodes 4 exposed from the insulator layer 3, and at least a portion of the bottom surface 41 has a step portion 40, which increases the contact area between the bottom surface 41 and the solder during solder mounting. More specifically, the radio-frequency module 1 is mounted with the solder filling the step portion 40. This improves the strength of the joint.

[0024] Furthermore, in the high-frequency module 1 according to the first embodiment, the step 40 allows the position where stress is applied to be shifted from the boundary between the first surface 411 of the terminal electrode 4 and the solder to the second surface 412 of the terminal electrode 4, thereby preventing cracks from occurring at the boundary between the first surface 411 of the terminal electrode 4 and the solder. In conventional circuit boards, cracks can occur at the boundary between the terminal electrode and the solder when an external force is applied to the circuit board. For example, cracks can occur when stress is applied to the boundary between the terminal electrodes when an external force is applied to the circuit board. Furthermore, cracks can also occur when stress is applied to the boundary due to differences in the linear expansion coefficients of the terminal electrodes and the insulator layer.

[0025] The high-frequency module 1 according to the first embodiment further has a step portion 30 or a step portion 50, which can alleviate the stress applied to the boundary between the first surface 411 of the terminal electrode 4 and the solder, thereby suppressing the occurrence of cracks.

[0026] In the radio frequency module 1 according to the first embodiment, the terminal electrodes 4 are arranged at the corners of the radio frequency module 1 in a plan view seen from the thickness direction of the circuit board 2. The corners of the circuit board 2 refer to locations that are not the center of the circuit board 2 in a plan view. In other words, the terminal electrodes 4 are arranged at positions that do not include the center of the radio frequency module 1 in a plan view. Alternatively, the terminal electrodes 4 are arranged so that the centers of the terminal electrodes 4 are different from the center of the radio frequency module 1 in a plan view. Stress is more likely to be applied to the corners of the radio frequency module 1 than to the center. In the radio frequency module 1 according to the first embodiment, the terminal electrodes 4 are arranged at the corners of the radio frequency module 1, and can relieve stress applied to the boundary between the first surface 411 and the solder, thereby suppressing the occurrence of cracks.

[0027] 1-2. Summary As described above, the high-frequency module 1 according to the first embodiment includes the circuit board 2, the terminal electrodes 4, and the insulator layer 3, which is an example of an insulator. The terminal electrodes 4 are connected to the lower surface 22 (an example of a first main surface) of the circuit board 2 and have a bottom surface 41 (an example of a second main surface) on the opposite side of the lower surface 22. The insulator layer 3 covers at least a portion of the terminal electrodes 4 and the lower surface 22. The bottom surface 41 is exposed from the insulator layer 3 and has a step portion 40 (an example of a first step portion) on at least a portion of the bottom surface 41. With this configuration, when the terminal electrodes 4 are soldered to the motherboard, the area covered by the solder on the terminal electrodes 4 can be increased, thereby improving the strength of the joint between the terminal electrodes 4 and the motherboard.

[0028] The step portion 40 may be formed on at least a part of the outer periphery of the lower surface 22 of the circuit board 2 in a plan view seen from the thickness direction of the circuit board 2. With this configuration, the boundary between the first surface 411 of the terminal electrode 4 and the solder is covered with solder, making it possible to suppress the occurrence of cracks originating from the boundary. In addition, the position where stress is applied can be shifted from the boundary between the first surface 411 of the terminal electrode 4 and the solder to the second surface 412 of the terminal electrode 4, making it possible to suppress the occurrence of cracks at the boundary between the first surface 411 of the terminal electrode 4 and the solder.

[0029] The insulator layer 3 may have a step portion 50 (an example of a second step portion) along the step portion 40. With this configuration, the step portion 50 can relieve stress applied to the boundary between the first surface 411 of the terminal electrode 4 and the solder, thereby suppressing the occurrence of cracks.

[0030] The distance between the bottom surface of the step portion 40 and the bottom surface 41 of the terminal electrode 4 may be shorter than the distance between the bottom surface of the step portion 40 and the lower surface 22 of the circuit board 2. This configuration also makes it possible to alleviate stress applied to the boundary between the first surface 411 of the terminal electrode 4 and the solder, thereby suppressing the occurrence of cracks.

[0031] The terminal electrodes 4 may be circular in plan view seen from the thickness direction of the circuit board 2. This configuration also increases the area of ​​the terminal electrodes 4 that is covered by solder when the terminal electrodes 4 are soldered to the motherboard, thereby improving the strength of the joint between the terminal electrodes 4 and the motherboard.

[0032] The terminal electrodes 4 may be disposed at the corners of the high-frequency module 1 in a plan view seen from the thickness direction of the circuit board 2. According to this configuration, the terminal electrodes 4, which can relieve stress applied to the boundary between the first surface 411 and the solder, are disposed at the corners of the high-frequency module 1, thereby making it possible to suppress the occurrence of cracks.

[0033] 2. Second Embodiment A high-frequency module according to a second embodiment of the present invention will be described below. In the following description, descriptions of the same configuration as that of the high-frequency module 1 according to the first embodiment may be omitted.

[0034] Fig. 3 is a bottom view of the high-frequency module 1a according to the second embodiment, and Fig. 4 is a cross-sectional view showing a cut surface including line B-B of the high-frequency module 1a in Fig. 3. Compared to the high-frequency module 1 according to the first embodiment, the high-frequency module 1a according to the second embodiment includes terminal electrodes 4a instead of the terminal electrodes 4 of the first embodiment.

[0035] In the high-frequency module 1 according to the first embodiment, the entire outer periphery 42 of the terminal electrode 4 is located within the step portion 40 when viewed from the thickness direction (see FIGS. 1 and 2). In contrast, in the high-frequency module 1a according to the second embodiment, as shown in FIGS. 3 and 4, the step portion 40a is formed such that only a portion of the outer periphery 42 of the terminal electrode 4a is located within the step portion 40a when viewed from the thickness direction.

[0036] 4 , for example, in the high-frequency module 1a according to the second embodiment, a step portion 50a is formed from a portion of the terminal electrode 4a to a side surface of the insulator layer 3. In the illustrated example, the step portion 50a includes a step portion 40a formed by cutting out a portion of the terminal electrode 4a and a step portion 30a formed by cutting out a portion of the insulator layer 3. After the bottom surfaces of the terminal electrode 4a and the insulator layer 3 are formed flush, they are removed mechanically, chemically, or optically.

[0037] The shape of the step portion 50 a is not limited to this. For example, the shape of the step portion 50 a in the high-frequency module 1 according to the first embodiment may be a shape in which a part of the step portion 50 is filled with either or both of the terminal electrode 4 and the insulator layer 3.

[0038] As described above, in the high-frequency module 1a according to the second embodiment, the step portion 40a is formed so that at least a portion of the outer periphery 42 of the terminal electrode 4a is within the step portion 40a when viewed from the thickness direction. This configuration increases the area of ​​the terminal electrode 4a that is covered by solder when the terminal electrode 4a is soldered to the motherboard, thereby improving the strength of the joint between the terminal electrode 4a and the motherboard. It also reduces the occurrence of cracks in the terminal electrode 4a.

[0039] 3. Third Embodiment A high-frequency module according to a third embodiment of the present invention will be described below. In the following description, descriptions of the same configurations as those of the first or second embodiment may be omitted.

[0040] FIG. 5 is a bottom view of a high-frequency module 1b according to the third embodiment, and FIG. 6 is a cross-sectional view of the high-frequency module 1b in FIG. 5 taken along line A-A. Compared to the high-frequency module 1 according to the first embodiment, the terminal electrodes 4 of the high-frequency module 1b according to the third embodiment are provided with recesses 43 (an example of a first step portion). As shown in FIG. 5, the contour of the recesses 43 is circular in plan view, but the shape of the recesses 43 is not limited to this. The recesses 43 only need to be formed inside the outer periphery of the bottom surface 41 in plan view, and the position of the recesses 43 is not limited to the position illustrated in FIG. 5.

[0041] According to this configuration, when the terminal electrode 4 is soldered to the motherboard, the solder flows into the recess 43. This increases the area of ​​the terminal electrode 4 that the solder covers, improving the strength of the joint between the terminal electrode 4 and the motherboard. Also, an IMC (Intermetallic Compound) layer is formed between the solder and the terminal electrode 4, but because the solder flows into the recess 43, the shape of the formed IMC layer is curved at the recess 43. In this way, the recess 43 prevents the IMC layer from extending on a single plane, and suppresses the progression of cracks along the bottom surface 41.

[0042] The terminal electrode 4 may further include a hole opening in the bottom surface 41 (a hole dug from the bottom surface 41). Fig. 7 is a bottom view of a high-frequency module 1c according to such a modified example of the third embodiment, and Fig. 8 is a cross-sectional view showing a cut surface including line A-A of the high-frequency module 1c in Fig. 7.

[0043] 7 and 8 , a hole 44 is provided in the terminal electrode 4 of the high-frequency module 1c. The hole 44 is provided at a position different from the recess 43 in a plan view. In the illustrated example, the diameter of the hole 44 is smaller than the diameter of the recess 43. For example, the diameter of the hole 44 is 10 to 30 μm, which prevents solder from flowing into the hole 44 when the terminal electrode 4 is soldered to the motherboard. Therefore, the IMC layer extending along the bottom surface 41 is interrupted by the hole 44. In this way, the hole 44 can prevent the IMC layer from extending in a single plane, and can suppress the progression of cracks along the bottom surface 41.

[0044] 4. Fourth Embodiment A high-frequency module according to a fourth embodiment of the present invention will be described below. In the following description, descriptions of the same configuration as in any of the first to third embodiments may be omitted.

[0045] 9 is a bottom view of a high-frequency module 1d according to the fourth embodiment. Compared to the high-frequency module 1 according to the first embodiment, the high-frequency module 1d according to the third embodiment has a terminal electrode 4 provided with grooves 45a and 45b (examples of first stepped portions).

[0046] 9, the groove 45a extends in the X direction, the groove 45b extends in the Y direction, and the two intersect at the center of the terminal electrode 4 in a bottom view. However, the extending direction and intersecting position of the grooves 45a and 45b are not limited to the example shown in Fig. 9. Furthermore, the terminal electrode 4 of the high-frequency module 1d does not need to have both the grooves 45a and 45b, and may have only one groove.

[0047] With this configuration, when the terminal electrode 4 is soldered to the motherboard, the solder flows into the grooves 45a and 45b. This increases the area over which the solder covers the terminal electrode 4, improving the strength of the joint between the terminal electrode 4 and the motherboard. Furthermore, the IMC layer extending along the bottom surface 41 is bent by the grooves 45a and 45b. In this way, the grooves 45a and 45b prevent the IMC layer from extending in a single plane, thereby suppressing the progression of cracks along the bottom surface 41.

[0048] 5. Other Embodiments The above embodiments have been described as examples of the technology of the present invention. However, the technology of the present invention is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate. Furthermore, it is also possible to combine the components described in the above embodiments to create new embodiments. Therefore, below, examples of modified examples as other embodiments will be given.

[0049] In the first embodiment, an example in which the terminal electrode 4 is made of metal has been described, but the terminal electrode 4 is not limited to being made of a single type of metal. The terminal electrode 4 may include an alloy layer covering at least a portion of the bottom surface.

[0050] Fig. 10 is a cross-sectional view showing such a terminal electrode 4 according to a first modified example. In the example shown in Fig. 10, the terminal electrode 4 includes an alloy layer 413 formed on the bottom and side surfaces of the terminal electrode 4. The alloy layer 413 is formed by, for example, plating. By covering at least a portion of the bottom surface of the terminal electrode 4, the alloy layer 413 can prevent the terminal electrode 4 from being oxidized and damaged by external forces. Alternatively, or in addition, the alloy layer 413 can ensure good bonding between the terminal electrode 4 and the motherboard during soldering.

[0051] Similarly, the terminal electrode 4a of the second embodiment may also include an alloy layer that covers at least a portion of the bottom surface.

[0052] 5-2. Second to Fifth Modifications In the above embodiments, various shapes that the terminal electrode, particularly the first step portion of the terminal electrode, can have have been described, but the shape of the terminal electrode is not limited to these. The shapes of the terminal electrode 4 according to such second to fifth modifications will be described below.

[0053] Fig. 11 is a bottom view of a high-frequency module 1e according to a second modified example, and Fig. 12 is a cross-sectional view of the high-frequency module 1e taken along line A-A in Fig. 11. A groove 46 is provided in the terminal electrode 4 of the high-frequency module 1e as an example of a first step portion. The groove 46 is a circular groove dug in the bottom surface 41 of the terminal electrode 4.

[0054] 13 is a bottom view of a high-frequency module 1f according to a third modification. Grooves 47a, 47b, and 47c are provided in the terminal electrodes 4 of the high-frequency module 1f as an example of first stepped portions. While the example in FIG. 13 illustrates three grooves 47a, 47b, and 47c, the number of grooves may be less than three or may be four or more.

[0055] 14 is a bottom view of a high-frequency module 1g according to a fourth modification. Grooves 48a, 48b, 48c, and 48d are provided in the terminal electrode 4 of the high-frequency module 1g as an example of a first step portion. While the example in FIG. 14 illustrates four grooves 47a, 47b, and 47c, the number of grooves may be less than four or may be five or more.

[0056] Fig. 15 is a bottom view of a radio-frequency module 1h according to a fifth modified example. A terminal electrode 4 of the radio-frequency module 1h is provided with a step portion 49 as an example of a first step portion. The shape of the step portion 49 will be further described with reference to Fig. 16. Fig. 16 is a perspective view for explaining the structure of the terminal electrode 4 of Fig. 15. For ease of explanation, Fig. 16 omits illustration of components of the radio-frequency module 1h other than the terminal electrode 4. The step portion 49 has a shape that combines a circular depression opening on the bottom surface 41 with a notch that cuts out the terminal electrode 4.

[0057] According to the second to fifth modifications, when the terminal electrode 4 is soldered to the motherboard, the solder flows into the first step portion. This increases the area over which the solder covers the terminal electrode 4, thereby improving the strength of the joint between the terminal electrode 4 and the motherboard.

[0058] Furthermore, according to the second to fifth modified examples, the IMC layer extending along the bottom surface 41 is bent by the first step portion. In this way, the second to fifth modified examples can prevent the IMC layer from extending on a single plane, and can suppress the progression of cracks along the bottom surface 41.

[0059] Furthermore, the first step portions of the terminal electrodes 4 according to the second to fifth modifications can be formed by, for example, laser processing. Unlike the technology described in Patent Document 1, which determines the shape of the exposed terminal by adjusting the area on the substrate where resist is applied, the terminal electrodes 4 according to the second to fifth modifications do not require resist to be formed. Therefore, the high-frequency modules according to the second to fifth modifications can be configured without using resist.

[0060] The high-frequency modules according to the above-described embodiments and the first modified example can also be configured without using a resist, and therefore the following description also applies to the high-frequency modules according to the above-described embodiments and the first modified example.

[0061] The distance (hereinafter also referred to as "standoff") between the high-frequency module according to each of the above embodiments and modifications and the mounting surface of a module substrate such as a motherboard is smaller by the thickness of the resist compared to the standoff between substrates coated with resist. A smaller standoff reduces parasitic resistance components. Therefore, by using the high-frequency module according to each of the above embodiments and modifications, the standoff can be reduced, thereby reducing parasitic resistance components and loss. Furthermore, by reducing the standoff, the high-frequency module according to each of the above embodiments and modifications can achieve a low profile.

[0062] Furthermore, if a resist is applied to the surface of the substrate, stress occurs mainly at the interface between the resist and the metal when heat is applied to the substrate due to the difference in thermal expansion coefficient between the resist and the metal. This may lead to destruction of the substrate. In contrast, the high-frequency modules according to the above-described embodiments and modifications can be configured without using resist, and therefore do not suffer from the above-described thermal expansion problem.

[0063] In the high-frequency modules according to the above-described embodiments and modifications, the shape of the electrodes can be easily changed simply by changing the mask, and therefore the shape of the electrodes can be changed at low cost.

[0064] 6. Examples of Embodiments The following are examples of embodiments of the present invention.

[0065] <Aspect 1> An electronic module comprising: a circuit board; a terminal electrode connected to a first main surface of the circuit board and having a second main surface opposite the first main surface; and an insulator covering at least a portion of the terminal electrode and the first main surface, wherein the second main surface is exposed from the insulator and has a first step portion in at least a portion thereof.

[0066] Aspect 2 The electronic module according to aspect 1, wherein the first step portion is formed on at least a part of the outer periphery of the second main surface in a plan view seen in a thickness direction of the circuit board.

[0067] <Aspect 3> The electronic module according to aspect 1 or 2, wherein the first step portion is formed inside an outer periphery of the second main surface in a plan view seen in a thickness direction of the circuit board.

[0068] <Aspect 4> The electronic module according to aspect 3, wherein the terminal electrode further includes a hole or a groove that opens to the second main surface.

[0069] <Aspect 5> The electronic module according to aspect 2, wherein the insulator has a second step portion along the first step portion.

[0070] Aspect 6 The electronic module according to any one of Aspects 1 to 5, wherein the second main surface is covered with an alloy layer.

[0071] Aspect 7 The electronic module according to any one of Aspects 1 to 6, wherein the distance between the bottom surface of the first step portion and the second main surface is shorter than the distance between the bottom surface and the first main surface.

[0072] Aspect 8 The electronic module according to any one of Aspects 1 to 7, wherein the terminal electrodes are circular in plan view seen from the thickness direction of the circuit board.

[0073] Aspect 9 The electronic module according to any one of aspects 1 to 8, wherein the terminal electrodes are arranged at corners of the electronic module in a plan view seen from the thickness direction of the circuit board.

[0074] The present invention is applicable to electronic modules such as high frequency modules.

[0075] REFERENCE SIGNS LIST 1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h High frequency module 2 Circuit board 21 Upper surface 22 Lower surface (first main surface) 3 Insulator layer 30, 30a, 40, 40a, 50, 50a Step portion 31 Third surface 4, 4a Terminal electrode 41 Bottom surface (second main surface) 411 First surface 412 Second surface 42 Outer periphery 43 Recess 44 Hole 45a, 45b Groove 46 Groove 47a, 47b, 47c Groove 48a, 48b, 48c, 48d Groove 49 Step portion 5 Mounting electrode 6 Electronic component

Claims

1. An electronic module comprising: a circuit board; a terminal electrode connected to a first main surface of the circuit board and having a second main surface opposite the first main surface; and an insulator covering at least a portion of the terminal electrode and the first main surface, wherein the second main surface is exposed from the insulator and has at least a first step portion.

2. The electronic module according to claim 1, wherein the first step portion is formed on at least a part of the outer periphery of the second main surface when viewed in a plan view in the thickness direction of the circuit board.

3. The electronic module according to claim 1 or 2, wherein the first step portion is formed inside the outer periphery of the second main surface when viewed in a plan view in the thickness direction of the circuit board.

4. The electronic module according to claim 3, wherein the terminal electrodes further comprise holes or grooves opening into the second main surface.

5. The electronic module of claim 2, wherein the insulator has a second step along the first step.

6. An electronic module according to any one of claims 1 to 5, wherein the second main surface is covered with an alloy layer.

7. An electronic module according to any one of claims 1 to 6, wherein the distance between the bottom surface of the first step portion and the second main surface is shorter than the distance between the bottom surface and the first main surface.

8. The electronic module according to any one of claims 1 to 7, wherein the terminal electrodes are circular in plan view seen in the thickness direction of the circuit board.

9. The electronic module according to any one of claims 1 to 8, wherein the terminal electrodes are arranged at corners of the electronic module when viewed in a plan view in the thickness direction of the circuit board.

Images