Method for manufacturing component mounting substrate

Abstract

The disclosed manufacturing method is a manufacturing method of a component mounting substrate. The manufacturing method includes the following steps in this order: a solder pre-coating layer forming step of forming a solder pre-coating layer on a plurality of first pads on a first surface of a circuit board; a first arrangement step in which a plurality of first members are arranged on the solder pre-coated portion; a first reflow step in which the plurality of first components are brazed by heating the circuit board on which the plurality of first components are arranged; a solder paste coating step of coating solder paste on the plurality of second pads on the second surface of the circuit board; a second disposing step of disposing a plurality of second members on the solder paste; and a second reflow step in which the plurality of second components are brazed by heating the circuit board on which the plurality of second components are arranged. The brazing difficulty of the first surface is higher than the brazing difficulty of the second surface.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a manufacturing method of a component mounting substrate. BACKGROUND

[0002] As a method of mounting a plurality of electronic components on a substrate, a reflow soldering method of mounting electronic components on a substrate using solder paste is known.

[0003] In claim 1 of Patent Literature 1 (JP Laid-Open Patent Publication No. 6-334323), "a solder precoat method characterized by, after solder is applied to pads on a surface of a substrate by solder paste printing, not mounting components on the pads on which solder precoat should be performed, and dissolving the solder on the pads in a reflow soldering process" is described.

[0004] PRIOR ART LITERATURE

[0005] PATENT LITERATURE

[0006] Patent Literature 1: JP Laid-Open Patent Publication No. 6-334323 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In order to increase the mounting density of components, components are mounted on both surfaces of a circuit substrate. However, in the case where components are mounted on both surfaces of a circuit substrate, since conditions change between mounting of components on one surface and mounting of components on the other surface, in the conventional method, defects are easily generated. The higher the mounting density, the more easily defects are generated at the time of mounting. Under such circumstances, one of the objects of the present disclosure is to provide a manufacturing method of a component mounting substrate in which defects are less likely to be generated.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] One aspect of the present disclosure relates to a first manufacturing method of a component mounting substrate. In the first manufacturing method, the component mounting substrate includes a circuit substrate having a first surface and a second surface opposite to the first surface, and a plurality of components mounted on both surfaces of the circuit substrate, and the manufacturing method of the component mounting substrate includes, in order: a solder precoat portion forming step of forming a solder precoat portion on a plurality of first lands of the first surface of the circuit substrate; a first arrangement step of arranging a plurality of first components on the solder precoat portion; a first reflow soldering step of performing soldering of the plurality of first components by heating the circuit substrate on which the plurality of first components are arranged; a solder paste applying step of applying solder paste on a plurality of second lands of the second surface of the circuit substrate; a second arrangement step of arranging a plurality of second components on the solder paste; and a second reflow soldering step of performing soldering of the plurality of second components by heating the circuit substrate on which the plurality of second components are arranged, the soldering difficulty level of the first surface being higher than the soldering difficulty level of the second surface.

[0011] Another aspect of the present disclosure relates to a second manufacturing method of a component mounting substrate. In the second manufacturing method, the component mounting substrate includes a circuit substrate having a first surface and a second surface opposite to the first surface, and a plurality of components mounted on both surfaces of the circuit substrate, and the manufacturing method of the component mounting substrate includes: a solder precoat portion forming step of forming a solder precoat portion on a plurality of first lands of the first surface of the circuit substrate; a first arrangement step of arranging a plurality of first components on the solder precoat portion; a first reflow soldering step of performing soldering of the plurality of first components by heating the circuit substrate on which the plurality of first components are arranged; a solder paste applying step of applying solder paste on a plurality of second lands of the second surface of the circuit substrate; a second arrangement step of arranging a plurality of second components on the solder paste; a second reflow soldering step of performing soldering of the plurality of second components by heating the circuit substrate on which the plurality of second components are arranged, the number of lands having an area of 0.04 mm 2 or more among the plurality of first lands being larger than the number of lands having an area of 0.04 mm 2 or more among the plurality of second lands.

[0012] Another aspect of the present disclosure relates to a third manufacturing method of a component mounting substrate. In the third manufacturing method, the component mounting substrate includes a circuit substrate having a first surface and a second surface opposite to the first surface, and a plurality of components mounted on both surfaces of the circuit substrate, and the manufacturing method of the component mounting substrate includes: a solder precoat portion forming step of forming a solder precoat portion on a plurality of first lands of the first surface of the circuit substrate; a first arrangement step of arranging a plurality of first components on the solder precoat portion; a first reflow soldering step of performing soldering of the plurality of first components by heating the circuit substrate on which the plurality of first components are arranged; a solder paste applying step of applying solder paste on a plurality of second lands of the second surface of the circuit substrate; a second arrangement step of arranging a plurality of second components on the solder paste; and a second reflow soldering step of performing soldering of the plurality of second components by heating the circuit substrate on which the plurality of second components are arranged, the number of lands adjacent to each other at a distance of 0.1 mm or less among the plurality of first lands is more than the number of lands adjacent to each other at a distance of 0.1 mm or less among the plurality of second lands.

[0013] Another aspect of the present disclosure relates to a fourth manufacturing method of a component mounting substrate. In the fourth manufacturing method, the component mounting substrate includes a circuit substrate having a first surface and a second surface opposite to the first surface, and a plurality of components mounted on both surfaces of the circuit substrate, and the manufacturing method of the component mounting substrate includes: a solder precoat portion forming step of forming a solder precoat portion on a plurality of first lands of the first surface of the circuit substrate; a first arrangement step of arranging a plurality of first components on the solder precoat portion; a first reflow soldering step of performing soldering of the plurality of first components by heating the circuit substrate on which the plurality of first components are arranged; a solder paste applying step of applying solder paste on a plurality of second lands of the second surface of the circuit substrate; a second arrangement step of arranging a plurality of second components on the solder paste; and a second reflow soldering step of performing soldering of the plurality of second components by heating the circuit substrate on which the plurality of second components are arranged, the plurality of first components include minute components having a size of 0402 size or less determined by JIS standard, and the number of the minute components adjacent to each other at a distance of 0.1 mm or less among the plurality of first components is more than the number of the minute components adjacent to each other at a distance of 0.1 mm or less among the plurality of second components.

[0014] Effects of Invention

[0015] According to the manufacturing method of the present disclosure, generation of defects in manufacturing of the component mounting substrate can be suppressed. New features of the present application are described in the appended claims, but the application, both as to its organization and content, together with the object thereof, best understood by referring to the following detailed description in conjunction with the accompanying drawings in which like reference characters refer to like elements throughout the several views, and in which: BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1A is a view schematically showing a part of a manufacturing method of one example related to Embodiment 1.

[0017] Figure 1B is a view schematically showing one example of a process immediately after Figure 1A .

[0018] Figure 1C is a view schematically showing one example of a process immediately after Figure 1B .

[0019] Figure 1D is a view schematically showing one example of a process immediately after Figure 1C .

[0020] Figure 1E is a view schematically showing one example of a process immediately after Figure 1D .

[0021] Figure 2A is a view schematically showing one example of a process immediately after Figure 1E .

[0022] Figure 2B is a view schematically showing one example of a process immediately after Figure 2A .

[0023] Figure 2C is a view schematically showing one example of a process immediately after Figure 2B .

[0024] Figure 3 is a view schematically showing one example of a process shown in Figure 1C .

[0025] Figure 4 is a view showing another example of a manufacturing process related to Embodiment 1.

[0026] Figure 5A is a view showing one example of a configuration of first pads of a circuit substrate before mounting components.

[0027] Figure 5B is a view schematically showing a first surface of a circuit substrate after mounting components.

[0028] Figure 6A is a view for explaining one example of a distance between adjacent pads.

[0029] Figure 6B is a view for explaining another example of a distance between adjacent pads.

[0030] Figure 7 is a view for explaining a distance between adjacent components.

[0031] Figure 8A is a view showing an example of a configuration of the second pads of the circuit board before mounting the components.

[0032] Figure 8B is a view showing an example of the second surface of the circuit board after mounting the components. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments to which the present disclosure pertains will be explained by way of examples, but the present disclosure is not limited to the examples explained below. In the following explanation, specific numerical values and materials are sometimes exemplified, but other numerical values and other materials can also be used as long as the effects of the present disclosure are obtained. In the present specification, a description such as "numerical value A to numerical value B" includes the numerical value A and the numerical value B, and can be changed to a description of "numerical value A or more and numerical value B or less". In the following explanation, in a case where a lower limit and an upper limit of a numerical value related to a specific property, condition, or the like are exemplified, as long as the lower limit is not more than the upper limit, any one of the exemplified lower limits and any one of the exemplified upper limits can be arbitrarily combined. In the following explanation, in a case where examples of constituent elements, examples of methods are listed, as long as not particularly described, either only one of the listed examples can be used or a plurality of the listed examples can be used in combination.

[0034] (Method for manufacturing component mounting board)

[0035] The manufacturing method to which the present embodiment pertains will be sometimes referred to as "manufacturing method (M)" hereinafter. The manufacturing method (M) is a manufacturing method of a component mounting board including a circuit board having a first surface and a second surface on the opposite side of the first surface, and a plurality of components mounted on both surfaces of the circuit board. The manufacturing method (M) successively includes a solder precoat layer portion forming step, a first arrangement step, a first reflow soldering step, a solder paste applying step, a second arrangement step, and a second reflow soldering step. The solderability of the first surface is higher than the solderability of the second surface.

[0036] When mounting a component on the second surface, the component needs to be disposed from above the second surface while the first surface is supported. Therefore, mounting of the component on the second surface is difficult when the component is mounted on the first surface. In the manufacturing method (M), mounting of the component on the second surface is performed after mounting of the component on the first surface, which is difficult to solder. Therefore, defects in mounting of the component can be reduced. In the manufacturing method (M), by setting the surface of the circuit board on which soldering is difficult to the first surface, mounting of the component on both surfaces of the circuit board can be performed with a low defect rate. Each step of the manufacturing method (M) will be described below.

[0037] (Solder precoat portion forming step)

[0038] The solder precoat portion forming step is a step of forming a solder precoat portion on a plurality of first lands on the first surface of the circuit board. The method of forming the solder precoat portion is not particularly limited, and a known method can be used. In one example, first, a solder paste (paste-like solder) is applied to the first lands. Next, after the solder paste is heated to melt solder particles in the solder paste and then cooled, a solder precoat portion (solder layer) can be formed on the first lands. The solder paste can use a solder paste containing solder particles and other components (e.g., flux). The solder paste is not particularly limited, and a known solder paste used in the formation of the solder precoat portion can be used. The method of applying the solder paste is not particularly limited, and a known method (e.g., screen printing) can be used.

[0039] The circuit board is not particularly limited, and a known circuit board can be used. The circuit board includes: a substrate portion; a plurality of first lands formed on one surface of the substrate portion; and a plurality of second lands formed on the other surface of the substrate portion. The substrate portion can use an insulating and plate-shaped substrate. A wiring that penetrates the substrate portion is formed in the substrate portion as needed.

[0040] The first surface of the circuit board is the surface of the one side of the two surfaces of the circuit board on which soldering is difficult.

[0041] (First disposing step)

[0042] The first disposing step is a step of disposing a plurality of first components on the solder precoat portion. The method of disposing the components is not particularly limited, and a known disposing method can be used. For example, a chip mounter can be used to dispose the first components on the solder precoat portion.

[0043] The first components include components of various kinds and various sizes. The first components can include components having a size of 0402 size or less determined by Japanese Industrial Standards (JIS standards). Hereinafter, the components having a size of 0402 size or less determined by the JIS standards are sometimes referred to as "minute components". In addition, the 0402 size determined by the JIS standards is a size of 0.4 mm or less in length and 0.2 mm or less in width of a planar shape.

[0044] The first components can also include components having a size larger than the 0402 size. The components (the first components and the second components) mounted to the circuit board are not particularly limited and include general components mounted to the circuit board. In examples of the components, various chip components (for example, electronic components), CSPs (Chip Size Packages), BGAs (Ball Grid Arrays), connectors, and other components used in electronic devices are included. The first components and the second components can each include components having a size of 1608 size or more determined by the JIS standards or components having a size of 0402 size or less determined by the JIS standards.

[0045] (First reflow soldering step)

[0046] The first reflow soldering step is a step of brazing the plurality of first components by heating the circuit board on which the plurality of first components are arranged. The first reflow soldering step can be performed by heating the solder precoat portion to a temperature at which the solder precoat portion melts and then cooling the solder precoat portion. In addition, the heating and the cooling of the solder precoat portion are usually performed by heating and cooling the entire circuit board on which the first components are arranged. The first reflow soldering step can be performed using a publicly known reflow soldering furnace.

[0047] (Solder paste application step)

[0048] The solder paste application step is a step of applying solder paste to the plurality of second pads on the second surface of the circuit board. The solder paste is not particularly limited and can be a solder paste used in surface mounting of electronic components. For example, the solder paste can use a solder paste including solder particles and other components (for example, flux). The application method of the solder paste is not limited and can use the application method described in the solder precoat formation step. The solder used in the formation of the solder precoat and the solder used in the solder paste application step can be the same or different.

[0049] (Second arrangement step)

[0050] The second component placement step is a step of placing a plurality of second components on the solder paste applied in the solder paste application step. The method of placing the second components is not particularly limited, and the method described in the first component placement step can be used. The second components can include components of various kinds and various sizes.

[0051] (Second reflow soldering step)

[0052] The second reflow soldering step is a step of brazing the plurality of second components by heating the circuit board on which the plurality of second components are placed. The second reflow soldering step can be performed by heating the solder paste to a temperature at which the solder particles in the solder paste melt and then cooling the solder paste. In addition, the heating and cooling of the solder paste are usually performed by heating and cooling the entire circuit board on which the second components are placed. The second reflow soldering step can be performed using a publicly known reflow soldering furnace.

[0053] Through the above steps, the plurality of first components are mounted on the first surface of the circuit board, and the plurality of second components are mounted on the second surface. In one aspect, the manufacturing method (M) includes: a first mounting step of mounting the plurality of first components on the first surface; and a second mounting step of mounting the plurality of second components on the second surface. The first mounting step includes, in order, the solder precoat layer formation step, the first component placement step, and the first reflow soldering step. Each step of the first mounting step is usually performed with the first surface facing upward and the second surface supported from below.

[0054] The second mounting step includes, in order, the solder paste application step, the second component placement step, and the second reflow soldering step. Each step of the second mounting step is usually performed with the second surface facing upward and the first surface supported from below.

[0055] As described above, the brazing difficulty of the first surface is higher than the brazing difficulty of the second surface. Empirically, in a case where at least one (for example, any one) of the following conditions (1) to (4) is satisfied, it can be said that the brazing difficulty of the first surface is higher than the brazing difficulty of the second surface. In other words, the condition "the brazing difficulty of the first surface is higher than the brazing difficulty of the second surface" can be changed to a statement of at least one (for example, any one) of the following conditions (1) to (4).

[0056] (1) The plurality of first components include a small component having a size of 0402 or less as determined by the JIS standard, and the number of the small components included in the plurality of first components is greater than the number of the small components included in the plurality of second components.

[0057] (2) The number of pads having an area of 0.04 mm 2 in the plurality of first pads is greater than the number of pads having an area of 0.04 mm 2 in the plurality of second pads.

[0058] (3) The number of pads adjacent to each other at a distance of 0.1 mm or less among the plurality of first pads is larger than the number of pads adjacent to each other at a distance of 0.1 mm or less among the plurality of second pads.

[0059] (4) The plurality of first components include minute components having a size of 0402 or less according to JIS standards, and the number of minute components adjacent to each other at a distance of 0.1 mm or less among the plurality of first components is larger than the number of minute components adjacent to each other at a distance of 0.1 mm or less among the plurality of second components.

[0060] Regarding condition (1), the more the number of minute components, the higher the brazing difficulty. In addition, the number of minute components included in the plurality of second components can be zero. That is, the plurality of second components can not include minute components.

[0061] Regarding condition (2), the more the number of pads having a small area, the higher the brazing difficulty.

[0062] Regarding condition (3), the narrower the interval of adjacent pads, the higher the brazing difficulty.

[0063] Regarding condition (4), the more the number of minute components adjacent to each other at a distance of 0.1 mm or less, the higher the brazing difficulty

[0064] The manufacturing method (M) can include other processes in addition to the above processes. Examples of the other processes include a process of checking the state of arrangement of the components in the component arrangement process, a process of checking the state of brazing in the reflow soldering process, a process of checking the state of application of the solder paste in the solder paste application process, and other processes. For example, the manufacturing method (M) can include a flattening process of flattening the solder precoat portion before the first arrangement process. The flattening process is a process of flattening the solder precoat portion by flattening it. By performing the flattening process, it is possible to suppress the first components arranged on the solder precoat portion in the first arrangement process from deviating from a given position.

[0065] The flattening process can be performed by pressing the solder precoat portion from above the first face with a pressing member while supporting the second face from below. The pressing member can be a plate-shaped member or a roll-shaped member.

[0066] In the planarization process, it is important to prevent the circuit board from being deflected in the thickness direction due to the load of the pressing member. This is because, if the circuit board is deflected in the thickness direction, the solder precoat layer portion cannot be planarized. For this reason, the planarization process is preferably performed in a state where the circuit board is supported by a flat support table (flat work table). In the manufacturing method (M), since the components are mounted on the first surface in a state where the components are not mounted on the second surface, the second surface can be supported by the flat work table in the planarization process. By using the flat work table, in addition to being able to uniformly support the second surface, it is also possible to reduce the manufacturing cost of the component mounting board.

[0067] Here, as long as the deflection of the circuit board at the time of planarization can be prevented, the second surface can be supported by a support unit other than the flat work table. Examples of the support unit include a plurality of pins, a support unit that supports the vicinity of the outer edge of the board, a support unit that has a recess in a portion of the first component, and the like. These support units can also be used in combination.

[0068] The manufacturing method (M) can include a flux application process of applying flux (solder flux) on the solder precoat layer after the solder precoat layer forming process and before the first arrangement process. In the case where the manufacturing method (M) includes the flux application process and the planarization process, the flux application process can be performed before the planarization process. The flux and the method of applying the flux are not particularly limited, and a publicly known flux and a publicly known method (for example, screen printing) can be used. In addition, solder paste can be applied instead of the flux.

[0069] Each process for mounting a plurality of second components on the second surface (each process of the second mounting process) can be performed in a state where the circuit board is supported by a support unit having a configuration that does not interfere with the plurality of first components that are brazed to the first surface. For example, a support unit that supports only a portion of the board can be used. Examples of such a support unit include a plurality of pins, a support unit that supports the vicinity of the outer edge of the board, a support unit that has a recess in a portion of the first component, and the like. These support units can also be used in combination.

[0070] Hereinafter, one example of the embodiment to which the present disclosure pertains will be specifically described with reference to the drawings. The embodiment described below can be changed based on the above description. In addition, the matters described below can be applied to the above embodiment. Furthermore, in the embodiment described below, matters that are not essential in the manufacturing method (M) to which the present disclosure pertains can be omitted. In the following drawings, the illustration of a part of the reference numerals can be omitted at times.

[0071] (Embodiment 1)

[0072] In Embodiment 1, one example of the manufacturing method (M) to which the present disclosure pertains will be described. In the manufacturing method (M), a plurality of first components are mounted on the first surface of the circuit board, and a plurality of second components are mounted on the second surface of the circuit board. Figure 1AThe circuit board 10 used in Embodiment 1 is schematically shown. The circuit board 10 has a first surface 10a and a second surface 10b opposite to the first surface 10a. The circuit board 10 includes: a substrate portion 11; a plurality of first pads 10aL formed on the first surface 10a side; and a plurality of second pads 10bL formed on the second surface 10b side. The soldering difficulty of the first surface 10a is higher than that of the second surface 10b.

[0073] Wiring (not shown) including pads is formed on the first surface 10a and the second surface 10b respectively. The wiring on the first surface 10a is connected to the wiring on the second surface 10b as needed through wiring (not shown) formed inside the substrate portion 11.

[0074] In manufacturing method (M), a plurality of first components are mounted on the first surface 10a via a first mounting step. The first mounting step is performed with the first surface 10a facing upwards and the second surface 10b supported. In the first mounting step, firstly, as... Figure 1B As shown, solder pre-coating portions 21 are formed on a plurality of first pads 10aL on the first surface 10a.

[0075] Next, as Figure 1C As shown, the top of the solder pre-coated portion 21 is flattened through a planarization process, making the top more flat. Figure 3 As shown, the planarization process can be performed by moving the roller 92 while the second surface 10b is supported by the planar worktable 91, and flattening the top of the solder pre-coating portion 21.

[0076] Next, as Figure 1D As shown, flux 22 is applied to the solder pre-coating portion 21, and a plurality of first components 51 are disposed on the solder pre-coating portion 21 via flux 22. Figure 1D The first component 51 shown is an example of a chip-type electronic component having terminal portions 51y at both ends of the main body portion 51x. As described above, solder paste can be applied instead of flux, but in this case, solder paste needs to be applied to prevent short circuits with adjacent pads.

[0077] Next, the circuit board 10, on which the plurality of first components 51 are disposed, is heated and cooled to perform brazing of the plurality of first components 51. When the circuit board 10 is heated, the solder pre-coating portion 21 melts into a liquid solder, but the oxide film on the terminal portion 51y is removed by the reduction action of the flux 22, thus the liquid solder wets and spreads to the surface of the terminal portion 51y. Afterwards, the circuit board 10 is cooled to solidify the liquid solder, thereby completing the brazing process. Figure 1E As shown, the first component 51 is connected to the first pad 10aL via solder 21x.

[0078] Next, a plurality of second components are mounted on the second surface 10b by a second mounting step. The second mounting step is performed in a state where the second surface 10b is directed upward and the first surface 10a is supported. In the second mounting step, first, as shown in FIG. 6, solder paste 31 is applied to a plurality of second pads 10bL on the second surface 10b of the circuit board 10. Figure 2A

[0079] Next, as shown in FIG. 7, a plurality of second components 52 are arranged on the solder paste 31. Figure 2B Figure 2B The second component 52 shown in FIG. 8 is an example of a chip-type electronic component having a terminal portion 52y at both ends of a main body portion 52x. Next, as shown in FIG. 9, soldering of the plurality of second components 52 is performed by heating and cooling the circuit board 10 on which the plurality of second components 52 are arranged. The second components 52 are connected to the second pads 10bL by the solder 31x. In this way, a component mounting board 10x on which components are mounted on the first surface 10a and the second surface 10b is obtained. Figure 2C

[0080] An example of a process of the manufacturing method (M) is shown in FIG. 10. Figure 4 The manufacturing method shown in FIG. 11 includes a first mounting step 110 and a second mounting step 120. The first mounting step 110 and the second mounting step 120 each include the respective steps shown in FIGS. 12 to 16. Figure 4 Figure 4

[0081] An example of an arrangement of the first pads 10aL formed on the first surface 10a of the circuit board 10 is shown in FIG. 17. The first pads 10aL have various shapes and sizes corresponding to the mounted components. In the example shown in FIG. 17, the first pads 10aL are arranged in a matrix pattern. Figure 5A A top view in which a plurality of first components are arranged on the first pads 10aL shown in FIG. 18. In the example shown in FIG. 18, the plurality of first components include a minute component (chip component) 51a, a small chip component 51b, a large component 51c, and a package component 51d. Examples of the large component 51c include a capacitor and the like. Examples of the package component 51d include a BGA, a CSP, and a flat package IC, and the like. Figure 5B Figure 5A Figure 5B

[0082] An enlarged view of the area A of FIG. 19 is shown in FIG. 20. Figure 6A Figure 5A An enlarged view of the area A of FIG. 19 is shown in FIG. 20. Figure 6A ​​​​​​​​​The pads shown include: two first pads 10aL1 connecting a micro-component (first component) 51a1; and two first pads 10aL2 connecting a micro-component (first component) 51a2 disposed next to it. In an example shown in Figure 6, the distance between pads connecting different components is W1. Furthermore, the distance between pads connecting the same components is W2. The aforementioned "number of adjacent pads with a distance of 0.1 mm or less" is determined by considering both W1 and W2. That is, as long as either W1 or W2 is 0.1 mm or less, the number of two adjacent pads at that distance is counted as "the number of adjacent pads with a distance of 0.1 mm or less".

[0083] exist Figure 6B Show Figure 5A A magnified view of region B. Figure 6B The pads shown include multiple first pads 10aL3 that connect to the terminals of CSPs and BGAs, which are called bumps. CSPs and BGAs mostly contain multiple bumps arranged in a grid pattern, and the multiple first pads 10aL3 are also formed in positions consistent with this arrangement. Generally, if the size of the bumps becomes smaller, the area of ​​the first pad 10aL3 (shown in shaded areas) and the distances W3 and W4 to adjacent first pads 10aL3 also become smaller, increasing the difficulty of soldering. The aforementioned "number of adjacent pads with a distance of 0.1 mm or less" is determined by considering the distances to W3 and W4. That is, if either the distance to W3 or W4 is 0.1 mm or less, then two pads adjacent at that distance are counted as "the number of adjacent pads with a distance of 0.1 mm or less".

[0084] exist Figure 7 Show Figure 5B An enlarged view of region C. Two minute components (component 1) 51a1 and 51a2 are configured in region C. Figure 7 The distance W5 between two adjacent micro-parts (micro-parts 51a1 and 51a2) is shown.

[0085] exist Figure 8A An example of the configuration of the second pad 10bL formed on the second surface 10b of the circuit board 10 is shown. The second pad 10bL has various shapes and sizes corresponding to the components to be mounted. Figure 8B Shown in Figure 8A The top view shown depicts a configuration of multiple second components on the second pad 10bL. Figure 8B In one example shown, the multiple second components include a micro component (chip component) 52a, a small chip component 52b, a large component 52c, and a package component 52d. In one example shown in Figure 8, the large component 52c is a connector. An example of the package component 52d includes the aforementioned package component.

[0086] In Embodiment 1, the surface of the circuit board 10, between the first surface 10a and the second surface 10b, for which soldering is difficult, is set as the first surface 10a, but the pad pattern, components, for which soldering is difficult, can be concentrated on the first surface 10a at the design stage of the circuit board 10.

[0087] (Addendum)

[0088] The following technology is disclosed by the above description.

[0089] (Technology 1)

[0090] A method of manufacturing a component mounting board including a circuit board having a first surface and a second surface opposite to the first surface, and a plurality of components mounted on both surfaces of the circuit board, the method of manufacturing the component mounting board successively includes: a solder precoat portion forming step of forming a solder precoat portion on a plurality of first pads of the first surface of the circuit board; a first arrangement step of arranging a plurality of first components on the solder precoat portion; a first reflow soldering step of performing soldering of the plurality of first components by heating the circuit board on which the plurality of first components are arranged; a solder paste applying step of applying a solder paste on a plurality of second pads of the second surface of the circuit board; a second arrangement step of arranging a plurality of second components on the solder paste; and a second reflow soldering step of performing soldering of the plurality of second components by heating the circuit board on which the plurality of second components are arranged, the soldering of the first surface being more difficult than the soldering of the second surface.

[0091] (Technology 2)

[0092] In the method of manufacturing described in Technology 1, the plurality of first components include a minute component having a size of 0402 or less as determined by JIS standards, and the number of the minute components included in the plurality of first components is more than the number of the minute components included in the plurality of second components.

[0093] (Technology 3)

[0094] In the method of manufacturing described in Technology 1 or 2, the plurality of first pads include a pad having an area of 0.04 mm 2 In the method of manufacturing described in Technology 1 or 2, the plurality of second pads include a pad having an area of 0.04 mm 2 In the method of manufacturing described in Technology 1 or 2, the plurality of second pads include a pad having an area of 0.04 mm

[0095] (Technology 4)

[0096] In the manufacturing method according to any one of the above-mentioned techniques 1 to 3, the number of pads adjacent to each other at a distance of 0.1 mm or less among the plurality of first pads is larger than the number of pads adjacent to each other at a distance of 0.1 mm or less among the plurality of second pads.

[0097] (Technique 5)

[0098] In the manufacturing method according to any one of the above-mentioned techniques 1 to 4, the plurality of first components include minute components having a size of 0402 or less according to JIS standards, and the number of the minute components adjacent to each other at a distance of 0.1 mm or less among the plurality of first components is larger than the number of the minute components adjacent to each other at a distance of 0.1 mm or less among the plurality of second components.

[0099] (Technique 6)

[0100] In the manufacturing method according to any one of the above-mentioned techniques 1 to 5, a planarization step of flattening the solder precoat portion is performed before the first arrangement step.

[0101] (Technique 7)

[0102] In the manufacturing method according to the above-mentioned technique 6, the planarization step is performed while the circuit substrate is supported by a flat support table.

[0103] (Technique 8)

[0104] In the manufacturing method according to any one of the above-mentioned techniques 1 to 7, each step for mounting the plurality of second components on the second surface is performed while the circuit substrate is supported by a support unit having a configuration that does not interfere with the plurality of first components soldered to the first surface.

[0105] (Technique 9)

[0106] A manufacturing method of a component mounting substrate including a circuit substrate having a first surface and a second surface opposite to the first surface, and a plurality of components mounted on both surfaces of the circuit substrate, the manufacturing method of the component mounting substrate including: a solder precoat portion forming step of forming a solder precoat portion on a plurality of first pads of the first surface of the circuit substrate; a first arrangement step of arranging a plurality of first components on the solder precoat portion; a first reflow soldering step of performing soldering of the plurality of first components by heating the circuit substrate on which the plurality of first components are arranged; a solder paste applying step of applying a solder paste on a plurality of second pads of the second surface of the circuit substrate; a second arrangement step of arranging a plurality of second components on the solder paste; and a second reflow soldering step of performing soldering of the plurality of second components by heating the circuit substrate on which the plurality of second components are arranged, the area of a pad among the plurality of first pads being 0.04 mm2 The number of pads having an area of 0.04 mm 2 or less among the plurality of second pads is greater than the number of pads having an area of 0.04 mm

[0107] (Technology 10)

[0108] A method of manufacturing a component mounting substrate including a circuit substrate having a first surface and a second surface opposite to the first surface, and a plurality of components mounted on both surfaces of the circuit substrate, the method of manufacturing the component mounting substrate including: a solder precoat portion forming step of forming a solder precoat portion on a plurality of first pads of the first surface of the circuit substrate; a first arrangement step of arranging a plurality of first components on the solder precoat portion; a first reflow soldering step of performing soldering of the plurality of first components by heating the circuit substrate on which the plurality of first components are arranged; a solder paste application step of applying a solder paste on a plurality of second pads of the second surface of the circuit substrate; a second arrangement step of arranging a plurality of second components on the solder paste; and a second reflow soldering step of performing soldering of the plurality of second components by heating the circuit substrate on which the plurality of second components are arranged, the number of pads adjacent to each other at a distance of 0.1 mm or less among the plurality of first pads is greater than the number of pads adjacent to each other at a distance of 0.1 mm or less among the plurality of second pads.

[0109] (Technology 11)

[0110] A method of manufacturing a component mounting substrate including a circuit substrate having a first surface and a second surface opposite to the first surface, and a plurality of components mounted on both surfaces of the circuit substrate, the method of manufacturing the component mounting substrate including: a solder precoat portion forming step of forming a solder precoat portion on a plurality of first pads of the first surface of the circuit substrate; a first arrangement step of arranging a plurality of first components on the solder precoat portion; a first reflow soldering step of performing soldering of the plurality of first components by heating the circuit substrate on which the plurality of first components are arranged; a solder paste application step of applying a solder paste on a plurality of second pads of the second surface of the circuit substrate; a second arrangement step of arranging a plurality of second components on the solder paste; and a second reflow soldering step of performing soldering of the plurality of second components by heating the circuit substrate on which the plurality of second components are arranged, the plurality of first components include minute components having a size of 0402 size or less determined by JIS standard, and the number of the minute components adjacent to each other at a distance of 0.1 mm or less among the plurality of first components is greater than the number of the minute components adjacent to each other at a distance of 0.1 mm or less among the plurality of second components.

[0111] (Technology 12)

[0112] The manufacturing method according to any one of techniques 9 to 11, wherein the planarization process is performed before the first arrangement process.

[0113] (Technique 13)

[0114] The manufacturing method according to technique 12, wherein the planarization process is performed while the circuit substrate is supported by a flat support table.

[0115] (Technique 14)

[0116] The manufacturing method according to any one of techniques 9 to 13, wherein each process for mounting the plurality of second components on the second face is performed while the circuit substrate is supported by a support unit having a configuration that does not interfere with the plurality of first components soldered to the first face.

[0117] Industrial Applicability

[0118] The present disclosure can be utilized in a manufacturing method of a component mounting substrate.

[0119] The preferred embodiments regarding the current time point explain the present application, but such disclosure is not to be construed limitatively. By reading the above disclosure, those skilled in the art belonging to the technical field of the present application will surely ascertain various modifications and changes without error. Therefore, the appended claims should be construed to include all modifications and changes not departing from the true spirit and scope of the present application.

[0120] Explanation of Reference Numerals

[0121] 10: Circuit substrate

[0122] 10a: First face

[0123] 10aL: First land

[0124] 10b: Second face

[0125] 10bL: Second land

[0126] 10x: Component mounting substrate

[0127] 11: Substrate portion

[0128] 21: Solder precoat portion

[0129] 21x, 31x: Solder

[0130] 31: Solder paste

[0131] 51: First component

[0132] 52: Second component

Claims

1. A manufacturing method of a component mounting substrate including a circuit substrate having a first surface and a second surface opposite to the first surface, and a plurality of components mounted on both surfaces of the circuit substrate, the manufacturing method of the component mounting substrate successively including: a solder precoat portion forming step of forming a solder precoat portion on a plurality of first lands of the first surface of the circuit substrate; a first arranging step of arranging a plurality of first components on the solder precoat portion; a first reflow soldering step of performing soldering of the plurality of first components by heating the circuit substrate on which the plurality of first components are arranged; a solder paste applying step of applying a solder paste on a plurality of second lands of the second surface of the circuit substrate; a second arranging step of arranging a plurality of second components on the solder paste; and a second reflow soldering step of performing soldering of the plurality of second components by heating the circuit substrate on which the plurality of second components are arranged, the soldering difficulty of the first surface being higher than the soldering difficulty of the second surface.

2. The manufacturing method according to claim 1, wherein the plurality of first components include minute components having a size of 0402 or less as determined by JIS standards, and the number of the minute components included in the plurality of first components is larger than the number of the minute components included in the plurality of second components.

3. The manufacturing method according to claim 1 or 2, wherein the plurality of first lands include lands having a size of 0402 or less as determined by JIS standards.

4. The manufacturing method according to claim 1 or 2, wherein the number of lands adjacent to each other at a distance of 0.1 mm or less among the plurality of first lands is larger than the number of lands adjacent to each other at a distance of 0.1 mm or less among the plurality of second lands.

5. The manufacturing method according to claim 1, wherein the plurality of first components include minute components having a size of 0402 or less as determined by JIS standards, and the number of the minute components adjacent to each other at a distance of 0.1 mm or less among the plurality of first components is larger than the number of the minute components adjacent to each other at a distance of 0.1 mm or less among the plurality of second components.

6. The manufacturing method according to claim 1 or 2, wherein the manufacturing method includes: a flattening step of flattening the solder precoat portion before the first arranging step.

7. The manufacturing method according to claim 6, wherein the flattening step is performed in a state where the circuit substrate is supported by a flat support table.

8. The manufacturing method according to claim 7, wherein each step for mounting the plurality of second components on the second surface is performed in a state where the circuit substrate is supported by a support unit having a configuration that does not interfere with the plurality of first components soldered to the first surface.

9. A manufacturing method of a component mounting substrate including a circuit substrate having a first surface and a second surface opposite to the first surface, and a plurality of components mounted on both surfaces of the circuit substrate, the manufacturing method of the component mounting substrate including: a solder precoat portion forming step of forming a solder precoat portion on a plurality of first lands of the first surface of the circuit substrate; ​ ​ ​ ​ The number of pads in the plurality of first pads whose area is 0.04 mm 2 The number of pads in the plurality of second pads whose area is 0.04 mm 2 The number of pads. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ a first reflow soldering process of performing soldering of the plurality of first components by heating the circuit board on which the plurality of first components are arranged; a solder paste application process of applying solder paste on a plurality of second pads of the second surface of the circuit board; a second arrangement process of arranging a plurality of second components on the solder paste; and a second reflow soldering process of performing soldering of the plurality of second components by heating the circuit board on which the plurality of second components are arranged, 10. A manufacturing method of a component mounting board including a circuit board having a first surface and a second surface opposite to the first surface, and a plurality of components mounted on both surfaces of the circuit board, The number of pads whose area is 0.04 mm 2 The number of pads whose area is 0.04 mm 2 The number of pads whose area is 0.04 mm the manufacturing method of the component mounting board including: a solder precoat portion forming process of forming a solder precoat portion on a plurality of first pads of the first surface of the circuit board; a first arrangement process of arranging a plurality of first components on the solder precoat portion; a first reflow soldering process of performing soldering of the plurality of first components by heating the circuit board on which the plurality of first components are arranged; a solder paste application process of applying solder paste on a plurality of second pads of the second surface of the circuit board; a second arrangement process of arranging a plurality of second components on the solder paste; and a second reflow soldering process of performing soldering of the plurality of second components by heating the circuit board on which the plurality of second components are arranged, the number of pads adjacent to each other at a distance of 0.1 mm or less among the plurality of first pads is larger than the number of pads adjacent to each other at a distance of 0.1 mm or less among the plurality of second pads.

11. A manufacturing method of a component mounting board including a circuit board having a first surface and a second surface opposite to the first surface, and a plurality of components mounted on both surfaces of the circuit board, the manufacturing method of the component mounting board including: a solder precoat portion forming process of forming a solder precoat portion on a plurality of first pads of the first surface of the circuit board; a first arrangement process of arranging a plurality of first components on the solder precoat portion; a first reflow soldering process of performing soldering of the plurality of first components by heating the circuit board on which the plurality of first components are arranged; a solder paste application process of applying solder paste on a plurality of second pads of the second surface of the circuit board; a second arrangement process of arranging a plurality of second components on the solder paste; and a second reflow soldering process of performing soldering of the plurality of second components by heating the circuit board on which the plurality of second components are arranged, the plurality of first components include a minute component having a size of 0402 size or less determined by JIS standard, the number of the minute components adjacent to each other at a distance of 0.1 mm or less among the plurality of first components is larger than the number of the minute components adjacent to each other at a distance of 0.1 mm or less among the plurality of second components.

12. The manufacturing method according to any one of claims 9 to 11, wherein ​ The manufacturing method includes: a flattening process for flattening the solder pre-coating portion before the first arrangement process.

13. The manufacturing method according to claim 12, wherein The flattening process is performed in a state where the circuit substrate is supported by a flat support table.

14. The manufacturing method according to claim 13, wherein Each process for mounting the plurality of second components on the second face is performed in a state where the circuit substrate is supported by a support unit of a configuration that does not interfere with the plurality of first components that are brazed to the first face.

Images