Wiring circuit board

Abstract

To provide a wiring circuit board that enables more accurate control of expansion and contraction of a piezoelectric element.SOLUTION: A circuitized suspension substrate 1 is provided, comprising a first pattern 141 having a first terminal 141A electrically connected to one end of a piezoelectric element Pz1, a second pattern 142 having a second terminal 1421A electrically connected to the other terminal of the piezoelectric element Pz1, and a third pattern 143 connected in parallel to a series circuit consisting of the first pattern 141, the second pattern 142, and the piezoelectric element Pz1 while the piezoelectric element Pz1 is mounted on the circuitized suspension substrate 1. A wiring line 143A of the third pattern 143 is longer than that of a wiring line 1423A of the second pattern 142.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wiring circuit board.

Background Art

[0002] Conventionally, as an example of a wiring circuit board, a suspension board with a circuit capable of mounting a slider and a piezoelectric element is known (see, for example, Patent Document 1).

[0003] The suspension board with a circuit includes a first element connection terminal connected to one end of the piezoelectric element and a second element connection terminal connected to the other end of the piezoelectric element. The first element connection terminal is grounded to the metal support layer of the suspension board with a circuit. The second element connection terminal is connected to an external connection terminal via a power supply wiring.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the suspension board with a circuit as described in Patent Document 1, the piezoelectric element may be electrically polarized.

[0006] When a voltage is applied to the piezoelectric element in a state where the piezoelectric element is electrically polarized, the expansion and contraction of the piezoelectric element may become excessively large or excessively small.

[0007] An object of the present invention is to provide a wiring circuit board capable of more accurately controlling the expansion and contraction of a piezoelectric element.

Means for Solving the Problems

[0008] The present invention [1] relates to a wiring circuit board on which a piezoelectric element can be mounted, and includes a first pattern having a first terminal electrically connected to one end of the piezoelectric element, a second terminal electrically connected to the other end of the piezoelectric element, and a wiring connected to the second terminal. It also includes a second pattern disposed away from the first pattern, and a third pattern having a wiring that is connected in parallel to a series circuit composed of the first pattern, the second pattern, and the piezoelectric element in a state where the piezoelectric element is mounted on the wiring circuit board. The length of the wiring of the third pattern is longer than the length of the wiring of the second pattern.

[0009] According to such a configuration, in a state where the piezoelectric element is mounted on the wiring circuit board, a parallel circuit in which the third pattern is connected in parallel to a series circuit composed of the first pattern, the piezoelectric element, and the second pattern is formed.

[0010] Therefore, when the piezoelectric element becomes polarized, in a state where no voltage is applied to the piezoelectric element, the charges in the polarized piezoelectric element can be released to the third pattern, and the polarization of the piezoelectric element can be eliminated.

[0011] Also, the length of the wiring of the third pattern is longer than the length of the wiring of the second pattern.

[0012] Therefore, when a voltage is applied to the piezoelectric element, the wiring of the third pattern functions as a resistor, and the voltage can be accurately applied to the piezoelectric element.

[0013] As a result, the expansion and contraction of the piezoelectric element can be controlled more accurately.

[0014] The present invention [2] includes the wiring circuit board according to [1] above, wherein the length of the wiring of the third pattern is 2 times or more the length of the wiring of the second pattern.

[0015] According to such a configuration, the resistance value of the wiring of the third pattern can be increased with respect to the wiring of the second pattern.

[0016] The present invention [3] includes the wiring circuit board of [1] or [2] above, wherein the thickness of the wiring of the third pattern is thinner than the thickness of the wiring of the second pattern.

[0017] According to such a configuration, the resistance value of the wiring of the third pattern can be increased with respect to the wiring of the second pattern.

[0018] The present invention [4] includes the wiring circuit board of any one of [1] to [3] above, wherein the first pattern and the second pattern are made of copper, and the third pattern is made of a conductor or semiconductor containing at least one metal selected from the group consisting of chromium, nickel, titanium, tin, molybdenum, and palladium.

[0019] According to such a configuration, the resistance value of the wiring of the third pattern can be increased with respect to the wiring of the second pattern.

[0020] The present invention [5] further includes a metal support layer and a first insulating layer disposed on the metal support layer and having through holes, and the first pattern and the third pattern are electrically connected to the metal support layer through the through holes of the first insulating layer, including the wiring circuit board of any one of [1] to [4] above.

[0021] According to such a configuration, the first pattern and the third pattern are grounded to the metal support layer.

[0022] Therefore, even when there is little space for providing the third pattern, the above-described parallel circuit can be formed using the metal support layer.

[0023] The present invention [6] further includes a metal support layer and a first insulating layer disposed on the metal support layer, and the second pattern and the third pattern are disposed on the first insulating layer, including the wiring circuit board of any one of [1] to [5] above.

[0024] The present invention [7] further includes a metal support layer, a first insulating layer disposed on the metal support layer, and a second insulating layer disposed on the first insulating layer, wherein the third pattern is disposed on the first insulating layer and covered by the second insulating layer, and the second pattern is disposed on the second insulating layer, and includes any one of the wiring circuit boards of [1] to [5] above.

[0025] The present invention [8] further includes a metal support layer, a first insulating layer disposed on the metal support layer, and a second insulating layer disposed on the first insulating layer, wherein the second pattern is disposed on the first insulating layer and covered by the second insulating layer, and the third pattern is disposed on the second insulating layer, and includes any one of the wiring circuit boards of [1] to [5] above.

Advantages of the Invention

[0026] The wiring circuit board of the present invention can more accurately control the expansion and contraction of the piezoelectric element.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

[0028] 1. Wiring Circuit Board With reference to FIGS. 1 to 3, a suspension substrate with a circuit 1 as an example of a wiring circuit board will be described.

[0029] The suspension substrate with a circuit 1 is a component that constitutes a head gimbal assembly of a hard disk drive.

[0030] As shown in FIG. 1, the suspension substrate with a circuit 1 can mount a slider S and two piezoelectric elements Pz1, P2. The slider S has a magnetic head. The magnetic head can read data from the recording surface of the hard disk and write data to the recording surface of the hard disk.

[0031] Specifically, the suspension substrate with a circuit 1 has a mounting portion 2, a wiring portion 3, and a neck portion 4.

[0032] The mounting portion 2 is mounted with a slider S. The mounting portion 2 is located at one end of the suspension substrate 1 with a circuit. The mounting portion 2 extends in the first direction and the second direction. The first direction is orthogonal to the thickness direction of the metal support layer 11 (see FIG. 2A). The metal support layer 11 will be described later. The second direction is orthogonal to the first direction and the thickness direction. The shape of the mounting portion 2 is not limited. The mounting portion 2 has, for example, a substantially rectangular flat plate shape. At one end of the mounting portion 2 in the first direction, a first terminal 141A is arranged. At the other end of the mounting portion 2 in the first direction, a first terminal 141B is arranged. The first terminal 141A and the first terminal 141B will be described later.

[0033] The wiring portion 3 is arranged on the other side of the mounting portion 2 in the second direction. The wiring portion 3 is arranged away from the mounting portion 2. The wiring portion 3 extends in the second direction. The wiring portion 3 has a belt shape.

[0034] The neck portion 4 is arranged between the mounting portion 2 and the wiring portion 3 in the second direction. The neck portion 4 is arranged between the first terminal 141A and the first terminal 141B in the first direction. In the first direction, the dimension of the neck portion 4 is smaller than the dimensions of the mounting portion 2 and the wiring portion 3. The neck portion 4 extends in the second direction. One end of the neck portion 4 in the second direction is connected to the mounting portion 2. The other end of the neck portion 4 in the second direction is connected to the wiring portion 3.

[0035] As shown in FIG. 2A, the suspension substrate 1 with a circuit includes a metal support layer 11, a first insulating layer 12, a second insulating layer 13, a circuit pattern 14 (see FIG. 1), and a third insulating layer 15.

[0036] (1) Metal support layer The metal support layer 11 supports the first insulating layer 12, the second insulating layer 13, the circuit pattern 14, and the third insulating layer 15. The metal support layer 11 is arranged in the mounting portion 2, the wiring portion 3, and the neck portion 4. The metal support layer 11 of the mounting portion 2 is connected to the metal support layer 11 of the wiring portion 3 via the metal support layer 11 of the neck portion 4. Examples of the material of the metal support layer 11 include stainless steel and copper alloy.

[0037] (2) First insulating layer The first insulating layer 12 is formed at least in a portion where the third pattern 143 is formed. The third pattern 143 will be described later. The first insulating layer 12 is disposed on the metal support layer 11 in the thickness direction of the metal support layer 11. The first insulating layer 12 is disposed between the metal support layer 11 and the third pattern 143. The first insulating layer 12 insulates the third pattern 143 from the metal support layer 11. The first insulating layer 12 is made of resin. Examples of the resin include polyimide, maleimide, epoxy resin, polybenzoxazole, and polyester. The first insulating layer 12 is preferably made of polyimide. The first insulating layer 12 has two through holes 12A and 12B (see FIG. 1).

[0038] (3) Second insulating layer The second insulating layer 13 is formed in a portion where the first pattern 141 (see FIG. 2B), the second pattern 142, and the fourth pattern 144 are formed. The first pattern 141, the second pattern 142, and the fourth pattern 144 will be described later. In a portion where the first insulating layer 12 is formed, the second insulating layer 13 is disposed on the first insulating layer 12 in the thickness direction. The second insulating layer 13 covers the third pattern 143. In a portion where the first insulating layer 12 is not formed, the second insulating layer 13 is disposed on the metal support layer 11 in the thickness direction. The first insulating layer 12 insulates the first pattern 141, the second pattern 142, and the fourth pattern from the metal support layer 11 and the third pattern 143. The second insulating layer 13 is made of resin. Examples of the resin include the resins described above. The second insulating layer 13 is preferably made of the same resin as the first insulating layer 12. The second insulating layer 13 has four through holes 13A, 13B, 13C, and 13D (see FIG. 1).

[0039] (4) Circuit pattern As shown in FIG. 1, the circuit pattern 14 has a first pattern 141, a second pattern 142, a third pattern 143, and a fourth pattern 144. In other words, the circuit-mounted suspension substrate 1 includes the first pattern 141, the second pattern 142, the third pattern 143, and the fourth pattern 144.

[0040] (4-1) First Pattern The first pattern 141 is grounded to the metal support layer 11 (see FIG. 2B). Specifically, the first pattern 141 has two first terminals 141A and 141B. In the present embodiment, the first pattern 141 consists of the first terminals 141A and 141B.

[0041] The first terminal 141A is disposed at one end of the mounting portion 2 in the first direction. The first terminal 141A is disposed away from the neck portion 4 in the first direction. The first terminal 141A is disposed on the opposite side of the neck portion 4 to the first terminal 141B in the first direction. In a state where the piezoelectric element Pz1 is mounted on the circuit-mounted suspension substrate 1, the first terminal 141A is electrically connected to one end of the piezoelectric element Pz1. The first terminal 141A has a square land shape.

[0042] The first terminal 141B is disposed at the other end of the mounting portion 2 in the first direction. The first terminal 141B is disposed away from the neck portion 4 in the first direction. The first terminal 141B is disposed on the opposite side of the neck portion 4 to the first terminal 141A in the first direction. In a state where the piezoelectric element Pz2 is mounted on the circuit-mounted suspension substrate 1, the first terminal 141B is electrically connected to one end of the piezoelectric element Pz2. The first terminal 141B has a square land shape.

[0043] As shown in FIG. 2B, the first terminals 141A and 141B are disposed on the second insulating layer 13 in the thickness direction. In other words, the first pattern 141 is disposed on the second insulating layer 13 in the thickness direction. The first terminal 141A is connected to the metal support layer 11 through the through hole 13A of the second insulating layer 13. The first terminal 141B is connected to the metal support layer 11 through the through hole 13B of the second insulating layer 13. That is, the first pattern 141 is electrically connected to the metal support layer 11. In other words, the first pattern 141 is grounded to the metal support layer 11.

[0044] The first pattern 141 is made of a first conductor. The first conductor has a first electrical resistivity. Examples of the first conductor include copper, silver, gold, iron, aluminum, and alloys thereof. The first pattern 141 is preferably made of copper.

[0045] All of the first pattern 141 may be made of the first conductor. Further, the first pattern 141 may have a conductor layer made of the first conductor, a first protective layer, and a second protective layer.

[0046] The first protective layer is disposed between the conductor layer and the first insulating layer 12. The first protective layer protects the conductor layer. The first protective layer is made of a metal different from the first conductor. Examples of the material of each of the first protective layers include chromium, nickel, titanium, and alloys thereof. Preferably, the material of the first protective layer is chromium.

[0047] The second protective layer covers the surface of the conductor layer. The second protective layer, together with the first protective layer, protects the conductor layer. The first pattern 141 may have a plurality of second protective layers. The second protective layer is made of a metal different from the first conductor. Examples of the material of each of the second protective layers include chromium, nickel, titanium, gold, tin, and alloys thereof. Preferably, the materials of the second protective layer are nickel and gold. More specifically, the first terminals 141A and 141B may have at least one of a nickel plating layer and a gold plating layer as the second protective layer.

[0048] The first electrical resistivity is, for example, less than 1.0×10 -7 Ω·m, preferably, 5.0×10 -8 Ω or less. The first electrical resistivity is, for example, 1.5×10 -8 Ω or more.

[0049] The resistance value of each of the first terminals 141A and 141B is, for example, less than 1.0×10 5 Ω, preferably, 1.0×10 2 Ω or less. The resistance value of each of the first terminals 141A and 141B is, for example, 1.0 Ω or more.

[0050] (4-2) Second pattern As shown in FIG. 1, the second pattern 142 is a wiring pattern for supplying power to the piezoelectric elements Pz1 and Pz2 in a state where the piezoelectric elements Pz1 and Pz2 are mounted on the circuit-mounted suspension substrate 1. Specifically, the second pattern 142 includes two second terminals 1421A and 1421B, two external connection terminals 1422A and 1422B, and two wirings 1423A and 1423B. In the present embodiment, the second pattern 142 is composed of two second terminals 1421A and 1421B, two external connection terminals 1422A and 1422B, and two wirings 1423A and 1423B.

[0051] The second terminal 1421A is disposed at one end of the wiring portion 3 in the first direction. The second terminal 1421A is disposed away from the first terminal 141A in the second direction. The second terminal 1421A is disposed away from the neck portion 4 in the first direction. The second terminal 1421A is disposed on the opposite side of the second terminal 1421B with respect to the neck portion 4 in the first direction. In a state where the piezoelectric element Pz1 is mounted on the circuit-mounted suspension substrate 1, the second terminal 1421A is electrically connected to the other end of the piezoelectric element Pz1. The second terminal 1421A has a square land shape.

[0052] The second terminal 1421B is disposed at the other end of the wiring portion 3 in the first direction. The second terminal 1421B is disposed away from the first terminal 141B in the second direction. The second terminal 1421B is disposed away from the neck portion 4 in the first direction. The second terminal 1421B is disposed on the opposite side of the neck portion 4 to the second terminal 1421A in the first direction. In a state where the piezoelectric element Pz2 is mounted on the suspension substrate 1 with a circuit, the second terminal 1421B is electrically connected to the other end of the piezoelectric element Pz2. The second terminal 1421B has a square land shape.

[0053] The external connection terminals 1422A and 1422B are disposed at the other end of the suspension substrate 1 with a circuit. The external connection terminal 1422A is disposed away from the second terminal 1421A. The external connection terminal 1422B is disposed away from the second terminal 1421B. The external connection terminals 1422A and 1422B are electrically connected to, for example, a control board of a hard disk drive. Each of the external connection terminals 1422A and 1422B has a square land shape.

[0054] The wiring 1423A electrically connects the second terminal 1421A and the external connection terminal 1422A. One end of the wiring 1423A is connected to the second terminal 1421A. The other end of the wiring 1423A is connected to the external connection terminal 1422A. In a state where the piezoelectric element Pz1 is mounted on the suspension substrate 1 with a circuit, power from an external power source is supplied to the piezoelectric element Pz1 through the external connection terminal 1422A and the wiring 1423A.

[0055] The wiring 1423B electrically connects the second terminal 1421B and the external connection terminal 1422B. One end of the wiring 1423B is connected to the second terminal 1421B. The other end of the wiring 1423B is connected to the external connection terminal 1422B. In a state where the piezoelectric element Pz2 is mounted on the suspension substrate 1 with a circuit, power from an external power source is supplied to the piezoelectric element Pz2 through the external connection terminal 1422B and the wiring 1423B.

[0056] As shown in FIGS. 2A and 2C, the second pattern 142 is disposed on the second insulating layer 13 in the thickness direction. The second pattern 142 is not connected to the metal support layer 11. The second pattern 142 is made of a first conductor. The second pattern 142 is made of the same material as the first pattern 141. The second pattern 142 is preferably made of copper. Similarly to the first pattern 141, the entire second pattern 142 may be made of a first conductor, or may have a conductor layer made of a first conductor, a first protective layer, and a second protective layer. Specifically, the wirings 1423A and 1423B may have a nickel plating layer as the second protective layer. The second terminals 1421A and 1421B, and the external connection terminals 1422A and 1422B may have at least one of a nickel plating layer and a gold plating layer as the second protective layer.

[0057] The thickness T1 (see FIG. 2C) of the wirings 1423A and 1423B is, for example, 1 μm to 10 μm, preferably 3 μm to 7 μm.

[0058] The length of the wirings 1423A and 1423B is, for example, 1 mm to 500 mm, preferably 10 mm to 100 mm.

[0059] The respective resistance values of the wirings 1423A and 1423B are, for example, less than 1.0×10 5 Ω, preferably 1.0×10 2 Ω or less. The respective resistance values of the wirings 1423A and 1423B are, for example, 1.0 Ω or more.

[0060] (4-3) The third pattern As shown in FIG. 1, the third pattern 143 is electrically connected to the second pattern 142 and the metal support layer 11 (see FIG. 2A).

[0061] Specifically, the third pattern 143 has two wirings 143A and 143B. In the present embodiment, the third pattern 143 consists of two wirings 143A and 143B.

[0062] One end of the wiring 143A is connected to the metal support layer 11 through the through hole 12A of the first insulating layer 12 (see FIG. 2A). That is, the wiring 143A is grounded to the metal support layer 11. The other end of the wiring 143A is connected to the wiring 1423A through the through hole 13C of the second insulating layer 13 (see FIG. 2C).

[0063] As a result, as shown in FIG. 3, in a state where the piezoelectric element Pz1 is mounted on the circuit - attached suspension substrate 1, a parallel circuit in which the wiring 143A is connected in parallel to a series circuit composed of the external connection terminal 1422A, the wiring 1423A, the second terminal 1421A, the piezoelectric element Pz1, and the first terminal 141A is formed. That is, in a state where the piezoelectric element Pz1 is mounted on the circuit - attached suspension substrate 1, the third pattern 143 is connected in parallel to a series circuit composed of the first pattern 141, the second pattern 142, and the piezoelectric element Pz1.

[0064] Also, as shown in FIG. 1, one end of the wiring 143B is connected to the metal support layer 11 through the through hole 12B of the first insulating layer 12 (see FIG. 2A). That is, the wiring 143B is grounded to the metal support layer 11. The other end of the wiring 143B is connected to the wiring 1423B through the through hole 13D of the second insulating layer 13 (see FIG. 2C).

[0065] As a result, in a state where the piezoelectric element Pz2 is mounted on the circuit - attached suspension substrate 1, a parallel circuit in which the wiring 143B is connected in parallel to a series circuit composed of the external connection terminal 1422B, the wiring 1423B, the second terminal 1421B, the piezoelectric element Pz2, and the first terminal 141B is formed.

[0066] As shown in FIG. 2C, the third pattern 143 is disposed on the first insulating layer 12 in the thickness direction. The third pattern 143 is covered by the second insulating layer 13.

[0067] The third pattern 143 is made of, for example, a second conductor or a semiconductor. The second conductor or semiconductor contains at least one metal selected from the group consisting of copper, silver, gold, iron, aluminum, chromium, nickel, titanium, tin, molybdenum, and palladium.

[0068] Specifically, examples of the second conductor include chromium, nickel, titanium, tin, molybdenum, palladium, their alloys, and their oxides.

[0069] Examples of the semiconductor include an oxide semiconductor containing at least one metal selected from the group consisting of copper, silver, gold, iron, aluminum, chromium, nickel, titanium, tin, molybdenum, and palladium.

[0070] The third pattern 143 is preferably made of a second conductor, more preferably made of chromium. The third pattern 143 may also be made of the first conductor described above.

[0071] The second conductor has a second electrical resistivity. The second electrical resistivity is higher than the first electrical resistivity. The second electrical resistivity is, for example, 1.0×10 -8 Ω·m or more, preferably 1.0×10 -7 Ω·m or more. The second electrical resistivity is, for example, 1.5×10 -7 Ω·m or less.

[0072] The thickness T2 of the wirings 143A and 143B is thinner than the thickness T1 of the wirings 1423A and 1423B of the second pattern 142. The thickness T2 of the wirings 143A and 143B is, for example, 100 nm or less, preferably 70 nm or less. The thickness T2 of the wirings 143A and 143B is, for example, 10 nm or more. The thickness T2 of the wirings 143A and 143B may be 10 nm to 100 nm, or 10 nm to 70 nm.

[0073] The length of wiring 143A is longer than that of wiring 1423A. The length of wiring 143B is longer than that of wiring 1423B. In this embodiment, as shown in FIG. 1, at least a part of each of wirings 143A and 143B is meandering. Therefore, the length of wiring 143A is longer than that of wiring 1423A, and the length of wiring 143B is longer than that of wiring 1423B.

[0074] The length of wiring 143A is, for example, 2 times or more, preferably 5 times or more, more preferably 10 times or more the length of wiring 1423A. The length of wiring 143A is, for example, 30 times or less the length of wiring 1423A.

[0075] Similarly, the length of wiring 143B is, for example, 2 times or more, preferably 5 times or more, more preferably 10 times or more the length of wiring 1423B. The length of wiring 143B is, for example, 30 times or less the length of wiring 1423B.

[0076] The length of wiring 143B may be different from the length of wiring 143A.

[0077] Specifically, the lengths of wirings 143A and 143B are, for example, 0.2 m or more, preferably 0.8 m or more. The lengths of wirings 143A and 143B are, for example, 1.0 m or less.

[0078] The resistance value of wiring 143A is higher than that of wiring 1423A. The resistance value of wiring 143B is higher than that of wiring 1423B. The resistance values of wirings 143A and 143B are, for example, 1.0×10 5 Ω to 1.0×10 9 Ω, preferably 1.0×10 5 Ω to 1.0×10 6 Ω.

[0079] (4-4) Fourth pattern As shown in FIG. 1, the fourth pattern 144 is a wiring pattern that is electrically connected to the magnetic head with the slider S mounted on the circuit-mounted suspension substrate 1.

[0080] The fourth pattern 144 has a plurality of magnetic head connection terminals 1441A, 1441B, 1441C, 1441D, a plurality of external connection terminals 1442A, 1442B, 1442C, 1442D, and a plurality of wirings 1443A, 1443B, 1443C, 1443D. In this embodiment, the fourth pattern 144 consists of the magnetic head connection terminals 1441A, 1441B, 1441C, 1441D, the external connection terminals 1442A, 1442B, 1442C, 1442D, and the wirings 1443A, 1443B, 1443C, 1443D.

[0081] The magnetic head connection terminals 1441A, 1441B, 1441C, 1441D are arranged on the mounting portion 2. In a state where the slider S is mounted on the mounting portion 2, the magnetic head connection terminals 1441A, 1441B, 1441C, 1441D are electrically connected to the magnetic head. The magnetic head connection terminals 1441A, 1441B, 1441C, 1441D are arranged in the first direction. Each of the magnetic head connection terminals 1441A, 1441B, 1441C, 1441D has a square land shape.

[0082] The external connection terminals 1442A, 1442B, 1442C, 1442D are arranged at the other end of the circuit board with suspension 1 in the first direction. The external connection terminals 1442A, 1442B, 1442C, 1442D are electrically connected to, for example, the control board of a hard disk drive. The external connection terminals 1442A, 1442B, 1442C, 1442D are arranged in the first direction. Note that the direction in which the external connection terminals 1442A, 1442B, 1442C, 1442D are arranged may be different from the direction in which the magnetic head connection terminals 131A, 131B, 131C, 131D are arranged. Each of the external connection terminals 1442A, 1442B, 1442C, 1442D has a square land shape.

[0083] The wiring 1443A electrically connects the magnetic head connection terminal 1441A and the external connection terminal 1442A. One end of the wiring 1443A is connected to the magnetic head connection terminal 1441A. The other end of the wiring 1443A is connected to the external connection terminal 1442A.

[0084] The wiring 1443B electrically connects the magnetic head connection terminal 1441B and the external connection terminal 1442B. One end of the wiring 1443B is connected to the magnetic head connection terminal 1441B. The other end of the wiring 1443B is connected to the terminal 1442B.

[0085] The wiring 1443C electrically connects the magnetic head connection terminal 1441C and the external connection terminal 1442C. One end of the wiring 1443C is connected to the magnetic head connection terminal 1441C. The other end of the wiring 1443C is connected to the external connection terminal 1442C.

[0086] The wiring 1443D electrically connects the magnetic head connection terminal 1441D and the external connection terminal 1442D. One end of the wiring 1443D is connected to the magnetic head connection terminal 1441D. The other end of the wiring 1443D is connected to the external connection terminal 1442D.

[0087] As shown in FIGS. 2A to 2C, the fourth pattern 144 is disposed on the second insulating layer 13 in the thickness direction. The fourth pattern 144 is not connected to the metal support layer 11. The fourth pattern 144 is made of a first conductor. The fourth pattern 144 is made of the same material as the first pattern 141 and the second pattern 142.

[0088] (5) Third insulating layer As shown in FIG. 1, the third insulating layer 15 covers the wirings 1423A, 1423B, 1443A, 1443B, 1443C, 1443D. The third insulating layer 15 does not cover the first terminals 141A, 141B, the second terminals 1421A, 1421B, the magnetic head connection terminals 1441A, 1441B, 1441C, 1441D, and the external connection terminals 1422A, 1422B, 1442A, 1442B, 1442C, 1442D.

[0089] As shown in FIGS. 2A to 2C, the third insulating layer 15 is disposed on the second insulating layer 13 in the thickness direction. The third insulating layer 15 is made of resin. Examples of the resin include the resins described above. The third insulating layer 15 is preferably made of the same resin as the first insulating layer 12.

[0090] 2. Manufacturing method of wiring circuit board Next, with reference to FIGS. 4A to 4D and FIG. 2A, a manufacturing method of a wiring circuit board will be described.

[0091] The manufacturing method of the wiring circuit board includes a first step (see FIG. 4A), a second step (see FIG. 4B), a third step (see FIG. 4C), a fourth step (see FIG. 4D), and a fifth step (see FIG. 2A).

[0092] (1) First step As shown in FIG. 4A, in the first step, a first insulating layer 12 is formed on the metal support layer 11.

[0093] Specifically, a solution (varnish) of photosensitive resin is applied onto the metal support layer 11 and dried to form a coating film of photosensitive resin.

[0094] Next, the coating film of photosensitive resin is exposed and developed. Thereby, the first insulating layer 12 is formed.

[0095] (2) Second step Next, as shown in FIG. 4B, in the second step, following the first step, a third pattern 143 is formed on the first insulating layer 12.

[0096] Specifically, to form the third pattern 143, first, a thin layer made of a second conductor or semiconductor is formed on the surfaces of the metal support layer 11 and the first insulating layer 12, for example, by sputtering.

[0097] Next, an etching resist is bonded onto the thin layer, and the etching resist is exposed in a state where the portion where the third pattern 143 is not to be formed is shielded from light.

[0098] Next, the exposed etching resist is developed. Then, the etching resist in the shielded portion is removed, and the etching resist in the portion where the third pattern 143 is to be formed remains.

[0099] Next, the thin layer exposed by removing the etching resist is removed by etching.

[0100] After the etching is completed, the etching resist is peeled off.

[0101] As described above, the third pattern 143 is formed on the first insulating layer 12.

[0102] (3) Third step Next, as shown in FIG. 4C, in the third step, following the second step, a second insulating layer 13 is formed on the metal support layer 11 and the first insulating layer 12. The second insulating layer 13 is formed in the same manner as the above-described first insulating layer 12.

[0103] (4) Fourth step Next, as shown in FIG. 4D, in the fourth step, following the third step, a first pattern 141 (see FIG. 2B), a second pattern 142, and a fourth pattern 144 are formed on the second insulating layer 13.

[0104] Specifically, first, a seed layer is formed on the surface of the second insulating layer 13. The seed layer is formed, for example, by sputtering. Examples of the material of the seed layer include chromium, copper, nickel, titanium, and alloys thereof.

[0105] Next, a plating resist is bonded onto the second insulating layer 13 on which the seed layer is formed, and the plating resist is exposed in a state where the portions where the first pattern 141, the second pattern 142, and the fourth pattern 144 are formed are shielded from light.

[0106] Next, the exposed plating resist is developed. Then, the plating resist in the shielded portion is removed, and the seed layer is exposed in the portions where the first pattern 141, the second pattern 142, and the fourth pattern 144 are formed. Note that the plating resist in the exposed portion, that is, the portion where the first pattern 141, the second pattern 142, and the fourth pattern 144 are not formed, remains.

[0107] Next, on the exposed seed layer, the first pattern 141, the second pattern 142, and the fourth pattern 144 are formed by electrolytic plating. After the electrolytic plating is completed, the plating resist is peeled off.

[0108] Next, the seed layer exposed by peeling off the plating resist is removed by wet etching.

[0109] (5) The fifth step Next, as shown in FIG. 2A, in the fifth step, following the fourth step, the third insulating layer 15 is formed on the second insulating layer 13. The third insulating layer 15 is formed in the same manner as the above-described first insulating layer 12.

[0110] Thereafter, the metal support layer 11 is processed into a predetermined shape by etching the metal support layer 11.

[0111] Thus, the circuit-attached suspension substrate 1 is obtained.

[0112] 3. Operational effects (1) According to the circuit-attached suspension substrate 1, as shown in FIG. 1, the wiring 143A is connected to the wiring 1423A and the metal support layer 11 (see FIG. 2A).

[0113] Thereby, in a state where the piezoelectric element Pz1 is mounted on the circuit-attached suspension substrate 1, as shown in FIG. 3, a parallel circuit in which the third pattern 143 (wiring 143A) is connected in parallel to a series circuit including the second pattern 142 (external connection terminal 1422A, wiring 1423A, and second terminal 1421A), the piezoelectric element Pz1, and the first pattern 141 (first terminal 141A) is formed.

[0114] Therefore, when the piezoelectric element Pz1 is polarized, in a state where no voltage is applied to the piezoelectric element Pz1, the charges in the polarized piezoelectric element Pz1 are allowed to escape to the wiring 143A, and the polarization of the piezoelectric element Pz1 can be eliminated.

[0115] Also, the length of the wiring 143A of the third pattern 143 is longer than the length of the wiring 1423A of the second pattern 142.

[0116] Therefore, when applying a voltage to the piezoelectric element Pz1, the wiring 143A of the third pattern 143 functions as a resistor, and the voltage can be accurately applied to the piezoelectric element Pz1.

[0117] As a result, the expansion and contraction of the piezoelectric element Pz1 can be controlled more accurately.

[0118] (2) According to the circuit-mounted suspension substrate 1, as shown in FIG. 1, the length of the wiring 143A of the third pattern 143 is twice or more the length of the wiring 1423A of the second pattern 142.

[0119] Therefore, the resistance value of the wiring 143A of the third pattern 143 can be increased with respect to the wiring 1423A of the second pattern 142.

[0120] (3) According to the circuit-mounted suspension substrate 1, as shown in FIGS. 2A to 2C, the thickness T2 of the wiring 143A of the third pattern 143 is thinner than the thickness T1 of the wiring 1423A of the second pattern 142.

[0121] Therefore, the resistance value of the wiring 143A of the third pattern 143 can be increased with respect to the wiring 1423A of the second pattern 142.

[0122] (4) According to the circuit-mounted suspension substrate 1, the first pattern 141 and the second pattern 142 are made of copper, and the third pattern is made of a conductor (second conductor) or semiconductor containing at least one metal selected from the group consisting of chromium, nickel, titanium, tin, molybdenum, and palladium.

[0123] Therefore, the resistance value of the wiring 143A of the third pattern 143 can be increased with respect to the wiring 1423A of the second pattern 142.

[0124] According to the suspended circuit board 1 with a circuit, as shown in FIGS. 2A and 2B, the first pattern 141 and the third pattern 143 are grounded to the metal support layer 11.

[0125] Therefore, even when there is little space for providing the third pattern 143, the above-described parallel circuit can be formed by using the metal support layer 11.

[0126] 4. Modification Hereinafter, the modification will be described. In the modification, the same members as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0127] (1) The second insulating layer 13 may not be disposed between the first terminals 141A and 141B (see FIG. 2) and the metal support layer 11. The first terminals 141A and 141B may be disposed on the metal support layer 11.

[0128] (2) As shown in FIG. 5, one end of the wiring 143A may be connected to the first terminal 141A. One end of the wiring 143B may be connected to the first terminal 141B.

[0129] Specifically, as shown in FIG. 6, one end of the wiring 143A is disposed between a part of the first terminal 141A and the metal support layer 11. The first terminal 141A is connected to one end of the wiring 143A through the through hole 13A of the second insulating layer 13.

[0130] Also, the first terminal 141A is grounded to the metal support layer 11. For example, the suspended circuit board 1 with a circuit may have a ground wiring 20A (see FIG. 5) that connects the first terminal 141A to the metal support layer 11. The first terminal 141A may be grounded to the metal support layer 11 through a through hole (not shown).

[0131] Also, a first insulating layer 12 is disposed between one end of the wiring 143A and the metal support layer 11. The wiring 143A may be grounded to the metal support layer 11 through a through hole (not shown) of the first insulating layer 12.

[0132] Even in this modified example, as shown in FIG. 7, with the piezoelectric element Pz1 mounted on the circuit-equipped suspension substrate 1, a parallel circuit is formed in which the wiring 143A is connected in parallel to a series circuit consisting of the external connection terminal 1422A, the wiring 1423A, the second terminal 1421A, the piezoelectric element Pz1, and the first terminal 141A.

[0133] Therefore, even in this modified example, the same operational effects as those of the above-described embodiment can be obtained.

[0134] (3) As shown in FIGS. 8A and 8B, the second pattern 142 and the third pattern 143 may be disposed on the first insulating layer 12. In this case, as shown in FIG. 8B, a part of the wiring 1423A of the second pattern 142 is disposed on the other end portion of the wiring 143A of the third pattern 143. Also, a part of the wiring 1423B of the second pattern 142 is disposed on the other end portion of the wiring 143B of the third pattern 143. The wirings 1423A, 1423B, 143A, and 143B are covered by the second insulating layer 13.

[0135] Note that in this modified example, the fourth pattern 144 may also be disposed on the first insulating layer 12 and covered by the second insulating layer 13.

[0136] Even in this modified example, the same operational effects as those of the above-described embodiment can be obtained.

[0137] (4) As shown in FIGS. 9A and 9B, the second pattern 142 may be disposed on the first insulating layer 12 and covered by the second insulating layer 13.

[0138] In this case, the third pattern 143 is disposed on the second insulating layer 13. The other end portion of the wiring 143A of the third pattern 143 is connected to the wiring 1423A of the second pattern 142 through the through hole 13C of the second insulating layer 13. The other end portion of the wiring 143B of the third pattern 143 is connected to the wiring 1423B of the second pattern 142 through the through hole 13D of the second insulating layer 13.

[0139] Note that also in this modification example, the fourth pattern 144 may be disposed on the first insulating layer 12 and covered by the second insulating layer 13.

[0140] Also in this modification example, the same operational effects as those of the above-described embodiment can be obtained.

Explanation of Reference Numerals

[0141] 1 Suspension substrate with circuit (an example of a wiring circuit board) 11 Metal support layer 12 First insulating layer 12A Through hole 13 Second insulating layer 141 First pattern 141A First terminal 142 Second pattern 1421A Second terminal 1423A Wiring Pz1 Piezoelectric element

Claims

1. A wiring circuit board capable of mounting a piezoelectric element, having a first pattern having a first terminal electrically connected to one end of the piezoelectric element, having a second terminal electrically connected to the other end of the piezoelectric element and a wiring connected to the second terminal, and a second pattern disposed away from the first pattern, and having a third pattern having a wiring connected in parallel to a series circuit composed of the first pattern, the second pattern, and the piezoelectric element in a state where the piezoelectric element is mounted on the wiring circuit board and comprising: The wiring circuit board, wherein the length of the wiring of the third pattern is longer than the length of the wiring of the second pattern.

2. The wiring circuit board according to claim 1, wherein the length of the wiring of the third pattern is twice or more the length of the wiring of the second pattern.

3. The wiring circuit board according to claim 1, wherein the thickness of the wiring of the third pattern is thinner than the thickness of the wiring of the second pattern.

4. The first pattern and the second pattern are made of copper, and the third pattern is made of a conductor or semiconductor containing at least one metal selected from the group consisting of chromium, nickel, titanium, tin, molybdenum, and palladium. The wiring circuit board according to claim 1.

5. a metal support layer, and a first insulating layer disposed on the metal support layer and having a through hole further comprising: The wiring circuit board according to any one of claims 1 to 4, wherein the first pattern and the third pattern are electrically connected to the metal support layer through the through hole of the first insulating layer.

6. a metal support layer, and a first insulating layer disposed on the metal support layer further comprising: The second pattern and the third pattern are disposed on the first insulating layer, and the wiring circuit board according to any one of claims 1 to 4.

7. A metal support layer, A first insulating layer disposed on the metal support layer, A second insulating layer disposed on the first insulating layer, and further comprising: The third pattern is disposed on the first insulating layer and covered by the second insulating layer, The second pattern is disposed on the second insulating layer, and the wiring circuit board according to any one of claims 1 to 4.

8. A metal support layer, A first insulating layer disposed on the metal support layer, A second insulating layer disposed on the first insulating layer, and further comprising: The second pattern is disposed on the first insulating layer and covered by the second insulating layer, The third pattern is disposed on the second insulating layer, and the wiring circuit board according to any one of claims 1 to 4.

Images