JP2019102109A - Suspension substrate assembly with circuit - Google Patents

Abstract

To provide a suspension substrate assembly with a circuit in which piezoelectric elements are mounted with high positional accuracy.SOLUTION: A suspension substrate assembly 1 with a circuit includes: a suspension substrate 2 with a circuit having an element connection terminal 61 and a gold plating layer 8 provided on the element connection terminal 61; a piezoelectric element 3 in which an element terminal 32 electrically connected to the element connection terminal 61 is provided; and a solder layer 9 disposed between the gold plating layer 8 and the element terminal 32. A solder composition containing at least Sn is contained in the solder layer 9, and the thickness of the solder layer 9 is formed to satisfy the following formula (1). Formula (1) Y≥10X+1.5 (In the formula (1), Y represents the thickness of the solder layer 9 and X represents the thickness of the gold plating layer 8).SELECTED DRAWING: Figure 3

Description

  The present invention relates to a suspension board assembly with circuit, and more particularly, to a suspension board assembly with circuit including a suspension board with circuit and a piezoelectric element.

  There is known a suspension board assembly with circuit that includes a suspension board with circuit on which a head slider is mounted and a piezoelectric element that can be expanded and contracted to displace the head slider. The piezoelectric element is connected by solder to a terminal provided in the suspension board with circuit.

  For example, a suspension has been proposed in which a gold plating layer is provided on the element connection terminal of the suspension substrate, and the SnBi solder material is connected to the gold plating layer and connected to the electrode of the piezoelectric element (for example, patented) Reference 1).

  In such a suspension, after the SnBi solder material is disposed on the gold plated layer of the element connection terminal by the solder jet method, the piezoelectric element is disposed to be in contact with the solder material and then reflowed to form the solder material. It fuses and manufactures by connecting a piezoelectric element and an element connection terminal.

Unexamined-Japanese-Patent No. 2014-106993

  However, in the mounting of the piezoelectric element on the suspension substrate described in Patent Document 1, the piezoelectric element is disposed offset from the predetermined position, and the piezoelectric element is offset from the predetermined position by the subsequent reflow, and the suspension substrate is May be glued.

  In consideration of such a case, it is considered to improve the positional accuracy of the piezoelectric element by causing the piezoelectric element to self-align using the surface tension of the melted solder material at the time of reflow.

  The surface tension of the solder material is proportional to the volume of the solder material to be melted. Therefore, in order to self-align the piezoelectric element accurately, it is necessary to secure a sufficient volume of the solder material to be melted.

  However, in the mounting process of the piezoelectric element described in Patent Document 1, at the time of reflow, Sn contained in the solder material and Au contained in the gold plating layer may form an SnAu alloy. Such a SnAu alloy has a high melting point as compared to a SnBi-based solder material, and is not sufficiently melted at the time of reflow.

  Therefore, the volume of the solder material to be melted is reduced, and the surface tension of the solder material can not be sufficiently secured. As a result, it is difficult to self-align the piezoelectric element with high accuracy, and there is a limit to improving the positional accuracy of the piezoelectric element.

  Therefore, the present invention provides a suspension board assembly with circuit in which piezoelectric elements are mounted with high position accuracy.

  The present invention [1] includes a suspension board with circuit including a terminal and a gold plating layer provided on the terminal, a piezoelectric element including an element terminal electrically connected to the terminal, the gold plating layer, and the gold plating layer And a solder layer disposed between the element terminal and the solder layer, wherein the solder layer includes a solder composition containing at least Sn, and the thickness of the solder layer satisfies the following formula (1): Contains the assembly.

Formula (1)
Y 10 10X + 1.5
(In formula (1), Y shows the thickness of the said solder layer, X shows the thickness of the said gold plating layer.)
According to such a configuration, since the thickness of the solder layer satisfies the above formula (1), Sn contained in the solder composition and Au contained in the gold plating layer when the solder composition is melted And forming the SnAu alloy can be suppressed.

  Therefore, it can suppress that the volume of the solder composition fuse | melted at the time of reflow falls, and it can suppress that the surface tension of a solder composition falls by extension.

  As a result, the piezoelectric element can be accurately self-aligned, and the positional accuracy of the piezoelectric element can be improved.

  In the present invention [2], the solder layer contains the solder composition and an SnAu alloy, and the content ratio of the solder composition in the solder layer is 15% by volume or more. And a suspension board assembly with a circuit.

  According to such a configuration, since the content ratio of the solder composition in the solder layer is equal to or more than the above-described lower limit, the volume of the solder composition melted at the time of reflow can be sufficiently secured. Therefore, the piezoelectric element can be self-aligned more accurately, and the positional accuracy of the piezoelectric element can be reliably improved.

  The present invention [3] includes the suspension board assembly with circuit according to the above [1] or [2], wherein the solder composition contains Sn, Ag and Cu.

  According to such a configuration, since the solder composition contains Sn, Ag and Cu, the surface tension can be improved as compared to the Sn-Bi solder composition. Therefore, the piezoelectric element can be sufficiently self-aligned by a relatively small amount of the solder composition.

  As a result, while the positional accuracy of the piezoelectric element can be improved, the thickness of the solder layer can be reduced, and consequently, the thickness of the portion on which the piezoelectric element is mounted can be reduced.

  The present invention [4] includes the suspension board assembly with circuit according to any one of the above [1] to [3], wherein the thickness of the gold plating layer is 0.5 μm or less.

  According to such a configuration, since the thickness of the gold plating layer is not more than the above upper limit, when the solder composition is melted, Sn of the solder composition and Au of the gold plating layer form a SnAu alloy. Can be reliably suppressed.

  In the suspension board assembly with circuit of the present invention, the piezoelectric element can be mounted with high position accuracy.

FIG. 1 is a plan view of an embodiment of a suspension board assembly with circuit of the present invention, showing a state in which a cover insulating layer is removed. FIG. 2 is a bottom view of the suspension board assembly with circuit shown in FIG. FIG. 3 is a cross-sectional view of the first element connection terminal and the second element connection terminal shown in FIG. FIG. 4A is an explanatory diagram for describing an embodiment of a method of manufacturing the suspension board assembly with circuit shown in FIG. 1, and shows a process of preparing a suspension board with circuit. FIG. 4B shows the process of arrange | positioning a solder material on a gold plating layer following FIG. 4A. FIG. 4C shows, following FIG. 4B, a step of arranging the piezoelectric element so that the element terminal is in contact with the solder material. FIG. 4D shows a step of melting the solder material to form a solder layer, following FIG. 4C. FIG. 5 is an explanatory view for explaining the self alignment of the piezoelectric element shown in FIG. 4D. FIG. 6 is a graph showing the relationship of the solder layer to the thickness of the gold plating layer in Example 1, Example 15, Example 33 and Example 53.

First Embodiment
A suspension board assembly with circuit 1 which is an embodiment of a suspension board assembly with circuit of the present invention will be described with reference to FIGS. 1 to 3.

  As shown in FIG. 1, the suspension board assembly with circuit 1 includes a suspension board with circuit 2, a piezoelectric element 3, and a solder layer 9 (see FIG. 3) connecting the suspension board with circuit 2 and the piezoelectric element 3. . In FIG. 1, for convenience, the piezoelectric element 3 is indicated by an imaginary line.

1. Suspension board with circuit The suspension board with circuit 2 has a substantially flat belt shape extending in a predetermined direction.

  In FIG. 1, the vertical direction in the drawing is the longitudinal direction (first direction) of the suspension board with circuit 2, one side in the longitudinal direction (one side in the first direction) in the longitudinal direction, and the other side in the longitudinal direction The other side).

  In FIG. 1, the left-right direction in the drawing is the width direction of the suspension board with circuit 2 (second direction orthogonal to the first direction), the right side in the drawing is one side in the width direction (one side in the second direction) It is the direction other side (the second direction other side).

  In FIG. 1, the thickness direction in the drawing is the thickness direction of the suspension board with circuit 2 (third direction orthogonal to both the first direction and the second direction), and the front side in the drawing is one side in the thickness direction (third direction one side) The back side in the drawing is the other side in the thickness direction (the other side in the third direction). Specifically, the direction follows the direction arrow described in each figure.

  As shown in FIG. 3, the suspension board with circuit 2 has a laminated structure, and the metal support layer 4, the base insulating layer 5, the conductor pattern 6, and the cover insulating layer 7 are on the other side in the thickness direction It prepares in order from one side to the other side. In addition, in FIG. 1, the cover insulating layer 7 is abbreviate | omitted for convenience.

  As shown in FIG. 2, the metal support layer 4 is a metal support that supports the conductor pattern 6 (see FIG. 1), and extends in the longitudinal direction. The metal support layer 4 includes a stage 40, a main body 41, and a connecting portion 42.

  The stage 40 is a portion that supports the slider 11 (see FIG. 1) and is located at one longitudinal end of the metal support layer 4. The stage 40 has a substantially rectangular shape in a bottom view.

  The main body portion 41 is a portion supported by the load beam 15 (described later), and is located on the other side in the longitudinal direction with respect to the stage 40. The main body 41 extends in the longitudinal direction. The main body 41 has an opening 43. The opening 43 is located at one longitudinal end of the main body 41. The opening 43 has a concave shape opened toward one longitudinal side. One longitudinal end edge of the main body portion 41 forms a recess 44 which is recessed to the other longitudinal side along the opening 43.

  The connecting portion 42 extends in the longitudinal direction, and connects the other end of the stage 40 in the longitudinal direction and one end of the main body portion 41 in the longitudinal direction.

  Examples of the material of the metal support layer 4 include metal materials such as stainless steel. The thickness of the metal supporting layer 4 is, for example, 10 μm or more, preferably 15 μm or more, for example, 35 μm or less, preferably 25 μm or less.

  As shown in FIG. 3, the insulating base layer 5 is disposed on one side in the thickness direction of the metal supporting layer 4, specifically, on one side in the thickness direction of the metal supporting layer 4. As shown in FIG. 1, the insulating base layer 5 has a predetermined pattern corresponding to the conductor pattern 6. The base insulating layer 5 includes a stage base 50 and a main body base 51.

  The stage base 50 is disposed on the stage 40. The stage base 50 has a substantially rectangular shape in plan view.

  The main body base 51 is disposed on the main body portion 41. The main body base 51 has a plurality of terminal openings 52 at positions overlapping with the recesses 44 (see FIG. 2) when viewed in the thickness direction. The plurality of terminal openings 52 are arranged at intervals in the width direction corresponding to the plurality of first element connection terminals 65 (described later). The terminal opening 52 has a rectangular shape in plan view extending in the width direction.

  Examples of the material of the base insulating layer 5 include synthetic resins such as polyimide resin. The thickness of the base insulating layer 5 is, for example, 1 μm or more, preferably 3 μm or more, for example, 25 μm or less, preferably 15 μm or less.

  The conductor pattern 6 includes a plurality of (four) magnetic head connection terminals 60, a plurality of (six) external connection terminals 62, a plurality of (four) element connection terminals 61 as an example of terminals, and a plurality (four) Magnetic head wiring 63 and a plurality (four) of element wiring 64.

  When the slider 11 is mounted on the suspension board with circuit 2, a plurality of (four) magnetic head connection terminals 60 are provided via a magnetic head (not shown) provided in the slider 11 and a conductive material (for example, solder etc.) Electrically connected. The plurality of magnetic head connection terminals 60 are spaced apart from each other in the width direction on the stage base 50.

  A plurality of (six) external connection terminals 62 are disposed on the other end of the main body base 51 in the longitudinal direction. The plurality of external connection terminals 62 are arranged at intervals in the width direction.

  The plurality of (four) element connection terminals 61 are electrically connected to the piezoelectric element 3 via the solder layer 9 (described later) when the piezoelectric element 3 is mounted on the suspension board with circuit 2. The plurality of element connection terminals 61 include a plurality of (two) first element connection terminals 65 and a plurality of (two) second element connection terminals 66.

  The first element connection terminal 65 is disposed in the corresponding terminal opening 52. The first element connection terminal 65 has a substantially rectangular shape in plan view. The first element connection terminal 65 is adjacent to one longitudinal end of the terminal opening 52 with respect to the other longitudinal end thereof. The first element connection terminal 65 is exposed from the metal support layer 4 and the base insulating layer 5 when viewed from the other side in the thickness direction.

  The plurality of second element connection terminals 66 are adjacent to the other longitudinal end of the stage base 50 in the other longitudinal direction. The plurality of second element connection terminals 66 are arranged at intervals in the width direction. The second element connection terminal 66 has a substantially rectangular shape in plan view. The second element connection terminal 66 is spaced apart from the first element connection terminal 65 on one side in the longitudinal direction. The second element connection terminal 66 is exposed from the metal support layer 4 and the base insulating layer 5 when viewed from the other side in the thickness direction.

  The dimension in the longitudinal direction of the element connection terminal 61 (each of the first element connection terminal 65 and the second element connection terminal 66) is, for example, 30 μm or more, preferably 50 μm or more, for example 100 μm or less, preferably 90 μm or less is there.

  The dimension in the width direction of the element connection terminal 61 (each of the first element connection terminal 65 and the second element connection terminal 66) is, for example, 120 μm or more, preferably 210 μm or more, for example 250 μm or less, preferably 230 μm or less is there.

  The plurality of (four) magnetic head wires 63 electrically connect the plurality of magnetic head connection terminals 60 and the same number of external connection terminals 62 as the plurality of magnetic head connection terminals 60.

  The plurality of (four) element wires 64 are connected to the plurality of element connection terminals 61. Specifically, the plurality of element wirings 64 include a plurality of power supply wirings 67 connected to the plurality of first element connection terminals 65 and a plurality of ground wirings 68 connected to the plurality of second element connection terminals 66.

  The plurality of power supply wirings 67 electrically connect the plurality of first element connection terminals 65 and the external connection terminals 62 not connected to the magnetic head wiring 63 among the plurality of external connection terminals 62.

  The plurality of ground wirings 68 are connected to the plurality of second element connection terminals 66 and penetrate (contact) the stage 40 through the stage base 50 (ground).

  The cover insulating layer 7 is disposed on one side in the thickness direction of the base insulating layer 5, specifically, on one side in the thickness direction of the base insulating layer 5 so as to cover the plurality of magnetic head wires 63 and the plurality of element wires 64. Be done. In addition, the cover insulating layer 7 exposes the magnetic head connection terminal 60 and the external connection terminal 62 and covers the element connection terminal 61 as viewed from one side in the thickness direction. Examples of the material of the cover insulating layer 7 include synthetic resins such as polyimide resin. The thickness of the cover insulating layer 7 is appropriately set.

  Further, as shown in FIG. 3, the suspension board with circuit 2 includes a gold plating layer 8 provided on the element connection terminal 61. The material of the gold plating layer 8 is gold, and the gold plating layer 8 is a thin layer made of gold.

  The gold plating layer 8 is disposed on the other side in the thickness direction with respect to the element connection terminal 61. The gold plating layer 8 may be provided directly on the other surface of the element connection terminal 61 in the thickness direction, and the thickness direction of the element connection terminal 61 may be formed via a plating layer made of another material (for example, nickel) other than gold. It may be provided on the other side. The number of layers of the plating layer interposed between the gold plating layer 8 and the element connection terminal 61 is not particularly limited, and may be one or two or more.

  Specifically, the gold plating layer 8 is disposed on the other side in the thickness direction of the first element plating terminal 8 and the first gold plating layer 8A disposed on the other side in the thickness direction of the first element connection terminal 65. And 2 gold-plated layer 8B. The first gold plating layer 8A overlaps the entire first element connection terminal 65 when viewed from the other side in the thickness direction, and has the same shape and size as the first element connection terminal 65. The second gold plating layer 8B overlaps the entire second element connection terminal 66 when viewed from the other side in the thickness direction, and has the same shape and size as the second element connection terminal 66.

  The thickness of the gold plating layer 8 is, for example, 0.1 μm or more, preferably 0.2 μm or more, for example, less than 1.0 μm, preferably 0.5 μm or less, and more preferably 0.3 μm or less.

  If the thickness of the gold plating layer 8 is in the above range, it can be stably suppressed that Sn of the solder composition and Au of the gold plating layer form a SnAu alloy in a reflow process described later.

  Although not shown, the gold plating layer 8 is also provided on one surface in the thickness direction of each of the plurality of magnetic head connection terminals 60 and the plurality of external connection terminals 62.

2. Piezoelectric Element The piezoelectric element 3 is an actuator that can expand and contract in a predetermined direction, and is supplied with electricity and is expanded and contracted by controlling its voltage. In the present embodiment, two piezoelectric elements 3 are mounted on the suspension board with circuit 2.

  Each piezoelectric element 3 is positioned on the other side in the thickness direction with respect to the plurality of element connection terminals 61 (the first element connection terminals 65 and the second element connection terminals 66). The piezoelectric element 3 is formed of, for example, a known piezoelectric material, more specifically, a piezoelectric ceramic or the like.

As piezoelectric ceramics, for example, BaTiO ₃ (barium titanate), PbTiO ₃ (lead titanate), Pb (Zr, Ti) O ₃ (lead zirconate titanate (PZT)), SiO ₂ (quartz), LiNbO ₃ Lithium niobate), PbNb ₂ O ₆ (lead meta niobate), etc. are mentioned, and preferably PZT is mentioned.

  The piezoelectric element 3 also includes a plurality of (two) element terminals 32. The plurality of element terminals 32 include a first element terminal 30 corresponding to the first element connection terminal 65 and a second element terminal 31 corresponding to the second element connection terminal 66.

  The first element terminal 30 is electrically connected to the first element connection terminal 65 through the solder layer 9. The first element terminal 30 has the same shape and size as the first element connection terminal 65.

  The second element terminal 31 is electrically connected to the second element connection terminal 66 through the solder layer 9. The second element terminal 31 is spaced apart from the first element terminal 30 in a predetermined direction. The second element terminal 31 has the same shape and size as the second element connection terminal 66.

3. Solder Layer The solder layer 9 is disposed between the gold plating layer 8 and the element terminal 32. Specifically, the solder layer 9 includes a first solder layer 9A disposed between the first gold-plated layer 8A and the first element terminal 30, a second gold-plated layer 8B and a second element terminal 31. And a second solder layer 9B disposed therebetween.

  The solder layer 9 contains a solder composition containing at least Sn, and preferably further contains a SnAu alloy. That is, the solder layer 9 can be made of a solder composition, but preferably contains a solder composition and a SnAu alloy, and more preferably consists of a solder composition and a SnAu alloy.

  The solder composition preferably comprises Sn, Ag and Cu, and more preferably consists of Sn, Ag and Cu. Hereinafter, a solder composition containing Sn, Ag, and Cu will be referred to as a SnAgCu-based solder composition.

  When the solder composition is a SnAgCu-based solder composition, the surface tension of the solder composition can be improved.

  In the SnAgCu-based solder composition, the content ratio of Ag is, for example, 1% by mass or more, preferably 2% by mass or more, for example, 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass It is.

  The content ratio (Ag / Cu) of Ag to Cu is, for example, 4 or more, preferably 5 or more, for example, 8 or less, preferably 7 or less.

  In the SnAgCu-based solder composition, the content ratio of Cu is, for example, 0.3% by mass or more, preferably 0.4% by mass or more, for example, 0.7% by mass or less, preferably 0.6% by mass or less More preferably, it is 0.5 mass%.

  In the SnAgCu-based solder composition, the content ratio of Sn is the balance of the above content ratio of Ag and Cu.

  Specifically, as a solder composition, what is represented as Sn-3Ag-0.5Cu is mentioned. A commercial item can be used as such a solder composition.

  The melting point of such a solder composition is, for example, 200 ° C. or more, preferably 210 ° C. or more, for example, 230 ° C. or less, preferably 220 ° C. or less.

  The content ratio of the solder composition in the solder layer 9 is, for example, 10% by volume or more, preferably 15% by volume or more, more preferably 30% by volume or more, particularly preferably 50% by volume or more, for example 100% by volume It is below. The content ratio of each component in the solder layer 9 can be calculated from the area ratio of each component in the cross-sectional photograph of the cross-sectional photograph of the solder layer 9 (the same applies hereinafter).

  When the content ratio of the solder composition in the solder layer 9 is equal to or more than the above lower limit, the volume of the solder composition melted in the reflow process described later can be sufficiently ensured, and the improvement of the positional accuracy of the piezoelectric element is surely achieved. be able to.

  The SnAu alloy is an alloy of Sn and Au, and is formed by heating in a state in which the solder material 10 (described later) containing the solder composition is disposed on the gold plating layer 8 in the reflow step described later. Do. The SnAu alloy contains at least Sn and Au, and preferably consists of Sn and Au. The SnAu alloy can further contain, for example, Ag, Cu, and the like.

In the SnAu alloy, the content ratio of Sn is, for example, 70% by mass or more, preferably 75% by mass or more, for example, 95% by mass or less, preferably 85% by mass or less.
In the SnAu alloy, the content ratio of Au is, for example, 5% by mass or more, preferably 15% by mass or more, for example, 30% by mass or less, preferably 25% by mass or less.

  The melting point of such SnAu alloy is higher than the melting point of the solder composition and higher than the reflow temperature described later. Specifically, the melting point of the SnAu alloy is, for example, more than 260 ° C., preferably 290 ° C. or more, for example, 320 ° C. or less, preferably 300 ° C. or less.

  The content ratio of the SnAu alloy in the solder layer 9 is, for example, 0 volume% or more, for example, 90 volume% or less, preferably 85 volume% or less, more preferably 70 volume% or less, particularly preferably 50 volume% or less It is.

  The volume ratio of SnAu alloy to the volume of the solder composition (volume of SnAu alloy / volume of solder composition) is, for example, 0.1 or more, for example, 10 or less, preferably 6 or less, more preferably 2 Or less, particularly preferably 1 or less.

  The thickness of the solder layer 9 is in proportion to the thickness of the gold plating layer 8 and satisfies the following formula (1).

Formula (1)
Y 10 10X + 1.5
(In formula (1), Y shows the thickness of a solder layer, X shows the thickness of a gold plating layer.)
In addition, said Formula (1) is calculated | required by the Example mentioned later.

  When the thickness of the solder layer 9 satisfies the formula (1), formation of an SnAu alloy can be suppressed in a reflow process described later, and the positional accuracy of the piezoelectric element can be improved.

  In addition, the thickness of the solder layer 9 is preferably 14 times or more, more preferably 20 times or more, for example, 100 times or less, preferably 80 times or less, more preferably, with respect to the thickness of the gold plating layer 8. , 70 times or less.

  Specifically, the thickness of the solder layer 9 is, for example, 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, particularly preferably 5 μm or more, for example, 15 μm or less, preferably 13 μm or less, more preferably Is 9 μm or less.

  If the thickness of the solder layer 9 is equal to or more than the above lower limit, the gold plating layer 8 and the element terminal 32 can be connected reliably.

  However, the suspension board assembly 1 with circuit is mounted on a hard disk drive (not shown) by supporting the main body 41 (see FIG. 2) of the metal support layer 4 by the load beam 15. At this time, the front end portion of the load beam 15 is located on the lower side (the other side in the thickness direction) with respect to the piezoelectric element 3.

  Therefore, when the thickness of the solder layer 9 exceeds the above-mentioned upper limit, the piezoelectric element 3 and the load beam 43 come in contact with each other. On the other hand, when the thickness of the solder layer 9 is less than or equal to the above upper limit, contact between the piezoelectric element 3 and the load beam 15 can be suppressed while improving the positional accuracy of the piezoelectric element 3.

4. Method of Manufacturing Suspension Board Assembly with Circuit Next, a method of manufacturing the suspension board assembly with circuit 1 will be described with reference to FIGS. 4A to 4D. The method of manufacturing the suspension board assembly with circuit 1 includes the steps of preparing the suspension board with circuit 2 (FIG. 4A), disposing the solder material 10 on the gold plating layer 8 (FIG. 4B), and disposing the piezoelectric element 3. And a step of reflowing the suspension board with circuit 2 on which the piezoelectric element 3 is disposed (FIG. 4D, hereinafter referred to as a reflow step).

  In the suspension board assembly with circuit 1, first, as shown in FIG. 4A, the suspension board with circuit 2 described above is prepared.

  Next, as shown in FIG. 4A, the solder material 10 is disposed on the gold plating layer 8 by a known method (for example, printing by a known printing machine, application by a dispenser, etc.). Specifically, the solder material 10 is disposed on the other surface in the thickness direction of the first gold plating layer 8A, and is disposed on the other surface in the thickness direction of the second gold plating layer 8B. Moreover, while the solder material 10 contains the above-described solder composition, it does not contain the above-described SnAu alloy.

Moreover, the volume of the solder material 10 arrange | positioned on the gold plating layer 8 is set so that the thickness of the solder layer 9 formed in a reflow process may satisfy | fill said Formula (1). Specifically, the volume of the solder material 10 disposed on the first gold plating layer 8A is, for example, 3.5 × 10 ⁻⁸ cm ³ or more, preferably 7.9 × 10 ⁻⁸ cm ³ or more, For example, 1.9 × ¹⁰ -7 cm ³ or less, preferably, 1.3 × ¹⁰ -7 cm ³ or less. Further, the range of the volume of the solder material 10 disposed on the second gold plated layer 8B is the same as the range of the volume of the solder material 10 disposed on the first gold plated layer 8A.

  Next, as shown in FIG. 4C, in the piezoelectric element 3, while the first element terminal 30 is in contact with the solder material 10 on the first gold plated layer 8A, the second element terminal 31 is on the second gold plated layer 8B. Place in contact with the solder material 10.

  Next, as shown in FIG. 4D, the suspension board with circuit 2 on which the piezoelectric element 3 is disposed is reflowed.

  The reflow temperature is, for example, 230 ° C. or more, preferably 240 ° C. or more, for example, 260 ° C. or less, preferably 250 ° C. or less. The reflow time is, for example, 3 seconds or more, preferably 5 seconds or more, for example, 300 seconds or less, preferably 200 seconds or less.

  Thereby, the solder material 10 is melted so as to wet and spread on the entire surface in the other thickness direction of the gold plating layer 8 (each of the first gold plating layer 8A and the second gold plating layer 8B).

  At this time, Sn of the solder composition contained in the solder material 10 and Au contained in the gold plating layer may form an SnAu alloy. However, as described above, since the amount of the solder material 10 is adjusted so that the thickness of the solder layer 9 satisfies the above equation (1), the formation of the SnAu alloy can be suppressed, and the surface tension of the solder composition It is possible to suppress the decrease.

  Therefore, the piezoelectric element 3 can be self-aligned accurately. Specifically, in the step of arranging the piezoelectric element 3, as shown in FIG. 5, the piezoelectric element 3 may be arranged to be deviated from the predetermined position and inclined in the width direction. In this case, the center of the first element connection terminal 65 and the center of the first element terminal 30 are offset from each other when viewed from the thickness direction, and the center of the second element connection terminal 66 and the center of the second element terminal 31 Positioned out of alignment.

  Next, when the suspension board with circuit 2 on which the piezoelectric element 3 is disposed is reflowed, the solder material 10 is in the thickness direction of the element connection terminal 61 (each of the first element connection terminal 65 and the second element connection terminal 66) It melts so that it spreads in the whole of the direction.

  At this time, due to the surface tension of the melted solder material 10, the center of the first element connection terminal 65 and the center of the first element terminal 30 coincide with each other and the center of the second element connection terminal 66 when viewed from the thickness direction. A force is applied to the piezoelectric element 3 so that the center of the second element terminal 31 is aligned. As a result, as shown in FIG. 1, the piezoelectric element 3 is self-aligned from the state of being displaced from the predetermined position toward the predetermined position.

  And as shown to FIG. 4D, the solder material 10 forms the solder layer 9, and joins the 1st element connection terminal 65 and the 1st element terminal 30, and the 2nd element connection terminal 66 and the 2nd element terminal 31. Do. Thereby, the suspension board with circuit 2 and the piezoelectric element 3 are electrically connected.

  Thus, the suspension board assembly with circuit 1 is manufactured. As shown in FIG. 1, the suspension board assembly with circuit 15 may or may not include the slider 11 having the magnetic head.

  In such a suspension board assembly with circuit 1, since the thickness of the solder layer 9 satisfies the above formula (1), when the solder composition is melted, Sn contained in the solder composition and the gold plating layer 8 It is possible to suppress the formation of an SnAu alloy with Au contained.

  Therefore, it can suppress that the volume of the solder composition fuse | melted in a reflow process falls, and it can suppress that the surface tension of a solder composition falls by extension.

  As a result, the piezoelectric element 3 can be self-aligned accurately, and the positional accuracy of the piezoelectric element 3 can be improved.

  In addition, the content ratio of the solder composition in the solder layer 9 is preferably equal to or more than the above lower limit. Therefore, the volume of the solder composition melted in the reflow process can be sufficiently secured. Therefore, the piezoelectric element 3 can be self-aligned more accurately, and the positional accuracy of the piezoelectric element 3 can be reliably improved.

  The solder composition is preferably a SnAgCu-based solder composition containing Sn, Ag and Cu. Therefore, the surface tension of the solder composition can be improved. As a result, the piezoelectric element 3 can be sufficiently self-aligned by a relatively small amount of the solder composition. As a result, while the positional accuracy of the piezoelectric element 3 can be improved, the thickness of the solder layer 9 can be reduced, and consequently, the thickness of the portion on which the piezoelectric element 3 is mounted can be reduced.

  The thickness of the gold plating layer 8 is preferably equal to or less than the above upper limit. Therefore, in the reflow process, it can be reliably suppressed that Sn of the solder composition and Au of the gold plating layer 8 form a SnAu alloy.

  Hereinafter, the present invention will be described more specifically by showing Examples and Comparative Examples. The present invention is not limited to the examples and comparative examples. In addition, specific numerical values such as mixing ratios (content ratios), physical property values, parameters, etc. used in the following description are the mixing ratios corresponding to those described in the above-mentioned “embodiments for carrying out the invention” Content ratio), physical property values, parameters, etc. may be replaced by the upper limit (numeric values defined as "below", "less than") or lower limits (numeric values defined as "more than", "excess") it can.

Examples 1 to 74 and Comparative Examples 1 to 26
The number of the suspension board assemblies with circuit, in which the thickness of the gold plating layer and the thickness of the solder layer are the values of Tables 1 and 2, were prepared as shown in Tables 1 and 2.

  Each suspension board assembly with circuit includes a suspension board with circuit and two piezoelectric elements mounted on the suspension board with circuit, and the solder layer is a SnAgCu-based solder composition (Sn content ratio: balance, Ag content ratio: 3 ± 1 mass%, Cu content ratio: 0.5 ± 0.1 mass%).

  In Example 7 (thickness of plating layer: 0.5 μm), in the solder layer, the content ratio of the solder composition is 15.8% by volume, and the content ratio of the SnAu alloy is 84.2% by volume. there were.

  In Example 22 (thickness of plating layer: 0.3 μm), in the solder layer, the content ratio of the solder composition is 38.3% by volume, and the content ratio of the SnAu alloy is 61.7% by volume. there were.

  Moreover, in Example 42 (thickness of plating layer: 0.2 μm), in the solder layer, the content ratio of the solder composition is 52.8 vol%, and the content ratio of the SnAu alloy is 47.2 vol%. there were.

  In Example 63 (the thickness of the plating layer: 0.1 μm), in the solder layer, the content ratio of the solder composition is 84.3% by volume, and the content ratio of the SnAu alloy is 15.7% by volume. there were.

  In Comparative Example 7 (thickness of the plating layer: 0.5 μm), the content ratio of the solder composition in the solder layer is 4.8% by volume, and the content ratio of the SnAu alloy is 95.2% by volume. there were.

  Next, the number of defective products was determined by the following evaluation, and the production efficiency (number of defective products / number of products × 100) was calculated. The results are shown in Tables 1 and 2.

  A Y-axis reference line of the suspension board with circuit (an imaginary line passing through the center in the width direction of the suspension board with circuit and along the longitudinal direction) was defined.

  Next, an X-axis reference line (an imaginary line along the width direction) perpendicular to the Y-axis reference line was defined. An intersection point of the Y-axis reference line and the X-axis reference line is set as a reference point (0, 0).

  Next, first virtual lines were extracted along both widthwise end edges (edges) of the piezoelectric element. Then, the angle (inclination θ) formed by the first virtual lines (both end edges in the width direction of the piezoelectric element) with respect to the Y-axis reference line was measured.

  Next, second virtual lines were extracted along the longitudinal opposite end edges (edges) of the piezoelectric element. Then, vertices (four corners) of the piezoelectric element were extracted from the intersections of the first virtual line and the second virtual line.

  Subsequently, the center coordinates of the piezoelectric element were calculated from the coordinates of the vertex of the piezoelectric element. Then, the amount of deviation of the center coordinates of the piezoelectric element (the amount of X coordinate deviation, the amount of Y coordinate deviation) was calculated from the reference point.

  The deviation amount of the center coordinates of the piezoelectric element, the angle (inclination θ), the number of non-standard ones were counted as the defective product. The production efficiency was calculated by dividing the number of defective products by the number of evaluations. The production efficiency was set at 97% as a threshold.

  Next, among the examples in which the thickness of the plating layer is constant, the thickness of the solder layer was plotted against the thickness of the gold plating layer in an example in which the manufacturing efficiency is 97% or more and the thickness of the solder layer is the smallest. . Specifically, the thickness of the solder layer was plotted against the thickness of the gold plating layer in Example 1, Example 15, Example 33 and Example 53. The results are shown in FIG.

  Moreover, the said Formula (1) was calculated | required as an approximation formula of the plotted result.

  That is, it was confirmed that the relationship (area) between the thickness of the gold plating layer and the thickness of the solder layer which are excellent in the positional accuracy of the piezoelectric element is determined by the above equation (1).

DESCRIPTION OF SYMBOLS 1 Suspension board assembly with circuit 2 Suspension board with circuit 3 Piezoelectric element 8 Gold plating layer 9 Solder layer 32 Element terminal 61 Element connection terminal

Claims (4)

A suspension board with circuit including a terminal and a gold plating layer provided on the terminal;
A piezoelectric element comprising an element terminal electrically connected to the terminal;
A solder layer disposed between the gold plating layer and the element terminal;
The solder layer contains a solder composition containing at least Sn,
The thickness of the solder layer satisfies the following equation (1).
Y 10 10X + 1.5
(In formula (1), Y shows the thickness of the said solder layer, X shows the thickness of the said gold plating layer.)
Suspension board assembly with circuit, characterized in that The solder layer comprises the solder composition and a SnAu alloy,
The suspension board assembly with circuit according to claim 1, wherein a content ratio of the solder composition in the solder layer is 15% by volume or more.   The suspension board assembly with circuit according to claim 1, wherein the solder composition contains Sn, Ag, and Cu.   The suspension board assembly with circuit according to any one of claims 1 to 3, wherein a thickness of the gold plating layer is 0.5 μm or less.

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