JP2011077062A - Printed wiring board assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed wiring board assembly in which countermeasures are taken to minimize fire spread of pattern wiring due to tracking between different poles of the circuit wiring pattern or solder crack in soldering of lead portions of electronic components. <P>SOLUTION: The printed wiring board assembly includes a circuit wiring pattern formed of a copper alloy on an insulating member and a resist coating for covering the circuit wiring pattern, wherein the lead portions of the electronic components are soldered to a land portion of the circuit wiring pattern. A through-hole penetrating the insulating member is provided on the circuit wiring pattern in the vicinity of the land portion, the through-hole has an internal diameter of equal to or more than the width of the circuit wiring pattern and has the copper foil continuing to the circuit wiring pattern on the internal circumferential surface. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a printed wiring board assembly suitable for measures against the spread of pattern wiring that occurs due to tracking between different polarities of the pattern wiring and solder cracks at the soldered portion of the lead portion of the electronic component. is there.

Conventionally, as a solution for tracking between different wiring patterns of a printed wiring board, a pair of pads formed so as to be opposed to the pattern wiring with a gap is soldered with a low melting point solder, and the gap between the pair of pads is There is an example of connecting with a solder bridge. (For example, refer to Patent Document 1.)
In addition, there is an example in which a jumper line is provided in the middle so that the length of the section where the distance between the pattern wirings (conductor patterns) is short does not continue for a predetermined length or more. (For example, refer nonpatent literature 1.)

JP-A-2005-203686

Japan Society for Invention and Innovation Open Technical Report No. 2007-503344

  In Patent Document 1, in an example in which a pair of pads formed so as to be opposed to a pattern wiring through a gap is soldered with a low melting point solder, and the pair of pads are connected by a solder bridge, In addition, there was a problem that a low melting point solder had to be used. In addition, it is supposed that a part of the pattern wiring is cut and soldered, but there is a concern that the wiring may be disconnected for some reason in normal times.

  Further, in Non-Patent Document 1, in an example in which a jumper wire is provided in the middle so that the length of a section where the distance between the pattern wires is short is not longer than a predetermined length, a measure for tracking between the different polarities of the pattern wires is provided. As a countermeasure against the spread of pattern wiring that occurs due to solder cracks in the soldered part of the lead part of an electronic component, the effect of preventing the spread of fire at the jumper wire part can be expected. Due to restrictions, there is a case where the jumper wire cannot be arranged in the immediate vicinity of the countermeasure main part, and there is a problem that the fire spread cannot be prevented sufficiently.

According to a first aspect of the present invention, there is provided a printed wiring board assembly comprising a circuit wiring pattern formed of copper foil on an insulating member and a lead portion of an electronic component soldered to a land portion of the circuit wiring pattern. A through hole penetrating the insulating member is provided on the circuit wiring pattern in the vicinity of the land portion. The through hole has an inner diameter equal to or larger than the width of the circuit wiring pattern, and is continuous with the circuit wiring pattern on an inner peripheral surface thereof. It is characterized by having a copper foil.
Therefore, when the fire is ignited at the land portion and spreads along the circuit wiring pattern, the copper foil is difficult to turn over due to the presence of the through holes, and the spread of the fire is difficult to proceed. As a result, combustion continues only in the vicinity of the land portion that has been burned so far, and local carbonization proceeds, eventually leading to disconnection on the spot.

The second invention is characterized in that the through-hole is filled with a nonflammable conductive material.
When the fire spreads along the circuit wiring pattern, the heat dissipation is improved by filling the through hole with the non-combustible conductive material. As a result, the combustion continues only in the vicinity of the land portion that has been burned so far, and the local carbonization proceeds. Finally, the circuit wiring pattern is disconnected on the spot.

According to a third aspect of the present invention, a circuit wiring pattern formed of copper foil on an insulating member, a resist film covering the circuit wiring pattern, and a lead portion of an electronic component are soldered to a land portion of the circuit wiring pattern. In the printed wiring board assembly comprising: a copper foil exposed portion that is not covered with the resist film on the circuit wiring pattern in the vicinity of the land portion, and the copper foil exposed portion is filled with a nonflammable conductive material. It is characterized by that.
Therefore, when the fire spreads along the circuit wiring pattern, the copper foil is not easily turned over because there is a nonflammable conductive material in the exposed portion of the copper foil, and the fire spread is difficult to proceed. In addition, the non-combustible conductive material also increases heat dissipation, so that it can be expected that the progress is further suppressed. As a result, the combustion continues only in the vicinity of the land portion that has been burned so far, and the local carbonization proceeds. Finally, the circuit wiring pattern is disconnected on the spot.

  According to the present invention, in the printed wiring board assembly, it is possible to reduce the spread of the pattern wiring caused by the tracking between the different polarities of the circuit wiring pattern and the solder crack in the land portion where the lead portion of the electronic component is soldered. This can be reduced without using melting point solder, jumper wires, etc., and especially in the soldered part, it is possible to prevent the most recent fire spread, so the risk of fire and smoke from the product can be greatly reduced.

The bottom view of the printed wiring board assembly in 1st embodiment of this invention (before electronic component mounting) Sectional drawing of the printed wiring board assembly shown in FIG. The figure which shows the state which mounted the electronic component in the printed wiring board assembly shown in FIG. 1, and implemented soldering. Sectional drawing of the printed wiring board assembly shown in FIG. The figure which shows the modification of the printed wiring board assembly shown in FIG. Sectional drawing of the printed wiring board assembly shown in FIG. Bottom view of printed wiring board assembly according to second embodiment of the present invention (before electronic component mounting) Sectional drawing of the printed wiring board assembly shown in FIG. The figure which shows the state which mounted the electronic component in the printed wiring board assembly shown in FIG. 7, and implemented soldering. Sectional drawing of the printed wiring board assembly shown in FIG. The figure which shows the modification of the printed wiring board assembly shown in FIG. Sectional drawing of the printed wiring board assembly shown in FIG.

  FIGS. 1-4 is an example of the figure which shows the printed wiring board assembly which concerns on 1st embodiment of this invention. 1 and 2 are a bottom view and a cross-sectional view of the printed wiring board before the electronic component is mounted, and FIGS. 3 and 4 are bottom views of the printed wiring board on which the electronic component is mounted and soldered. It is a figure and sectional drawing.

  In the printed wiring board assembly of this embodiment, a circuit wiring pattern 6 formed of copper foil as a conductor is formed on the bottom surface of a plate-like insulating member 5 formed of a ceramic material, a glass epoxy material, or the like. . The surface of the insulating member is provided with a resist film 7 for protecting the circuit wiring pattern 6. In the circuit wiring pattern 6, an area excluding the component mounting land 2 as a land portion on which an electronic component is mounted is provided. A resist film 7 is applied.

  The through hole 3 is disposed in the vicinity of the component mounting land 2 and has an inner diameter equal to or larger than the width of the circuit wiring pattern 6 before and after the through hole 3. A copper foil is formed on the inner peripheral surface of the through hole 3 and on the outer side in the width direction so as to be continuous with the circuit wiring pattern 6, and this portion functions as the circuit wiring pattern 6. Note that the resist film 7 is not formed around the through-hole 3 and the circuit wiring pattern 6 is exposed. The through hole 3 is preferably formed as close as possible to the component mounting land 2.

  3 and FIG. 4 show that the electronic component F1 is mounted on the component mounting land 2 of the printed wiring board shown in FIGS. 1 and 2, and the component mounting land 2 of the circuit wiring pattern 6 that is not covered with the resist film 7, the through hole. 3 is an example in which a nonflammable conductive material (solder) 4 is filled.

Hereinafter, the present invention will be described based on the drawings.
When a crack occurs in the soldering part 9 of the lead part 8 of the component mounting land 2 for some reason, a spark discharge occurs due to a slight contact between the lead part 8 and the soldering part 9 according to the energization current. Spark discharge continues and the component mounting land portion 2 causes abnormal heat generation. The abnormal heat generation carbonizes the insulating member 5 around the component mounting land 2, and at the same time, the circuit wiring pattern 6 is heated to cause combustion. As long as energization continues, the carbonization of the insulating member 5 and the combustion of the circuit wiring pattern 6 are continued, and further progresses to reach the fire spread state through the circuit wiring pattern 6. In the present invention, even when the circuit wiring pattern 6 reaches the fire spread state, if the through hole 3 is arranged in the middle of the circuit wiring pattern 6, the copper foil is difficult to turn and the fire spread does not easily proceed. Become. Further, when there is a non-combustible conductive material (solder) 4 filled in the through hole 3, since heat dissipation is improved, it can be expected that the progress is further suppressed and the fire spread is blocked. As a result, combustion will continue only in the part that has been burned so far, local carbonization will proceed, eventually leading to disconnection on the spot, risk of ignition and smoke from the product Can be greatly reduced.
In the above case, the nonflammable conductive material is solder, but it goes without saying that the solder is not limited to solder.

  Next, a modified example in the first embodiment will be described. 5 and 6, the component mounting land 2 and the through hole 3 shown in FIG. 3 are connected by a solder bridge. In this case, a crack occurs in the soldering portion 9 of the lead portion 8 of the component mounting land 2, and even when the circuit wiring pattern 6 is heated, the heat generation is effectively filled with the nonflammable conductive material (solder) 4. There is a merit to be conducted to the hole 3, and the same effect as the example shown above can be obtained. Further, it is not necessary to manage the solder bridge during the manufacturing process of the printed wiring board assembly, and the productivity is improved.

  In the first embodiment, the positional relationship between the component mounting lands 2 and the through-holes 3 can be more effective in preventing the spread of fire if it is arranged as close as possible. If there is no, the component mounting land 2 and the through hole 3 may be connected. Further, in FIG. 1, the shape of the through hole 3 is shown as a rectangle. However, as long as the size of the copper foil can be suppressed and the heat dissipation effect can be increased as in the above embodiment, both ends in the longitudinal direction are half. It may be circular.

  Next, the printed wiring board assembly which concerns on 2nd embodiment of this invention is demonstrated. 7 and 8 are a bottom view and a cross-sectional view of the printed wiring board before the electronic component is mounted, and FIGS. 9 and 10 are bottom views of the printed wiring board on which the electronic component is mounted and soldered. It is a figure and sectional drawing.

  Similarly to the first embodiment described above, the printed wiring board assembly of this embodiment is formed of a copper foil as a conductor on the bottom surface of a plate-like insulating member 5 formed of a ceramic material, a glass epoxy material, or the like. A circuit wiring pattern 6 is formed. The surface of the insulating member is provided with a resist film 7 for protecting the circuit wiring pattern 6. In the circuit wiring pattern 6, an area excluding the component mounting land 2 as a land portion on which an electronic component is mounted is provided. A resist film 7 is applied.

  The copper foil exposed portion 11 is disposed in the vicinity of the component mounting land 2, and the circuit wiring pattern 6 is formed in a width greater than or equal to the width of the circuit wiring pattern 6 before and after the copper foil exposed portion 11, and the resist film 7 is formed there. In other words, this is a region where the circuit wiring pattern 6 is widely exposed. The copper foil exposed portion 11 is preferably formed as close as possible to the component mounting land 2.

  As in the embodiment of FIGS. 1 and 2, the surface layer of the insulating member 5 in FIGS. 7 and 8 is covered with a resist film 7 except for the copper foil exposed portions of the component mounting land 2 and the circuit wiring pattern 6. .

  9 and FIG. 10, the electronic component F1 is mounted on the component mounting land 2 of the printed wiring board shown in FIG. 7, and the circuit wiring pattern 6, the component mounting land 2, and the copper foil exposed portion 11 not covered with the resist film 7 are shown. In this example, a nonflammable conductive material (solder) 4 is filled.

Hereinafter, the present invention will be described based on the drawings.
When a crack occurs in the soldering part 9 of the lead part 8 of the component mounting land 2 for some reason, a spark discharge occurs due to a slight contact between the lead part 8 and the soldering part 9 according to the energization current. Spark discharge continues and the component mounting land portion 2 causes abnormal heat generation. The abnormal heat generation carbonizes the insulating member 5 around the component mounting land 2, and at the same time, the circuit wiring pattern 6 is heated to cause combustion. As long as energization continues, the carbonization of the insulating member 5 and the combustion of the circuit wiring pattern 6 are continued, and further progresses to reach the fire spread state through the circuit wiring pattern 6. In the present invention, even when the circuit wiring pattern 6 reaches a fire spread state, when there is a nonflammable conductive material (solder) 4 filled in the exposed copper foil portion in the middle of the circuit wiring pattern 6, Copper foil is difficult to turn over, making it difficult to spread fire. At the same time, since heat dissipation is improved, it can be expected that the progress is further suppressed and fire spread is blocked. As a result, combustion will continue only in the part that has been burned so far, local carbonization will proceed, eventually leading to disconnection on the spot, risk of ignition and smoke from the product Can be greatly reduced.
In the above case, the nonflammable conductive material is solder, but it goes without saying that the solder is not limited to solder.

  Next, a modification of the second embodiment will be described. 11 and 12, the component mounting land 2 shown in FIG. 7 and the copper foil exposed portion 11 filled with the nonflammable conductive material (solder) 4 are connected by the solder bridge 10. In this case, a crack is generated in the soldering portion 9 of the lead portion 8 of the component mounting land 2, and even when the circuit wiring pattern 6 is heated, the heat is effectively generated by the copper filled with the nonflammable conductive material (solder) 4. There is a merit which is conducted to the foil exposed part 11, and the same effect as the example shown above is obtained. Further, it is not necessary to manage the solder bridge 10 during the manufacturing process of the printed wiring board, and the productivity is improved.

In the second embodiment, the circuit mounting pattern 6 can be designed more effectively by disposing the component mounting land 2 and the copper foil exposed portion 11 as close to each other as possible. Or when there is no restriction | limiting in manufacture, the component mounting land 2 and the copper foil exposed part 11 may be connected.
Moreover, although the shape of the copper foil exposure part 11 is shown by the rectangle in FIG. 7, if the magnitude | size which suppresses turning of copper foil and the heat dissipation effect is obtained like the said Example is obtained, a rhombus, a trapezoid, etc. The shape may be any.

  In the above two embodiments, the prevention of the fire spread of the circuit wiring pattern 6 mainly caused by solder cracks in the soldering portion 9 of the lead portion 8 of the electronic component F1 has been described in detail. The same effect can be expected for the circuit wiring pattern 6 caused by the inter-polar tracking by applying the same countermeasure in the middle of the wiring path.

F1 ... Electronic component (eg fuse)
2. Component mounting land (land part)
3 ... Through hole 4 ... Incombustible conductive material (solder)
5 ... Insulating member 6 ... Circuit wiring pattern 7 ... Resist film
8 ... Lead part 9 ... Soldering part 10 ... Solder bridge 11 ... Copper foil exposed part

Claims (3)

In a printed wiring board assembly formed by soldering a lead portion of an electronic component to a circuit wiring pattern formed of copper foil on an insulating member and a land portion of the circuit wiring pattern,
A through hole penetrating the insulating member is provided on the circuit wiring pattern in the vicinity of the land portion, and the through hole has an inner diameter equal to or larger than the width of the circuit wiring pattern, and the circuit wiring pattern is formed on an inner peripheral surface of the through hole. A printed wiring board assembly comprising a continuous copper foil. The printed wiring board assembly according to claim 1, wherein the through hole is filled with a nonflammable conductive material. A printed wiring board comprising a circuit wiring pattern formed of copper foil on an insulating member, a resist film covering the circuit wiring pattern, and a lead portion of an electronic component soldered to a land portion of the circuit wiring pattern In assembly,
A printed wiring board assembly comprising a copper foil exposed portion not covered with the resist film on the circuit wiring pattern in the vicinity of the land portion, and the copper foil exposed portion filled with a nonflammable conductive material. .

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