JP2010003892A - Wiring circuit board, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring circuit board that reduces transmission loss, and to provide a method of manufacturing the same. <P>SOLUTION: A first insulating layer 41 is formed on a suspension body portion 10. On the first insulating layer 41, wiring patterns W1 and W2 for writing are formed parallel at an interval. In a region on the first insulating layer 41 between the wiring patterns W1 and W2 for writing, a ground pattern G1 is formed. On the first insulating layer 41, a second insulating layer 42 is formed so as to cover the wiring patterns W1 and W2 for writing and the ground pattern G1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  An actuator is used in a drive device such as a hard disk drive device. Such an actuator includes an arm rotatably provided on a rotating shaft, and a suspension board for a magnetic head attached to the arm. The suspension board is a printed circuit board for positioning the magnetic head on a desired track of the magnetic disk.

A printed circuit board used as a suspension board has a signal line pair composed of two wiring patterns, for example. Patent Document 1 discloses a high-frequency wired circuit board in which a differential signal line composed of two signal lines parallel to the upper surface of a dielectric substrate is formed.
JP 2006-42098 A

  Incidentally, in recent years, it has been desired to reduce the transmission loss of the suspension board in order to reduce the power consumption of electronic devices. As described above, when signal line pairs are formed on the same plane, transmission loss increases.

  An object of the present invention is to provide a printed circuit board capable of reducing transmission loss and a manufacturing method thereof.

  (1) A printed circuit board according to a first aspect of the present invention includes an insulating layer, first and second wiring patterns formed on the insulating layer at intervals, and constituting a signal line pair, and first and second And a ground pattern formed between the wiring patterns.

  In this wired circuit board, a ground pattern is disposed between the first and second wiring patterns constituting the signal line pair. Thereby, transmission loss of the first and second wiring patterns is reduced.

  (2) The top surface of the ground pattern may not be positioned above the top surfaces of the first and second wiring patterns in the direction perpendicular to the top surface of the insulating layer. In this case, the transmission loss of the first and second wiring patterns can be more sufficiently reduced.

  (3) The upper surface of the ground pattern is located below the upper surfaces of the first and second wiring patterns in the direction perpendicular to the upper surface of the insulating layer, and above the lower surfaces of the first and second wiring patterns. May be located. In this case, the transmission loss of the first and second wiring patterns can be more sufficiently reduced.

  (4) The upper surface of the ground pattern may be positioned below the lower surfaces of the first and second wiring patterns in a direction perpendicular to the upper surface of the insulating layer. In this case, the transmission loss of the first and second wiring patterns can be more sufficiently reduced.

  (5) The printed circuit board further includes an elongated metal substrate and a head unit provided on the metal substrate for reading and writing signals, and the insulating layer is formed on the metal substrate, The second wiring pattern may be electrically connected to the head portion.

  In this case, the wired circuit board can be used as a suspension board for a drive device such as a hard disk drive device. Information can be written to or read from the magnetic disk by the first and second wiring patterns. In addition, since the transmission loss of the first and second wiring patterns is reduced, the power consumption of the drive device is reduced.

  (6) A method for manufacturing a printed circuit board according to a second invention includes a step of forming first and second wiring patterns constituting a signal line pair at intervals on an insulating layer; Forming a ground pattern between the wiring patterns.

  In this method for manufacturing a wired circuit board, a ground pattern is formed between the first and second wiring patterns constituting the signal line pair. Thereby, transmission loss of the first and second wiring patterns is reduced.

  According to the present invention, the ground pattern is arranged between the first and second wiring patterns constituting the signal line pair. Thereby, transmission loss of the first and second wiring patterns is reduced.

  Hereinafter, a printed circuit board and a manufacturing method thereof according to embodiments of the present invention will be described with reference to the drawings. Hereinafter, a structure of a suspension board used for an actuator of a hard disk drive device as a wired circuit board according to an embodiment of the present invention and a manufacturing method thereof will be described.

(1) First Embodiment (1-1) Structure of Suspension Board FIG. 1 is a top view of a suspension board according to the first embodiment of the present invention. As shown in FIG. 1, the suspension board 1 includes a suspension main body 10 formed of a long metal substrate. On the suspension body 10, write wiring patterns W1, W2 and read wiring patterns R1, R2 are formed as indicated by thick dotted lines.

  A magnetic head mounting portion (hereinafter referred to as a tongue portion) 12 is provided by forming a U-shaped opening 11 at the distal end portion of the suspension main body portion 10. The tongue portion 12 is bent at a location indicated by a broken line R so as to form a predetermined angle with respect to the suspension main body portion 10. Four electrode pads 21, 22, 23 and 24 are formed at the end of the tongue 12.

  Four electrode pads 31, 32, 33, and 34 are formed at the other end of the suspension body 10. The electrode pads 21 to 24 on the tongue 12 and the electrode pads 31 to 34 on the other end of the suspension body 10 are electrically connected by wiring patterns W1, W2, R1, and R2, respectively. A plurality of holes H are formed in the suspension body 10.

  In a hard disk device (not shown) provided with the suspension board 1, current flows through the pair of write wiring patterns W1, W2 when information is written to the magnetic disk. Further, a current flows through the pair of read wiring patterns R1, R2 when information is read from the magnetic disk.

  Next, the write wiring patterns W1, W2 and their peripheral portions of the suspension board 1 will be described in detail. FIG. 2 is a schematic longitudinal sectional view of the write wiring patterns W1, W2 and their peripheral portions of the suspension board 1 of FIG.

  As shown in FIG. 2, a first insulating layer 41 is formed on the suspension body 10. On the first insulating layer 41, write wiring patterns W1, W2 are formed in parallel at a distance. A ground pattern G1 is formed in a region on the first insulating layer 41 between the write wiring patterns W1, W2.

  A second insulating layer 42 is formed on the first insulating layer 41 so as to cover the write wiring patterns W1, W2 and the ground pattern G1.

(1-2) Method for Manufacturing Suspension Board A method for manufacturing the suspension board 1 will be described. Here, the description about the formation process of the tongue part 12, the electrode pads 21-24, 31-34, the hole H, and the reading wiring patterns R1, R2 in FIG. 1 is omitted.

  FIG. 3 is a longitudinal sectional view showing a manufacturing process of the suspension board 1 according to the embodiment of the present invention.

  First, as shown in FIG. 3A, a long substrate made of, for example, stainless steel (SUS) is prepared as the suspension body 10. Then, as shown in FIG. 3B, a first insulating layer 41 made of polyimide, for example, is formed on the suspension body 10.

  As the suspension body 10, other materials such as aluminum (Al) may be used instead of stainless steel. The thickness of the suspension body 10 is, for example, not less than 5 μm and not more than 50 μm, and preferably not less than 10 μm and not more than 30 μm.

  As the first insulating layer 41, another insulating material such as an epoxy resin may be used instead of polyimide. The thickness of the first insulating layer 41 is, for example, 3 μm or more and 20 μm or less, and preferably 5 μm or more and 15 μm or less.

  Subsequently, as shown in FIG. 3C, write wiring patterns W1, W2 and a ground pattern G1 made of, for example, copper (Cu) are formed on the first insulating layer 41. The write wiring patterns W1, W2 and the ground pattern G1 may be formed by using, for example, a semi-additive method or by using another method such as a subtractive method.

  The write wiring patterns W1, W2 and the ground pattern G1 are not limited to copper, and can be formed using other metals such as gold (Au) and aluminum, or alloys such as a copper alloy and an aluminum alloy.

  The thickness of the write wiring patterns W1, W2 is, for example, 3 μm or more and 16 μm or less, and preferably 6 μm or more and 13 μm or less. The widths of the write wiring patterns W1, W2 are, for example, 5 μm or more and 100 μm or less, and preferably 10 μm or more and 50 μm or less.

  The thickness of the ground pattern G1 is, for example, 3 μm to 16 μm, and preferably 6 μm to 13 μm. The width of the ground pattern G1 is, for example, 5 μm or more and 100 μm or less, and preferably 10 μm or more and 20 μm or less.

  The distance between the write wiring pattern W1 and the ground pattern G1 and the distance between the ground pattern G1 and the write wiring pattern W1 are, for example, 5 μm or more and 50 μm or less, and preferably 10 μm or more and 20 μm or less.

  In the above configuration, a metal thin film may be formed between the first insulating layer 41 and the write wiring patterns W1, W2 and between the first insulating layer 41 and the ground pattern G1. In this case, the adhesion between the first insulating layer 41 and the write wiring patterns W1, W2 and the adhesion between the first insulating layer 41 and the ground pattern G1 are improved.

  Subsequently, as shown in FIG. 3D, a second insulating layer 42 made of polyimide, for example, is formed on the first insulating layer 41 so as to cover the write wiring patterns W1, W2 and the ground pattern G1. To do.

  As the second insulating layer 42, another insulating material such as an epoxy resin may be used instead of polyimide. The thickness t1 of the second insulating layer 42 is, for example, not less than 1 μm and not more than 30 μm, and preferably not less than 3 μm and not more than 10 μm.

  In this way, the suspension board 1 shown in FIGS. 1 and 2 is completed.

(1-3) Effects In the suspension board 1 according to the present embodiment, the ground pattern G1 is formed on the first insulating layer 41 in the region between the write wiring patterns W1, W2. With such a configuration, transmission loss of the write wiring traces W1, W2 is reduced.

(2) Second Embodiment A suspension board according to a second embodiment of the present invention will be described while referring to differences from the suspension board 1 according to the first embodiment. FIG. 4 is a schematic longitudinal sectional view of the write wiring patterns W1, W2 and their peripheral portions of the suspension board according to the second embodiment.

  In the suspension board 1a of FIG. 4, a third insulating layer 43 made of polyimide, for example, is formed on the suspension body 10. A fourth insulating layer 44 made of, for example, polyimide is formed on the third insulating layer 43. On the fourth insulating layer 44, write wiring patterns W1, W2 are formed in parallel at a distance. A ground pattern G1 is formed so as to be partially embedded in the fourth insulating layer 44 between the write wiring patterns W1, W2. A fifth insulating layer 45 is formed on the fourth insulating layer 44 so as to cover the write wiring patterns W1, W2 and the ground pattern G1.

  The upper surface of the ground pattern G1 is higher than the lower surfaces of the write wiring patterns W1, W2, and is lower than the upper surfaces of the write wiring patterns W1, W2. The lower surface of the ground pattern G1 is at a position lower than the lower surfaces of the write wiring patterns W1, W2.

  The difference between the height of the upper surface of the write wiring patterns W1, W2 and the height of the upper surface of the ground pattern G1 is, for example, not less than 1 μm and not more than 20 μm, and preferably not less than 5 μm and not more than 15 μm.

  The distance H1 between the write wiring pattern W1 and the ground pattern G1 and the distance H2 between the ground pattern G1 and the write wiring pattern W2 in the direction parallel to the upper surface of the third insulating layer 43 are, for example, 5 μm or more and 50 μm or less. Yes, it is preferably 10 μm or more and 20 μm or less.

  As the third to fifth insulating layers 43 to 45, other insulating materials such as an epoxy resin may be used instead of polyimide. The thickness of the third insulating layer 43 is, for example, not less than 3 μm and not more than 20 μm, and preferably not less than 5 μm and not more than 15 μm. The thickness t2 of the fourth insulating layer 44 is, for example, 3 μm to 20 μm, and preferably 5 μm to 15 μm. The thickness t3 of the fifth insulating layer 44 is, for example, not less than 1 μm and not more than 30 μm, and preferably not less than 3 μm and not more than 10 μm.

  Also in the suspension board 1a according to the present embodiment, the transmission loss of the write wiring patterns W1, W2 is reduced.

(3) Third Embodiment A suspension board according to a third embodiment of the present invention will be described with respect to differences from the suspension board 1a (FIG. 4) according to the second embodiment. FIG. 5 is a schematic longitudinal sectional view of the write wiring patterns W1, W2 and their peripheral portions of the suspension board according to the third embodiment.

  In the suspension board 1 b of FIG. 5, the ground pattern G <b> 1 is formed on the third insulating layer 43. A sixth insulating layer 46 made of polyimide, for example, is formed in regions on the third insulating layer 43 on both sides of the land pattern G1. A write wiring pattern W1 is formed in a region on the sixth insulating layer 46 on one side of the ground pattern G1, and a write wiring pattern W2 is formed on a region on the sixth insulating layer 46 on the other side of the ground pattern G1. Is formed. A seventh insulating layer 47 made of polyimide, for example, is formed on the third and sixth insulating layers 43 and 46 so as to cover the write wiring patterns W1 and W2 and the ground pattern G1.

  The upper surface of the ground pattern G1 is at the same height as the lower surfaces of the write wiring patterns W1, W2, or at a position lower than the lower surfaces of the write wiring patterns W1, W2.

  The difference between the height of the lower surface of the write wiring patterns W1, W2 and the height of the upper surface of the ground pattern G1 is, for example, not less than 0 μm and not more than 17 μm, and preferably not less than 0 μm and not more than 10 μm.

  The distance H3 between the write wiring pattern W1 and the ground pattern G1 and the distance H4 between the ground pattern G1 and the write wiring pattern W2 in the direction parallel to the upper surface of the third insulating layer 43 are, for example, 5 μm or more and 50 μm or less. Yes, it is preferably 10 μm or more and 20 μm or less.

  As the sixth and seventh insulating layers 46 and 47, other insulating materials such as epoxy resin may be used instead of polyimide. The thickness of the sixth insulating layer 43 is, for example, 3 μm to 20 μm, and preferably 5 μm to 15 μm. The thickness t4 of the seventh insulating layer 47 is, for example, not less than 1 μm and not more than 30 μm, and preferably not less than 3 μm and not more than 10 μm.

  Also in suspension board 1b according to the present embodiment, transmission loss of write wiring patterns W1, W2 is reduced.

(4) Examples and Comparative Examples (4-1) Example 1
As Example 1, the suspension board 1 shown in FIG. In addition, the thickness of the insulating layer 41 of the first insulating layer 41 was 13 μm, and the thickness t1 (FIG. 3D) of the second insulating layer 42 was 15 μm. Further, the thicknesses of the write wiring patterns W1, W2 were 10 μm, respectively, and the widths of the write wiring patterns W1, W2 were 50 μm, respectively. The thickness of the ground pattern G1 was 10 μm, and the width of the ground pattern G1 was 15 μm. The distance between the write wiring pattern W1 and the ground pattern G1 and the distance between the ground pattern G1 and the write wiring pattern W2 were set to 20 μm.

(4-2) Example 2
As Example 2, the suspension board 1a shown in FIG. The thickness of the third insulating layer 43 was 5 μm, the thickness t2 (FIG. 4) of the fourth insulating layer 44 was 5 μm, and the thickness t3 (FIG. 4) of the fifth insulating layer was 15 μm. Further, the thicknesses of the write wiring patterns W1, W2 were 10 μm, respectively, and the widths of the write wiring patterns W1, W2 were 50 μm, respectively. The thickness of the ground pattern G1 was 10 μm, and the width of the ground pattern G1 was 15 μm.

  Further, the distance H1 (FIG. 4) between the write wiring pattern W1 and the ground pattern G1 and the distance H2 (FIG. 4) between the ground pattern G1 and the write wiring pattern W2 in the direction parallel to the upper surface of the third insulating layer 43. Each of 4) was 20 μm. Further, the difference between the height of the upper surface of the write wiring patterns W1, W2 and the height of the upper surface of the ground pattern G1 was set to 5 μm.

(4-3) Example 3
As Example 3, the suspension board 1b shown in FIG. The thickness of the third insulating layer 43 was 3 μm, the thickness of the sixth insulating layer 46 was 10 μm, and the thickness t4 (FIG. 5) of the seventh insulating layer 47 was 15 μm. Further, the thicknesses of the write wiring patterns W1, W2 were 10 μm, respectively, and the widths of the write wiring patterns W1, W2 were 50 μm, respectively. The thickness of the ground pattern G1 was 10 μm, and the width of the ground pattern G1 was 15 μm.

  Further, the distance H3 (FIG. 5) between the write wiring pattern W1 and the ground pattern G1 and the distance H4 (FIG. 5) between the ground pattern G1 and the write wiring pattern W2 in the direction parallel to the upper surface of the third insulating layer 43. Each of 5) was 20 μm. Further, the lower surfaces of the write wiring patterns W1, W2 and the upper surface of the ground pattern G1 were set to the same height.

(4-4) Comparative Example As a comparative example, a suspension board similar to that of Example 1 was manufactured except that the ground pattern G1 was not formed.

(4-5) Evaluation With respect to the suspension boards 1, 1a, and 1b of Examples 1 to 3 and the comparative example, losses in the differential mode input and the differential mode output (Sdd21) were calculated by simulation.

  FIG. 6 is a diagram illustrating simulation results of losses in the differential mode input and the differential mode output. In FIG. 6, the vertical axis represents gain, and the horizontal axis represents signal frequency. In this case, negative gain represents loss.

  As shown in FIG. 6, the loss in the suspension boards 1, 1a, 1b of Examples 1 to 3 was smaller than the loss in the suspension board of the comparative example. From this result, it was found that the transmission loss of the write wiring traces W1, W2 is reduced by forming the ground shield G1 at various heights between the write wiring traces W1, W2. .

(5) Other Embodiments In the above embodiment, an example in which the present invention is applied to a suspension board used for an actuator of a hard disk drive device has been described. However, the present invention is not limited to this, and the present invention is applied to other printed circuit boards. You may apply. In that case, the suspension body 10 need not be provided.

(6) Correspondence between each component of claim and each part of embodiment The following describes an example of a correspondence between each component of the claim and each part of the embodiment. It is not limited.

  In the above embodiment, the first, third, fourth, and sixth insulating layers 41, 43, 44, and 46 are examples of insulating layers, and the write wiring pattern W1 is an example of the first wiring pattern. The write wiring pattern W2 is an example of the second wiring pattern, the suspension main body portion 10 is an example of a metal substrate, and the tongue portion 12 is an example of a head portion.

  As each constituent element in the claims, various other elements having configurations or functions described in the claims can be used.

  The present invention can be used for various electric devices or electronic devices.

1 is a plan view of a suspension board according to a first embodiment. It is a typical longitudinal cross-sectional view of the wiring pattern for a write-in of the suspension board which concerns on 1st Embodiment, and its peripheral part. It is a figure which shows the manufacturing process of the suspension board based on 1st Embodiment. It is a typical longitudinal cross-sectional view of the wiring pattern for writing of the suspension board which concerns on 2nd Embodiment, and its peripheral part. It is a typical longitudinal cross-sectional view of the wiring pattern for writing of the suspension board which concerns on 3rd Embodiment, and its peripheral part. It is a figure which shows the simulation result of the loss in a differential mode input and a differential mode output.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Suspension board 10 Suspension main body part 12 Tongue part 41 1st insulating layer 42 2nd insulating layer 43 3rd insulating layer 44 4th insulating layer 45 5th insulating layer 46 6th insulating layer 47 7th Insulating layer G1 Ground pattern R1, R2 Read wiring pattern W1, W2 Write wiring pattern

Claims (6)

An insulating layer;
First and second wiring patterns that are formed on the insulating layer at an interval and constitute a signal line pair;
A printed circuit board comprising: a ground pattern formed between the first and second wiring patterns. 2. The printed circuit board according to claim 1, wherein the upper surface of the ground pattern is not positioned above the upper surfaces of the first and second wiring patterns in a direction perpendicular to the upper surface of the insulating layer. An upper surface of the ground pattern is positioned below the upper surfaces of the first and second wiring patterns in a direction perpendicular to the upper surface of the insulating layer, and is higher than the lower surfaces of the first and second wiring patterns. The printed circuit board according to claim 2, wherein the printed circuit board is located at a position. 3. The printed circuit board according to claim 2, wherein the upper surface of the ground pattern is located below the lower surfaces of the first and second wiring patterns in a direction perpendicular to the upper surface of the insulating layer. A long metal substrate;
A head portion provided on the metal substrate for reading and writing signals;
The insulating layer is formed on the metal substrate;
The printed circuit board according to claim 1, wherein the first and second wiring patterns are electrically connected to the head portion. Forming the first and second wiring patterns constituting the signal line pair at an interval on the insulating layer;
And a step of forming a ground pattern between the first and second wiring patterns.

Images