JP2005252124A - Substrate with ventilation holes - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate with ventilation holes in which soldering defects can be prevented in reflow of a large-sized electronic component of a large heat capacity or the like, excess heat is not applied to the body of the electronic component and further, limitations of the substrate with respect to the arrangement of a conductive pattern are also reduced. <P>SOLUTION: A ventilation hole 23 is formed between neighboring leads 20a of a surface-mounted component (switching transformer 20) having a large heat capacity, thereby suppressing excessive heating from being applied to the body of the switching transformer 20, while promoting temperature elevation of the leads 20a at reflow. Furthermore, by having no ventilation hole 23 to form on the extension line of each lead 20a, also easily laying of a conductive pattern 12 is facilitated also. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a substrate that is mounted by reflow soldering a surface-mounted component, and more particularly, to a substrate that can prevent solder failure during reflow.

  The printed circuit board is configured by forming a conductive pattern made of copper foil on an insulating plate and electrically connecting various electric / electronic components to the conductive pattern. The electrical connection between the conductive pattern and the electric / electronic component is generally performed by soldering, and one of the soldering methods is a reflow method. This is because it has become possible to place components on the conductive pattern surface side as the pitch between the leads of electrical and electronic components has been reduced in recent years and the size of the components has been reduced. Solder paste is applied on the pattern surface, the electrical / electronic component leads are placed on the surface, and the solder is melted in a heating furnace and then cooled, so that the electrical / electronic component is mounted on the board. It is what is done.

  There are many types of components (hereinafter referred to as surface mount components) arranged on the conductive pattern surface side as described above, and there is a large difference in their heat capacities. Therefore, a lead of a component having a small heat capacity (that is, a solder paste portion) is sent to the heating atmosphere in a short time, and the temperature of the lead of the component having a large heat capacity is the same as the heat capacity of the component. Therefore, it takes time according to the heat capacity until the heat is absorbed and the lead reaches a predetermined temperature. When such parts with different heat capacities are arranged on the same board, in order to ensure that all parts are soldered, the lead of the part with the largest heat capacity (ie, solder paste portion) Until the temperature reaches a predetermined temperature, the substrate needs to be heated in a heating atmosphere.

  On the other hand, there are many electrical / electronic components mounted on the board that are vulnerable to heat, and the heating time in the heating atmosphere is preferably as short as possible to prevent damage to the components. Therefore, heating temperature and time limits are provided. Therefore, if the heating temperature and time are determined based on the safety of such a low heat-resistant component, the temperature of the lead (that is, the solder paste portion) of the component having a large heat capacity does not rise sufficiently, resulting in poor soldering. There was a problem that occurred.

  Conventional techniques for such a problem are disclosed in Patent Document 1 and Patent Document 2.

Japanese Patent Laid-Open No. 5-110242 Japanese Patent Laid-Open No. 2002-232130

  As shown in FIG. 8, the prior art disclosed in Patent Document 1 makes the heat capacity of the substrate 90 uniform by opening a through hole 92 in the vicinity of the electronic component 91 mounted on the substrate 90. This is intended to eliminate solder melting unevenness.

  Further, as shown in FIG. 7, the prior art disclosed in Patent Document 2 is formed by penetrating a ventilation portion 83 in a region where an electronic component 81 is mounted on a substrate 80. Is heated by the heating atmosphere through the ventilation portion 83, thereby promoting the heating of the terminal portion 81 a of the electronic component 81 and trying to prevent solder failure during reflow.

  In the prior art disclosed in Patent Document 2, a ventilation hole is formed immediately below the electronic component body, and the electronic component body is heated, but the electronic component itself is not heated regardless of heat resistance. It is not preferred to be done. In the prior art disclosed in Patent Document 1, since the through hole is provided on the extension line of the lead provided in the electronic component and across the extension line of all the leads, Therefore, there is a problem that it is difficult to route conductive patterns to be connected, and the degree of freedom in designing the substrate is lost.

  In view of the above-described problems, the present invention can prevent a solder failure such as a large-sized electronic component having a large heat capacity at the time of reflow, and without excessive heat being applied to the electronic component body. It is an object of the present invention to provide a substrate having ventilation holes with less restrictions on the arrangement of conductive patterns.

  In the substrate having the ventilation holes according to claim 1, the conductive pattern is formed on the insulating plate, and the surface mount component is mounted on the land portion of the conductive pattern by reflow soldering the lead of the surface mount component. The surface mount component includes a plurality of leads, and a ventilation hole is formed between adjacent leads of the plurality of leads in a state where the surface mount component is mounted on the substrate. It is characterized by that.

  According to the above configuration, the ventilation holes are formed between the adjacent leads of the plurality of leads of the surface mount component, so that the surface area in contact with the atmosphere increases in the vicinity of the leads including the substrate, and heating is performed through the ventilation holes. The atmosphere circulates.

  The board provided with the ventilation hole according to claim 2 is the board provided with the ventilation hole according to claim 1, wherein a lead of the surface mounting component is provided so as to protrude from a side surface of the surface mounting component. The length of the hole in the direction parallel to the lead is substantially the same as the length in the direction parallel to the lead of the application range of the solder paste applied to solder the lead to the land portion of the conductive pattern. In addition, the vent hole is not formed on an extension line of each lead.

  According to the above configuration, the ventilation hole is formed only in the vicinity of the area where the solder paste for soldering the surface-mounted component to the substrate is applied, and the ventilation hole is not formed on the extension line of each lead.

  The board having the ventilation holes according to claim 3 is the board having the ventilation holes according to claim 1, wherein the leads of the surface mounting component are provided substantially in parallel to protrude from the side surface of the surface mounting component. The length of the ventilation hole in the direction parallel to the lead is substantially the same as the length of the protruding portion of the lead, and the ventilation hole is not formed on an extension line of each lead. To do.

  According to the above configuration, the ventilation hole is formed only in the vicinity of the protruding portion of the lead provided in the surface mount component, and the ventilation hole is not formed on the extension line of each lead.

  A substrate provided with a ventilation hole according to claim 4 is the substrate provided with the ventilation hole according to any one of claims 1 to 3, wherein the lead has a high thermal conductivity for a member having a large heat capacity. The surface mount component is configured by being connected by a member.

  According to the above configuration, the heat applied to the leads is transferred between the leads of the surface mount components where the heat of the lead portion is not easily increased because the heat is transferred to a member having a high thermal conductivity and is taken away by the member having a large heat capacity. Ventilation holes are drilled.

  The substrate having the vent holes according to claim 5 is the substrate having the vent holes according to claim 4, wherein the surface-mount component is a large electrolytic capacitor, or the member having a large heat capacity is an inductor. It is characterized by being.

  A substrate provided with a ventilation hole according to claim 6 is a substrate provided with the ventilation hole according to any one of claims 1 to 5, wherein the land portion of the conductive pattern and the surface mounting component are provided. The space between the ventilation holes formed so as to be disposed between the provided leads is 1.0 mm or less.

  According to the above configuration, the distance between the land portion of the conductive pattern and the ventilation hole is 1.0 mm or less, the surface area in contact with the atmosphere in the vicinity of the land portion of the conductive pattern is increased, and the circulation of the heating atmosphere through the ventilation hole is also performed. Near the land.

  The board having the vent hole according to claim 7 is the board having the vent hole according to claim 6, and is drilled so as to be disposed between the conductive pattern and the lead provided in the surface mount component. It is characterized in that a distance of 0.5 mm or more is provided between the vent holes.

  According to the above configuration, a distance of 0.5 mm or more is formed between the conductive pattern formed on the substrate and the ventilation hole formed in the substrate, and the conductive pattern is exposed on the inner surface of the ventilation hole. There is no.

  According to a first aspect of the present invention, there is provided a substrate on which a surface mount component is mounted by forming a conductive pattern on an insulating plate and reflow soldering a lead of the surface mount component to a land portion of the conductive pattern. The surface mount component includes a plurality of leads, and the surface mount component is mounted on the substrate, and a ventilation hole is formed between adjacent leads of the plurality of leads. According to the substrate having the ventilation holes, the surface area in contact with the atmosphere of the substrate is increased in the vicinity of the lead portion of the surface mount component, and the heating atmosphere is circulated through the ventilation holes so that an atmosphere having a substantially constant temperature is always obtained. Since the lead part is heated, the temperature rise of the lead part (that is, the part where the solder paste is applied) is effectively promoted, and solder failure due to insufficient melting of the solder can be prevented. That. Further, since the ventilation holes are formed between the adjacent leads, it is possible to prevent a short circuit between the leads due to defective solder.

  The lead of the surface mount component according to claim 2 of the present invention is provided so as to protrude from the side surface of the surface mount component, and the length of the ventilation hole in the direction parallel to the lead The length of the solder paste applied range to be soldered to the land of the pattern is substantially the same as the length in the direction parallel to the lead, and the ventilation hole is not formed on the extension line of the lead. According to the substrate having the ventilation holes according to claim 1, the ventilation holes are formed only in the vicinity of the area where the solder paste for soldering the surface mount component to the substrate is applied. Only the part where the paste is applied can be heated locally, suppressing excessive heat from being applied to the surface of the surface mount component itself as much as possible. It is possible to stop. Accordingly, it is possible to prevent the surface mount component from being damaged by heat. Further, since no ventilation hole is formed on the extension line of each lead, it is easy to route the conductive pattern electrically connected to the lead, and the degree of freedom in designing the board is ensured. Furthermore, the cooling of the solder portion can be promoted also during the cooling for solidifying the solder.

  The lead of the surface mounting component according to claim 3 of the present invention is provided substantially in parallel with protruding from the side surface of the surface mounting component, and the length of the ventilation hole in the direction parallel to the lead is the lead. 2. The surface mount component according to claim 1, wherein the length of the projecting portion is substantially the same, and the vent hole is not formed on an extension line of each lead. Since the ventilation hole is formed only in the vicinity of the protruding portion of the lead provided in the lead, the lead portion can be locally heated, and it is possible that excessive heat is applied to the surface mount component itself. While suppressing, it is possible to prevent a solder failure due to insufficient melting of the solder, and to prevent damage to the surface-mounted component due to heat.

  4. The surface mount component according to claim 4, wherein the lead is connected to a member having a large heat capacity by a member having a high heat conductivity. According to the substrate provided with the ventilation hole according to any one of the above, the heat applied to the lead is transmitted through a member having a high thermal conductivity and is taken away by a member having a large heat capacity so that the temperature of the lead portion is hardly increased. Because surface ventilation parts are drilled between the leads of surface mount parts (that is, parts where solder paste is applied, the temperature rise is slow, and solder defects are likely to occur), the solder defects of the surface mount parts Can be prevented.

  According to claim 5 of the present invention, the surface-mounted component is a large electrolytic capacitor, or the member having a large heat capacity is an inductor. For example, it is possible to prevent solder failure during reflow, such as a large electrolytic capacitor having a large heat capacity or a transformer having a large heat capacity including an inductor therein.

  According to claim 6 of the present invention, the gap between the land portion of the conductive pattern and the ventilation hole formed so as to be disposed between the leads provided in the surface mount component is 1.0 mm or less. According to the substrate provided with the ventilation hole according to any one of claims 1 to 5, the space between the lead and the ventilation hole is 1.0 mm or less, and therefore passes through the ventilation hole. Heat in the heating atmosphere is effectively transmitted to the solder paste portion, and solder defects can be prevented.

  According to claim 7 of the present invention, a distance of 0.5 mm or more is provided between the conductive pattern and a vent hole formed so as to be disposed between the leads provided in the surface mount component. According to the substrate provided with the ventilation holes according to claim 6, since the conductive pattern is not exposed on the inner side surface of the ventilation holes, unintended short-circuiting between conductors is caused by the solder flowing down to the ventilation holes. It is possible to prevent problems such as the occurrence of

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The following embodiment is one form when the present invention is embodied, and is not intended to limit the present invention within the scope thereof.

  FIG. 1 is a perspective view schematically showing a substrate having ventilation holes according to the present embodiment, FIG. 2 is a top view of the same, and FIG. 3 is an enlarged view of a portion where a switching transformer, which is a surface mounting component, is mounted. 4 is an enlarged view of the lead portion of the switching transformer of FIG. 3, and FIG. 5 is a cross-sectional view taken along line AA of FIG.

  As shown in FIGS. 1 to 5, a substrate 10 (hereinafter simply referred to as a substrate 10) having ventilation holes of this embodiment has a copper foil conductive pattern 12 formed on an insulating plate 11, and a solder resist thereon. 15 is applied. As shown in FIGS. 4 and 5, the solder resist 15 is applied except for the land portion 12 a to which the lead (the lead 20 a in FIG. 5) of the surface mount component (such as the switching transformer 20) is soldered. A solder paste 25 is applied to the land portion 12a of the conductive pattern 12 to which the solder resist 15 is not applied, and a surface mount component is placed on the land portion 12a and then sent into the heating atmosphere of the reflow apparatus. When the solder paste 25 is solidified by melting 25 and then being cooled, the surface mount component is mounted on the substrate 10. Various electric / electronic components having different heat resistance and heat capacity, such as a coil 13, capacitors 14 and 19, a semiconductor 16, a chip component 17, and a connector 18, are mounted on the substrate 10. The switching transformer 20 includes an inductor having a large heat capacity inside, and the inductor is connected to the lead 20a by a copper wire which is a member having high thermal conductivity.

  As shown in FIGS. 3 and 4, the substrate 10 is provided with ventilation holes 23 between the leads 20 a protruding from the side surface of the switching transformer 20. The length of the ventilation hole 23 in the direction parallel to the lead 20a is substantially the same as the length of the land portion 12a, which is the application range of the solder paste 25, and the ventilation hole 23 is formed on the extension line of each lead 20a. Not. The ventilation hole 23 is formed so that the interval x between the ventilation hole 23 and the land portion 12a is 1 mm or less, and the interval y between the conductive pattern 12 and the ventilation hole 23 is 0.5 mm or more. The Since the land portion 12a is a part of the conductive pattern 12, y is a concept including x.

  According to the substrate 10 of the present embodiment, by providing the ventilation holes 23, the surface area in contact with the atmosphere is increased in the vicinity of the land portion 12 a that is the application range of the solder paste 25, and the heating atmosphere is transmitted through the ventilation holes 23. Since the lead 20a and the solder paste 25 are always heated in an atmosphere having a substantially constant temperature by circulating the solder, it is possible to prevent a defective solder due to insufficient melting of the solder paste 25 during reflow. Further, the ventilation holes 23 are formed only in the vicinity of the area where the solder paste 25 is applied, and only the portion where the solder paste 25 is applied can be locally heated, so that the switching transformer 20 itself can be heated. It can be suppressed as much as possible. Further, as shown in FIGS. 3 and 4, since the ventilation holes 23 are not formed on the extended lines of the respective leads 20a, the conductive pattern 12 electrically connected to the leads 20a can be easily routed. The degree of freedom of design is also secured.

  Further, in the vicinity of the switching transformer 20 having a large heat capacity, the temperature change is slow during overheating and cooling, and a temperature difference from other parts is likely to occur. Due to such non-uniform heat distribution, stress is generated in the substrate 20 or the mounted component (chip component 17 or the like), and in the worst case, the mounted component may be damaged. Therefore, by providing the ventilation hole 23, the non-uniformity of the heat distribution in the vicinity of the switching transformer 20 is alleviated, and damage to the chip component 17 and the like can be prevented.

  In this embodiment, the ventilation holes (ventilation holes 23) are formed between the adjacent leads (leads 20a) of the surface mount component (switching transformer 20). However, the present invention is not limited to this. For example, a ventilation hole may be provided every two leads, and can be applied by appropriately changing according to the heat capacity of the surface-mounted component.

  FIG. 6 is an enlarged view of the lead portion of the switching transformer provided in the substrate provided with the ventilation holes of the present embodiment. The basic configuration of the substrate provided with the vent holes of the present embodiment is the same as that of the first embodiment, and thus the description thereof is omitted. The same components as those of the first embodiment are the same as those of the first embodiment. Use a sign.

  As shown in FIG. 6, the substrate 70 (hereinafter simply referred to as the substrate 70) having the ventilation holes of the present embodiment is provided with ventilation holes 73 between the respective leads 20 a protruding from the side surfaces of the switching transformer 20. It is done. The length of the ventilation hole 73 in the direction parallel to the lead 20a is substantially the same as the length of the protruding portion of the lead 20a, and the ventilation hole 73 is not formed on the extension line of each lead 20a. The distance between the ventilation hole 73 and the land portion 12a is 1 mm or less, and the distance between the conductive patterns 60 and 12 and the ventilation hole 73 is 0.5 mm or more, as in the first embodiment. It is.

  According to the substrate 70 of the present embodiment, by providing the ventilation holes 73, the surface area in contact with the atmosphere is increased in the vicinity of the lead 20a, and the heating atmosphere circulates through the ventilation holes 73 so that the heating atmosphere circulates at a substantially constant level. Since the atmosphere of temperature heats the vicinity of the lead 20a, the heat applied to the lead 20a, such as the switching transformer 20, passes through a member (copper wire) having a high thermal conductivity and becomes a member (inductor) having a large heat capacity. Even in a surface-mounted component that is deprived and the temperature of the lead 20a does not easily rise, the temperature of the lead 20a can be raised sufficiently to prevent solder failure due to insufficient melting of the solder paste 25 during reflow. Further, as shown in FIG. 6, the conductive pattern 60 that is electrically connected to the lead 20a can be routed more easily, and the degree of freedom of the arrangement of the conductive pattern 12 is increased.

The perspective view which shows the outline of the board | substrate provided with the ventilation hole of Example 1. FIG. The top view which shows the outline of the board | substrate provided with the ventilation hole of Example 1. FIG. The enlarged view of the part by which the switching transformer of the board | substrate provided with the ventilation hole of Example 1 is mounted. The enlarged view of the lead | read | reed part of the switching transformer of the board | substrate provided with the ventilation hole of Example 1 Sectional drawing along the AA line of FIG. The enlarged view of the lead part of the switching transformer with which the board | substrate provided with the ventilation hole of Example 2 is equipped. Illustration of conventional example Explanatory drawing of another conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Board | substrate provided with ventilation hole 11 Insulation board 12.60 Conductive pattern 12a Land part 15 Solder resist 20 Switching transformer (surface mount component)
20a Lead 23/73 Ventilation hole 25 Solder paste

Claims (7)

  A conductive pattern is formed on an insulating plate, and a surface mount component is mounted on a land portion of the conductive pattern by reflow soldering to the land portion of the conductive pattern. A board having a ventilation hole, wherein the surface mounting component is mounted on the board, and a ventilation hole is formed between adjacent leads of the plurality of leads. .   The lead of the surface mounting component is provided so as to protrude from the side surface of the surface mounting component, and the length of the ventilation hole in the direction parallel to the lead solders the lead to the land portion of the conductive pattern. 2. The length of the solder paste coating range to be applied is substantially the same as the length in the direction parallel to the leads, and the ventilation holes are not formed on the extension lines of the leads. Substrate with ventilation holes.   The lead of the surface mount component is provided substantially parallel to the side surface of the surface mount component, and the length of the ventilation hole in the direction parallel to the lead is substantially the same as the length of the protruding portion of the lead. The board having a vent hole according to claim 1, wherein the vent hole is not formed on an extension line of each lead.   The ventilation hole according to any one of claims 1 to 3, wherein the lead is connected to a member having a large heat capacity by a member having high thermal conductivity to constitute the surface mount component. With a substrate.   5. The substrate with vent holes according to claim 4, wherein the surface-mounted component is a large electrolytic capacitor, or the member having a large heat capacity is an inductor.   The space between the land portion of the conductive pattern and the vent hole formed so as to be disposed between the leads provided in the surface mount component is 1.0 mm or less. The board | substrate provided with the ventilation hole as described in any one of Claim 5.   The distance of 0.5 mm or more was provided between the said conductive pattern and the ventilation hole drilled so that it might be arrange | positioned between the leads with which the said surface mounting component is equipped. Substrate with ventilation holes.

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