JP7021329B2 - Wiring circuit board and its manufacturing method - Google Patents

Description

The present invention relates to a wiring circuit board and a method for manufacturing the same.

Conventionally, wiring circuit boards have been used in various electric devices or electronic devices. Patent Document 1 describes a suspension board used as an actuator of a hard disk drive device as a wiring circuit board.

In the wiring circuit board of Patent Document 1, the first insulating layer is formed on the suspension main body portion. The first and second wiring patterns are formed in parallel on the first insulating layer at intervals. A second insulating layer is formed in the region on the first insulating layer on both sides of the first and second wiring patterns. A third wiring pattern is formed in the region on the second insulating layer on the second wiring pattern side, and a fourth wiring pattern is formed in the region on the second insulating layer on the first wiring pattern side. ..

The first wiring pattern and the third wiring pattern are connected to each other at predetermined points to form the first writing wiring pattern. The second wiring pattern and the fourth wiring pattern are connected to each other at predetermined points to form a second wiring pattern for writing. The first writing wiring pattern and the second writing wiring pattern form a pair of signal line pairs.

In the wiring circuit board of Patent Document 1, the first and second wiring patterns are formed at positions lower than the third and fourth wiring patterns. Therefore, the distance between the first to fourth wiring patterns is longer than when the first to fourth wiring patterns are formed on the same plane. Therefore, the proximity effect between the first to fourth wiring patterns is reduced. Thereby, the loss of the electric signal transmitting the first to fourth wiring patterns is reduced.

Japanese Unexamined Patent Publication No. 2010-3893

However, in recent years, the frequency of electric signals used in electric devices or electronic devices has been increasing. Therefore, the wiring circuit board is required to further reduce the transmission loss of the electric signal in the high frequency band.

An object of the present invention is to provide a wiring circuit board in which the loss of an electric signal is reduced in a high frequency band and a method for manufacturing the same.

(1) The wiring circuit board according to the first invention is smaller than the support substrate formed of the conductive material, the first portion formed on the support substrate and having the first thickness, and the first thickness. It is formed in a first insulating layer including a second portion having a second thickness and a second portion of the first insulating layer so as to be electrically connected to the support substrate, and is higher than the support substrate. A ground layer having electrical conductivity, a second insulating layer formed on the first insulating layer so as to cover the ground layer, and a second insulating layer so as to overlap the first and second portions of the first insulating layer. It is provided with an upper wiring pattern formed on the insulating layer of 2.

In the wiring circuit board, a first insulating layer including the first and second portions is formed on the support board. A ground layer is formed on the second portion of the first insulating layer. Further, a second insulating layer is formed on the first insulating layer so as to cover the ground layer. Further, an upper wiring pattern is formed on the second insulating layer so as to overlap the first and second portions of the first insulating layer. In this case, the electric signal can be transmitted to the upper wiring pattern.

When an electric signal having a high frequency band transmits an upper wiring pattern, an electromagnetic wave is generated from the upper wiring pattern. When the electromagnetic wave is incident on the support substrate or the ground layer, an eddy current is generated in the support substrate or the ground layer, and the upper wiring pattern and the support substrate or the ground layer are electromagnetically coupled. The electrical signal transmitted through the upper wiring pattern has a loss depending on the magnitude of the eddy current generated in the support substrate or the ground layer. The larger the eddy current, the larger the loss of the electric signal, and the smaller the eddy current, the smaller the loss.

The eddy current generated in a conductor by applying an electromagnetic wave to the conductor is larger as the electric conductivity of the conductor is lower, and smaller as the electric conductivity of the conductor is higher. The ground layer has a higher electrical conductivity than the support substrate. Therefore, the eddy current generated in the ground layer by the electromagnetic wave is smaller than the eddy current generated in the support substrate by the electromagnetic wave.

According to the above configuration, since the ground layer is located between at least a part of the upper wiring pattern and the support board, at least a part of the electromagnetic wave radiated from the upper wiring pattern toward the support board is in the ground layer. It is incident and does not reach the support substrate.

Further, when an electric signal having a high frequency band transmits an upper wiring pattern, a loss corresponding to the line length of the upper wiring pattern occurs in the electric signal transmitting the upper wiring pattern. The loss of the electric signal is larger as the line length of the upper wiring pattern is larger, and is smaller as the line length of the upper wiring pattern is smaller. In the wiring circuit board according to the present invention, a ground layer is formed on the second portion of the first insulating layer. In this case, the difference between the position of the upper surface of the first portion of the first insulating layer and the position of the upper surface of the ground layer in the stacking direction of the support substrate, the first insulating layer and the second insulating layer is small. can do. As a result, a step due to the presence or absence of the ground layer is hardly formed on the first portion of the first insulating layer and the upper surface of the second insulating layer formed on the ground layer. Therefore, the upper wiring pattern can be formed linearly on the second insulating layer. Therefore, it is possible to prevent the wiring length of the upper wiring pattern from becoming long.

As a result, the loss of the electrical signal transmitting the upper wiring pattern in the high frequency band is reduced.

(2) The upper wiring pattern extends in the first direction, and the first insulating layer has a plurality of first portions and a plurality of second portions, and a plurality of first portions and a plurality of second portions. The portions may be arranged alternately in the first direction.

In this case, the upper wiring pattern overlaps the portions of the plurality of ground layers intermittently arranged in the first direction. Thereby, the uniformity of the characteristic impedance of the upper wiring pattern can be improved.

(3) The wiring circuit board according to the second invention is a support substrate formed of a conductive material and a grounding layer formed in a first region on the support substrate and having a higher electric conductivity than the support substrate. A first insulating layer formed in a second region different from the first region on the support substrate, a ground layer, a second insulating layer formed on the ground layer and the first insulating layer, and a support substrate. The upper wiring pattern is formed on the second insulating layer so as to overlap the first and second regions of the above, the upper wiring pattern extends in the first direction, and the support substrate has a plurality of first regions. In addition to having a plurality of second regions, the plurality of first regions and the plurality of second regions are alternately arranged in the first direction.

In the wiring circuit board, a ground layer is formed on the first region of the support substrate, and the first insulating layer is formed on the second region of the support substrate. Further, a second insulating layer is formed on the ground layer and on the first insulating layer. Further, an upper wiring pattern is formed on the second insulating layer so as to overlap the first and second regions of the first insulating layer. In this case, the electric signal can be transmitted to the upper wiring pattern.

According to the above configuration, since the ground layer is located between at least a part of the upper wiring pattern and the support board, at least a part of the electromagnetic wave radiated from the upper wiring pattern toward the support board is in the ground layer. It is incident and does not reach the support substrate.

Further, when an electric signal having a high frequency band transmits an upper wiring pattern, a loss corresponding to the line length of the upper wiring pattern occurs in the electric signal transmitting the upper wiring pattern. The loss of the electric signal is larger as the line length of the upper wiring pattern is larger, and is smaller as the line length of the upper wiring pattern is smaller. In the wiring circuit board according to the present invention, the ground layer is formed on the first region of the support substrate, and the first insulating layer is formed on the second region. Thereby, the difference between the position of the upper surface of the ground layer and the position of the upper surface of the first insulating layer can be reduced in the stacking direction of the support substrate, the first insulating layer and the second insulating layer. As a result, a step due to the presence or absence of the ground layer is hardly formed on the upper surface of the ground layer and the second insulating layer formed on the first insulating layer. Therefore, the upper wiring pattern can be formed linearly on the second insulating layer. Therefore, it is possible to prevent the wiring length of the upper wiring pattern from becoming long.

As a result, the loss of the electrical signal transmitting the upper wiring pattern in the high frequency band is reduced.

The upper wiring pattern extends in the first direction, the support substrate has a plurality of first regions and a plurality of second regions, and the plurality of first regions and the plurality of second regions are the first. They are arranged alternately in the direction of 1.

In this case, the upper wiring pattern overlaps the portions of the plurality of ground layers intermittently arranged in the first direction. Thereby, the uniformity of the characteristic impedance of the upper wiring pattern can be improved.

(4) The wiring circuit board further includes a lower wiring pattern formed on the first insulating layer, and the second insulating layer may be formed on the first insulating layer so as to cover the lower wiring pattern. good. In this case, an electric signal can be transmitted to each of the lower wiring pattern and the upper wiring pattern.

(5) The support substrate may contain stainless steel, and the ground layer may contain copper.

In this case, the stainless steel can ensure sufficient rigidity of the support substrate required to support the upper wiring pattern. In addition, a passivation film is formed on the surface of stainless steel. As a result, deterioration of the support substrate due to corrosion is suppressed. Copper has higher electrical conductivity than stainless steel. Thereby, the eddy current generated in the ground layer by the electromagnetic wave can be reduced.

(6) The wiring circuit board may further include a third insulating layer formed on the second insulating layer so as to cover the upper wiring pattern. In this case, the upper wiring pattern is protected by the third insulating layer.

(7) The method for manufacturing a wiring circuit board according to a third invention is a first portion having a first thickness on a support substrate formed of a conductive material and a second thickness smaller than the first thickness. A step of forming a first insulating layer including a second portion having a support substrate and a second portion of the first insulating layer so as to be electrically connected to the support substrate have a higher electrical conductivity than the support substrate. The step of forming the ground layer having the above, the step of forming the second insulating layer on the first insulating layer so as to cover the ground layer, and the step of overlapping the first and second portions of the first insulating layer. Includes a step of forming an upper wiring pattern on the second insulating layer.

In the wiring circuit board obtained by the manufacturing method, since the ground layer is located between at least a part of the upper wiring pattern and the support board, most of the electromagnetic waves radiated from the upper wiring pattern toward the support board are supported. It is blocked by the ground layer without reaching the substrate. Further, the loss of the electric signal transmitted through the upper wiring pattern is smaller as the line length of the upper wiring pattern is smaller. According to the above configuration, the difference between the position of the upper surface of the first insulating layer and the position of the upper surface of the ground layer in the stacking direction can be reduced. As a result, a step due to the presence or absence of the ground layer is hardly formed on the upper surface of the second insulating layer. Therefore, since the upper wiring pattern can be formed in a straight line, it is possible to prevent the wiring length of the upper wiring pattern from becoming long. As a result, the loss of the electrical signal transmitting the upper wiring pattern in the high frequency band is reduced.

(8) In the method for manufacturing a wiring circuit board according to a fourth invention, a ground layer having a higher electric conductivity than that of a support substrate is formed in a plurality of first regions on a support substrate formed of a conductive material. A step, a step of forming the first insulating layer in a plurality of second regions different from the plurality of first regions on the support substrate, and a second insulating layer on the ground layer and the first insulating layer. A plurality of first regions, including a step of forming and a step of forming an upper wiring pattern extending in the first direction on the second insulating layer so as to overlap the first and second regions of the support substrate. The plurality of second regions are alternately arranged in the first direction.

In the wiring circuit board obtained by the manufacturing method, since the ground layer is located between at least a part of the upper wiring pattern and the support board, most of the electromagnetic waves radiated from the upper wiring pattern toward the support board are supported. It is blocked by the ground layer without reaching the substrate. Further, the loss of the electric signal transmitted through the upper wiring pattern is smaller as the line length of the upper wiring pattern is smaller. According to the above configuration, the difference between the position of the upper surface of the first insulating layer and the position of the upper surface of the ground layer in the stacking direction can be reduced. As a result, a step due to the presence or absence of the ground layer is hardly formed on the upper surface of the second insulating layer. Therefore, since the upper wiring pattern can be formed in a straight line, it is possible to prevent the wiring length of the upper wiring pattern from becoming long. As a result, the loss of the electrical signal transmitting the upper wiring pattern in the high frequency band is reduced.

According to the present invention, the loss of electrical signals is reduced in the high frequency band.

It is a top view of the suspension board which concerns on 1st Embodiment. (A) is an enlarged plan view of a portion of the suspension substrate of FIG. 1 surrounded by an alternate long and short dash line, (b) is a sectional view taken along line A1-A1 of (a), and (c) is B1 of (a). -B1 line sectional view. (A) is a cross-sectional view taken along the line C1-C1 of FIG. 2 (a), and FIG. 2 (b) is a cross-sectional view taken along the line D1-D1 of FIG. 2 (a). (A) is a partially enlarged plan view of the suspension substrate according to the reference embodiment, (b) is a sectional view taken along line A0-A0 of (a), and (c) is a sectional view taken along line B0-B0 of (a). Is. (A) is a cross-sectional view taken along the line C0-C0 of FIG. 4 (a), and FIG. 4 (b) is a cross-sectional view taken along the line D0-D0 of FIG. 4 (a). It is a schematic process sectional view which shows the manufacturing method of the suspension substrate of FIG. It is a schematic process sectional view which shows the manufacturing method of the suspension substrate of FIG. It is a schematic process sectional view which shows the manufacturing method of the suspension substrate of FIG. It is a schematic process sectional view which shows the manufacturing method of the suspension substrate of FIG. It is a schematic process sectional view which shows the manufacturing method of the suspension substrate of FIG. It is a schematic process sectional view which shows the manufacturing method of the suspension substrate of FIG. (A) is a partially enlarged plan view of the suspension substrate according to the second embodiment, (b) is a sectional view taken along line A2-A2 of (a), and (c) is B2- of (a). It is a B2 line sectional view. (A) is a cross-sectional view taken along the line C2-C2 of FIG. 12 (a), and FIG. 12 (b) is a cross-sectional view taken along the line D2-D2 of FIG. 12 (a). It is a schematic process sectional view which shows the manufacturing method of the suspension substrate which concerns on 2nd Embodiment. It is a schematic process sectional view which shows the manufacturing method of the suspension substrate which concerns on 2nd Embodiment. It is a schematic process sectional view which shows the manufacturing method of the suspension substrate which concerns on 2nd Embodiment. It is a schematic process sectional view which shows the manufacturing method of the suspension substrate which concerns on 2nd Embodiment. It is a schematic process sectional view which shows the manufacturing method of the suspension substrate which concerns on 2nd Embodiment. It is a schematic process sectional view which shows the manufacturing method of the suspension substrate which concerns on 2nd Embodiment. (A) is a partially enlarged plan view of the suspension substrate according to the third embodiment, (b) is a sectional view taken along line A3-A3 of (a), and (c) is B3- of (a). It is a B3 line sectional view. (A) is a sectional view taken along line C3-C3 of FIG. 20 (a), and FIG. 20 (b) is a sectional view taken along line D3-D3 of FIG. 20 (a). (A) is a plan view of the suspension substrate according to the embodiment, and (b) is a sectional view taken along line E1-E1 of (a). (A) is a sectional view taken along line F1-F1 of FIG. 22 (a), and FIG. 22 (b) is a sectional view taken along line G1-G1 of FIG. 22 (a). (A) is a plan view of a suspension substrate according to a comparative example, and (b) is a sectional view taken along line E0-E0 of (a). (A) is a sectional view taken along line F0-F0 of FIG. 24 (a), and FIG. 24 (b) is a sectional view taken along line G0-G0 of FIG. 24 (a). It is a figure which shows the simulation result about the suspension board of an Example and a comparative example.

Hereinafter, the wiring circuit board and the manufacturing method thereof according to the embodiment of the present invention will be described with reference to the drawings. As a wiring circuit board according to an embodiment of the present invention, a suspension board with a circuit (hereinafter, abbreviated as suspension board) used for an actuator of a hard disk drive device will be described.

[1] First Embodiment (1) Structure of Suspension Board FIG. 1 is a plan view of the suspension board according to the first embodiment. In FIG. 1, the direction in which the arrow points is called forward, and the opposite direction is called backward. As shown in FIG. 1, the suspension substrate 1 includes a support substrate 10 made of, for example, stainless steel as a suspension main body portion. In FIG. 1, the support substrate 10 extends substantially in the front-rear direction.

The suspension substrate 1 is supported by a long support plate 90. As shown by the dotted line in FIG. 1, the writing wiring patterns W1 and W2, the reading wiring patterns R1 and R2, and the power supply wiring patterns P1 and P2 are formed on the suspension substrate 1. The writing wiring patterns W1 and W2 and the reading wiring patterns R1 and R2 are high-frequency lines for transmitting an electric signal having a high frequency band. The power supply wiring patterns P1 and P2 are low-frequency lines for transmitting an electric signal having a frequency band lower than that of the electric signal for transmitting the writing wiring patterns W1 and W2 and the reading wiring patterns R1 and R2.

A magnetic head mounting portion (hereinafter referred to as a tongue portion) 12 is provided at the tip end portion of the support substrate 10 by forming a U-shaped opening portion 11. The tongue portion 12 is bent at the portion of the alternate long and short dash line R so as to form a predetermined angle with respect to the support substrate 10.

Four connection terminals 21, 22, 23, 24 are formed on the upper surface of the tongue portion 12 at one end of the support substrate 10. Further, two connection terminals 25 and 26 are formed on both side portions near the central portion of the support substrate 10 in the direction in which the support substrate 10 extends (front-rear direction), respectively. A head slider (not shown) having a magnetic head is mounted on the upper surface of the tongue portion 12. The terminals of the magnetic head of the head slider are connected to the connection terminals 21 to 24 of the tongue portion 12.

Six connection terminals 31, 32, 33, 34, 35, 36 are formed on the upper surface of the other end of the support substrate 10. An electronic circuit such as a preamplifier is connected to the connection terminals 31 to 34. A power supply circuit for the piezoelectric elements 95 and 96, which will be described later, is connected to the connection terminals 35 and 36. The connection terminals 21 to 26 and the connection terminals 31 to 36 are electrically connected by the writing wiring patterns W1 and W2, the reading wiring patterns R1 and R2, and the power supply wiring patterns P1 and P2, respectively. Further, a plurality of holes H are formed in the central portion of the support substrate 10.

The support plate 90 has a front end region 91, a rear end region 92 and a central region 93. The rear end region 92 has a rectangular shape. The front end region 91 has a trapezoidal shape, and its width gradually decreases from the rear to the front. The central region 93 has a rectangular shape extending in the front-rear direction, and is arranged between the front end region 91 and the rear end region 92. In a state where the suspension substrate 1 is supported on the upper surface of the support plate 90, the end portion of the suspension substrate 1 including the connection terminals 31 to 36 projects rearward from the rear end region 92.

A piezoelectric element mounting region 94 is provided in a part of the central region 93. The piezoelectric element mounting region 94 overlaps with the connection terminals 25 and 26 of the suspension substrate 1. Both sides of the piezoelectric element mounting region 94 project outward so as to be curved. Further, a through hole 94h extending in the width direction (direction orthogonal to the front-rear direction) is formed in the piezoelectric element mounting region 94. According to this configuration, the portion of the piezoelectric element mounting region 94 of the support plate 90 has elasticity in the front-rear direction.

The piezoelectric elements 95 and 96 are mounted on the lower surface of the piezoelectric element mounting region 94 so as to straddle the through hole 94h. The piezoelectric elements 95 and 96 are located on both sides of the suspension substrate 1, respectively. The piezoelectric elements 95 and 96 are connected to the connection terminals 25 and 26 of the suspension substrate 1 through the through holes 94h, respectively.

A voltage is applied to the piezoelectric element 95 via the connection terminals 25 and 35 and the power supply wiring pattern P1, and a voltage is applied to the piezoelectric element 96 via the connection terminals 26 and 36 and the power supply wiring pattern P2. As a result, the support plate 90 expands and contracts in the front-rear direction as the piezoelectric elements 95 and 96 expand and contract. By controlling the voltage applied to the piezoelectric elements 95 and 96, it is possible to finely align the magnetic head of the head slider on the suspension substrate 1.

The suspension board 1 supported by the support plate 90 is provided on the hard disk device. When writing information to a magnetic disk, a current flows through a pair of writing wiring patterns W1 and W2. The write wiring pattern W1 and the write wiring pattern W2 form a differential signal line pair for transmitting a differential write signal. Further, when reading information from the magnetic disk, a current flows through the pair of reading wiring patterns R1 and R2. The reading wiring pattern R1 and the reading wiring pattern R2 form a differential signal line pair for transmitting a differential read signal.

(2) Wiring pattern for writing and wiring pattern for power supply FIG. 2 (a) is an enlarged plan view of a portion Q of the suspension board 1 of FIG. It is the A1-A1 line sectional view of a), and FIG. 2 (c) is the B1-B1 line sectional view of FIG. 2 (a). 3 (a) is a sectional view taken along line C1-C1 of FIG. 2 (a), and FIG. 3 (b) is a sectional view taken along line D1-D1 of FIG. 2 (a). As shown in FIG. 2A, in the portion Q of FIG. 1, the writing wiring patterns W1 and W2 and the power supply wiring pattern P1 extend in the front-rear direction, respectively. Further, the writing wiring patterns W1 and W2 and the power supply wiring pattern P1 are arranged in a direction orthogonal to the front-rear direction.

As shown in FIGS. 3A and 3B, a first insulating layer 41 made of, for example, polyimide is formed on the support substrate 10. The support substrate 10 has conductivity and is made of, for example, stainless steel. The first insulating layer 41 includes a first portion 41A and a second portion 41B. The second portion 41B has a smaller thickness than the first portion 41A.

On the second portion 41B of the first insulating layer 41, a ground layer 50 having an electric conductivity higher than that of the support substrate 10 is formed. The ground layer 50 is electrically connected to the support substrate 10. The electrical connection between the ground layer 50 and the support substrate 10 is realized by using, for example, vias or wirings formed on the first insulating layer 41.

As the material of the ground layer 50, for example, copper is used. When the support substrate 10 is made of stainless steel as described above, gold or silver may be used as the material of the ground layer 50. Alternatively, an alloy containing any of gold, silver and copper and having a higher electric conductivity than stainless steel may be used as the material of the ground layer 50. The ground layer 50 may have a multi-layer structure. For example, the grounding layer 50 may have a two-layer structure in which a nickel layer or a silver layer is laminated on a copper layer when the support substrate 10 is made of stainless steel, or the nickel layer and gold may be formed on the copper layer. It may have a three-layer structure in which layers are laminated. When the grounding layer 50 has a multilayer structure including a copper layer, another metal layer such as a nickel layer, a silver layer or a gold layer is formed on the upper surface and the side surface of the copper layer so as to cover the surface of the copper layer. It may be formed.

A power supply wiring pattern P1 is formed on the first portion 41A of the first insulating layer 41. For example, copper is used as the material of the power supply wiring pattern P1. The surface of the power supply wiring pattern P1 may be covered with a nickel layer, a silver layer, or the like.

A second insulating layer 42 made of, for example, polyimide is formed on the first insulating layer 41 so as to cover the ground layer 50 and the power supply wiring pattern P1.

As shown in FIG. 2B, on the support substrate 10 in the A1-A1 line of FIG. 2A, the plurality of first portions 41A and the plurality of second portions 41B of the first insulating layer 41 are present. They line up alternately in the front-back direction. A writing wiring pattern W1 is formed on the second insulating layer 42 so as to overlap the plurality of first portions 41A and the plurality of second portions 41B of the first insulating layer 41. Similar to the writing wiring pattern W1, the writing wiring pattern is placed on the second insulating layer 42 so as to overlap the plurality of first portions 41A and the plurality of second portions 41B of the first insulating layer 41. W2 is formed.

In this example, the ground layer 50 is formed on the second portion 41B of the first insulating layer 41. As a result, the portion of the writing wiring patterns W1 and W2 that overlaps with the second portion 41B of the first insulating layer 41 also overlaps with the ground layer 50.

As the material of the writing wiring patterns W1 and W2, for example, copper is used. The surfaces of the writing wiring patterns W1 and W2 may be covered with a nickel layer, a silver layer, or the like. A third insulating layer 60 made of, for example, polyimide is formed on the second insulating layer 42 so as to cover the writing wiring patterns W1 and W2.

2 (a) shows the first insulating layer 41, the second insulating layer 42, and the third insulating layer 60 of FIGS. 2 (b) and 2 (c) and FIGS. 3 (a) and 3 (b). It is omitted. Further, in FIG. 2A, the writing wiring patterns W1 and W2 are shown by thick solid lines and hatching, the power supply wiring pattern P1 is shown by thick alternate long and short dash lines and hatching, and the ground layer 50 is shown by solid lines and dot patterns. Further, the support substrate 10 is shown by a two-dot chain line.

When an electric signal having a high frequency band transmits the writing wiring patterns W1 and W2, electromagnetic waves are generated from the writing wiring patterns W1 and W2. When the generated electromagnetic wave is incident on the support substrate 10 or the ground layer 50, an eddy current is generated in the support substrate 10, and the writing wiring patterns W1 and W2 are electromagnetically coupled to the support substrate 10 or the ground layer 50. In the electric signal transmitting the writing wiring patterns W1 and W2, a loss is generated according to the magnitude of the eddy current generated in the support substrate 10 or the ground layer 50. The loss of the electric signal is larger as the generated eddy current is larger, and smaller as the generated eddy current is smaller.

The eddy current generated in a conductor by applying an electromagnetic wave to the conductor is larger as the electric conductivity of the conductor is lower, and smaller as the electric conductivity of the conductor is higher. The ground layer 50 has a higher electrical conductivity than the support substrate 10. Therefore, the eddy current generated in the ground layer 50 by the electromagnetic wave is smaller than the eddy current generated in the support substrate 10 by the electromagnetic wave.

According to the above configuration, since the ground layer 50 is located between at least a part of the writing wiring patterns W1 and W2 and the support board 10, the writing wiring patterns W1 and W2 are directed toward the support board 10. At least a part of the emitted electromagnetic wave enters the ground layer 50 and does not reach the support substrate 10. As a result, the loss of the electric signal transmitting the writing wiring patterns W1 and W2 in the high frequency band is reduced.

The value of the characteristic impedance of the writing wiring patterns W1 and W2 is determined according to the area of the portion where the writing wiring patterns W1 and W2 overlap with the support substrate 10 and the ground layer 50. For example, the value of the characteristic impedance of the writing wiring pattern W1 is the entire writing wiring pattern W1 and the supporting substrate as compared with the case where a part of the writing wiring pattern W1 overlaps with the support board 10 and the ground layer 50. It is larger when the 10 and the ground layer 50 overlap each other. Further, the value of the characteristic impedance is a part of the writing wiring pattern W1 and the support board 10 and the ground layer 50 as compared with the case where the writing wiring pattern W1 and the support board 10 and the ground layer 50 do not overlap. Is larger when they overlap.

Therefore, in the present embodiment, the writing wiring patterns W1 and W2 overlap with the support substrate 10 and the ground layer 50 so that the characteristic impedance values of the writing wiring patterns W1 and W2 approach a desired value. The area of the part is adjusted. Specifically, as shown in FIGS. 2 (a) and 2 (b) and FIG. 3 (b), a plurality of first openings overlapping the writing wiring patterns W1 and W2 according to the preset impedance. The portion 19 is formed on the support substrate 10. Further, a plurality of second openings 59 each overlapping the plurality of first openings 19 are formed in the ground layer 50.

The plurality of first openings 19 and the plurality of second openings 59 are basically formed intermittently so that the writing wiring patterns W1 and W2 are arranged in the extending direction. Thereby, the uniformity of the characteristic impedance of the writing wiring patterns W1 and W2 can be improved. Depending on the impedance to be set, the plurality of first openings 19 may not be formed on the support substrate 10.

In the following description, the direction in which the support substrate 10, the first insulating layer 41, and the second insulating layer 42 are laminated is referred to as a substrate stacking direction. As shown in FIG. 2A, the first opening 19 and the second opening 59 that overlap each other have the inner edge of the first opening 19 when the suspension substrate 1 is viewed along the substrate stacking direction. It is formed so as to surround the inner edge of the second opening 59. According to this configuration, after the electromagnetic wave radiated from the writing wiring patterns W1 and W2 toward the second opening 59 passes through the second opening 59, the first opening of the support substrate 10 Incident to the inner edge of 19 is reduced. As a result, the generation of eddy currents in the support substrate 10 is reduced.

As shown in FIGS. 3A and 3B, in the suspension substrate 1, the grounding layer 50 is formed on the second portion 41B of the first insulating layer 41, which has a small thickness. In this case, the difference between the position (height) of the upper surface of the ground layer 50 and the position (height) of the upper surface of the first portion 41A of the first insulating layer 41 is small in the substrate stacking direction. As a result, a step due to the presence or absence of the grounding layer 50 is hardly formed on the upper surface of the second insulating layer 42. Therefore, as shown in FIG. 2B, the writing wiring patterns W1 and W2 are formed linearly on the upper surface of the second insulating layer 42 which is substantially flat.

Here, the suspension substrate according to the reference embodiment will be described as being different from the suspension substrate 1 of FIG. 4 (a) is a partially enlarged plan view of the suspension substrate according to the reference embodiment, FIG. 4 (b) is a sectional view taken along line A0-A0 of FIG. 4 (a), and FIG. 4 (c) is FIG. It is a cross-sectional view taken along the line B0-B0 of (a). 5 (a) is a sectional view taken along line C0-C0 of FIG. 4 (a), and FIG. 5 (b) is a sectional view taken along line D0-D0 of FIG. 4 (a). The plan view of FIG. 4 (a) and the cross-sectional view of FIGS. 4 (b), (c) and 5 (a), (b) are the plan view of FIG. 2 (a) and FIGS. 2 (b), (c). ) And the cross-sectional views of FIGS. 3 (a) and 3 (b).

In the suspension substrate according to the reference embodiment, as shown in FIGS. 4 (b) and 4 (c) and FIGS. 5 (a) and 5 (b), the first insulating layer 41 formed on the support substrate 10 is constant. Has a thickness. A ground layer 50 is formed on the upper surface of the first insulating layer 41 together with the power supply wiring pattern P1. In this case, the thickness of the ground layer 50 is between the position (height) of the upper surface of the ground layer 50 and the position (height) of the upper surface of the first portion 41A of the first insulating layer 41 in the substrate stacking direction. There is a difference of about the same size as. As a result, a step is formed on the upper surface of the second insulating layer 42 due to the presence or absence of the grounding layer 50. Therefore, as shown in FIG. 4B, the writing wiring patterns W1 and W2 are formed in a wavy line shape on the upper surface of the second insulating layer 42 so as to overcome the plurality of steps.

When an electric signal having a high frequency band transmits the writing wiring patterns W1 and W2, the electric signal for transmitting the writing wiring patterns W1 and W2 depends on the line length of the writing wiring patterns W1 and W2. There will be a loss. The loss of the electric signal is larger as the line length of the writing wiring patterns W1 and W2 is larger, and is smaller as the line length of the writing wiring patterns W1 and W2 is smaller. As described above, in the suspension substrate according to the reference embodiment, the writing wiring patterns W1 and W2 are formed in a wavy line shape. On the other hand, in the suspension substrate 1 according to the present embodiment, the writing wiring patterns W1 and W2 are formed substantially linearly. As a result, the writing wiring patterns W1 and W2 according to the present embodiment have shorter line lengths than the wavy line-shaped writing wiring patterns W1 and W2 (FIG. 4B). In this way, it is possible to suppress the increase in the wiring length of the writing wiring patterns W1 and W2, so that the loss of the electric signal transmitting the writing wiring patterns W1 and W2 is reduced in the high frequency band. .. In the present embodiment, the wiring length means the length of the line passing through the central axis of the transmission line.

The reading wiring patterns R1 and R2 in FIG. 1, the power supply wiring pattern P2, and the configurations in the vicinity thereof are the writing wirings in FIGS. 2 (a) to 2 (c) and FIGS. 3 (a) and 3 (b). It is basically the same as the configurations of the patterns W1 and W2 and the power supply wiring pattern P1 and the configurations in the vicinity thereof.

(3) Manufacturing Method of Suspension Board A manufacturing method of the suspension board 1 will be described. 6 to 11 are schematic process sectional views showing a method of manufacturing the suspension substrate 1 of FIG. 1. In each of FIGS. 6 to 11, (a) corresponds to the C1-C1 line sectional view of FIG. 2 (a), and (b) corresponds to the D1-D1 line sectional view of FIG. 2 (a). .. Here, the description of the steps of forming the tongue portion 12, the plurality of connection terminals 21 to 26, 31 to 36, the plurality of hole portions H, the reading wiring patterns R1 and R2, and the power supply wiring pattern P2 of FIG. 1 will be omitted. ..

First, a long substrate made of stainless steel is prepared as the support substrate 10. Subsequently, as shown in FIGS. 6A and 6B, a first insulating layer 41 made of polyimide is formed on the support substrate 10. The thickness of the support substrate 10 is, for example, 8 μm or more and 100 μm or less. The thickness of the first insulating layer 41 is, for example, 1 μm or more and 25 μm or less.

Next, as shown in FIGS. 7A and 7B, the recess 41C is formed in a predetermined region on the upper surface of the first insulating layer 41. The depth of the recess 41C is, for example, 1 μm or more and 24 μm or less. The portion of the first insulating layer 41 in which the recess 41C is not formed becomes the first portion 41A, and the portion of the first insulating layer 41 in which the recess 41C is formed becomes the second portion 41B.

Here, the recess 41C is formed, for example, by using a gradation exposure technique when forming the first insulating layer 41. Alternatively, the recess 41C may be formed by etching a part of the first insulating layer 41 formed with a constant thickness, or a part of the first insulating layer 41 formed with a constant thickness. May be formed by laser processing.

Next, as shown in FIGS. 8A and 8B, a grounding layer 50 made of copper is formed on the second portion 41B of the first insulating layer 41. Further, at the same time as the formation of the ground layer 50, the power supply wiring pattern P1 made of copper is formed on the predetermined region of the first portion 41A. At this time, as shown in FIG. 8 (b), the plurality of second openings 59 in FIG. 2 (a) are formed in the ground layer 50. The thickness of the ground layer 50 and the power supply wiring pattern P1 is, for example, 1 μm or more and 20 μm or less.

At the time of forming the grounding layer 50, the grounding layer 50 and the support substrate 10 may be electrically connected by forming vias (not shown) or the like in the first insulating layer 41, for example.

Next, as shown in FIGS. 9A and 9B, a second insulating layer 42 made of polyimide is formed on the first insulating layer 41 so as to cover the ground layer 50 and the power supply wiring pattern P1. do. The thickness of the second insulating layer 42 is, for example, 1 μm or more and 25 μm or less.

Next, as shown in FIGS. 10A and 10B, from copper on the second insulating layer 42 so as to overlap the first portion 41A and the second portion 41B of the first insulating layer 41. The writing wiring patterns W1 and W2 are formed.

The thickness of the writing wiring patterns W1 and W2 is, for example, 1 μm or more and 20 μm or less. The widths of the writing wiring patterns W1 and W2 are, for example, 6 μm or more and 100 μm or less. The spacing between the writing wiring patterns W1 and W2 is, for example, 6 μm or more and 100 μm or less.

Next, as shown in FIGS. 11A and 11B, a third insulating layer 60 made of polyimide is formed on the second insulating layer 42 so as to cover the writing wiring patterns W1 and W2. .. The third insulating layer 60 is used to protect the writing wiring patterns W1 and W2. The thickness of the third insulating layer 60 is, for example, 2 μm or more and 25 μm or less.

Finally, the outer edge of the support substrate 10 is processed according to the design dimensions, and a plurality of first openings 19 are formed in the plurality of predetermined portions of the support substrate 10. As a result, the suspension substrate 1 having the configurations shown in FIGS. 3 (a) and 3 (c) is completed.

(4) Effect In the suspension board 1 according to the present embodiment, since the ground layer 50 is located between at least a part of the writing wiring patterns W1 and W2 and the support board 10, the writing wiring pattern W1 , At least a part of the electromagnetic wave radiated from W2 toward the support substrate 10 is blocked by the ground layer 50. As a result, the generation of eddy currents in the support substrate 10 is reduced.

Further, the loss of the electric signal for transmitting the writing wiring patterns W1 and W2 becomes smaller as the line length of the writing wiring patterns W1 and W2 becomes smaller. According to the above configuration, the difference between the position (height) of the upper surface of the ground layer 50 and the position (height) of the upper surface of the first portion 41A of the first insulating layer 41 in the substrate stacking direction is small. can do. As a result, a step due to the presence or absence of the grounding layer 50 is hardly formed on the upper surface of the second insulating layer 42. Therefore, since the writing wiring patterns W1 and W2 can be formed in a straight line, it is possible to prevent the wiring lengths of the writing wiring patterns W1 and W2 from becoming long.

As a result, the loss of the electric signal transmitting the writing wiring patterns W1 and W2 in the high frequency band is reduced.

[2] Second Embodiment The suspension substrate according to the second embodiment will be described as different from the suspension substrate 1 according to the first embodiment. 12 (a) is a partially enlarged plan view of the suspension substrate according to the second embodiment, FIG. 12 (b) is a sectional view taken along line A2-A2 of FIG. 12 (a), and FIG. 12 (c). ) Is a cross-sectional view taken along the line B2-B2 of FIG. 12 (a). 13 (a) is a sectional view taken along line C2-C2 of FIG. 12 (a), and FIG. 13 (b) is a sectional view taken along line D2-D2 of FIG. 12 (a). The plan view of FIG. 12 (a) and the cross-sectional views of FIGS. 12 (b), 12 (c) and 13 (a), (b) are the plan view of FIG. 2 (a) and FIGS. 2 (b), (c). ) And the cross-sectional views of FIGS. 3 (a) and 3 (b). In FIG. 12 (a), as in the example of FIG. 2 (a), some of the components of the plurality of components of the suspension board 1 are shown in different modes from each other, and the illustration of the other components is omitted. is doing.

In the suspension substrate 1 according to the present embodiment, as shown in FIGS. 13 (a) and 13 (b), the ground layer 50 is provided on a partial region (first region 10A described later) of the upper surface of the support substrate 10. It is formed. As a result, in a part of the region of the support substrate 10, the upper surface of the support substrate 10 and the lower surface of the ground layer 50 are in contact with each other. Further, the first insulating layer 41 is formed on the region (second region 10B described later) where the grounding layer 50 of the support substrate 10 is not formed.

A second insulating layer 42 is formed on the ground layer 50 and on the first insulating layer 41. The writing wiring patterns W1 and W2 are formed on the second insulating layer 42 so as to overlap the ground layer 50 and the first insulating layer 41.

Also in the above configuration, since the ground layer 50 is located between at least a part of the writing wiring patterns W1 and W2 and the support board 10, radiation is emitted from the writing wiring patterns W1 and W2 toward the support board 10. At least a part of the electromagnetic wave generated is incident on the ground layer 50 and does not reach the support substrate 10. As a result, the loss of the electric signal transmitting the writing wiring patterns W1 and W2 in the high frequency band is reduced.

The thickness of the ground layer 50 and the thickness of the first insulating layer 41 are set to be substantially equal to each other. In this case, the difference between the position (height) of the upper surface of the ground layer 50 and the position (height) of the upper surface of the first portion 41A of the first insulating layer 41 is small in the substrate stacking direction. As a result, a step due to the presence or absence of the grounding layer 50 is hardly formed on the upper surface of the second insulating layer 42. Therefore, similarly to the suspension substrate 1 according to the first embodiment, the writing wiring patterns W1 and W2 are formed linearly on the upper surface of the second insulating layer 42 which is substantially flat. Therefore, it is possible to suppress the increase in the wiring length of the writing wiring patterns W1 and W2, so that the loss of the electric signal transmitting the writing wiring patterns W1 and W2 is reduced in the high frequency band.

In the present embodiment, as shown in FIG. 12A, the first opening 19 and the second opening 59 that overlap each other are the second when the suspension substrate 1 is viewed along the substrate stacking direction. The inner edge of the opening 59 is formed so as to surround the inner edge of the first opening 19. According to this configuration, the inner edge of each second opening 59 of the ground layer 50 is covered with the second insulating layer 42. As a result, the inner edge of each second opening 59 of the ground layer 50 is not exposed from between the second insulating layer 42 and the support substrate 10 to the outside of the suspension substrate 1. Therefore, the ground layer 50 is prevented from corroding from the inner edge of each second opening 59.

A method for manufacturing the suspension substrate 1 according to the second embodiment will be described. 14 to 19 are schematic process sectional views showing a method of manufacturing the suspension substrate 1 according to the second embodiment. In each of FIGS. 14 to 19, (a) corresponds to the C2-C2 line sectional view of FIG. 12 (a), and (b) corresponds to the D2-D2 line sectional view of FIG. 12 (a). .. Here, the description of the steps of forming the tongue portion 12, the plurality of connection terminals 21 to 26, 31 to 36, the plurality of hole portions H, the reading wiring patterns R1 and R2, and the power supply wiring pattern P2 of FIG. 1 will be omitted. ..

Similar to the first embodiment, first, a long substrate made of stainless steel is prepared as the support substrate 10. Here, as shown in FIGS. 14 (a) and 14 (b), in the present embodiment, the ground layer 50 of FIGS. 13 (a) and 13 (b) is formed on the upper surface of the support substrate 10. A region 10A of 1 and a second region 10B on which the ground layer 50 is not formed are predetermined.

Subsequently, after forming the first insulating layer 41 made of polyimide on the support substrate 10, the first region 10A on the upper surface of the support substrate 10 is upward as shown in FIGS. 15A and 15B. The opening 41D is formed so as to be exposed. The opening 41D is formed, for example, by using a gradation exposure technique when forming the first insulating layer 41. Alternatively, the opening 41D may be formed by etching a part of the first insulating layer 41, or may be formed by laser processing a part of the first insulating layer 41.

Next, as shown in FIGS. 16A and 16B, the ground layer 50 is formed on the first region 10A of the support substrate 10 exposed upward. Further, at the same time as the formation of the ground layer 50, the power supply wiring pattern P1 is formed on the predetermined region of the first insulating layer 41 that overlaps with the second region 10B of the support substrate 10. At this time, as shown in FIG. 16 (b), the plurality of second openings 59 in FIG. 12 (a) are formed in the ground layer 50.

Next, as shown in FIGS. 17A and 17B, a second insulating layer 42 made of polyimide is formed on the ground layer 50 and the first insulating layer 41 so as to cover the power supply wiring pattern P1. do.

Next, as shown in FIGS. 18A and 18B, writing made of copper on the second insulating layer 42 so as to overlap the first region 10A and the second region 10B of the support substrate 10. The wiring patterns W1 and W2 are formed.

Next, as shown in FIGS. 19A and 19B, a third insulating layer 60 made of polyimide is formed on the second insulating layer 42 so as to cover the writing wiring patterns W1 and W2. ..

Finally, the outer edge of the support substrate 10 is processed according to the design dimensions, and a plurality of first openings 19 are formed in the plurality of predetermined portions of the support substrate 10. As a result, the suspension substrate 1 having the structures shown in FIGS. 13 (a) and 13 (b) is completed.

[3] Third Embodiment The suspension substrate according to the third embodiment will be described as different from the suspension substrate 1 according to the second embodiment. 20 (a) is a partially enlarged plan view of the suspension substrate according to the third embodiment, FIG. 20 (b) is a sectional view taken along line A3-A3 of FIG. 20 (a), and FIG. 20 (c) is a cross-sectional view taken along the line A3-A3. ) Is a sectional view taken along line B3-B3 of FIG. 20 (a). 21 (a) is a sectional view taken along line C3-C3 of FIG. 20 (a), and FIG. 21 (b) is a sectional view taken along line D3-D3 of FIG. 20 (a). The plan view of FIG. 20 (a) and the cross-sectional views of FIGS. 20 (b), (c) and 21 (a), (b) are the plan view of FIG. 12 (a) and FIGS. 12 (b), (c). ) And the cross-sectional views of FIGS. 13 (a) and 13 (b). In FIG. 20 (a), as in the example of FIG. 12 (a), some of the components of the plurality of components of the suspension board 1 are shown in different modes from each other, and the illustration of the other components is omitted. is doing.

As shown in FIGS. 20 (a) and 20 (b) and 21 (b), when the suspension substrate 1 according to the present embodiment is viewed along the substrate stacking direction, each second opening of the ground layer 50 The inner edge of the 59 and the inner edge of each first opening 19 of the support substrate 10 overlap each other. In this configuration, by using a material having excellent corrosion resistance such as gold as the grounding layer 50, corrosion of the grounding layer 50 from the inner edge of each second opening 59 is prevented.

As described above, in the method for manufacturing the suspension substrate 1 according to the second embodiment, when the grounding layer 50 is formed on the support substrate 10, a plurality of second openings 59 are formed (FIG. 6). 16 (b)). On the other hand, in the method for manufacturing a suspension substrate according to the present embodiment, a plurality of second openings 59 are not formed in the step of forming the ground layer 50 on the support substrate 10. After the step of forming the third insulating layer 60 shown in FIG. 19B, in the step of forming the plurality of first openings 19 in the support substrate 10, the plurality of first openings 19 are formed and the plurality of first openings 19 are formed. A plurality of second openings 59 are formed in the ground layer 50.

Also in the suspension substrate according to the present embodiment, the position (height) of the upper surface of the ground layer 50 and the position (height) of the upper surface of the first portion 41A of the first insulating layer 41 are defined in the substrate stacking direction. The difference between them is small. As a result, a step due to the presence or absence of the grounding layer 50 is hardly formed on the upper surface of the second insulating layer 42. Therefore, similarly to the suspension substrate 1 according to the second embodiment, the writing wiring patterns W1 and W2 are formed linearly on the upper surface of the second insulating layer 42 which is substantially flat. Therefore, it is possible to prevent the wiring lengths of the writing wiring patterns W1 and W2 from becoming long.

[4] Other Embodiments In the above embodiment, the power supply wiring patterns P1 and P2 are low frequency lines for transmitting an electric signal having a low frequency band, but the present invention is not limited thereto. If the loss of the electric signal for transmitting the power supply wiring patterns P1 and P2 is tolerated to some extent, the electric power signal having a high frequency band may be transmitted to the power supply wiring patterns P1 and P2. That is, the power supply wiring patterns P1 and P2 may be used as the high frequency line.

[5] Correspondence between each component of the claim and each part of the embodiment The example of correspondence between each component of the claim and each part of the embodiment will be described below. Not limited.

In the above embodiment, the support substrate 10 is an example of the support substrate, the first portion 41A is an example of the first portion, the second portion 41B is an example of the second portion, and the first The insulating layer 41 is an example of the first insulating layer, the ground layer 50 is an example of the ground layer, the second insulating layer 42 is an example of the second insulating layer, and the wiring pattern W1 for writing is written. W2 is an example of an upper wiring pattern, and suspension board 1 is an example of a wiring circuit board.

Further, the first opening 19 is an example of the first opening, the second opening 59 is an example of the second opening, and the first region 10A is an example of the first region. The second region 10B is an example of the second region, the power supply wiring pattern P1 is an example of the lower wiring pattern, and the third insulating layer 60 is an example of the third insulating layer.

As each component of the claim, various other components having the structure or function described in the claim can also be used.

[6] Examples and Comparative Examples The following suspension boards are assumed as examples and comparative examples. 22 (a) is a plan view of the suspension substrate according to the embodiment, and FIG. 22 (b) is a sectional view taken along line E1-E1 of FIG. 22 (a). 23 (a) is a sectional view taken along line F1-F1 of FIG. 22 (a), and FIG. 23 (b) is a sectional view taken along line G1-G1 of FIG. 22 (a).

As shown in FIG. 22A, the suspension substrate of the embodiment includes a wiring pattern L10 extending in one direction and a ground layer 50. The wiring pattern L10 includes two lines L11 and L12. The lines L11 and L12 form a differential signal line pair. The ground layer 50 is formed so as to extend in a band shape in one direction. Further, the ground layer 50 has a plurality of openings 58 arranged in one direction at regular intervals.

As shown in FIGS. 23 (a) and 23 (b), a first insulating layer 41 made of polyimide is formed on a support substrate 10 made of stainless steel. The first insulating layer 41 includes a first portion 41A and a second portion 41B having different thicknesses. The thickness of the second portion 41B is smaller than the thickness of the first portion 41A. A grounding layer 50 made of copper is formed on the second portion 41B of the first insulating layer 41. A second insulating layer 42 made of polyimide is formed on the first insulating layer 41 so as to cover the ground layer 50. A wiring pattern L10 made of copper is formed on the second insulating layer 42.

In FIG. 22 (a), the first insulating layer 41 and the second insulating layer 42 in FIGS. 22 (b) and 23 (a) and 23 (b) are not shown. Further, in FIG. 22A, the wiring pattern L10 is shown by a thick solid line and hatching, and the ground layer 50 is shown by a solid line and a dot pattern. Further, the support substrate 10 is shown by a two-dot chain line.

In the suspension substrate of the embodiment, there is a difference between the position (height) of the upper surface of the ground layer 50 and the position (height) of the upper surface of the first portion 41A of the first insulating layer 41 in the substrate stacking direction. small. As a result, a step due to the presence or absence of the grounding layer 50 is hardly formed on the upper surface of the second insulating layer 42. Further, in the suspension substrate of the embodiment, the thickness of the second insulating layer 42 is adjusted at a plurality of portions so that the upper surface of the second insulating layer 42 is flat. As a result, as shown in FIG. 22B, the lines L11 and L12 of the wiring pattern L10 extend linearly.

In the suspension board of the embodiment, the lengths of the lines L11 and L12 in the direction in which the wiring pattern L10 extends are set to 20 mm. Further, the width d11 and the thickness d12 of the lines L11 and L12 were set to 100 μm and 8 μm, respectively, and the distance d13 of the lines L11 and L12 was set to 30 μm. Further, the thickness d14 of the ground layer 50 was set to 5 μm. Further, the thickness d21 of the support substrate 10 is 18 μm, the thickness d22a of the first portion 41A of the first insulating layer 41 is 5 μm, and the thickness d22b of the second portion 41B of the first insulating layer 41 is 1.5 μm. And said. Further, the thickness d23a of the portion of the second insulating layer 42 overlapping the first portion 41A of the first insulating layer 41 is set to 7.5 μm, and the second portion overlapping the second portion 41B of the first insulating layer 41 is set. The thickness d23b of the portion of the insulating layer 42 was set to 6 μm. Further, in the direction in which the wiring pattern L10 extends, the dimension d01 of each opening 58 overlapping the wiring pattern L10 and the dimension d02 between each of the two adjacent openings 58 are set to 500 μm and 500 μm, respectively.

FIG. 24A is a plan view of the suspension substrate according to the comparative example, and FIG. 24B is a sectional view taken along line E0-E0 of FIG. 24A. 25 (a) is a sectional view taken along line F0-F0 of FIG. 24 (a), and FIG. 25 (b) is a sectional view taken along line G0-G0 of FIG. 24 (a). In FIG. 24A, as in the example of FIG. 22A, some of the components of the plurality of components of the suspension board are shown in different modes from each other, and the illustration of the other components is omitted. There is. The suspension substrate of the comparative example has the same configuration as the suspension substrate of the embodiment except for the following points.

As shown in FIGS. 24 (b) and 25 (a) and 25 (b), in the suspension substrate of the comparative example, the first insulating layer 41 is formed to have a constant thickness so as to cover the entire upper surface of the support substrate 10. Will be done. The ground layer 50 is formed on the first insulating layer 41.

In the suspension substrate of the comparative example, the difference between the position (height) of the upper surface of the ground layer 50 and the position (height) of the upper surface of the first insulating layer 41 is large in the substrate stacking direction. As a result, a step is formed on the upper surface of the second insulating layer 42 due to the presence or absence of the grounding layer 50. As a result, as shown in FIG. 24B, the lines L11 and L12 of the wiring pattern L10 extend in a wavy line shape.

In the suspension board of the comparative example, the lengths of the lines L11 and L12 in the direction in which the wiring pattern L10 extends are set to 20 mm. Further, the width d11 and the thickness d12 of the lines L11 and L12 were set to 100 μm and 8 μm, respectively, and the distance d13 of the lines L11 and L12 was set to 30 μm. Further, the thickness d14 of the ground layer 50 was set to 5 μm. Further, the thickness d21 of the support substrate 10 was set to 18 μm, the thickness d22 of the first insulating layer 41 was set to 5 μm, and the thickness d23 of the second insulating layer 42 was set to 6 μm. Further, in the direction in which the wiring pattern L10 extends, the dimension d01 of each opening 58 overlapping the wiring pattern L10 and the dimension d02 between each of the two adjacent openings 58 are set to 500 μm and 500 μm, respectively.

The dimensions of each part of the suspension substrate of Examples and Comparative Examples are shown in Table 1 below.

実施例および比較例のサスペンション基板の配線パターンＬ１０を電気信号が伝送するときの透過特性を表すＳパラメータＳｄｄ２１をシミュレーションにより求めた。ＳパラメータＳｄｄ２１は、差動モード入力および差動モード出力での減衰量を示す。

The S-parameter Sdd21 representing the transmission characteristic when the electric signal transmits the wiring pattern L10 of the suspension board of the examples and the comparative examples was obtained by simulation. The S-parameter Sdd21 indicates the amount of attenuation at the differential mode input and the differential mode output.

FIG. 26 is a diagram showing simulation results for suspension substrates of Examples and Comparative Examples. In FIG. 26, the vertical axis represents the S parameter Sdd21 [dB], and the horizontal axis represents the frequency [GHz] of the electric signal. Further, in FIG. 26, the simulation results for the examples are shown by thick solid lines. The simulation results for the comparative example are shown by the alternate long and short dash line.

In FIG. 26, the negative gain shown on the vertical axis indicates the loss. Therefore, the lower the value of the S parameter Sdd21, the larger the attenuation amount, and the closer the value of the S parameter Sdd21 is to 0, the smaller the attenuation amount.

According to the simulation result of FIG. 26, the attenuation amount of the electric signal transmitted through the suspension substrate of the embodiment is smaller than the attenuation amount of the electric signal transmitted through the suspension substrate of the comparative example in the frequency band of 0 to 20 GHz. As a result, the difference between the position (height) of the upper surface of the ground layer 50 and the position (height) of the upper surface of the first insulating layer 41 in the substrate stacking direction is reduced, so that the frequency band is wide. It was found that it is possible to reduce the amount of attenuation of the electric signal.

[7] Reference form (1) The wiring circuit board according to the first reference form is formed in a support substrate formed of a conductive material and a first region on the support substrate, and has higher electricity than the support substrate. A ground layer having conductivity, a first insulating layer formed in a second region different from the first region on the support substrate, and a second insulating layer formed on the ground layer and the first insulating layer. It includes an insulating layer and an upper wiring pattern formed on the second insulating layer so as to overlap the first and second regions of the support substrate.

In the wiring circuit board, a ground layer is formed on the first region of the support substrate, and the first insulating layer is formed on the second region of the support substrate. Further, a second insulating layer is formed on the ground layer and on the first insulating layer. Further, an upper wiring pattern is formed on the second insulating layer so as to overlap the first and second regions of the first insulating layer. In this case, the electric signal can be transmitted to the upper wiring pattern.

According to the above configuration, since the ground layer is located between at least a part of the upper wiring pattern and the support board, at least a part of the electromagnetic wave radiated from the upper wiring pattern toward the support board is in the ground layer. It is incident and does not reach the support substrate.

Further, when an electric signal having a high frequency band transmits an upper wiring pattern, a loss corresponding to the line length of the upper wiring pattern occurs in the electric signal transmitting the upper wiring pattern. The loss of the electric signal is larger as the line length of the upper wiring pattern is larger, and is smaller as the line length of the upper wiring pattern is smaller. In the wiring circuit board according to this reference embodiment, the ground layer is formed on the first region of the support substrate, and the first insulating layer is formed on the second region. Thereby, the difference between the position of the upper surface of the ground layer and the position of the upper surface of the first insulating layer can be reduced in the stacking direction of the support substrate, the first insulating layer and the second insulating layer. As a result, a step due to the presence or absence of the ground layer is hardly formed on the upper surface of the ground layer and the second insulating layer formed on the first insulating layer. Therefore, the upper wiring pattern can be formed linearly on the second insulating layer. Therefore, it is possible to prevent the wiring length of the upper wiring pattern from becoming long.

As a result, the loss of the electrical signal transmitting the upper wiring pattern in the high frequency band is reduced.

(2) The upper wiring pattern extends in the first direction, and the support substrate has a plurality of first regions and a plurality of second regions, and has a plurality of first regions and a plurality of second regions. May alternate in the first direction.

In this case, the upper wiring pattern overlaps the portions of the plurality of ground layers intermittently arranged in the first direction. Thereby, the uniformity of the characteristic impedance of the upper wiring pattern can be improved.

(3) A first opening may be formed in at least a part of the first region of the support substrate, and a second opening overlapping the first opening may be formed in the ground layer.

The value of the characteristic impedance of the upper wiring pattern is determined according to the area of the portion where the upper wiring pattern overlaps with the support board and the ground layer. According to the above configuration, first and second openings are formed in the support substrate and the ground layer. Therefore, by adjusting the size and number of the first and second openings, the value of the characteristic impedance of the upper wiring pattern can be easily adjusted.

(4) The wiring circuit board further includes a lower wiring pattern formed on the first insulating layer, and the second insulating layer may be formed on the first insulating layer so as to cover the lower wiring pattern. good. In this case, an electric signal can be transmitted to each of the lower wiring pattern and the upper wiring pattern.

(5) The support substrate may contain stainless steel, and the ground layer may contain copper.

In this case, the stainless steel can ensure sufficient rigidity of the support substrate required to support the upper wiring pattern. In addition, a passivation film is formed on the surface of stainless steel. As a result, deterioration of the support substrate due to corrosion is suppressed. Copper has higher electrical conductivity than stainless steel. Thereby, the eddy current generated in the ground layer by the electromagnetic wave can be reduced.

(6) The wiring circuit board may further include a third insulating layer formed on the second insulating layer so as to cover the upper wiring pattern. In this case, the upper wiring pattern is protected by the third insulating layer.

(7) The method for manufacturing a wiring circuit board according to a second reference embodiment is a step of forming a ground layer having a higher electrical conductivity than a support substrate in a first region on a support substrate formed of a conductive material. A step of forming a first insulating layer in a second region different from the first region on the support substrate, and a step of forming a second insulating layer on the ground layer and the first insulating layer. It includes a step of forming an upper wiring pattern on the second insulating layer so as to overlap the first and second regions of the support substrate.

In the wiring circuit board obtained by the manufacturing method, since the ground layer is located between at least a part of the upper wiring pattern and the support board, most of the electromagnetic waves radiated from the upper wiring pattern toward the support board are supported. It is blocked by the ground layer without reaching the substrate. Further, the loss of the electric signal transmitted through the upper wiring pattern is smaller as the line length of the upper wiring pattern is smaller. According to the above configuration, the difference between the position of the upper surface of the first insulating layer and the position of the upper surface of the ground layer in the stacking direction can be reduced. As a result, a step due to the presence or absence of the ground layer is hardly formed on the upper surface of the second insulating layer. Therefore, since the upper wiring pattern can be formed in a straight line, it is possible to prevent the wiring length of the upper wiring pattern from becoming long. As a result, the loss of the electrical signal transmitting the upper wiring pattern in the high frequency band is reduced.

The present invention can be effectively used for various wiring circuit boards.

1 Suspension board 10 Support board 10A 1st area 10B 2nd area 11,58 Opening 12 Tongue part 19 1st opening 21-26, 31-36 Connection terminal 41 1st insulating layer 41A 1st part 41B Second part 41C Recess 41D Opening 42 Second insulating layer 50 Ground layer 59 Second opening 60 Third insulating layer 90 Support plate 91 Front end area 92 Rear end area 93 Central area 94 Piezoelectric element mounting area 94h Penetration Holes 95,96 Piezoelectric elements d01, d02 Dimensions d11 Width d12, d14 Thickness d13 Interval L10 Wiring pattern L11, L12 Lines P1, P2 Power supply wiring pattern R1, R2 Reading wiring pattern W1, W2 Writing wiring pattern

Claims (8)

A support substrate formed of a conductive material and
A first insulating layer formed on the support substrate and including a first portion having a first thickness and a second portion having a second thickness smaller than the first thickness.
A ground layer formed in the second portion of the first insulating layer so as to be electrically connected to the support substrate and having a higher electrical conductivity than the support substrate.
A second insulating layer formed on the first insulating layer so as to cover the ground layer, and a second insulating layer.
A wiring circuit board comprising an upper wiring pattern formed on the second insulating layer so as to overlap the first and second portions of the first insulating layer. The upper wiring pattern extends in the first direction.
The first insulating layer has a plurality of the first portions and a plurality of the second portions.
The wiring circuit board according to claim 1, wherein the plurality of first portions and the plurality of second portions are alternately arranged in the first direction. A support substrate formed of a conductive material and
A grounding layer formed in the first region on the support substrate and having a higher electrical conductivity than the support substrate.
A first insulating layer formed in a second region different from the first region on the support substrate,
A second insulating layer formed on the ground layer and the first insulating layer,
It comprises an upper wiring pattern formed on the second insulating layer so as to overlap the first and second regions of the support substrate.
The upper wiring pattern extends in the first direction.
The support substrate has a plurality of the first regions and a plurality of the second regions.
The plurality of first regions and the plurality of second regions are wiring circuit boards that are alternately arranged in the first direction. Further comprising a lower wiring pattern formed on the first insulating layer
The wiring circuit board according to any one of claims 1 to 3, wherein the second insulating layer is formed on the first insulating layer so as to cover the lower wiring pattern. The wiring circuit board according to any one of claims 1 to 4, wherein the support board contains stainless steel and the ground layer contains copper. The wiring circuit board according to any one of claims 1 to 5, further comprising a third insulating layer formed on the second insulating layer so as to cover the upper wiring pattern. A first insulating layer including a first portion having a first thickness and a second portion having a second thickness smaller than the first thickness is formed on a support substrate formed of a conductive material. Steps to do and
A step of forming a ground layer having a higher electrical conductivity than the support substrate in the second portion of the first insulating layer so as to be electrically connected to the support substrate.
A step of forming a second insulating layer on the first insulating layer so as to cover the ground layer,
A method for manufacturing a wiring circuit board, comprising a step of forming an upper wiring pattern on the second insulating layer so as to overlap the first and second portions of the first insulating layer. A step of forming a ground layer having a higher electrical conductivity than the support substrate in a plurality of first regions on the support substrate formed of the conductive material.
A step of forming a first insulating layer in a plurality of second regions different from the plurality of first regions on the support substrate.
A step of forming a second insulating layer on the ground layer and the first insulating layer,
Including a step of forming an upper wiring pattern extending in the first direction on the second insulating layer so as to overlap the first and second regions of the support substrate.
A method for manufacturing a wiring circuit board, wherein the plurality of first regions and the plurality of second regions are alternately arranged in the first direction.

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