JPWO2005072032A1 - Circuit board, circuit board mounting structure, and circuit board mounting method - Google Patents

Abstract

A solder dam 10 is formed on the peripheral edge of the surface land 6 on the circuit board 1, and a component receiver 11 is provided for securing a mounting height of the insertion type electronic component to a predetermined height. Flow soldering is performed with the electronic component 13 floating from the substrate.

Description

  The present invention relates to a circuit board for soldering an insertion-type electronic component with lead-free solder, and a mounting structure and mounting method using the circuit board. In particular, the present invention has lands on the front and back surfaces, and the space between the front and back lands is between The present invention relates to a circuit board for mounting an insertion-type electronic component on a circuit board connected by a plated through hole, a mounting structure using the circuit board, and a mounting method.

  Many leadless electronic components are surface-mounted on a circuit board, but some electronic components such as connectors and variable resistors have plated through holes (hereinafter referred to as “inserted electronic components”). , Simply referred to as through-holes) and soldered. FIG. 1 is a cross-sectional view of a soldering portion showing a conventional structure for mounting an insertion-type electronic component on a circuit board.

  A circuit board used for mounting electronic components is manufactured as follows by taking the most common subtractive method as an example. Using a copper-clad laminate in which a copper foil is pasted on a laminate of a prepreg in which a thermosetting resin such as an epoxy resin is impregnated into a base material in which glass or the like is folded into a fiber shape, Patterning the copper foil to produce a wiring board having a predetermined number of inner layer patterns, laminating the wiring board and the copper-clad laminate through a prepreg so that the copper-clad laminate is the outermost layer, and heating with pressure And a substrate having the inner layer wiring 3 in the resin laminate 2 is produced.

  Next, an opening 5 is formed by drilling, and activation treatment, 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 the substrate surface side (in this specification, the mounting surface of the insertion type electronic component is the surface side, and the opposite surface is The front surface land 6 is formed on the back surface side, and the back surface land 7 is formed on the back surface side.

  Thereafter, a photosensitive solder resist material is printed and applied to the areas other than the soldered portions on the front and back surfaces of the substrate, and exposed to form a solder resist 9. Finally, although not shown, a white display paint is applied by a screen printing method or the like to form display symbols such as electronic component mounting positions, component numbers, and board numbers. The process is complete.

  The process of soldering an electronic component using the circuit board 1 manufactured in this way is generally a reflow process for mounting a surface mount type component such as a chip component or a QFP (Quad Flat Package). Thereafter, a flow process for mounting the insertion type electronic component is performed. In the reflow process, solder paste is supplied to the lands for mounting the surface-mounted components on the circuit board, and after applying a temporary fixing thermosetting adhesive to prevent falling and component displacement, the surface-mounted components are mounted. And soldering by heating in a reflow furnace or the like. In the next flow step, the electronic component is mounted by inserting the lead 12 of the insertion-type electronic component 13 into the through hole 8, and in that state, the molten solder is brought into contact with a wave solder tank or the like. By soldering. As a result, a solder fillet 14 is formed, and the lead 12 is electrically and mechanically coupled to the lands 6 and 7 and the through hole 8. When mounting a surface-mounted component on the back side of the circuit board, the surface-mounted component is soldered simultaneously with the insertion-type electronic component in this flow step. In this case, a thermosetting adhesive for temporary fixing is applied, a surface-mounted component such as a chip component is mainly mounted and the adhesive is cured by heating, and then an insertion-type electronic component 13 is mounted. , Flow soldering.

  In the conventional mounting method, the solder used in the reflow process and the flow process is a tin-lead eutectic solder. However, in recent years, environmental pollution caused by lead has been increasingly switched to lead-free solders that do not contain lead due to the growing environmental awareness. This lead-free solder is mainly composed of tin, and is made of silver, copper, zinc, bismuth, indium, antimony, nickel, germanium, or the like.

  Currently, the main lead-free solder is tin-zinc-based solder (mainly Sn-9.0wt% Zn, which is a eutectic composition of tin-zinc), and the amount of zinc can be changed or other elements added The tin-zinc-based solder is generally referred to as Sn-8.0Zn-3.0Bi) or tin-copper-based solder (Sn-0.7 wt% Cu, which is a eutectic composition of tin-copper). In general, tin-copper-based solders whose characteristics are improved by changing the amount of copper or by adding other elements are referred to as tin-copper solders, typical examples being Sn-0.7Cu-0.3Ag) and tin Silver-based solder (Sin-silver-based solder is a generic term for Sn-3.5wt% Ag, which is the eutectic composition of tin-silver, whose characteristics are improved by changing the amount of silver or adding other elements. Typical examples include solder (Sn-3.0Ag-0.5Cu, Sn-3.5Ag-0.75Cu).

  These lead-free solders have higher metal tensile strength, creep strength, and less elongation compared to tin-lead eutectic solder (Sn63 wt%, remaining Pb), which has been used most often for soldering electronic devices. have. For this reason, stress relaxation is less likely to occur in the soldered part than lead solder, and the melting temperature is higher at 190 ° C. to 230 ° C. for lead-free solder than that of tin lead eutectic solder is 183 ° C. Residual stress due to thermal expansion difference after solder solidification tends to increase.

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

  As shown in FIG. 2, the lead 12 fixed with lead-free solder is greatly inclined as it goes from the center of the electronic component 13 to the end. In FIG. 2, the inclination of the lead is shown exaggerated from the actual. Actually, the lead 12 located at the end is inclined about half the radius of the lead with respect to the center of the through hole 8. Therefore, due to the mismatch between the thermal expansion coefficient of the casing of the electronic component 13 and the thermal expansion coefficient of the substrate material of the circuit board 1, particularly a large stress is applied to the lead 12 at the end. Along with this, a great amount of stress is generated in the through hole into which the lead 12 at the end is inserted and the solder fillet formed there. Conventionally, tin-lead eutectic solder is very susceptible to creep deformation, so even if such stress occurs, the stress has been absorbed by the creep deformation of the solder itself. However, in 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 stress relaxation as that of the tin-lead eutectic solder cannot be expected.

  Furthermore, due to the high melting temperature, a large stress is generated due to thermal expansion / contraction, causing a phenomenon that the through-hole plating peels from the substrate (hereinafter referred to as through-hole peeling), and disconnection occurs around the through-hole. Will occur. FIG. 3 shows a state where the through-hole peeling 15 has occurred. This 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, and the circuit board 14 generated at the time of soldering is observed. The stress in the X-Y direction (substrate surface direction) is concentrated at the interface between the through-hole plating and the circuit board 1.

  In addition, when lead-free solder is used, a phenomenon in which the surface land 6 peels from the substrate surface (hereinafter referred to as land peeling) as shown in FIG. 4 is also confirmed. Since the land peeling 16 has a higher melting point of the lead-free solder, the leadless solder fillet 14 formed on the surface land 6 is first solidified at a higher temperature than the tin-lead eutectic solder. The shrinkage in the Z direction of the circuit board 1 after the solder fillet 14 is formed on the surface increases, and stress is concentrated on the end of the solder fillet 14.

  These problems do not occur in a single-sided circuit board in which lands and wiring patterns are formed only on one side. On the single-sided substrate, a through hole for inserting a lead of an insertion type electronic component is formed, but an electrolytic plated through hole is not formed. Further, since the land (corresponding to the back surface land of the present invention) is formed only on one side, there is nothing on the electronic component side that hits the front surface land, and no solder fillet is formed. Furthermore, since soldering is performed only on the back surface land side in the single-sided circuit board, the lead is in a free state in which the inside of the through hole of the circuit board and the electronic component side are not fixed. Therefore, stress concentration does not occur in the soldered portion, and through-hole peeling, land peeling, etc. do not occur on the electronic component side.

  However, as shown in FIG. 2, both 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 both the front surface land 6 and the rear surface land 7 are interposed through the through holes 8. In a double-sided or multilayer circuit board on which a solder fillet is formed, residual stress and accompanying through-hole peeling and land peeling are serious problems that affect reliability. Thus, in recent years, higher density and higher performance are accelerating, and multilayer circuit boards are essential.

  The present invention has been made to solve the above problems, and its purpose is to provide a highly reliable circuit board that does not cause through-hole peeling even when soldering with lead-free solder. It is to provide a mounting structure and a mounting method.

  In order to achieve the above object, according to the present invention, there is a conductive through hole into which a lead of a component with lead is inserted and soldered, and a surface land is provided on the mounting surface of the component with lead, and the surface on the opposite side. In the circuit board having a back surface land electrically connected to the front surface land through the conductive through hole, a plurality of component receivers for regulating the mounting height of the leaded component are provided on the mounting surface of the leaded component. A circuit board is provided.

  Preferably, a land coating for covering the peripheral edge of the surface land is formed on the mounting surface of the leaded component.

  In order to achieve the above object, according to the present invention, a surface land is electrically connected to the mounting surface of the leaded component, and the surface on the opposite side is electrically connected to the surface land via a conductive through hole. In a circuit board mounting structure in which a component with a lead is mounted on a mounting surface of a component with a lead on a circuit board having a back surface land, and the lead is inserted and soldered into the conductive through-hole. A circuit board mounting structure is provided in which a plurality of component receivers for regulating the mounting height of the leaded component are provided on the circuit substrate under the leaded component.

  In order to achieve the above object, according to the present invention, a surface land is electrically connected to the mounting surface of the leaded component, and the surface on the opposite side is electrically connected to the surface land via a conductive through hole. A first step of providing a plurality of component receivers for restricting the mounting height of the leaded component on the mounting surface of the leaded component of the circuit board having the back surface land; and the leaded component, the lead being the conductive through hole And a second step of mounting by soldering and mounting the circuit board.

  According to the present invention having the above configuration, a certain distance (standoff) can be ensured between the circuit board and the bottom surface of the insertion type electronic component. This suppresses the deformation of the lead of the electronic component when the molten solder solidifies and the electronic component or circuit board contracts, and occurs in the lead or solder fillet due to the difference in thermal expansion coefficient between the electronic component housing and the circuit board. To relieve stress. This situation will be described more specifically with reference to FIG. FIG. 5 simulates two leads of an insertion type electronic component. The model is based on the assumption that the left lead 12a is fixed and the right lead 12b is deformed due to thermal change between the leads 12a-12b. It is shown. When the electronic component 13 having the lead 12a and the lead 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, whereby the electronic component 13 The thermal expansion coefficient αy (82 ppm / ° C.) and the thermal expansion coefficient (XY direction) αx (16 ppm / ° C.) of the circuit board 1 cause thermal deformation. At this time, the lead 12b is deformed by a ratio of αy−αx = αz on the electronic component housing side. However, when the standoff L is large, the lead 12b is displaced by the width W in the XY direction. On the other hand, when the stand-off is as small as L ′, the displacement of the lead 12b becomes a large displacement amount as shown by the width W ′, and a large stress is applied to the soldered portion and the through hole. Therefore, by increasing the standoff L, it is possible to suppress the displacement of the lead 12b and to suppress an increase in stress generated in the through hole.

  Table 2 shows the electronic components having different thermal expansion coefficients αy, pin lengths in the longitudinal direction of the housing, and standoffs L from −40 ° C. (30 minutes) to 25 ° C. (5 minutes) to 125 ° C. (30 minutes). It is a table | surface which shows the relationship with the number of disconnection cycles until it reaches a disconnection at the time of performing a temperature cycle test for 1 cycle. As a result, like the parts D, E, and F, the thermal expansion coefficient αy of the casing is 80 ppm / ° C. or more, the pin diameter in the longitudinal direction of the casing is 0.5 mm or more, and the standoff is 1. It can be seen that in the electronic component 4 of 0 mm or less, a very large stress is generated in the soldered portion, and therefore, it is easy to break early. In these parts, through-hole peeling as shown in FIG. 3 is particularly likely to occur, which greatly affects the reliability. However, if the standoff L is increased as in the case of the component C, even if the electronic component has a thermal expansion coefficient αy 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 Since the amount of deformation is small, the stress concentration on the soldered portion and the circuit board can be reduced. Therefore, it is desirable that the height viewed from the substrate surface of the component receiver is determined based on the substrate material of the circuit substrate, the thermal expansion coefficient of the electronic component casing, and the lead diameter of the electronic component.

  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 ensure a certain standoff between the circuit board and the electronic component, thereby reducing the stress inside the through hole. It is possible to suppress the occurrence of peeling of the through hole and improve the reliability of the mounting structure by the circuit board.

  Here, the method of increasing the standoff L does not require changing design specifications such as the component housing material and the pin diameter.

  Moreover, according to the structure which coat | covers the peripheral part of a surface land with an insulating film, it can prevent a solder from spreading to the edge part of a surface land, and stress of a solder fillet is applied to the edge part of a surface land. Thus, it becomes easier to follow the thermal expansion / contraction of the circuit board, and the stress concentration on the peripheral edge can be relaxed to prevent land peeling.

It is sectional drawing which shows the conventional mounting structure. It is sectional drawing for demonstrating the problem of a prior art example. It is sectional drawing which shows the trouble of a prior art example. It is sectional drawing which shows the trouble of a prior art example. It is sectional drawing which shows the mounting structure for demonstrating the advantage of this invention. It is sectional drawing which shows the circuit board of the 1st Embodiment of this invention. It is sectional drawing which shows the mounting structure of the 1st Embodiment of this invention. It is sectional drawing which shows the circuit board of the 2nd Embodiment of this invention. It is sectional drawing which shows the mounting structure of the 2nd Embodiment of this invention. It is sectional drawing which shows the mounting structure of Example 1 of this invention. It is a top view which shows the mounting structure of Example 1 of this invention. It is sectional drawing which shows the mounting structure of Example 2 of this invention. It is a top view which shows the mounting structure of Example 2 of this invention. It is sectional drawing which shows the mounting structure of Example 3 of this invention. It is a top view which shows the mounting structure of Example 3 of this invention. It is sectional drawing which shows the mounting structure of Example 4 of this invention. It is a top view which shows the mounting structure of Example 4 of this invention.

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

  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 layer wiring 3 inside thereof and an outer layer wiring 4 on the outer surface thereof. An opening 5 is opened at a lead insertion portion of the circuit board, and a front surface land 6 and a rear surface land 7 are formed around the opening on the front and back surfaces of the substrate. The front surface land 6 and the back surface land 7 are electrically connected by a through hole (plated through hole) 8. 6A and 6B show an example having two layers of inner-layer wiring 3, but the number of layers is not limited. Further, it may be a double-sided circuit board having no inner layer wiring. The areas other than the soldering portions on the front and back surfaces of the substrate are covered with the 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. Further, when the component mounting position, the component number, the substrate number, and the like are printed on the surface of the substrate using the white display paint, they may be formed with the same paint. Thereby, the man-hour increase for forming the solder dam 10 can be prevented. Although not shown, a solder dam may also be formed on the back surface land 7 so as to cover its peripheral edge. Thereby, reliability can further be improved.

  A component receiver 11 is provided on the surface of the substrate for regulating the mounting height of the insertion type electronic component. The installation location of the component receiver 11 is not particularly limited as long as it is directly below the electronic component to be mounted. Also, the number of installations may be several or more, and there is no special limitation on this. The component receiver 11 can be formed by printing and applying a heat resistant resin once or a plurality of times. Moreover, when printing and applying a thermosetting adhesive for temporarily fixing the surface-mounted component, the component receiver 11 may be formed simultaneously using the same material. Thereby, the man-hour increase for forming the component receiver 11 can be prevented. 6A and 6B show an example in which the component receiver 11 is provided at a position different from the solder dam 10, the component receiver 11 may be provided on the solder dam 10. Thereby, the component receptacle 11 of required altitude can be formed efficiently.

  The component receiver 11 can be formed by bonding a resin, metal, or ceramic spacer 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 applied at the same time using the same material when printing and applying an adhesive for temporarily fixing the surface mount electronic component. Alternatively, the component receiver 11 may be formed of a material that can be soldered at least partially, and soldered onto the substrate in a reflow soldering process. In this case, it is desirable to perform 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 in the figure, it is assumed that the mounting of the surface mounting type electronic component is completed before mounting the electronic component 13 shown in FIG. 6B. An electronic component 13 is mounted on the circuit board 1 by inserting leads 12 into the through holes 8 of the circuit board. At this time, when the bottom surface of the electronic component 13 is in contact with the top surface of the component receiver 11, it is possible to ensure a certain standoff or more. In this state, the back surface of the substrate is immersed in a wave solder bath or the like to perform flow soldering. Thereby, the lead 12 of the electronic component 13 and the through hole 8, the front surface land 6, and the back surface land 7 of the circuit board 1 are electrically and mechanically coupled by the solder fillet 14.

  After the end 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.

  7A and 7B are a cross-sectional view of a circuit board according to a second embodiment of the present invention and a cross-sectional view showing a mounting state of electronic components on the circuit board. 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 redundant descriptions are omitted. A difference from the first embodiment shown in FIGS. 6A and 6B of the present embodiment is that no solder dam is formed, and instead, the solder resist 9 is a peripheral edge between the front surface land 6 and the rear surface land 7. It is the point extended to the part and the point by which the component receiver 11 is made into the spherical body.

  The component receiver 11 is formed of resin, metal, or ceramics, and is bonded by an adhesive that is applied on the substrate in advance. Or you may make it arrange | position the spherical body by which the adhesive agent was apply | coated to the surface on a board | substrate.

  A first embodiment 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 an electronic component is 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 surface on the electronic component side. . 8A and 8B, the same reference numerals are given to the same parts as those of the embodiment shown in FIGS. 6A and 6B, and FIGS. 7A and 7B. Omitted. 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 that is used for marking printing such as placement of electronic components, part numbers, and board numbers. In the process of forming the display portion, a solder dam is also formed at the same time. In addition, the display paints have been proven with heat resistance to heat applied during soldering.

  In the present embodiment, the component receiver 11 is formed so as to overlap the solder dam 10 by using a thermosetting adhesive used for temporarily fixing the surface-mounted electronic component. Since the component receiver 11 is formed in the adhesive layer forming step for temporarily fixing the surface mount type component, the number of man-hours is not increased.

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

  In this embodiment, a solder resist 9 used to protect the outer layer wiring 4 on the substrate surface is applied to the peripheral edge of the surface land 6. Moreover, the component receiver 11 is formed in the position away from the surface land 6 using the thermosetting adhesive agent which is an adhesive for temporary fixing.

  FIG. 10A is a cross-sectional view illustrating a structure in which an electronic component is mounted on a circuit board according to a third embodiment of the present invention, and FIG. 10B is a perspective plan view when FIG. 10A is viewed from the upper surface on the electronic component side. .

  In the present embodiment, the solder dam 10 is formed using a thermosetting adhesive for temporarily fixing the surface mount electronic component. A component receiver 11, which is a resin spacer, is adhered to the substrate with an adhesive that constitutes the solder dam 10.

  FIG. 11A is a cross-sectional view illustrating a structure in which an electronic component is mounted on a circuit board according to a fourth embodiment of the present invention, and FIG. 11B is a perspective plan view when FIG. 11A is viewed from the upper surface on the electronic component side. .

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 is configured such that the surface of a resin ball 11a, which is a resin sphere, is covered with an adhesive 11b. The component receiver 11 is provided by placing a resin sphere previously coated with a thermosetting adhesive on a substrate and performing a heat treatment to cure the adhesive.

Claims (24)

There are conductive through-holes into which the leads of the leaded component are inserted and soldered, and a surface land is provided on the mounting surface of the leaded component, and the surface land is connected to the opposite surface via the conductive through-hole. In a circuit board having electrically connected backside lands,
A circuit board comprising a plurality of component receivers for regulating a mounting height of the leaded component on a mounting surface of the leaded component.   The circuit board according to claim 1, wherein a land coating that covers a peripheral portion of the surface land is formed on a mounting surface of the component with leads.   The circuit board according to claim 2, wherein the land coating covers the entire periphery of the peripheral portion of the surface land.   The circuit board according to claim 2, wherein the component receiver is formed on the land film.   The circuit board according to claim 2, wherein the component receiver is formed of a thermosetting adhesive.   6. The circuit board according to claim 2, wherein the component receiver is formed by adhering a spacer formed of resin, metal, or ceramics.   The solder resist is formed on the front and back surfaces of the circuit board, and the land coating is formed of a solder resist material as an extension of the solder resist. 2. The circuit board according to item 1.   The circuit board according to claim 2, wherein the land coating is made of a heat resistant resin.   The circuit board according to any one of claims 2 to 8, wherein the land coating is formed of the same material as the display portions formed on the front surface and the back surface of the circuit board.   The circuit board according to any one of claims 1 to 6, wherein a back surface land coating that covers a peripheral portion of the back surface land is formed on a surface opposite to a mounting surface of the leaded component. .   The circuit according to claim 10, wherein a solder resist is formed on the front and back surfaces of the circuit board, and the back surface land film is formed of a solder resist material as an extension of the solder resist. substrate.   The circuit board according to claim 10, wherein the back surface land film is formed of a heat resistant resin.   The circuit board according to any one of claims 10 to 12, wherein the back surface land film is formed of the same material as the display portions formed on the front surface and the back surface of the circuit board. Lead to the mounting surface of the leaded component of the circuit board having a surface land on the mounting surface of the leaded component and a back surface land electrically connected to the surface land through a conductive through hole on the opposite surface In the mounting structure of the circuit board in which the attached component is mounted in such a manner that the lead is inserted into the conductive through hole and soldered,
A circuit board mounting structure, wherein a plurality of component receivers for restricting the mounting height of the leaded component are provided on the circuit substrate under the leaded component.   15. The circuit board mounting structure according to claim 14, wherein a bottom surface of the housing of the leaded component is in contact with a top of at least one of the component receivers.   The circuit board mounting structure according to claim 14 or 15, wherein a thermal expansion coefficient of a material of a housing of the leaded component is larger than a thermal expansion coefficient of a board material of the circuit board.   The circuit board mounting structure according to any one of claims 14 to 16, wherein the lead of the leaded component is soldered by lead-free solder.   The height of the component receiver viewed from the substrate surface is determined based on a substrate material of the circuit board, a thermal expansion coefficient of the leaded component, and a lead diameter of the leaded component. The circuit board mounting structure according to any one of 14 to 17. A surface land is mounted on the mounting surface of the component with lead, and a mounting surface of the component with lead on the circuit board having a back surface land electrically connected to the surface land through 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;
A second step of mounting the leaded component by inserting the lead into the conductive through hole and soldering;
A circuit board mounting method comprising:   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.   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. The circuit board mounting method described in 1.   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 The method of mounting a circuit board according to claim 20 or 21, further comprising a step of mounting the surface-mounted component by reflow.   23. The method according to any one of claims 19 to 22, wherein a step of forming a land film covering a peripheral edge of the surface land is added prior to the first step, and the component receiver is provided on the land film. 2. A circuit board mounting method according to item 1.   24. The circuit board mounting method according to claim 23, wherein in the step of forming the land film, the display portion is simultaneously formed using a material for forming the land film.

Images