JP2007095954A - Circuit board, electronic equipment using it, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board capable of surely and stably mounting an electronic element without confirming the melted state of a solder interposed between the electronic element and the circuit board, when mounting electronic elements on the circuit board. <P>SOLUTION: An insulating board 1 comprises a mounting part 2 for electronic elements on its surface with a joint pad 4 of first solder formed on the mounting part 2, and a labelled part 6 where a second solder 5 is coated on the surface except for the mounting part 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a circuit board for mounting an electronic element, an electronic device, and a manufacturing method thereof.

  In recent years, electronic devices of electronic devices used for CDs (Compact Disks), DVDs (Digital Video Disks) and the like have been required to have high output, and a conventional circuit board on which such electronic devices are mounted will be described.

  A perspective view of a conventional circuit board is shown in FIG. 3, 104 is a circuit board, 21 is an insulating substrate, 22 is an electronic component mounting portion, 23 is a wiring conductor layer, and 24 is a bonding pad. The insulating substrate 21 has an electronic element mounting portion 22 on the surface. And a wiring conductor layer 23, a bonding pad 24 made of a brazing material is formed on the mounting portion 22, and an electronic element is mounted via the bonding pad 24. The electronic element and the wiring conductor layer 23 are electrically connected via a bonding wire or the like, whereby the circuit board 104 on which the electronic element is mounted is obtained.

  In addition, an electronic device can be obtained by mounting the circuit board 104 on which such electronic elements are mounted on a base, and attaching a frame, a lid, or the like to the base so as to surround the electronic elements as necessary. It is done.

In such an electronic device, for example, when the semiconductor element is an optical semiconductor element, the drive signal supplied from the external electric circuit via the external lead terminal excites the optical semiconductor element, and then the light emitted from the optical semiconductor element Is transmitted to the outside through an optical fiber or the like to be used for high-speed optical communication or the like. In recent years, such optical semiconductor devices have been increasingly required to have good high frequency characteristics at 2.5 Gbps or more, downsizing, low profile, low cost, and the like.
JP 1999-168147 A

  However, when an electronic element is mounted on the mounting portion 22 of the conventional circuit board 104, the following problems have been encountered.

  That is, when an electronic element is mounted on the circuit board 104, it is mounted on the mounting portion 22 via the bonding pad 24 as described above. At this time, the brazing material for forming the bonding pad 24 on the mounting portion 22 is used. The molten state is hidden by the electronic element and is difficult to confirm. For this reason, there has been a problem that electronic devices cannot be stably bonded under appropriate conditions.

  The present invention has been completed in view of the problems of the prior art, and an object of the present invention is to provide a circuit board on which electronic elements can be stably and reliably mounted.

  The circuit board of the present invention has a mounting portion for an electronic element on the surface, a bonding pad made of a first brazing material is formed on the mounting portion, and a second brazing material is covered on the surface excluding the mounting portion. An insulating substrate having a sign portion attached thereto is provided.

  In the circuit board according to the present invention, preferably, the second brazing material is made of a brazing material having the same composition as the first brazing material.

  In the circuit board of the present invention, preferably, the second brazing material has a corner portion on an outer peripheral portion in a plan view.

  In the circuit board according to the present invention, preferably, the arithmetic average roughness Ra of the surface of the mark portion where the second brazing material is attached is R1, and the arithmetic average roughness Ra of the surface of the mounting portion is R2. Then, it has a relationship of R1 ≦ R2.

  In the circuit board of the present invention, preferably, the second brazing material and the bonding pad have the same shape in plan view.

  An electronic device of the present invention includes the circuit board of the present invention and an electronic component mounted on the circuit board.

  The electronic device manufacturing method of the present invention includes a step of observing the state of the second brazing material and mounting the electronic element on the insulating substrate.

  The electronic device according to the present invention is an insulating substrate in which an electronic element is bonded to a surface via a bonding material, and a pattern for estimating a molten state of the bonding material is provided on the insulating substrate excluding a portion where the electronic element is mounted It is characterized by having.

  The circuit board of the present invention has an electronic element mounting portion on the surface, a bonding pad made of a first brazing material is formed on the mounting portion, and a second brazing material is deposited on the surface excluding the mounting portion. By providing the insulating substrate having the marking portion, when the electronic element is mounted on the circuit board, even if the melting state of the first brazing material forming the bonding pad cannot be confirmed, By confirming the molten state of the deposited second brazing material, the molten state of the first brazing material can be estimated, and the electronic element can be mounted on the mounting portion under appropriate conditions. Therefore, the electronic device and the circuit resulting from the molten state of the first brazing material, such as the first brazing material is not sufficiently melted or the first brazing material is melted and flows out of the mounting portion region. It is possible to provide a circuit board capable of suppressing poor connection with the board and stably mounting the electronic element with high reliability.

  In the circuit board according to the present invention, the second brazing material is made of the brazing material having the same composition as the first brazing material, so that when the electronic element is mounted on the circuit board, the second brazing material has the same composition as the first brazing material. By confirming the molten state of the brazing filler metal, the electronic element can be bonded under more appropriate conditions. In other words, since the second brazing material applied to the marking portion and the first brazing material forming the bonding pad have the same composition, even if heat is applied when the electronic element is mounted, almost the same molten state I am doing. Therefore, it becomes easier to mount the electronic element on the circuit board in a desired state by confirming the molten state of the second brazing material attached to the marking portion.

  In the circuit board of the present invention, since the second brazing material has corners on the outer peripheral portion in plan view, the movement of the second brazing material at the start of melting becomes easier to visually recognize, and the electronic element is more optimal. It becomes possible to join on condition. That is, when the second brazing material applied to the marking portion is melted, the second brazing material at the position where the corner portion is formed melts due to a change in shape such as rounded shape. It becomes easier to confirm the melting start state of the second brazing material deposited on the metal. Therefore, by confirming the melting state of the second brazing material, particularly at the corners, it becomes easier to understand the melting start state of the bonding pad made of the first brazing material.

  In the circuit board of the present invention, when the arithmetic average roughness Ra of the surface of the portion where the second brazing material of the marking portion is attached is R1, and the arithmetic average roughness Ra of the surface of the mounting portion is R2, R1 ≦ By having the relationship of R2, it becomes easy to bond the electronic element to the circuit board under more optimal conditions. This is because, in general, those formed on a smoother surface have more fluidity, and in the present invention, a marker portion formed on a smoother surface than the mounting portion of the electronic element. Since the second brazing material applied to is melted in a larger shape than the first brazing material forming the bonding pad formed on the mounting portion of the electronic element at the start of melting, the second brazing material becomes easy to visually recognize.

  In the circuit board of the present invention, the first brazing material and the second brazing material can be brought into a closer state by making the second brazing material and the bonding pad the same shape in plan view. In addition, the electronic device can be further bonded under optimum conditions.

  The electronic device according to the present invention includes the circuit board according to the present invention and the electronic component mounted on the circuit board, and thus has high operational reliability in which electronic elements are stably bonded.

  According to the method for manufacturing an electronic device of the present invention, by observing the state of the second brazing material and mounting the electronic element on the insulating substrate, the electronic element is mounted on the circuit board in an appropriate state. In addition, an electronic device with high operation reliability can be obtained.

  The electronic device of the present invention has an insulating substrate in which an electronic element is bonded to the surface via a brazing material, and a pattern for estimating the melting state of the brazing material is provided on the insulating substrate excluding a portion where the electronic device is mounted. Thus, the electronic element can be mounted in a desired state according to the molten state of the brazing material.

  Next, the circuit board of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing an example of an embodiment of a circuit board according to the present invention. In FIG. 1, 14 is a circuit board, 1 is an insulating substrate, 2 is an electronic element mounting portion, 3 is a wiring conductor, 4 is a bonding pad made of a first brazing material, 5 is a second brazing material, and 6 is conductive. The circuit board 14 has an electronic element mounting portion 2 on the surface, and a bonding pad 4 made of a first brazing material is formed on the mounting portion 2, excluding the mounting portion 2. An insulating substrate 1 having a marking portion 6 having a second brazing material 5 attached on the surface thereof is provided.

The insulating substrate 1 has a function of mounting electronic elements, and is, for example, a rectangular parallelepiped having a length of about 0.5 to 10 mm, a width of 0.5 to 5 mm, and a thickness of about 0.1 to 1 mm, and aluminum oxide (Al ₂ O ₃ ) Quality sintered body, aluminum nitride (AlN) type sintered body, silicon carbide (SiC) type sintered body, silicon nitride (Si ₃ N ₄ ) type sintered body, ceramics such as glass ceramics, epoxy resin and polyimide resin It is made of an insulating material containing a resin such as polyimide siloxane resin. When an optical semiconductor element is used as the electronic element, a material having a thermal conductivity of 40 W / m · K or more, such as an aluminum nitride sintered body, a silicon carbide sintered body, a silicon nitride sintered body, or the like, This is preferable because heat at the time of driving can be efficiently dissipated.

  Further, such an insulating substrate 1 can be formed by, for example, a method of laminating ceramic green sheets in a sheet shape and firing at a temperature of about 1500 ° C.

  The mounting portion 2 formed on the surface of the insulating substrate 1 mounts an electronic element, and the wiring conductor 3 electrically connects the mounting portion 2 and an external electric circuit (not shown). The mounting portion 2 and the wiring conductor 3 are formed by a conventionally known thin film forming method such as a vapor deposition method, a sputtering method, a CVD method, or a plating method, and then a conventionally known photolithography method, etching method, lift-off method, or the like. Is processed into a predetermined pattern. The mounting portion 2 may be formed using the surface of the insulating substrate 1, or may be formed using a part of the wiring conductor 3 formed on the surface of the circuit substrate 14.

  Moreover, the mounting part 2 and the wiring conductor 3 are preferably composed of a conductor layer having a three-layer structure in which an adhesion metal layer, a diffusion prevention layer, and a main conductor layer are sequentially laminated, for example.

From the viewpoint of improving the adhesion with the insulating substrate 1 made of ceramics or the like, the adhesion metal layer is made of titanium (Ti), chromium (Cr), tantalum (Ta), niobium (Nb), nickel-chromium (Ni —Cr) alloy, tantalum nitride (Ta ₂ N), or the like, preferably made of at least one metal having a thermal expansion coefficient close to that of ceramics, and the thickness is preferably about 0.01 to 0.2 μm. If the thickness of the adhesion metal layer is less than 0.01 μm, it tends to be difficult to firmly adhere the adhesion metal layer to the insulating substrate 1. If the thickness exceeds 0.2 μm, the adhesion metal layer is caused by internal stress during film formation. Tends to peel from the insulating substrate 1.

  In addition, the diffusion preventing layer is made of platinum (Pt), palladium (Pd), rhodium (Rh), nickel (Ni), tungsten (W), from the viewpoint of preventing mutual diffusion between the adhesion metal layer and the main conductor layer. It is preferably made of at least one metal having good thermal conductivity such as Ni—Cr alloy or Ti—W alloy, and its thickness is preferably about 0.05 to 1 μm. If the thickness of the diffusion prevention layer is less than 0.05 μm, defects such as pinholes tend to occur and it becomes difficult to perform the function as the diffusion prevention layer. If the thickness exceeds 1 μm, the diffusion prevention layer is caused by internal stress during film formation. Tends to be easily peeled off from the adhesive metal layer. When a Ni—Cr alloy is used for the diffusion preventing layer, the Ni—Cr alloy has good adhesion to the insulating substrate 1, and therefore the adhesion metal layer can be omitted.

  Further, the main conductor layer may be made of at least one of gold (Au), Cu, Ni, and silver (Ag) having a low electric resistance from the viewpoint of reducing the electric resistance of the mounting portion 2 and the wiring conductor 3. The thickness is preferably about 0.1 to 5 μm. If the thickness of the main conductor layer is less than 0.1 μm, the electric resistance tends to be large and the electric resistance required for the wiring conductor 3 tends not to be satisfied. If the thickness exceeds 5 μm, the main conductor layer is caused by internal stress during film formation. Tends to be easily peeled off from the diffusion preventing layer. Since Au is a noble metal and expensive, it is preferably formed as thin as possible in terms of cost reduction. Further, since Cu is easily oxidized, a protective layer made of Ni and Au may be coated thereon.

  The bonding pad 4 made of the first brazing material is formed on the mounting portion 2 of the insulating substrate 1 by a conventionally known thin film forming method such as a vapor deposition method, a sputtering method, a CVD method, or a plating method, and then a conventionally known photolithography. It is provided in a predetermined pattern by a method, an etching method, a lift-off method, or the like. Such a first brazing material includes an Au—Ge alloy (melting point: about 356 ° C.), an Au—Si alloy (melting point: about 370 ° C.), a lead-tin (Pb—Sn) alloy (melting point: about 183 ° C.), Au— Sn alloy (melting point: about 280 ° C), Ag-Sn alloy (melting point: about 220 ° C), In-Pb alloy (melting point: about 172 ° C), In (melting point: about 157 ° C), etc., especially Au-Sn alloy. Is preferred. This is because electronic devices generally have a heat resistance of about 400 ° C., and the mounting temperature when mounting with the above-described Au—Ge alloy and Au—Si alloy is 400 ° C. or more, and the electronic devices are thermally deteriorated. there's a possibility that. In addition, the above-described In—Pb alloy and In low melting point brazing filler metal tend to have low bonding strength with electronic devices. Therefore, by using a brazing material made of an Au—Sn alloy, the electronic element can be mounted without being thermally deteriorated even when the first brazing material is melted at the time of mounting, and the bonding strength is increased. be able to.

  Further, the thickness of the bonding pad 4 is preferably 2 μm to 10 μm. When the thickness is less than 2 μm, a void is formed in the first brazing material between the mounted electronic device and the mounting portion 2, and the bonding strength (die shear strength) of the electronic device is likely to decrease. When the thickness exceeds 10 μm, the melted first brazing material scoops up the electronic element mounted on the circuit board 14 and may short circuit the circuit formed on the electronic element.

  The marking portion 6 is provided in a region excluding the mounting portion 2 of the insulating substrate 1 and may be formed using a part of the insulating substrate 1 or formed using a part of the wiring conductor 3. Also good. Moreover, as shown in FIG. 1, you may form from the electrically conductive film provided on the insulating substrate 1. FIG. For example, when the marking portion 6 is formed of a conductive film made of W or the like, since the conductive film and the insulating substrate 1 made of W or the like have high bonding properties, the marking portion 6 is formed directly on the insulating substrate 2. It is preferable because it can suppress peeling. The marker portion 6 made of such a conductive film is formed by a thick film forming method such as a conventionally known screen printing method or a thin film forming method such as a vapor deposition method, a sputtering method, a CVD method, or a plating method, and then conventionally known. These are processed into a predetermined pattern by the photolithography method, the etching method, the lift-off method or the like.

  The second brazing material 5 deposited on the marking portion 6 is formed on the marking portion 6 in the same manner as the bonding pad 4, and is composed of an Au—Ge alloy (melting point: about 356 ° C.), an Au—Si alloy (melting point). About 370 ° C.), Pb—Sn alloy (melting point: about 183 ° C.), Au—Sn alloy (melting point: about 280 ° C.), Ag—Sn alloy (melting point: about 220 ° C.), In—Pb alloy (about 172 ° C.), In ( The melting point is about 157 ° C.). The marking part 6 to which the second brazing material 5 is adhered functions as a pattern for estimating the molten state, and the molten state of the second brazing material 5 adhered to the marking part 6 is observed. As a result, the molten state of the first brazing material forming the bonding pad 4 can be estimated. Therefore, the first brazing material is not sufficiently melted, or the first brazing material protrudes from the mounting portion 2 and melts to short-circuit with other electronic elements formed on the circuit board 14. It is possible to suppress the occurrence of poor connection between the electronic element and the circuit board 14 due to the defective melting state of the brazing material, and to mount the electronic element on the mounting portion 2 of the circuit board 14 in a desired state. Here, the second brazing material is preferably made of a material having a melting point equal to or lower than the melting point of the first brazing material, and the difference between the melting points is 10 ° C. or less. It is good. If the melting point of the first brazing material is higher than 10 ° C. compared to the melting point of the second brazing material 5, the second brazing material 5 is melted at a much earlier stage than the first brazing material is melted. Therefore, it is difficult to sufficiently perform the function of estimating the molten state of the first brazing material.

  In addition, the label | marker part 6 to which the 2nd brazing material 5 was adhere | attached is formed in the position (for example, position visible from the upper direction of a circuit board etc.) visible when mounting an electronic component on the insulated substrate 1. FIG. Further, when the melting state of the second brazing material 5 is confirmed, no other parts are bonded to the surface of the second brazing material 5.

  Moreover, since the molten state of the second brazing material 5 attached to the marking portion 6 is observed as described above, the electronic element can be stably mounted on the insulating substrate, so that the first brazing The composition of the material and the second brazing material 5 is preferably a composition that approximates the molten state. As such a composition, for example, the first brazing material is composed of 96.5% Sn and 3.5% Ag, and the second brazing material 5 is composed of 96.5% Sn and 3% Ag. The case where 0.0% and Cu are comprised with 0.5% is considered.

  More preferably, the second brazing material 5 is made of a brazing material having the same composition as the first brazing material forming the bonding pad 4. This is because the molten state of the first brazing material forming the bonding pad 4 and the molten state of the second brazing material 5 attached to the marking portion 6 are further approximated by being composed of the same component. This is because checking the state of the brazing material 5 makes it easier to understand the state of the bonding pad 4 on which the electronic element is mounted. And it is preferable that the thickness of the 2nd brazing material 5 adhere | attached on the label | marker part 6 is the same thickness as the joining pad 4. FIG. This is because by forming with such a thickness, the molten state of the first brazing material and the molten state of the second brazing material 5 are further approximated.

  In addition, it is preferable that corners are formed on the outer peripheral portion of the second brazing material 5 in plan view. This is because when the second brazing material 5 attached to the marking portion 6 starts to melt when the electronic element is mounted, the shape of the second brazing material 5 changes in the vicinity of the corner, and the movement is confirmed. This is because the state of the bonding pad on which the electronic element is mounted becomes easier to understand, and the electronic element can be bonded under more optimal conditions.

  More preferably, R1 represents the arithmetic average roughness Ra of the surface of the portion 6 to which the second brazing material 5 of the marking portion 6 is attached, and R2 represents the arithmetic average roughness Ra of the surface of the mounting portion 2. It is preferable to have a relationship of ≦ R2. As a method for obtaining such a surface state, for example, first, a resist film is formed on a portion of the marking portion 6 where the second brazing material 5 is adhered by a conventionally known photolithography method or the like. Thereafter, sandblasting is performed to roughen the surface, and after the mounting portion 2 is formed on the insulating substrate 1 by the above-described method, the resist is peeled off to form the bonding pad 4 and the marker portion 6 so that R1 ≦ R2 is satisfied. A method for obtaining a surface state is conceivable. In general, a brazing material formed on a smooth surface has lower wettability than a brazing material formed on a rough surface, and melts with a greatly changed shape. Therefore, the circuit board 14 in which the surface of the marking portion 6 where the second brazing material 5 is attached is formed more smoothly than the surface of the mounting portion 2 of the electronic element is the second brazing material 5. It is preferable because the movement at the start of melting becomes larger and the visual recognition becomes easier.

  Further, it is preferable that the arithmetic average roughness R1 of the surface of the portion where the second brazing material 5 of the marking portion 6 is attached has a partly different value. Such a circuit board 14 is formed, for example, by covering a part of the marking portion 6 with a resist film, removing the resist film by sandblasting, and then depositing the second brazing material 5. Is done. As described above, since the movement of parts formed at different parts of the arithmetic average roughness Ra is generally different, the movement of the second brazing material 5 of the marking part 6 formed on a partly smooth surface is confirmed. By doing so, the movement at the start of melting of the first brazing material forming the bonding pad 4 becomes easier to visually recognize, and it is preferable to bond the electronic elements more appropriately.

  Further, when the second brazing material 5 and the bonding pad 4 are formed in the same shape in plan view, the heat transfer in the second brazing material 5 attached to the marker portion 6 and the bonding pad 2 are determined. The way of heat transfer in the first brazing material to be formed is more approximate, and the molten state of the first and second brazing materials 5 can be made closer. For this reason, an electronic element can be joined on more optimal conditions, and it is preferable.

  Further, when a monitor such as a monitor pattern for confirming electrical resistance, a monitor pattern for confirming film thickness, or a target pattern for alignment is provided on the circuit board 14, such a monitor is assumed to be the marking unit 6. This is preferable because it is not necessary to separately provide the marking portion 6 on the surface of the circuit board 14 and the surface of the circuit board 14 can be used effectively. Further, for example, when a target pattern is formed on the circuit board 14 as a monitor, such a target pattern is naturally monitored by optical image recognition or the like when aligning the electronic elements. Therefore, it is not necessary to separately provide a camera for observing the second brazing material 5 attached to 6. Furthermore, since the height of the target pattern is increased by the second brazing material 5, it becomes easier to recognize the target pattern due to the shadow.

  Next, an electronic device according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 2 is a cross-sectional view showing an example of an embodiment of an electronic device of the present invention. In the following description, an optical semiconductor element is used as an example of an electronic element, but the present invention is not limited to the optical semiconductor element.

  In FIG. 2, an electronic device 101 mainly includes an optical semiconductor element 103 and a circuit board 14 on which the optical semiconductor element 103 is mounted via a brazing material, and Ag is formed so as to surround the circuit board 14 on the upper surface of the base 105. The frame body 109 is joined via a brazing material such as a brazing alloy or an AuSn alloy or an adhesive. In such a frame 109, a lid 110 is attached to the upper surface via a brazing material or adhesive such as Ag brazing alloy or AuSn alloy, and the side portion facing the optical semiconductor element 103 via the lens 107. A through hole 109a for inserting the optical fiber 108 is formed in the optical fiber 108. A cylindrical fixing member 111 for fixing the optical fiber 108 is inserted into the through hole 109 a, and the circuit board 14 mounted on the upper surface of the base 105 is interposed via a TEC (thermoelectric cooler) 106. It is placed.

  Further, a flange (not shown) made of stainless steel or the like attached to the end of the optical fiber 108 is joined to the fixing member 111 by laser welding by irradiation with a YAG laser or the like, and the optical fiber 108 is framed. The electronic device 101 is obtained by being fixed to the body 109. Such an electronic device 101 includes the circuit board 14 of the present invention and the electronic component 103 mounted on the circuit board 14 so that the electronic element 103 can be stably bonded and has high operation reliability. It can be.

  Here, the method of manufacturing the electronic device 101 described above includes a step of observing the molten state of the second brazing material 5 attached to the marker 5 and mounting the electronic element on the insulating substrate 1. . By providing such a process, even when the electronic element is mounted on the insulating substrate 1, even if the electronic element overlaps the mounting portion in a plan view and the molten state of the first brazing material cannot be confirmed, the second By confirming the molten state of the brazing material 5 instead, a highly reliable electronic device in which electronic elements are stably connected and mounted can be manufactured.

  It should be noted that the present invention is not limited to the best mode described above, and various modifications may be made without departing from the gist of the present invention.

It is a perspective view which shows an example of embodiment of the circuit board of this invention. It is sectional drawing which shows an example of embodiment of the electronic device of this invention. It is a perspective view of the conventional circuit board.

Explanation of symbols

1: Insulating substrate 2: Mounting portion 3: Wiring conductor 4: Bonding pad 5 made of first brazing material 5: Second brazing material 6: Marking portion 14: Circuit board

Claims (8)

It has an electronic element mounting portion on the surface, a bonding pad made of a first brazing material is formed on the mounting portion, and a marking portion on which the second brazing material is attached on the surface excluding the mounting portion. A circuit board comprising an insulating substrate. The circuit board according to claim 1, wherein the second brazing material is made of a brazing material having the same composition as the first brazing material. The circuit board according to claim 1, wherein the second brazing material has a corner portion on an outer peripheral portion in a plan view. When the arithmetic average roughness Ra of the surface of the portion where the second brazing material of the labeling part is attached is R1, and the arithmetic average roughness Ra of the surface of the mounting part is R2, the relationship of R1 ≦ R2 is established. The circuit board according to claim 1, wherein the circuit board is provided. 5. The circuit board according to claim 1, wherein the second brazing material and the bonding pad have the same shape in a plan view. An electronic device comprising: the circuit board according to claim 1; and an electronic component mounted on the circuit board. 7. The method of manufacturing an electronic device according to claim 6, further comprising a step of observing a state of the second brazing material and mounting the electronic element on the insulating substrate. Production method. An electronic element is bonded to the surface via a brazing material, and the insulating substrate excluding a portion on which the electronic element is mounted has an insulating substrate provided with a pattern for estimating the melting state of the brazing material. Electronic equipment.

Images