JP4799359B2 - High frequency circuit board and method for manufacturing high frequency circuit board - Google Patents

Description

  The present invention relates to a high-frequency circuit board that has a through hole and can mount components on the surface, and a method of manufacturing the high-frequency circuit board.

  A conventional high-frequency circuit board having a through hole has a structure in which a dielectric substrate is bonded to a metal plate. As shown in FIG. 6, the surface of the metal plate 11 where the dielectric substrate 12 is not bonded is gold-plated 16 as shown by diagonal lines on the entire surface, and other than the through holes 14 are substantially flat. As shown in FIG. 7, the component 13 is mounted on the surface of the dielectric substrate 12 of the high-frequency circuit board using solder, and then the high-frequency circuit board is screwed to the case 10.

  However, since solder tends to flow on the gold-plated surface, the solder leaked from the through hole 14 at the time of component mounting may spread on the gold-plated surface. Further, the solder that has come out of the through hole 14 may solidify in a raised state. In such a case, when the high-frequency circuit board is screwed to the case, there is a problem that grounding becomes insufficient and a characteristic defect is caused.

In Patent Document 1, in a high-frequency circuit board having a PHS (Platted-Heat-Sink) structure formed on the back surface, a slit that passes through the position of the VIA hole is provided in a portion of the PHS structure. A technique is disclosed in which bubbles are driven out by slits and VIA holes when a substrate is bonded to a case.
JP 2003-218270 A

  However, in the technique described in Patent Document 1, the back surface has a PHS structure, and the surface of the PHS is formed of gold, so that solder flows easily. This technique can be used to solve the above problems. Can not.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a high-frequency circuit board having a through hole that does not cause solder flow or solder swell on the surface in contact with the case.

In order to achieve this object, the invention according to claim 1 includes a dielectric substrate and a metal plate, the dielectric substrate is bonded to the first surface of the metal plate, and faces the first surface of the metal plate. The second surface is gold-plated and provided with a through-hole penetrating the dielectric and the metal plate,
Provided is a high-frequency circuit board characterized in that a periphery of a through hole on the second surface of a metal plate is cut to a depth at least to remove gold plating.

  The invention according to claim 8 includes a step of bonding a dielectric to a metal plate, a step of providing a through hole in the metal plate and the dielectric substrate, a step of applying gold plating to one side of the metal plate, And a step of exposing a material of the metal plate by cutting the periphery of the through hole.

  According to the present invention, since the gold plating applied to the metal plate of the high-frequency circuit board is removed from the periphery of the through hole, the solder flow can be prevented, and the periphery of the through hole of the metal plate is cut to provide the recess. Even if the solder swells in the hole portion, this swell can be prevented from protruding from the plated surface of the metal plate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of the high-frequency circuit board according to the present embodiment as viewed from the back surface, that is, the surface in contact with the case 10. The high frequency circuit board of this embodiment includes a metal plate 11 and a dielectric substrate 12.

  The surface of the dielectric substrate 12 is gold-plated, and the surface on which the circuit pattern is not formed is bonded to the metal plate 11. A through hole 14 is provided so as to penetrate the dielectric substrate 12 and the metal plate 11.

  The metal plate 11 has a dielectric substrate 12 mounted on the first surface, and the second surface opposite to the first surface, that is, the surface not in contact with the dielectric substrate 12 is gold-plated. The gold plating is removed around the hole 14, and the metal material 15 is exposed. It is desirable that the metal plate 11 is further cut around the through hole 14 to form a recess having a depth that prevents the solder from the through hole 14 from protruding from the second surface of the metal plate 11. The metal plate 11 is made of a material that makes it harder for solder to flow than gold. Of these, copper or aluminum is preferable. In particular, aluminum is suitable because it is difficult for solder to flow and solder is difficult to adhere.

  In the high-frequency circuit board of this embodiment, as shown in FIG. 7, the component 13 is mounted on the surface of the dielectric substrate 12 of the high-frequency circuit board by using solder, and then the high-frequency circuit board is screwed to the case 10. Is done.

  The through hole 14 is usually gold-plated inside. Solder tends to flow on the gold plating surface, and the material of the metal plate 11 is less likely to flow than gold. In the present embodiment, the material of the metal plate 11 is exposed around the through hole 14 on the second surface of the metal plate 11 in order to prevent the solder from the through hole 14 from causing a solder flow.

  The thickness of the gold plating is usually 1 μm to 3 μm. The interval between the through holes 14 is usually 10 mm or less. For this reason, the periphery of the through hole 14 is the second surface of the metal plate 11, the inner side is the inner wall of the through hole 14, and the outer side is at least the distance from the inner wall of the through hole 14 is the gold plating of the inner wall of the through hole 14. A range that is larger than the thickness and less than or equal to the distance to the adjacent through-hole 14. In the present embodiment, the outside of the range meant by the words around the through hole 14 is such that the distance from the inner wall of the through hole 14 on the second surface of the metal plate 11 is greater than 1 μm and 10 mm or less. When the material of the metal plate 11 is exposed, at least the periphery of the through hole 14 is cut. The cutting shape is not limited, and it may be cut into a rectangle or a circle as shown in FIG.

  2 to 5 are views schematically showing a cutting method around the through hole 14 on the second surface of the metal plate 11. Usually, the inner surface of the through hole 14 is gold-plated, but the illustration is omitted. FIG. 2 shows a state before the gold plating is removed. The entire second surface is gold-plated except for the through hole 14.

  FIG. 3 is a first example of a cutting method in the present embodiment. The periphery of the through hole 14 is cut so that at least the gold plating 16 is removed. The depth of the cutting site 30 is set to be equal to or greater than the thickness of the gold plating. The gold plating 16 may be removed, and further, cutting may be performed within a range not penetrating the metal plate 11. If the gold plating is removed in this way, the material of the metal plate 11 is exposed, so that the solder flow can be prevented.

  FIG. 4 is a second example of the cutting method in the present embodiment. When the gold plating 16 is removed, the metal plate 11 is cut to a depth that removes a part of the material. Here, the depth at which a part of the material of the metal plate 11 is removed refers to a depth at which the cutting portion 40 does not penetrate the metal plate 11. By cutting in this way, the gold plating 16 is not left behind around the through hole 14, and solder flow can be prevented more reliably.

  FIG. 5 shows a third example of the cutting method in the present embodiment. The depth of the cutting part 50 is a depth at which the solder 17 that has come out of the through hole 14 does not protrude from the second surface of the metal plate 11 and does not penetrate the metal plate 11. Cutting deeper than the height of the solder rising from the through hole 14.

  The specific depth to be cut in this embodiment is as follows. The thickness of the metal plate 11 is usually 1 mm to 2 mm, and the thickness of the gold plating is usually 1 μm to 3 μm. For this reason, when the thickness of the metal plate 11 is 1 mm, the depth of cutting is desirably 0.8 mm or less, and when the thickness of the metal plate 11 is 2 mm, the depth of cutting is preferably 1 mm. Although it is desirable to make it 1 mm or less, it is sufficient if it does not penetrate the metal plate 11. In addition, you may use a well-known technique for cutting.

  In addition, the method of manufacturing the high-frequency circuit board according to the present embodiment includes a step of bonding the dielectric 12 to the metal plate 11, a step of providing the through hole 14 in the metal plate 11, and a step of applying gold plating to one side of the metal plate 11. Cutting the periphery of the through-hole 14 on the gold-plated surface to expose the material of the metal plate 11. Although it is desirable to perform the process of cutting the metal plate 11 after the process of performing gold plating, it is not limited to this.

  As described above, in the high frequency circuit board according to the present embodiment, since the gold plating applied to the metal plate 11 is removed around the through hole, the material of the metal plate 11 is exposed. For this reason, solder flow can be prevented. Further, by cutting the metal plate 11 to such a depth that the solder 17 coming out of the through hole 14 does not protrude from the second surface of the metal plate 11, the occurrence of poor grounding when the high-frequency circuit board is screwed to the case. Can be prevented.

  Moreover, in the manufacturing method of the high frequency circuit board of this embodiment, since it cuts after metal-plating the metal plate 11, it is easier to work than gold-plating after cutting.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

It is the perspective view which looked at the high frequency circuit board of this embodiment from the surface which contacts a case. It is the figure which represented typically the state before removing the gold plating of a metal plate. It is the figure which represented typically the 1st example of the cutting method around the through-hole of a metal plate. It is the figure which represented typically the 2nd example of the cutting method around the through-hole of a metal plate. It is the figure which represented typically the 3rd example of the cutting method around the through-hole of a metal plate. It is the perspective view which looked at the conventional high frequency circuit board from the surface which contacts a case. It is a figure showing the state which mounted components to the high frequency board, and was screwed to the case.

Explanation of symbols

10: Case,
11: Metal plate,
12: Dielectric substrate
13: Parts
14: Through hole,
15: Metal plate material surface,
16: Gold plating
17: Solder.

Claims (7)

A dielectric substrate and a metal plate, wherein the dielectric substrate is bonded to a first surface of the metal plate, a second surface opposite to the first surface of the metal plate is gold-plated, and the dielectric And a high-frequency circuit board provided with a through hole penetrating the metal plate,
A high-frequency circuit board, wherein the periphery of the through hole on the second surface of the metal plate is cut to a depth that removes at least the gold plating.   The periphery of the through hole on the second surface of the metal plate is cut to a depth that removes the gold plating and further removes part of the material of the metal plate. The high-frequency circuit board described.   Solder used when the periphery of the through hole on the second surface of the metal plate removes the gold plating and further mounts a component on the dielectric substrate coming out of the through hole is the second surface. The high frequency circuit board according to claim 1, wherein the high frequency circuit board is cut to a depth that does not protrude from the base.   The high frequency circuit board according to any one of claims 1 to 3, wherein a material of the metal plate is copper or aluminum.   The high frequency circuit board according to any one of claims 1 to 4, wherein a depth at which the metal plate is cut is 1 µm or more and 1 mm or less. A dielectric substrate having a through hole;
A through-hole, wherein the dielectric substrate is bonded to the first surface, the second surface facing the first surface is gold-plated, and the periphery of the through-hole on the second surface is the gold-plated A high frequency circuit board comprising: a metal plate that is removed and cut to a depth at which the material of the metal plate is exposed. Bonding the dielectric to the metal plate;
Providing a through hole in the metal plate and the dielectric substrate;
Applying gold plating to one side of the metal plate;
Cutting the periphery of the through-hole on the gold-plated surface to expose the material of the metal plate.

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