Component mounting method, method for manufacturing mounted substrate, and mounted substrate

Abstract

This component mounting method is for mounting and soldering a second chip component onto an upper surface of a first chip component that is disposed in advance on a substrate, the first chip component having first terminals on the upper surface thereof. The second chip component has a body portion having an upper surface, a lower surface, and side surfaces, and second terminals respectively solder-plated on both end portions of the body portion, wherein a central portion of the body portion sandwiched between both the end portions is thinner than both the end portions. The component mounting method includes a step of aligning the second terminals and the first terminals of the chip components to mount the second chip component onto the upper surface of the first chip component, and filling a space formed between the lower surface of the body portion of the second chip component and the upper surface of the first chip component with flux.

Description

Component mounting method, mounting board manufacturing method, and mounting board

[0001] This disclosure relates to a component mounting method, a method for manufacturing a mounting substrate, and a mounting substrate.

[0002] With the miniaturization of electronic devices, the need to mount electronic components at high density on circuit boards is increasing. In particular, a three-dimensional mounting method is being considered in which multiple chips are arranged vertically perpendicular to the circuit board surface in order to increase the capacitance of capacitors while increasing the mounting density.

[0003] Patent Document 1 discloses "an electronic component stack comprising at least one multilayer ceramic capacitor and an electronic element, wherein the at least one multilayer ceramic capacitor comprises first electrodes and second electrodes arranged alternately in parallel, with a dielectric material between adjacent first electrodes and second electrodes, the first electrodes having a first polarity and terminating on the first side of the multilayer ceramic capacitor, and the second electrodes having a second polarity and terminating on the second side of the multilayer ceramic capacitor; a first transition liquid phase sintering compatible material on the first side that is in electrical contact with each of the first electrodes; and a second transition liquid phase sintering compatible material on the second side that is in electrical contact with each of the second electrodes, wherein the electronic element comprises a first external end comprising a third transition liquid phase sintering compatible material on the first external end; a second external end comprising a fourth transition liquid phase sintering compatible material on the second external end; and a metallurgical coupling between the first transition liquid phase sintering compatible material and the third transition liquid phase sintering compatible material."

[0004] Patent Document 2 discloses "a circuit board on which chip components are mounted, comprising a board on which a wiring pattern is formed, a plurality of first chip components mounted on the board via a conductive bonding material, and at least one second chip component mounted on the opposite side of the plurality of first chip components from the board via a conductive bonding material, wherein the heights of one first chip component and another first chip component included in the plurality of first chip components on the board are substantially equal, and one electrode of the chip component included in the at least one second chip component is bonded to the electrode of the one first chip component and the other electrode is bonded to the electrode of the other first chip component."

[0005] Japanese Patent Application Laid-Open No. 2022-68307, Japanese Patent Application Laid-Open No. 2005-216884

[0006] When mounting a plurality of chip components vertically on a substrate and joining the chips together, a method of applying cream solder to the terminal portions of the chip components located on the lower side using a jet dispenser or the like is employed. At this time, variations in the application amount and displacement of the application position may occur. If the upper chip component is mounted and the solder is melted in a state where the application amount is small or the application position is displaced, no solder joint is formed between the terminal portion of the upper chip component and the solder, resulting in non-jointing, or the upper chip component is mounted at a position displaced from the center of the lower chip component, making the upper chip component more likely to fall from the lower chip component. On the other hand, if the upper chip component is mounted and the solder is melted in a state where the application amount is large, the solder is formed across the terminal portions of the chip component with different polarities, resulting in a bridge (short circuit).

[0007] In addition, cream solder for a jet dispenser is expensive because it uses solder formed in fine particle form, increasing the production cost.

[0008] One aspect of the present disclosure is a component mounting method in which a second chip component is mounted and soldered onto the upper surface of a first chip component that has been pre-placed on a substrate, wherein the first chip component has a main body having an upper surface, a lower surface and side surfaces, and first terminals extending from the lower surface through the side surfaces to the upper surface at each end of the main body, and the second chip component has a main body having an upper surface, a lower surface and side surfaces, and second terminals soldered at each end of the main body, wherein the vertical width of the central portion of the main body sandwiched between the two ends is narrower than the vertical width of the two ends, and the second terminals of the second chip component and the The present invention relates to a component mounting method comprising: a first step of aligning the first terminal of a chip component and mounting the second chip component on the upper surface of the first chip component, and filling the space between the lower surface of the main body of the second chip component and the upper surface of the first chip component with flux; a second step of heating the substrate and melting the solder plating while covering the surfaces of the first and second terminals with the flux; and a third step of cooling the substrate after the second step and solidifying the molten solder plating to form an inter-chip connection portion that connects the first and second terminals.

[0009] Another aspect of this disclosure relates to a method for manufacturing a mounted substrate in which a first chip component is soldered to a substrate and a second chip component is soldered to the upper surface of the first chip component, the method comprising the step of mounting and soldering the second chip component to the upper surface of the first chip component using the component mounting method described above.

[0010] Another aspect of this disclosure relates to a mounting substrate manufactured using the above-described component mounting method, wherein the solder forming the inter-chip connection portion is formed solely from solder derived from the solder plating and solder present on the surface of the first terminal prior to the second step.

[0011] According to this disclosure, when multiple chip components are placed vertically on a substrate and joined together, a stable solder joint can be formed between the upper chip component and the lower chip component.

[0012] Novel features of the present invention are described in the appended claims, but the present invention, both in terms of structure and content, and in conjunction with other objects and features of the present invention, will be better understood by the following detailed description in conjunction with the drawings.

[0013] Figure 1 is a cross-sectional view illustrating each step of a component mounting method according to one embodiment of the present disclosure. Figure 2 is a cross-sectional view illustrating an example of a flux coating step. Figure 3 is a cross-sectional view illustrating an example of a flux transfer step. Figure 4 is a cross-sectional view illustrating each step of a component mounting method according to another embodiment of the present disclosure. Figure 5 is a cross-sectional view illustrating each step of a component mounting method according to another embodiment of the present disclosure.

[0014] The embodiments relating to this disclosure will be described below with examples, but this disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be given as examples, but other numerical values ​​and materials may be applied as long as the effects of this disclosure are obtained. In this specification, the description "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be read as "greater than or equal to numerical value A and less than or equal to numerical value B". In the following description, when lower and upper limits of numerical values ​​relating to specific physical properties or conditions are given as examples, either the given lower limit and either the given upper limit may be arbitrarily combined, as long as the lower limit does not exceed the upper limit. In the following description, when examples of components or methods are listed, unless otherwise specified, only one of the listed examples may be used, or multiple of the listed examples may be used in combination.

[0015] Furthermore, this disclosure encompasses any combination of matters described in two or more claims, which may be arbitrarily selected from the multiple claims set forth in the attached claims. In other words, any combination of matters described in two or more claims, which may be arbitrarily selected from the multiple claims set forth in the attached claims, is possible, provided that no technical inconsistency arises.

[0016] In the following explanation, the term "contains (or includes)" encompasses expressions such as "contains (or includes)," "substantially consists of," and "consists of."

[0017] (Component Mounting Method) A component mounting method according to one embodiment of the present disclosure is a component mounting method in which a second chip component is mounted on the upper surface of a first chip component that has been pre-placed on a substrate and soldered. The first chip component has a first terminal on its upper surface. More specifically, for example, the first chip component has a main body having an upper surface, a lower surface, and side surfaces, and the first terminal portion extends from the lower surface through the side surfaces to the upper surface at each end of the main body. The second chip component has a main body having an upper surface, a lower surface, and side surfaces, and a second terminal that is solder-plated at each end of the main body, and the vertical width of the central portion of the main body sandwiched at both ends is narrower than the vertical width of the ends.

[0018] The component mounting method includes the following three steps:

[0019] Step 1: This step involves aligning the second terminal of the second chip component with the first terminal of the first chip component to mount the second chip component on the upper surface of the first chip component, and filling the space between the lower surface of the main body of the second chip component and the upper surface of the first chip component (hereinafter sometimes referred to as "space (S)") with flux.

[0020] Step 2: This step involves heating the substrate and melting the solder plating on the second terminal while covering the surfaces of the first and second terminals with flux.

[0021] Third step: After the second step, this step involves cooling the substrate and solidifying the molten solder plating to form an inter-chip connection portion that connects the first terminal and the second terminal.

[0022] This component mounting method does not use solder paste. Instead, a large amount of flux is applied to cover the entire top surface of the first chip component or the entire bottom surface of the second chip component using methods such as dispensing or transfer, and the second chip component is mounted on top of the first chip component. This suppresses the occurrence of bridges (short circuits). Furthermore, since solder paste is not used, it is low cost.

[0023] In addition, by filling the space (S) between the lower surface of the main body of the second chip component and the upper surface of the first chip component with flux and then melting the solder, the surface tension of the liquefied flux in the space (S) exerts a force on the second chip component that pulls it toward the first chip component below. This reduces the positioning margin when mounting the second chip component on top of the first chip component, allowing the second chip component to be stably mounted on top of the first chip component, and also allows for the stable formation of solder joints between the first and second terminals, suppressing unconnected areas.

[0024] As an example of a method for filling the space (S) with flux, the first step may include a flux application step in which flux is applied to the upper surface of the first chip component. Subsequently, a mounting step is performed in which the second chip component is mounted on the first chip component to which the flux has been applied, and the second step is performed. In the flux application step, by applying a sufficient amount of liquid flux to fill the space (S), in the second step, the surface tension of the liquefied flux in the space (S) effectively acts between the first chip component and the second chip component, and a stable solder joint is obtained between the first terminal and the second terminal.

[0025] Another example of a method for filling the space (S) with flux is that the first step may include a flux transfer step in which flux is applied to the underside of the second chip component. Subsequently, a mounting step is performed in which the second chip component with the flux applied is mounted onto the first chip component, and then the second step is performed. In the flux transfer step, flux is applied to the surface of the second terminal and the entire underside of the main body, so that in the second step, the space (S) is filled with a sufficient amount of liquid flux, and the surface tension of the liquefied flux in the space (S) effectively acts between the first chip component and the second chip component, resulting in a stable solder joint between the first terminal and the second terminal.

[0026] In the flux transfer process, for example, the lower surface of the second chip component is immersed in a flux film formed on a flat surface to adhere the flux to the entire lower surface of the second chip component. The thickness of the flux film should be greater than the difference in height between the second terminal and the main body on the lower surface of the second chip component.

[0027] In the first step, a substrate is prepared in which the first chip component is mounted on a solder pad provided on the substrate, and the second chip component may be mounted on the upper surface of the first chip component which is already mounted on the solder pad. In the subsequent second step, the solder pad is melted together with the solder plating of the second chip component to perform soldering. In other words, even with the second chip component mounted on the upper surface of the first chip component, the soldering of the first chip component to the substrate is not yet complete, and the soldering of the first chip component to the substrate and the soldering of the second chip component to the first chip component may be performed in parallel in the same heating process (second step).

[0028] In contrast, in the first step, a circuit board may be prepared with the first chip component already soldered to it, and the second chip component may be mounted on top of the first chip component which has already been soldered. In other words, the second chip component may be mounted on top of the first chip component which has already been soldered to the circuit board, and the second chip component may be soldered.

[0029] The first and second chip components are not particularly limited. The second chip component may be a capacitor element. The capacitor element may be a chip-type multilayer capacitor. Both the first and second chip components may be capacitor elements or chip-type multilayer capacitors. By arranging multiple chip capacitors vertically perpendicular to the substrate surface, high capacitance can be achieved while increasing mounting density.

[0030] Alternatively, the second chip component may be a resistor or an inductor.

[0031] The first chip component may be a component with the same configuration as the second chip component, or it may be a different component.

[0032] The sizes of the first and second chip components may be, for example, 0.4 mm in length and 0.2 mm in width, 0.3 mm in length and 0.15 mm in width, 0.25 mm in length and 125 mm in width, 0.2 mm in length and 0.1 mm in width, or 0.1 mm in length and 0.5 mm in width. The size of the second chip component may be 0.4 mm in length and 0.2 mm in width, 0.3 mm in length and 0.15 mm in width, 0.25 mm in length and 125 mm in width, 0.2 mm in length and 0.1 mm in width, or 0.1 mm in length and 0.5 mm in width. The second chip component may include electronic components such as 0402, 03015, 0201, and 01005 as defined by JIS (Japanese Industrial Standards).

[0033] As the size of the second chip component decreases, its mass also decreases. Therefore, when mounting a second chip component on top of a first chip component, it is necessary to precisely position the second chip component. Furthermore, because small second chip components have low mass, they are prone to bonding defects due to unintended movement, and when the second chip component is placed vertically on top of the first chip component, it is more likely to tip over. This tendency is particularly pronounced with extremely small components such as 03015, 0201, and 01005. However, as described above, the component mounting method according to this disclosure reduces the positioning margin when mounting a second chip component on top of a first chip component, allowing the second chip component to be mounted stably on top of the first chip component. The component mounting method according to this disclosure is particularly suitable when using such extremely small components.

[0034] (Method for manufacturing a mounted substrate) A method for manufacturing a mounted substrate according to one embodiment of the present disclosure is a method for manufacturing a mounted substrate in which a first chip component is soldered to a substrate and a second chip component is soldered to the upper surface of the first chip component, and uses a component mounting method having the above-described first to third steps. The method for manufacturing a mounted substrate includes a step of mounting and soldering the second chip component to the upper surface of the first chip component using the above-described component mounting method.

[0035] (Mounted Substrate) A mounted substrate according to one embodiment of the present disclosure is a mounted substrate manufactured using a component mounting method having the first to third steps described above. In the mounted substrate, a first chip component is soldered to the substrate, and a second chip component is soldered to the upper surface of the first chip component.

[0036] Here, the solder forming the inter-chip connection between the first terminal of the first chip component and the second terminal of the second chip component can be formed using only the solder derived from the solder plating that was formed on the surface of the second terminal of the second chip component, and the solder that was present on the surface of the first terminal of the first chip component prior to the second step.

[0037] The solder present on the surface of the first terminal of the first chip component prior to the second process includes the following (1) to (4): (1) Solder plating applied to the surface of the first terminal of the first chip component; (2) Solder derived from the solder plating, i.e., the solder plating of (1) that has melted and solidified; (3) Solder derived from the solder area that was previously provided on the land for soldering the first chip component to the land of the substrate, which, in the second process, is heated and spreads to the upper surface of the first chip component, fusing with (1) on the surface of the first terminal to form an inter-chip connection; (4) Solder derived from the solder area that forms a connection to connect the first chip component to the substrate, which, when the first chip component is soldered to the substrate, is heated and spreads to the upper surface of the first chip component, and is present on the upper surface of the first terminal during the first process.

[0038] Note that (3) occurs when the soldering of the first chip component to the substrate and the soldering of the second chip component to the first chip component are performed in parallel in the same heating process (second process). (4) occurs when the second chip component is mounted on top of the first chip component which has already been soldered to the substrate, and then the second chip component is soldered.

[0039] The substrate includes, for example, a plurality of lands to which a plurality of electronic components are soldered, and a plurality of solder precoats formed on the lands. A commercially available substrate may be used. A component mounting method and / or a method for manufacturing a mounted substrate according to one embodiment of this disclosure may include a step of forming a solder precoat on a substrate on which lands are formed. The method for forming the solder precoat is not limited, and a known method may be used.

[0040] The solder precoat may consist only of the solder layer. Alternatively, the solder precoat may include the solder layer and other layers formed on the surface of the solder layer. For example, the solder precoat may include the solder layer and a coating layer (e.g., an organic layer) formed on the surface of the solder layer. Examples of other layers include a layer of residue (flux residue) from when the solder layer was formed, and an antioxidant film. The organic layer is a layer whose main component is organic matter (content: 50% by mass). The flux residue layer is an organic layer.

[0041] The component mounting method and mounting substrate manufacturing method relating to this disclosure are particularly suitable for mounting multiple electronic components, including electronic components of JIS (Japanese Industrial Standards) 0402 or earlier. JIS 0402 electronic components have a length of 0.4 mm and a width of 0.2 mm. That is, manufacturing method (M) is particularly suitable for mounting multiple electronic components, including electronic components with a length of 0.4 mm or less and a width of 0.2 mm or less.

[0042] (Flux) Flux contains rosin-based resin, thixotropic agent, activator, and solvent as essential components. The viscosity of the flux can be adjusted by changing the types and ratios of the components. By increasing the ratio of the rosin-based resin, it is possible to lower the viscosity (lower the fluidity). By decreasing the ratio of the rosin-based resin, it is possible to increase the viscosity (increase the fluidity). By decreasing the ratio of the solvent, it is possible to lower the viscosity, and by increasing the ratio of the solvent, it is possible to increase the viscosity. The flux may contain other components in addition to the above-mentioned essential components. Examples of other components include surfactants, silane coupling agents, antioxidants, colorants, etc. The flux can be prepared by mixing its constituent components.

[0043] (Rosin-based resin) Examples of rosin-based resins include natural rosins such as gum rosin and wood rosin, and their derivatives (polymerized rosin, hydrogenated rosin, disproportionated rosin, acid-modified rosin, rosin ester, etc.).

[0044] (Thixotropic agent) The thixotropic agent imparts thixotropy, etc. to the flux. Examples of thixotropic agents include wax-based thixotropic agents, amide-based thixotropic agents, sorbitol-based thixotropic agents, etc. Examples of wax-based thixotropic agents include castor oil, etc. The thixotropic agent may be used alone or in combination of two or more.

[0045] (Activator) As the activator, a compound that reduces the oxide film covering the surface of the solder used for soldering electronic components is used. Examples of such solder include solder precoat and solder applied to the terminals (component electrodes) of electronic components. Note that resins such as rosin-based resins may also have a certain degree of activating effect. In this specification, the term "activator" means a compound other than rosin-based resin.

[0046] The activator reduces the oxide film and assists in forming a good joint. Examples of activators having a reducing action include organic acids, amines, halides, etc. The activator may be used alone or in combination of two or more.

[0047] Examples of the organic acid used as the activator include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dimer acid, propionic acid, 2,2-bishydroxymethylpropionic acid, tartaric acid, malic acid, glycolic acid, diglycolic acid, thioglycolic acid, dithioglycolic acid, stearic acid, 12-hydroxystearic acid, palmitic acid, oleic acid, and the like.

[0048] (Solvent) Examples of the solvent include water, alcohol solvents, glycol solvents, ketone solvents, hydrocarbon solvents, ester solvents, glycol ether solvents, terpineols, and the like. The solvent may be used alone or in combination of two or more.

[0049] Hereinafter, a component mounting method, a method for manufacturing a mounting substrate, and an example of a mounting substrate according to an embodiment of the present disclosure will be described with reference to the drawings as appropriate. However, the present invention is not limited thereto. The drawings shown below are schematic and do not accurately reflect the actual shape of the components.

[0050] The components of the examples described below can be applied to the examples described above. The components of the examples described below can be modified based on the above description. Further, the matters described below may be applied to the above embodiments. Among the components of the examples described below, components that are not essential for the methods, apparatuses, and systems according to the present embodiment may be omitted.

[0051] <First Embodiment> FIGS. 1(A) to 1(D) are process cross-sectional views for explaining each step of a component mounting method according to an embodiment of the present disclosure. FIGS. 1(A) to 1(D) also show a step of mounting a second chip component on the upper surface of a first chip component and soldering it, which is a part of a method for manufacturing a mounting substrate according to an embodiment of the present disclosure. Note that FIGS. 1(A) to 1(D) show a state where the first chip component is mounted on the substrate, and the soldering of the first chip component on the land is not completed. This is an example in which the soldering of the first chip component to the substrate and the soldering of the second chip component on the first chip component are simultaneously performed in one reflow.

[0052] (Preparation Step) First, a substrate on which the first chip component is mounted is prepared (preparation step). The first chip component is usually mounted on a land provided in a predetermined area of ​​the substrate. With the first chip component mounted on the substrate, the first chip component may be soldered on the land as shown in the examples in Figures 1(A) to 1(D) and in the examples in Figures 4(A) to 4(D) described later, or the soldering may be incomplete as shown in the examples in Figures 5(A) to 5(C) described later.

[0053] In the preparation step, first, the substrate 1 is prepared as shown in Figure 1(A). Lands 2 for connecting the first chip component are provided in a predetermined area of ​​the substrate 1. Solder precoat may be formed on the land 2.

[0054] Next, as shown in Figure 1(B), the first chip component 10 is mounted on the land 2 of the substrate 1. The first chip component 10 has a main body 12 and first terminals 14a and 14b. The first terminals 14a and 14b are spaced apart from each other at the end of the main body 12, and the surfaces of the first terminals 14a and 14b are solder-plated. At the end of the main body 12, each of the first terminals 14a and 14b continuously covers the side and top surfaces of the first chip component 10 from the bottom surface (mounting surface with the substrate 1). If the first chip component 10 is a capacitor (capacitor element), one of the first terminals 14a and 14b is the anode terminal of the capacitor, and the other is the cathode terminal of the capacitor.

[0055] The first chip component 10 may be placed on the substrate 1 such that the lower surfaces of the first terminals 14a and 14b overlap with the land 2, with the upper surface of the land 2 covered with flux, or with the lower surfaces of the first terminals 14a and 14b covered with flux. The first chip component 10 may be mounted on the substrate 1. Flux may be applied to the entire surface of the substrate 1 in advance before placing the first chip component 10 on the substrate 1. Flux may be applied in advance to the solder precoat formed on the land 2. Flux may be attached to the lower surfaces of the first terminals 14a and 14b by a transfer method. The flux application process or flux transfer process for the second chip component, described later, may be applied to the flux formation on the upper surface of the land 2 and / or the lower surfaces of the first terminals 14a and 14b.

[0056] (First step) Next, as shown in Figure 1(C), the second chip component 20 is mounted on the upper surface of the first chip component 10. At this time, the lower surface of the second terminal 24a of the second chip component 20 is aligned with the upper surface of the first terminal 14a of the first chip component 10, and the lower surface of the second terminal 24b of the second chip component 20 is aligned with the upper surface of the first terminal 14b of the first chip component 10.

[0057] The second chip component 20 has a main body 22 and second terminals 24a and 24b. The second terminals 24a and 24b are spaced apart from each other at both ends of the main body 22, and the surfaces of the second terminals 24a and 24b are solder-plated. Each of the second terminals 24a and 24b continuously covers the side and top surfaces of the second chip component 20 from the bottom surface at the end of the main body 22. If the second chip component 20 is a capacitor (capacitor element), one of the second terminals 24a and 24b is the anode terminal of the capacitor, and the other is the cathode terminal of the capacitor.

[0058] The second chip component 20 has a width (dimension perpendicular to the substrate) in the central part of its main body 22 that is narrower than the width (dimension perpendicular to the substrate) of the ends where the second terminals 24a and 24b are formed. Therefore, the lower surface of the second chip component 20 has a step. Due to this step, a space (S) exists between the lower surface of the main body 22 of the second chip component 20 and the upper surface of the first chip component 10, between the second terminals 24a and 24b. When the second chip component 20 is mounted on the upper surface of the first chip component 10, the space (S) is filled with flux 16.

[0059] When the second chip component is mounted on the upper surface of the first chip component 10, the space (S) may be filled with flux 16. For example, prior to mounting the second chip component 20 on the upper surface of the first chip component 10, a flux coating process or a flux transfer process as shown below may be performed. Figures 2(A) and 2(B) are cross-sectional view illustrating an example of the flux coating process. Figures 3(A) to 3(C) are cross-sectional view illustrating an example of the flux coating process.

[0060] (Flux application process) As shown in Figure 2(A), flux 16 is applied to the upper surface of the first chip component 10 mounted on the substrate 1 using an application nozzle 31 (dispenser). The application position is located between the second terminals 24a and 24b when the second chip component 20 is mounted. The application position may be between the first terminals 14a and 14b, or within the main body 12. Figure 2(B) shows the state of the first chip component 10 after the flux 16 has been applied.

[0061] (Flux Transfer Process) As shown in Figure 3(A), flux 16 is applied to the flat surface 34X formed on the film formation stage 34 using a blade 35 to form a flux film 36 on the flat surface 34X.

[0062] Subsequently, as shown in Figure 3(B), the second chip component 20 is attached to the suction nozzle 38 by suction. Then, the suction nozzle 38 with the second chip component 20 attached is lowered toward the film deposition stage 34, immersing the lower surface of the second chip component 20 in the flux film 36, and adhering flux to the entire lower surface of the second chip component 20. Preferably, the thickness T1 of the flux film 36 is greater than the height T2 of the step difference between the second terminals 24a, 24b and the main body portion 22 on the lower surface of the second chip component 20.

[0063] Subsequently, as shown in Figure 3(C), the flux 16 adheres to the lower surface of the second chip component 20 by raising the adsorption nozzle 38 away from the film deposition stage 34.

[0064] The above flux application step or flux transfer step makes it easy to cover the upper surface of the first chip component 10 or the lower surface of the second chip component 20 with a sufficient amount of flux to fill the space (S).

[0065] (Second step) Next, the substrate 1 is heated and reflow soldering is performed. The solder plating is melted while the flux 16 covers the surfaces of the first terminals 14a, 14b and the second terminals 24a, 24b. Due to the heating, the flux 16 flows upwards on the surfaces of the first terminals 14a, 14b and the second terminals 24a, 24b, covering the surfaces of the first terminals 14a, 14b and the second terminals 24a, 24b.

[0066] At this time, the solder precoat formed on the land 2 of the substrate 1 (if a solder precoat has been formed) and the solder plating formed on the lower surface of the first terminals 14a and 14b of the first chip component 10 are also melted.

[0067] (Third step) The substrate is then cooled and the molten solder plating is solidified to form an inter-chip connection portion 6a connecting the first terminal 14a and the second terminal 24a, and an inter-chip connection portion 6b connecting the first terminal 14b and the second terminal 24b. At this time, a connection portion 7 connecting the land 2 of the substrate 1 and the first terminals 14a and 14b of the first chip component 10 is formed simultaneously. The state of the substrate 1 at this time is shown in Figure 1(D). After that, a cleaning step may be performed to clean the substrate 1 and remove flux residue remaining in the steps (S).

[0068] By using the above component mounting method, a mounting board 8 is obtained in which the second chip component 20 is mounted and soldered to the upper surface of the first chip component 10 on the board 1.

[0069] <Second Embodiment> Figures 4(A) to 4(D) are cross-sectional views illustrating another embodiment of the component mounting method according to the present disclosure. Figures 4(A) to 4(D) show, similar to Figures 1(A) to 1(D), a first chip component mounted on a substrate, but the first chip component has not yet been soldered on the land. These figures illustrate an example where the soldering of the first chip component to the substrate and the soldering of the second chip component to the first chip component are performed simultaneously in a single reflow.

[0070] First, a substrate 1 is prepared, which has lands 2 for connecting the first chip component, as shown in Figure 1(A). Then, as shown in Figure 4(A), solder paste 5 is applied to a predetermined area of ​​the land 2, and then, as shown in Figure 4(B), the first chip component 10 is mounted on the land 2 of the substrate 1 via the solder paste 5.

[0071] Subsequently, steps 1 to 3 are carried out in the same manner as in the first embodiment. Figure 4(C) corresponds to Figure 1(C) of the first embodiment, and Figure 4(D) corresponds to Figure 1(D) of the first embodiment.

[0072] <Third Embodiment> Figures 5(A) to 5(C) are cross-sectional views illustrating another embodiment of the component mounting method according to the present disclosure. Figures 5(A) to 5(C) show an example in which a second chip component is mounted on a first chip component that has already been soldered to a substrate, and the second chip component is then soldered.

[0073] In the preparation step, the substrate 1 is prepared as shown in Figure 5(A). Lands 2 for connecting the first chip component are provided in a predetermined area of ​​the substrate 1, and the substrate 1 is soldered to the first terminals 14a and 14b of the first chip component 10 at the land 2, and a connection portion 7 connecting the land 2 of the substrate 1 and the first terminals 14a and 14b of the first chip component 10 is already formed.

[0074] Subsequently, steps 1 to 3 are carried out in the same manner as in the first embodiment. Figure 5(B) corresponds to Figure 1(C) of the first embodiment, and Figure 5(C) corresponds to Figure 1(D) of the first embodiment.

[0075] (Note) The above description of embodiments discloses the following technologies. (Technology 1) A component mounting method for mounting a second chip component onto the upper surface of a first chip component pre-placed on a substrate and soldering it, wherein the first chip component has a main body having an upper surface, a lower surface and side surfaces, and first terminals extending from the lower surface through the side surfaces to the upper surface at each end of the main body, the second chip component has a main body having an upper surface, a lower surface and side surfaces, and second terminals solder-plated at each end of the main body, the vertical width of the central portion of the main body sandwiched between the ends is narrower than the vertical width of the ends, the first step of aligning the second terminal of the second chip component with the first terminal of the first chip component and mounting the second chip component onto the upper surface of the first chip component, and filling the space sandwiched between the lower surface of the main body of the second chip component and the upper surface of the first chip component with flux, and the second step of heating the substrate and melting the solder plating while covering the surfaces of the first terminals and the second terminals with the flux, A component mounting method comprising: a third step of cooling the substrate after the second step and solidifying the molten solder plating to form an inter-chip connection portion that connects the first terminal and the second terminal. (Technical 2) A component mounting method according to Technical 1, wherein the first step includes a flux application step of applying the flux to the upper surface of the first chip component, and a mounting step of mounting the second chip component on the first chip component to which the flux has been applied, wherein in the flux application step, a sufficient amount of liquid flux to fill the space is applied. (Technical 3) A component mounting method according to Technical 1, wherein the first step includes a flux transfer step of adhering the flux to the lower surface of the second chip component, and a mounting step of mounting the second chip component to which the flux has been adhering on the first chip component, wherein in the flux transfer step, flux is adhering to the surface of the second terminal and the entire lower surface of the main body.(Technology 4) The component mounting method according to Technology 3, wherein in the flux transfer step, the lower surface of the second chip component is immersed in a flux film formed on a flat surface to adhere flux to the entire lower surface of the second chip component, and the thickness of the flux film is greater than the step difference between the second terminal and the main body on the lower surface of the second chip component. (Technology 5) The component mounting method according to any one of Technology 1 to 4, wherein the second chip component is a chip-type multilayer capacitor. (Technology 6) The component mounting method according to any one of Technology 1 to 5, wherein in the first step, the substrate is prepared with the first chip component mounted on a solder portion provided on a land of the substrate, and the second chip component is mounted on the upper surface of the first chip component which is pre-mounted on the solder portion. (Technology 7) The component mounting method according to any one of Technology 1 to 5, wherein in the first step, the substrate is prepared with the first chip component soldered to the substrate, and the second chip component is mounted on the upper surface of the first chip component which is pre-soldered. (Technology 8) A method for manufacturing a mounted substrate in which a first chip component is soldered to a substrate and a second chip component is soldered to the upper surface of the first chip component, comprising the step of mounting and soldering the second chip component to the upper surface of the first chip component using the component mounting method described in any one of Technologies 1 to 7. (Technology 9) A mounted substrate manufactured using the component mounting method described in any one of Technologies 1 to 7, wherein the solder forming the inter-chip connection portion is formed only by solder derived from the solder plating and solder present on the surface of the first terminal prior to the second step.

[0076] This disclosure can be used for a component mounting method, a mounting substrate manufacturing method, and a mounting substrate.

[0077] Although the present invention has been described in relation to preferred embodiments at present, such disclosure should not be interpreted restrictively. Various modifications and alterations will undoubtedly become apparent to those skilled in the art in the field to which the invention pertains by reading the above disclosure. Accordingly, the appended claims should be interpreted as encompassing all modifications and alterations without departing from the true spirit and scope of the invention.

[0078] 1: Substrate 2: Land 5: Solder paste 6a, 6b: Inter-chip connection 7: Connection 8: Mounting board 10: First chip component 12: Main body 14a, 14b: Terminal (first terminal) 16: Flux 20: Second chip component 22: Main body 24a, 24b: Terminal (second terminal) 31: Coating nozzle 34: Film deposition stage 34X: Flat surface 35: Blade 36: Flux film 38: Adsorption nozzle

Claims

1. A component mounting method for mounting a second chip component onto the upper surface of a first chip component pre-placed on a substrate and soldering it, wherein the first chip component has a main body having an upper surface, a lower surface, and side surfaces, and first terminals extending from the lower surface through the side surfaces to the upper surface at each end of the main body, the second chip component has a main body having an upper surface, a lower surface, and side surfaces, and second terminals solder-plated at each end of the main body, the vertical width of the central portion of the main body sandwiched between the ends is narrower than the vertical width of the ends, the first step of aligning the second terminal of the second chip component with the first terminal of the first chip component and mounting the second chip component onto the upper surface of the first chip component, and filling the space between the lower surface of the main body of the second chip component and the upper surface of the first chip component with flux, and the second step of heating the substrate and melting the solder plating while covering the surfaces of the first terminals and the second terminals with the flux, A component mounting method comprising: a third step of cooling the substrate after the second step and solidifying the molten solder plating to form an inter-chip connection portion that connects the first terminal and the second terminal.

2. The component mounting method according to claim 1, wherein the first step includes a flux application step of applying the flux to the upper surface of the first chip component, and a mounting step of mounting the second chip component onto the first chip component on which the flux has been applied, wherein in the flux application step, a sufficient amount of liquid flux to fill the space is applied.

3. The component mounting method according to claim 1, wherein the first step includes a flux transfer step of attaching the flux to the lower surface of the second chip component, and a mounting step of mounting the second chip component with the flux attached to it onto the first chip component, wherein in the flux transfer step, the flux is attached to the surface of the second terminal and the entire lower surface of the main body.

4. The component mounting method according to claim 3, wherein in the flux transfer step, the lower surface of the second chip component is immersed in a flux film formed on a flat surface to adhere flux to the entire lower surface of the second chip component, and the thickness of the flux film is greater than the step difference between the second terminal and the main body on the lower surface of the second chip component.

5. The component mounting method according to claim 1, wherein the second chip component is a chip-type multilayer capacitor.

6. The component mounting method according to claim 1, wherein in the first step, the substrate is prepared on which the first chip component is mounted on a solder portion provided on a land of the substrate, the second chip component is mounted on the upper surface of the first chip component which is already mounted on the solder portion, and then in the second step, the solder portion is melted together with the solder plating.

7. The component mounting method according to claim 1, wherein in the first step, a substrate is prepared with the first chip component soldered to the substrate, and the second chip component is mounted on the upper surface of the first chip component which has been pre-soldered.

8. A method for manufacturing a mounted substrate in which a first chip component is soldered to a substrate and a second chip component is soldered to the upper surface of the first chip component, the method comprising the step of mounting and soldering the second chip component to the upper surface of the first chip component using the component mounting method described in claim 1.

9. A mounting substrate manufactured using the component mounting method described in any one of claims 1 to 7, wherein the solder forming the inter-chip connection portion is formed only by solder derived from the solder plating and solder present on the surface of the first terminal prior to the second step.

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