JP2005072206A - High-frequency printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a high-frequency printed wiring board which can be improved in shielding and electrical properties by making a solder layer formed on a part of the board which comes into contact with a shield cover or a cutoff block uniform in thickness, so as to bring the board into stable contact with the shield cover or the cutoff block. <P>SOLUTION: Solder coating is applied to the high-frequency printed wiring board, and ground through-holes of the same diameters are uniformly arranged on a ground pattern spreading over a part that comes into contact with the shield cover or the cutoff block. The end of the ground pattern is set equal in shape to the center of the ground pattern. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a high-frequency printed wiring board, and more particularly to a high-frequency printed wiring board that is used in a high-frequency device and to which a solder coat is applied.

  FIG. 5 is a plan view showing a conventional high-frequency printed wiring board, and FIG. 6 is an enlarged sectional view taken along line AA of FIG. 5 and 6, 1 is a substrate, 2 is a high-frequency signal pattern formed on the substrate 1, 3 is a ground pattern formed on the substrate 1, and 4 a and 4 b are ground potentials formed in the ground pattern 3. Through hole 5, a portion of the substrate 1 that contacts the shield cover or cut-off block 6, solder applied to the surface of the ground pattern 3 and the high-frequency signal pattern 2, and 7 indicated by a broken line 7 is a shield cover or cut-off block , 8 are gaps between the shield cover or cut-off block and the ground pattern 3.

  Next, the operation will be described. 5 and 6, ground patterns 3 are provided on both sides of the high-frequency signal pattern 2, and the ground pattern 3 extends along the high-frequency signal pattern 2 in order to block electromagnetic waves generated from the high-frequency signal pattern 2. Two rows of ground through holes 4a are provided at intervals corresponding to the signal frequency. The number of columns may be one. The ground pattern 3 is provided with through holes 4b for ground stabilization in addition to 4a. The through hole diameter and through hole interval of the through holes 4a are determined by the frequency of the high frequency signal and are not constant. Further, since it is necessary to reduce the inductance of the through hole, the through hole 4b generally has a relatively large hole diameter of φ0.6 mm or more.

The high-frequency signal pattern 2 and the ground pattern 3 are formed by etching a copper foil, and a solder coating process is performed to prevent copper oxidation. This solder coating process is a process of flattening the solder surface by immersing the substrate 1 in molten solder, applying solder 6 to the surface of the copper pattern on the substrate 1 and then blowing hot air.
Next, a shield cover for blocking electromagnetic waves generated from the high-frequency signal pattern 2 or a cut-off block 7 for preventing an unnecessary transmission mode from being brought into contact with the solder 6 applied to the ground pattern 3 so as to be conducted. It is fixed by fixing parts such as screws.
Patent Document 1 is a similar prior art document.

JP 2001-77577 A

  The conventional high-frequency printed wiring board shown in FIGS. 5 and 6 has different through hole 4a and 4b hole diameters and through hole intervals at the portion 5 where the shield cover or cut-off block on the ground pattern 3 contacts. ing. For this reason, during solder coating treatment for preventing oxidation of the copper pattern, the height of the solder hole due to the surface tension of the solder is not stable due to the size of the through-hole diameter and the interval, and the solder 6 on the ground pattern 3 is not stable. Variation in thickness increases. When the shield cover or the cut-off block 7 is brought into contact with the ground pattern 3, a gap 8 is generated, resulting in a problem that the shielding effect is lowered and good electrical characteristics cannot be obtained.

  Further, in order to flatten the portion 5 in contact with the shield cover or cut-off block of the substrate 1, there is a method of performing gold plating as the pattern surface treatment of the substrate 1, but in this case, it is general to the shield cover or cut-off block. Since the aluminum material and gold used in this process cause electric corrosion, it is necessary to apply gold plating or nickel plating to the shield cover and cut-off block, resulting in high costs.

  The present invention has been made to solve the above-described problems, and uniformizes the solder thickness of the portion of the board that comes into contact with the shield cover or cut-off block to stabilize the contact with the shield cover or cut-off block. An object of the present invention is to obtain a high-frequency printed wiring board capable of ensuring good shielding properties and electrical characteristics.

  In the high frequency printed wiring board according to the present invention, in the high frequency printed wiring board to which the solder coat is applied, the ground through hole is formed in the ground pattern over the portion where the shield cover and the cut-off block are in contact, and the variation in the thickness of the applied solder coat is small. As shown in the figure, they are uniformly arranged with the same hole diameter.

  According to the high frequency printed wiring board of the present invention, since the small through holes having the same hole diameter are uniformly arranged over the portion where the shield cover and the cut-off block of the ground pattern are in contact, the variation in the solder thickness during the solder coating process The gap can be reduced when contacting with the shield cover or cut-off block, and good shielding properties and electrical characteristics can be obtained.

Embodiment 1 FIG.
Embodiments of the present invention will be described below with reference to the drawings. 1 is a plan view showing a high-frequency printed wiring board according to Embodiment 1 of the present invention, and FIG. 2 is an enlarged sectional view taken along line AA of FIG. 1 and 2, 1 is a substrate, 2 is a high-frequency signal pattern formed on the substrate 1, 3 is a ground pattern formed on the substrate 1, and 4a and 4b are ground potentials formed on the ground pattern 3. Through holes, 5 are portions of the substrate 1 that are in contact with the shield cover and cut-off block, 6 is solder applied to the surface of the ground pattern 3 and the high-frequency signal pattern 2, and 7 shown by a broken line is a shield cover or cut-off block is there.

  Next, the operation of the embodiment will be described. In FIG. 1 and FIG. 2, ground patterns 3 are provided on both sides of the high-frequency signal pattern 2, and the entire ground pattern 3 existing over the portion 5 where the shield cover and the cut-off block of the substrate 1 are in contact with each other is small. The through holes 4a having a hole diameter are arranged in a lattice pattern at the same interval (pitch). Further, a through hole 4b having a large hole diameter for ground stabilization is provided at a place other than the place where the shield cover and cut-off block of the ground pattern 3 are in contact. The high-frequency signal pattern 2 and the ground pattern 3 are formed by etching a copper foil, and are solder-coated to prevent copper oxidation.

  In this solder coating process, since the through holes 4a having the same hole diameter are arranged in a grid pattern at the same interval in the entire area where the shield cover and the cut-off block of the ground pattern 3 are in contact, there is little variation in solder thickness. Become. In the conventional high-frequency printed wiring board, the solder thickness variation was about 40 μm. In the first embodiment, the hole diameter of the through hole 4a is 0.4 mm or less and the interval (pitch) is 0.8 mm or less. As a result, the thickness variation of the solder is suppressed to about 10 μm, the gap can be reduced when contacting the shield cover and the cut-off block 7, and good shielding properties and electrical characteristics can be secured.

Embodiment 2. FIG.
FIG. 3 is a plan view showing the high-frequency printed wiring board of the second embodiment. In the first embodiment, the small-diameter through holes 4a are arranged in a grid where the shield cover and the cut-off block 7 on the ground pattern 3 are in contact with each other. However, as shown in FIG. In this case, since the interval between the through holes 4a can be formed narrower than in the first embodiment, the thickness variation of the solder 6 can be reduced, and the number of contact points with the shield cover and the cut-off block is increased. The ground can be stabilized and good shielding properties and electrical characteristics can be secured.

Embodiment 3 FIG.
FIG. 4 is a plan view showing the high-frequency printed wiring board according to the third embodiment. In the second embodiment, the end portion of the ground pattern 3 in contact with the shield cover or the cut-off block is a straight line. However, as shown in FIG. 4, the shape of the pattern end portion is a uniform shape at the center portion. In this case, the thickness variation of the solder 6 can be reduced in the entire area where the shield cover and the cut-off block of the ground pattern 3 are in contact with each other, and the ground can be stabilized more than in the second embodiment. Electrical characteristics can be secured.

  The present invention is particularly suitable for application to high-frequency printed wiring boards used in high-frequency equipment.

It is a top view which shows the high frequency printed wiring board in Embodiment 1 of this invention. It is an AA line expanded sectional view of FIG. 6 is a plan view showing a high-frequency printed wiring board according to Embodiment 2. FIG. 6 is a plan view showing a high-frequency printed wiring board according to Embodiment 3. FIG. It is a top view which shows the conventional high frequency printed wiring board. It is an AA line expanded sectional view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 High frequency signal pattern 3 Ground pattern 4a, 4b Through hole 5 The part which contacts a shield cover or a cut-off block 6 Solder 7 Shield cover or cut-off block 8 A clearance.

Claims (3)

  In high-frequency printed wiring boards to which solder coating is applied, ground through holes are formed in the ground pattern over the part where the shield cover and cut-off block come into contact with each other, so that variations in the thickness of the applied solder coating are reduced. A high-frequency printed wiring board characterized by being arranged.   2. The high-frequency printed wiring board according to claim 1, wherein the shape of the end portion of the ground pattern over the portion where the shield cover and the cut-off block come into contact is an extension of the uniform shape at the center portion.   2. The high frequency printed wiring board according to claim 1, wherein the ground through holes are uniformly arranged at the same hole diameter of φ0.4 mm or less and a pitch of 0.8 mm or less.

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