WO2005072032A1

WO2005072032A1 - Circuit board, mounting structure of circuit board, and mounting method for circuit board

Info

Publication number: WO2005072032A1
Application number: PCT/JP2005/000887
Authority: WO
Inventors: Naomi Ishizuka; Yoshifumi Kanetaka
Original assignee: Nec Corporation
Priority date: 2004-01-26
Filing date: 2005-01-25
Publication date: 2005-08-04
Also published as: JPWO2005072032A1

Abstract

A solder dam (10) is formed around a surface land (6) on a circuit board (1). A part receiver (11) for ensuring that the installation height of an insertion type electronic part is a predetermined height is provided. An electronic part (13) is flow-soldered in a state that it is lifted over the board.

Description

Specification

Circuit board, mounting structure of circuit board, and mounting method of circuit board

Technical field

The present invention relates to a circuit board for soldering a plug-in type electronic component with lead-free solder, and

In particular, with regard to the mounting structure and mounting method using the same, particularly, a plug-in type electronic component is mounted on a circuit board having lands on the front and back surfaces, and the front and back lands are connected by plated through holes. The present invention relates to a circuit board to be mounted, a mounting structure using the same, and a mounting method.

Background art

[0002] On a circuit board, a number of electronic components, such as a force S, a connector, and a variable resistor, on which many leadless electronic components are surface-mounted, have leads as insertable electronic components. It is inserted into a ted through hole (hereinafter simply referred to as a through hole) and soldered. FIG. 1 is a cross-sectional view of a soldered portion showing a conventional mounting structure of an insertion-type electronic component on a circuit board.

[0003] A circuit board used for mounting electronic components is manufactured as follows, taking the most common subtractive method as an example. A copper-clad laminate made by applying pressure and heat treatment to a copper foil on a laminate of a pre-predator impregnated with a thermosetting resin such as epoxy resin on a base material obtained by folding glass or the like into a fibrous form. Then, a copper foil is patterned to produce a wiring board having a predetermined number of inner layer patterns, and the wiring board and the copper-clad laminate are laminated via a pre-preder so that the copper-clad laminate becomes the outermost layer. Then, the substrates are integrated by pressurizing and heating to produce a substrate having the inner layer wiring 3 in the resin laminate 2.

[0004] Next, an opening 5 is formed by drilling, an activation process, electroless plating, and electrolytic plating are performed to form a through hole 8. Subsequently, patterning of the outermost copper layer is performed to form the outer layer wiring 4 and, at the same time, the substrate surface side (in this specification, the mounting surface of the insertion type electronic component is the front surface side, and The front surface land 6 is formed on the back surface, and the back surface land 7 is formed on the back surface side.

[0005] After that, a photosensitive solder resist material is applied to a region excluding a soldered portion on the front and back surfaces of the substrate. Print-coat and expose to form solder resist 9. Finally, although not shown, a white display paint is applied by a screen printing method or the like to form a display symbol such as a mounting position of the electronic component, a component number, a board number, and the like, thereby manufacturing the circuit board 1. The process is completed.

[0006] The process of soldering electronic components using the circuit board 1 manufactured as described above generally involves mounting a chip component or a surface mount type component such as a QFP (Quad Flat Package). After performing the reflow step, a flow step of mounting the import-type electronic component is performed. In the reflow process, solder is supplied to the land for mounting surface-mounted components on the circuit board, and a thermosetting adhesive for temporary fixing is applied to prevent falling and component displacement, and then surface mounting is performed. Soldering is performed by mounting the mold parts and heating them in a reflow oven. In the next flow step, the electronic component is mounted by inserting the lead 12 of the insertable electronic component 13 into the through hole 8, and in that state, the solder is brought into contact with the molten solder using a wave solder bath or the like. Then, soldering is performed. As a result, a solder fillet 14 is formed, and the lead 12 is electrically and mechanically coupled to the lands 6, 7 and the through hole 8. If surface-mounted components are also mounted on the back side of the circuit board, the surface-mounted components are soldered together with the insert-type electronic components in this flow step. In this case, a thermosetting adhesive for temporary fixing is applied, surface-mounted components such as chip components are mainly mounted, the adhesive is cured by heating, and then the insertion-type electronic components 13 are mounted. And perform flow soldering.

[0007] In the conventional mounting method, the solder used in the reflow step and the flow step is tin-lead eutectic solder. In recent years, however, environmental pollution due to lead has led to an increase in environmental consciousness, and a shift to lead-free solder that does not contain lead is in progress. This lead-free solder contains tin as a main component and is made of silver, copper, zinc, bismuth, indium, antimony, nickel, germanium, or the like.

[0008] Currently, the main lead-free solders are tin-zinc-based solders (tin-9, Owt% Zn, which is a eutectic composition of tin-zinc, and the amount of zinc is changed or other elements are added. The solders with improved characteristics are collectively referred to as tin-zinc-based solders, such as Sn-8.OZn-3.OBi) or tin-copper-based solder (Sn-0, a eutectic composition of tin-copper). With a focus on 7wt% Cu, the amount of copper changed or other elements added to improve the characteristics are collectively referred to as tin-copper solder. The amount of silver can be changed or other elements can be added, centered on Sn-0.7Cu-0.3Ag) or tin-silver solder (Sn-3.5wt% Ag, which is the eutectic composition of tin-silver). Those with improved characteristics are collectively referred to as “tin-silver based solders.” Typical columns are Sn-3.OAg-0. 5Cu, Sn_3.5Ag-0.

[0009] These lead-free solders have higher tensile strength and creep strength and elongation of metal than the tin-lead eutectic solder (Sn 63wt%, remaining Pb), which has been used most frequently for soldering of electronic equipment. It has the metal characteristic that there is little. For this reason, stress relaxation is less likely to occur in the soldered part than in lead solder.In addition, the melting temperature of tin-lead eutectic solder is 183 ° C, whereas that of lead-free solder is 190 ° C-230 ° C. Because of the increase, residual stress due to the difference in thermal expansion after solder solidification tends to increase.

[0010] FIGS. 2, 3, and 4 are cross-sectional views showing states of leads and solder fillets after soldering an electronic component having a housing made of a polyamide resin using a lead-free solder on a conventional circuit board. It is. 2, the right side of the figure shows the center of the electronic component 13, and the left side of the figure shows the end of the electronic component 13. Table 1 shows the coefficient of thermal expansion between the glass epoxy resin laminate as the substrate material of the circuit board 1 and the polyamide resin as the housing material of the electronic component 13. As can be seen from Table 1, there is a large difference in the coefficient of thermal expansion between the board material and the electronic component housing in the horizontal direction of the circuit board.

[0011] [Table 1]

As shown in FIG. 2, the lead 12 fixed with lead-free solder is greatly inclined from the center of the electronic component 13 to the end. In FIG. 2, the inclination of the lead is exaggerated. Actually, the lead 12 located at the end is inclined by about half the radius of the lead with respect to the center of the through hole 8. Therefore, the thermal expansion coefficient of the housing of the electronic component 13 and On the other hand, due to the mismatch with the thermal expansion coefficient of the substrate material of the circuit board 1, a large stress is applied particularly to the lead 12 at the end. Accordingly, a great deal of stress is generated in the through hole into which the lead 12 at the end is inserted and the solder fillet formed therein. Conventionally, since the tin-lead eutectic solder is very susceptible to creep deformation, even if such stress is generated, the stress has been absorbed by the creep deformation of the solder itself. However, in the case of the lead-free solder 6 in which the creep resistance of the solder itself is several tens to several hundred times that of the tin-lead eutectic, the effect of reducing the stress as much as the tin-lead eutectic solder cannot be expected.

[0013] Further, as the melting temperature increases, a large stress is generated due to thermal expansion / contraction, and a phenomenon occurs in which the through-hole plating peels from the substrate (hereinafter, referred to as through-hole peeling). Disconnection will occur in the periphery. Figure 3 shows the state where through-hole peeling 15 has occurred. The through-hole peeling 15 tends to occur mainly when the mismatch between the thermal expansion coefficient of the housing of the electronic component 13 and the thermal expansion coefficient of the circuit board 1 is large. In the X-Y direction (the direction of the board surface) is concentrated on the through-hole plating and the interface of the circuit board 1

When a lead-free solder is used, a phenomenon that the surface land 6 peels off from the substrate surface (hereinafter referred to as land peeling) as shown in FIG. 4 is also confirmed. Due to the higher melting point of the lead-free solder, the land peeling 16 solidifies earlier at a higher temperature than the solder fillet 14 of lead-free solder formed on the surface land 6 and the eutectic tin-tin solder. Therefore, the amount of shrinkage of the circuit board 1 in the Z direction after the solder fillet 14 is formed on the surface increases, and the stress is concentrated on the end of the solder fillet 14.

[0015] These problems do not occur on a single-sided circuit board having lands and wiring patterns formed only on one side. On the single-sided board, insert the lead of the plug-in type electronic component. The through-hole is formed. The through-hole is not formed by electrolytic plating. Also, since no force lands (corresponding to the back surface lands of the present invention) are formed on one side, there is no object hitting the front surface lands on the electronic component side, and no solder fillets are formed. Furthermore, since only the rear surface land is soldered on a single-sided circuit board, the leads are in a free state in which the leads are not fixed in the through holes of the circuit board and on the electronic component side. Therefore, the solder There is no stress concentration at the attachment part, and no through-hole peeling or land peeling occurs on the electronic component side.

However, as shown in FIG. 2, the front surface land 6 and the rear surface land 7 are provided on the front and rear surfaces so as to sandwich the resin laminate 2, and the front surface land 6 and the rear surface In a double-sided or multilayer circuit board in which solder fillets are formed on both of the lands 7, residual stress and the resulting through-hole peeling and land peeling have a serious effect on reliability. In recent years, high densification and high performance have been accelerated, and multilayer circuit boards have become essential.

Disclosure of the invention

The present invention has been made to solve the above problems, and an object of the present invention is to prevent through-hole peeling even when soldering with lead-free solder. An object of the present invention is to provide a circuit board having high performance and a mounting structure and a mounting method thereof.

According to the present invention, in order to achieve the above object, according to the present invention, there is provided a conductive through hole into which a lead of a leaded component is inserted and soldered, and a surface land is mounted on a mounting surface of the leaded component, and vice versa. A circuit board having a back surface land electrically connected to the front land via the conductive through hole on a side surface, a component for restricting a mounting height of the lead component on a mounting surface of the lead component. A circuit board characterized by having a plurality of receivers is provided.

[0019] Preferably, a land coating is formed on the mounting surface of the component with leads to cover the peripheral edge of the surface land.

Further, in order to achieve the above object, according to the present invention, the surface land is mounted on the mounting surface of the leaded component, and the surface land is electrically connected to the surface land via the conductive through hole on the opposite surface. The circuit is mounted in such a manner that the lead is inserted into the conductive through hole and soldered to the mounting surface of the leaded component of the circuit board having the back surface land connected to the lead. A circuit board mounting structure is provided, wherein a plurality of component receivers for regulating the mounting height of the leaded component are provided on the circuit board below the leaded component. Is done.

Further, according to the present invention, in order to achieve the above object, a surface on a mounting surface of a component with leads is provided. The mounting height of the leaded component is mounted on the mounting surface of the leaded component of the circuit board having the back surface land electrically connected to the surface land via a conductive through hole on the opposite surface. A first step of providing a plurality of component receivers for regulating the components, and a second step of mounting the component with leads by inserting the leads into the conductive through-holes and soldering. A method for mounting a circuit board is provided.

According to the present invention having the above configuration, a constant distance (stand-off) can be secured between the circuit board and the bottom surface of the plug-in electronic component. This suppresses deformation of the leads of the electronic component when the molten solder solidifies and the electronic components and the circuit board shrink, and is generated in the leads and solder fillets due to the difference in the thermal expansion coefficient between the electronic component housing and the circuit board. Stress can be reduced. This situation will be described more specifically with reference to FIG. FIG. 5 illustrates two leads of the plug-in type electronic component.It is assumed that the lead 12a on the left side is fixed and the lead 12b on the right side is deformed due to a thermal change between the leads 12a and 12b. Model is shown. When the electronic component 13 having the leads 12a and the leads 12b is mounted on the circuit board 1 and flow soldering is performed with lead-free solder, the electronic component 13 and the circuit board 1 are heated and then returned to room temperature. These cause thermal deformation at the ratio of the coefficient of thermal expansion ay (82 ppm / ° C) of the 13 case and the coefficient of thermal expansion (XY direction) _ax (16 ppm / ° C) of the circuit board 1. At this time, the lead 12b is on the housing side of the electronic component, and the force to be deformed by the ratio of a y_ct x = α ζ If the standoff L is large, the lead 12b is only the width W in the X—Y direction. If the standoff is as small as 1 /, the displacement of the lead 12b will be a large displacement as shown by the width W ', and a large stress will be applied to the soldered part and the through hole. . Therefore, by increasing the standoff L, the displacement of the lead 12b can be suppressed to a small value, and the force S for suppressing an increase in stress generated in the through hole can be suppressed.

[Table 2] Parts Thermal expansion coefficient Enclosure Hand-stand Stando Temperature cycle test

(ppn / :) Bin diameter (ran) F L (咖) Number of disconnection cycles (eye) Part A 20 0.3 1.5 2> 1000

Part B 83 0.3 1.5> 1000

Part C 82 1.14 9.0> 1000

83 0.64 0.1 7 300 Parts Ε 82 1.25 1.0 2 14

Tokyo i¾F 82 1.14 0.3 6 1

[0024] Table 2 shows electronic components having different thermal expansion coefficients y, pin diameters in the longitudinal direction of the housing, and standoffs L, respectively, at -40 ° C (30 minutes) and 25. This is a table showing the relationship between the number of disconnection cycles until disconnection when a temperature cycle test was performed with one cycle of C (5 minutes) and 125 ° C (30 minutes). Thus, like parts D, E, and F, the thermal expansion coefficient ay of the housing is 80 ppm / ° C or more, the pin diameter in the longitudinal direction of the housing is 0.5 mm or more, and the standoff is: !. With electronic components 4 of Omm or less, very large stress is generated in the soldered part, so it is clear that disconnection is easy at an early stage. These components are particularly prone to through-hole peeling as shown in Fig. 3 and have a significant impact on reliability immediately. However, if the standoff L is large as in the case of component C, even if the electronic component has a thermal expansion coefficient ay of 80 ppm / ° C or more and a pin diameter in the longitudinal direction of the housing of 0.5 mm or more, the lead of Since the amount of deformation is small, the concentration of stress on the soldered portion and the circuit board can be reduced. Therefore, it is desirable that the height of the component receiver viewed from the board surface be determined based on the board material of the circuit board, the coefficient of thermal expansion of the electronic component housing, and the diameter of the lead of the electronic component.

[0025] As described above, according to the present invention in which the component receiver is provided between the circuit board and the electronic component, it is possible to secure a certain or more standoff between the circuit board and the electronic component. Therefore, the occurrence of peeling of through holes can be suppressed, and the reliability of the mounting structure using the circuit board can be improved.

Here, in the method of increasing the standoff L, it is not necessary to change design specifications such as a component housing material and a pin diameter.

According to the configuration in which the peripheral edge of the surface land is covered with the insulating film, it is possible to prevent the solder from spreading to the edge of the surface land and to spread the solder to the edge of the surface land. Fillet stress is no longer applied, and it is easy to follow the thermal expansion and contraction of the circuit board, so that the concentration of stress on the peripheral portion can be reduced and land separation can be prevented.

Brief Description of Drawings

FIG. 1 is a cross-sectional view showing a conventional mounting structure.

FIG. 2 is a cross-sectional view for explaining a problem of a conventional example.

FIG. 3 is a cross-sectional view showing a problem of a conventional example.

FIG. 4 is a cross-sectional view showing a problem of a conventional example.

FIG. 5 is a cross-sectional view showing a mounting structure for explaining advantages of the present invention.

FIG. 6A is a sectional view showing a circuit board according to the first exemplary embodiment of the present invention.

FIG. 6B is a sectional view showing a mounting structure according to the first embodiment of the present invention.

FIG. 7A is a sectional view showing a circuit board according to a second exemplary embodiment of the present invention.

FIG. 7B is a sectional view showing a mounting structure according to the second embodiment of the present invention.

FIG. 8A is a cross-sectional view showing a mounting structure according to Example 1 of the present invention.

FIG. 8B is a plan view showing a mounting structure according to Example 1 of the present invention.

FIG. 9A is a cross-sectional view showing a mounting structure according to Example 2 of the present invention.

FIG. 9B is a plan view showing a mounting structure according to Example 2 of the present invention.

FIG. 10A is a cross-sectional view showing a mounting structure according to Example 3 of the present invention.

FIG. 10B is a plan view showing a mounting structure of Embodiment 3 of the present invention.

FIG. 11A is a sectional view showing a mounting structure according to Example 4 of the present invention.

FIG. 11B is a plan view showing a mounting structure according to Example 4 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

A preferred embodiment of a circuit board according to the present invention and a mounting structure using the same will be described below in detail with reference to the drawings.

FIGS. 6A and 6B are cross-sectional views showing the first embodiment of the present invention. As shown in FIG. 6A, the circuit board 1 has a resin laminate 2 made of glass epoxy or the like as a substrate material, and has an inner wiring 3 therein and an outer wiring 4 on its outer surface. An opening 5 is formed in the lead insertion portion of the circuit board, and a front land 6 and a back land 7 are formed around the opening on the front and rear surfaces of the substrate. Front land 6 and rear land 7 are through holes (Plated through holes) 8 electrically connected. FIGS. 6A and 6B show examples having two layers of inner layer wirings 3, but the number of layers is not limited. Further, a double-sided circuit board having no inner layer wiring may be used. Areas other than the soldering locations on the front and back surfaces of the substrate are covered with solder resist 9.

The peripheral edge of the surface land 6 on the substrate surface is covered with a solder dam 10 for preventing the solder from spreading. The solder dam can be formed by printing a heat-resistant resin using a screen printing method or the like. Also, when the component mounting position, part number, board number, etc. are printed on the board surface using a white display paint, the same paint may be used. Accordingly, it is possible to prevent the man-hour for forming the solder dam 10 from increasing. Although not shown, a solder dam covering the peripheral edge may be formed on the back surface land 7. Thereby, the reliability can be further improved.

[0032] On the surface of the substrate, there is provided a component receiver 11 for regulating the mounting height of the plug-in electronic component. The location of the component receiver 11 may be just below the electronic components to be mounted, and the location is not particularly limited. Also, the number of installations is not limited as long as it is several or more. The component receiver 11 can be formed by printing and applying a heat-resistant resin once or a plurality of times. Also, when printing and applying a thermosetting adhesive for temporarily fixing the surface mount type component, the component receiver 11 may be formed simultaneously using the same material. This can prevent an increase in man-hours for forming the component receiver 11. 6A and 6B show an example in which the component receiver 11 is provided at a position different from that of the solder dam 10, but the component receiver 11 may be provided on the solder dam 10. This makes it possible to efficiently form the component receiver 11 having a required altitude.

The component receiver 11 can be formed by bonding a spacer made of resin, metal or ceramic instead of a method of printing and applying a resin composition or the like by a printing method. The adhesive used in this case may be simultaneously applied using the same material when printing and applying an adhesive for temporarily fixing the surface-mounted electronic component. Alternatively, the component receiver 11 may be formed of a material that can be soldered at least partially, and may be soldered on the board in a reflow soldering process. In this case, it is desirable to perform the reflow soldering with the component receiver 11 temporarily fixed with an adhesive. FIG. 6B is a cross-sectional view showing a state where electronic components are mounted on the circuit board according to the first embodiment of the present invention shown in FIG. 6A. Although not shown, it is assumed that before mounting the electronic component 13 shown in FIG. 6B, the mounting of the surface-mounted electronic component has been completed. The electronic component 13 is mounted on the circuit board 1 by inserting the lead 12 into the through hole 8 of the circuit board. At this time, since the bottom surface of the electronic component 13 contacts the top surface of the component receiver 11, a certain level of standoff can be secured. In this state, the back surface of the substrate is immersed in a wave solder bath or the like to perform flow soldering. Thus, the leads 12 of the electronic component 13 and the through holes 8, the front lands 6, and the rear lands 7 of the circuit board 1 are electrically and mechanically coupled by the solder fillets 14.

After completion of the flow soldering, the electronic component 13 is often fixed with its bottom surface in contact with the component receiver 11 as shown in FIG. 6B, but is floated and fixed from the component receiver 11. There are things.

FIGS. 7A and 7B are a cross-sectional view of a circuit board according to the second embodiment of the present invention and a cross-sectional view showing a state where electronic components are mounted on the circuit board. In FIGS. 7A and 7B, parts that are the same as the parts of the first embodiment shown in FIGS. 6A and 6B are given the same reference numerals, and overlapping descriptions are omitted. The difference from the first embodiment shown in FIGS. 6A and 6B of the present embodiment is that no solder dam is formed, and solder-resist 9 replaces front surface land 6 and rear surface land 7. The point extending to the peripheral edge and the point where the component receiver 11 is formed into a spherical body.

[0037] The component receiver 11 is formed of resin, metal, or ceramics, and is bonded by an adhesive previously applied to a substrate. Alternatively, a spherical body having a surface coated with an adhesive may be arranged on the substrate.

Example 1

Example 1 of the present invention will be described with reference to FIGS. 8A and 8B. 8A is a cross-sectional view illustrating a structure in which electronic components are mounted on the circuit board according to the first embodiment of the present invention, and FIG. 8B is a perspective plan view when FIG. 8A is viewed from the upper side of the electronic components. is there. 8A and 8B, parts that are the same as the parts in the embodiment shown in FIGS. 6A and 6B, and FIGS. Omitted as appropriate To do. The same applies to the other embodiments shown in FIGS. 9A to 11B.

In the first embodiment, the solder dam 10 is formed by using a display paint used for marking and printing of electronic components, component numbers, board numbers, and the like. Then, in the process of forming the display portion, a solder dam is also formed at the same time. In addition, display paints have demonstrated heat resistance to heat applied during soldering.

Further, in the present embodiment, the component receiver 11 is formed on the solder dam 10 by using a thermosetting adhesive used for temporarily fixing the surface mount type electronic component. . And since the component receiver 11 is formed in the adhesive layer forming step for temporarily fixing the surface mount type component, the number of steps is not increased.

Example 2

FIG. 9A is a cross-sectional view showing a structure in which an electronic component is mounted on a circuit board according to the second embodiment of the present invention. FIG. 9B is a perspective plan view when FIG. 9A is viewed from the upper surface on the electronic component side. FIG.

In the present embodiment, the solder resist 9 used to protect the outer layer wiring 4 on the substrate surface is applied so as to extend to the peripheral edge of the surface land 6. The component receiver 11 is formed at a position away from the surface land 6 by using a thermosetting adhesive that is a temporary fixing adhesive.

Example 3

FIG. 10A is a cross-sectional view showing a structure in which electronic components are mounted on a circuit board according to Embodiment 3 of the present invention. FIG. 10B is a perspective view when FIG. 10A is viewed from the upper surface on the electronic component side. It is a top view.

In the present embodiment, the solder dam 10 is formed using a thermosetting adhesive for temporarily fixing the surface mount electronic component. Then, a component receiver 11 which is a spacer made of resin is adhered to the substrate by an adhesive constituting the solder dam 10.

Example 4

FIG. 11A is a cross-sectional view showing a structure in which electronic components are mounted on a circuit board according to Embodiment 4 of the present invention. FIG. 11B is a perspective view when FIG. 11A is viewed from the upper surface on the electronic component side. It is a top view. In this embodiment, no solder dam is formed, and the solder resist 9 is extended to the peripheral edge of the surface land 6 as in the second embodiment. The component receiver 11 has a configuration in which the surface of a resin ball 1 la, which is a resin sphere, is covered with 1 lb of an adhesive. The component receiver 11 is provided by arranging a resin ball on which a thermosetting adhesive is applied in advance on a substrate and performing heat treatment to cure the adhesive.

Claims

The scope of the claims

[1] There is a conductive through hole into which the lead of the leaded component is inserted and soldered. A surface land is provided on the mounting surface of the leaded component, and the conductive land is provided on the opposite surface through the conductive through hole. In a circuit board having a back land electrically connected to the front land,

A circuit board, wherein a plurality of component receivers for regulating a mounting height of the leaded component are provided on a mounting surface of the leaded component.

2. The circuit board according to claim 1, wherein a land coating covering a peripheral portion of the surface land is formed on a mounting surface of the component with leads.

3. The circuit board according to claim 2, wherein the land coating covers the entire periphery of the peripheral edge of the surface land.

4. The circuit board according to claim 2, wherein the component receiver is formed on the land coating.

[5] The circuit board according to any one of claims 2 to 4, wherein the component receiver is formed of a thermosetting adhesive.

6. The circuit board according to claim 4, wherein the component receiver is formed by bonding a spacer formed of resin, metal, or ceramic. .

[7] The solder resist is formed on the front and back surfaces of the circuit board, and the land film is formed of a solder resist material as an extension of the solder resist. The circuit board according to item 4;

[8] The circuit board according to any one of claims 2 to 7, wherein the land coating is formed of a heat-resistant resin.

[9] The circuit board according to any one of claims 2 to 8, wherein the land coating is formed of the same material as a display portion formed on the front and back surfaces of the circuit board. .

[10] The force according to any one of [1] to [6], wherein a back surface land coating is formed on a surface opposite to a mounting surface of the leaded component to cover a periphery of the back surface land. Description Circuit board.

11. The circuit board according to claim 10, wherein a solder resist is formed on the front and back surfaces of the circuit board, and the land coating on the back surface is formed of a solder resist material as an extension of the solder resist. The circuit board according to claim 1.

12. The circuit board according to claim 10, wherein the back surface land coating is formed of a heat-resistant resin.

13. The force according to claim 10, wherein the back surface land film is formed of the same material as a display portion formed on the front surface and the back surface of the circuit board. Circuit board.

[14] The component with a lead of the circuit board having a surface land on the mounting surface of the component with the lead and a rear surface land electrically connected to the surface land via a conductive through hole on the opposite surface. In a circuit board mounting structure in which a component with a lead is mounted on a mounting surface and the lead is inserted into the conductive through hole and soldered, the circuit board below the component with the lead is A circuit board mounting structure comprising a plurality of component receivers for regulating a mounting height of a component with a lead.

15. The circuit board mounting structure according to claim 14, wherein a bottom surface of the housing of the component with leads is in contact with a top of at least one of the component receivers.

16. The circuit board mounting structure according to claim 14, wherein a thermal expansion coefficient of a material of a housing of the component with a lead is larger than a thermal expansion coefficient of a substrate material of the circuit board.

17. The circuit board mounting structure according to claim 14, wherein the leads of the component with leads are soldered with lead-free solder.

[18] The height of the component receiver as viewed from the substrate surface is determined based on the substrate material of the circuit board, the coefficient of thermal expansion of the component with the lead, and the diameter of the lead of the component with the lead. 18. The mounting structure for a circuit board according to claim 4, wherein the circuit board has a force of any one of claims 14 to 17.

[19] The lead of the circuit board having a surface land on the mounting surface of the component with leads and a back land electrically connected to the surface land via a conductive through hole on the opposite surface. A first step of providing a plurality of component receivers for regulating the mounting height of the leaded component on the mounting surface of the component with a lead,

A second step of mounting the leaded component by inserting the lead into the conductive through hole and soldering the component;

A method for mounting a circuit board, comprising:

20. The circuit board mounting method according to claim 19, wherein the first step is a step of forming a component receiver by applying a heat-resistant adhesive.

[21] The first step is a step of forming a component receiver by a step of applying a heat-resistant adhesive and a step of bonding a spacer to a circuit board using the heat-resistant adhesive. 20. The method for mounting a circuit board according to claim 19, wherein the method is characterized in that:

[22] In the step of applying the heat-resistant adhesive in the first step, a heat-resistant adhesive for temporarily fixing the surface-mounted component is simultaneously applied to the mounting portion of the surface-mounted component, and the second step is performed. 22. The circuit board mounting method according to claim 20, wherein a step of mounting the surface mount component by reflow is added prior to the step.

23. The method according to claim 19, wherein a step of forming a land coating covering the peripheral portion of the surface land is added prior to the first step, and the component receiver is provided on the land coating. 23. The method of mounting a circuit board according to any one of 22.

24. The circuit board mounting method according to claim 23, wherein, in the step of forming the land film, a display portion is formed simultaneously using a material forming the land film.