JP2019134152A - Bonding capillary - Google Patents

Abstract

To provide a bonding capillary capable of obtaining high bonding strength.SOLUTION: A bonding capillary includes a first body part extending in the axial direction, a second body part provided on one end side of the first body part in the axial direction, and having cross sectional area decreasing toward the opposite side to the first body part, a bottleneck part provided at the end of the second body part on the opposite side to the first body part, and an insertion hole elongating in the axial direction, and penetrating the first body part, the second body part and the bottleneck part so as to enable insertion of a wire. The bottleneck part has a first portion and a second portion, where the first portion is provided between the second body part and the second portion, the second portion has a press surface for pressing the wire to the end on the opposite side to the first portion, and heat thermal resistance per unit length of the first portion in the axial direction is higher than the heat thermal resistance per unit length of the second portion in the axial direction.SELECTED DRAWING: Figure 3

Description

  Aspects of the invention generally relate to bonding capillaries.

  In the manufacturing process of a semiconductor device, wire bonding is performed in which a semiconductor element and a lead frame are connected by a bonding wire (hereinafter referred to as “wire”) (for example, Patent Documents 1 to 3). In wire bonding, one end of a wire is bonded to an electrode (electrode pad) of a semiconductor element using a bonding capillary (first bond). Next, the wire is drawn and joined to another electrode (lead) (second bond).

  In the second bond, for example, a main bonded portion (stitch bond) between the wire and the lead and a temporary bonded portion (tail bond) between the wire and the lead are formed. After such a second bond, the wire extending from the tail bond is cut (cut). Thereafter, the semiconductor device is manufactured by sealing the semiconductor element and the lead frame connected by the wire with a sealing resin.

  In wire bonding, a wire is pressed against an electrode pad or a lead by a bonding capillary, and an ultrasonic wave is applied to the bonding capillary while applying a load. Thereby, even when bonding is performed at high speed, a strong bonding strength can be obtained, and the bonding cycle can be shortened.

  However, in the semiconductor element, the wiring interval is made finer and the interlayer insulating film is made thinner, and the possibility of damaging the semiconductor element due to the stress applied to the semiconductor element during wire bonding is increasing. In particular, in a BOAC (Bond Over Active Circuit) device having an IC (Integrated Circuit) directly under the electrode pad, a crack may occur in an ILD (Inter Layer Dielectric) layer (interlayer insulating film) immediately under the electrode pad. It is growing.

  For this reason, in the bonding capillary, it is desired to obtain a high bonding strength while reducing the stress applied to the semiconductor element.

JP-A-7-99202 Special table 2003-53729 publication JP 2011-97042 A JP-A-62-158335 JP-A-63-090837

  The present invention has been made on the basis of recognition of such a problem, and an object thereof is to provide a bonding capillary capable of obtaining high bonding strength.

  According to a first aspect of the present invention, there is provided a first main body portion extending in the axial direction, a second main body portion provided on one end side in the axial direction of the first main body portion, and a cross-sectional area becoming smaller toward the opposite side to the first main body portion. A main body part, a bottleneck part provided at an end of the second main body part opposite to the first main body part, and extending in the axial direction, the first main body part, the second main body part, and the An insertion hole that allows a wire to pass through the bottleneck portion, and the bottleneck portion has a first portion and a second portion, and the first portion is Provided between the second body portion and the second portion, the second portion having a pressing surface that presses the wire at an end opposite to the first portion; The thermal resistance per unit length in the axial direction is the heat per unit length in the axial direction of the second part. A bonding capillary being higher than the coercive.

  In wire bonding, a semiconductor element is heated and diffusion bonding is performed with heat and ultrasonic waves. At this time, according to this bonding capillary, the thermal resistance per unit length in the axial direction of the first portion is higher than the thermal resistance per unit length in the axial direction of the second portion, so that the second portion Heat can be properly retained. That is, the heat retention effect at the capillary tip during bonding can be promoted. Thereby, the temperature between a wire and an electrode can be made high and joint strength can be improved. Therefore, high bonding strength can be obtained while reducing the stress applied to the semiconductor element.

  A second invention is the bonding capillary according to the first invention, wherein the thermal conductivity of the first part is lower than the thermal conductivity of the second part.

  According to this bonding capillary, heat can be appropriately retained by the second portion, and higher bonding strength can be obtained while reducing the stress applied to the semiconductor element.

  A third invention is the bonding capillary according to the first or second invention, wherein the thermal diffusivity of the first part is lower than the thermal diffusivity of the second part.

  According to this bonding capillary, heat can be appropriately retained by the second portion, and higher bonding strength can be obtained while reducing the stress applied to the semiconductor element.

  A fourth invention is the bonding capillary according to any one of the first to third inventions, wherein the apparent density of the first portion is lower than the apparent density of the second portion.

  According to this bonding capillary, heat can be appropriately retained by the second portion, and higher bonding strength can be obtained while reducing the stress applied to the semiconductor element.

  A fifth invention is the bonding capillary according to any one of the first to fourth inventions, wherein the true density of the first portion is lower than the true density of the second portion.

  According to this bonding capillary, heat can be appropriately retained by the second portion, and higher bonding strength can be obtained while reducing the stress applied to the semiconductor element.

  According to a sixth invention, in any one of the first to fifth inventions, a length of the first portion in the axial direction is longer than a length of the second portion in the axial direction. It is a bonding capillary.

  According to this bonding capillary, since the first portion is long, it is possible to suppress the transfer of heat from the second portion to the second main body portion via the first portion. Thereby, it becomes easy to accumulate heat more appropriately in the second portion, and the bonding strength can be further improved.

  In a seventh aspect based on the sixth aspect, the ratio of the axial length of the first portion to the axial length of the second portion is 3.20 or more and 7.76 or less. Is a bonding capillary characterized by

  According to this bonding capillary, since the ratio of the axial length of the first portion to the axial length of the second portion is 3.20 or more, the second portion is prevented from becoming long, and the capillary It is possible to suppress the heat at the tip from diffusing. Thereby, it becomes easy to accumulate heat more appropriately in the second portion, and the bonding strength can be further improved. Further, since the ratio of the axial length of the first portion to the axial length of the second portion is 7.76 or less, the second portion can be prevented from being shortened, and the total heat storage amount at the capillary tip is reduced. Can be secured. Thereby, it becomes easy to accumulate heat more appropriately in the second portion, and the bonding strength can be further improved.

  According to an eighth invention, in any one of the first to seventh inventions, a thermal resistance per unit length in the axial direction of the first main body portion and a unit length in the axial direction of the second main body portion. The bonding capillary is characterized in that the perimeter thermal resistance is higher than the thermal resistance per unit length in the axial direction of the second portion.

  According to this bonding capillary, heat can be appropriately retained by the second portion, and higher bonding strength can be obtained while reducing the stress applied to the semiconductor element.

  According to the aspect of the present invention, a bonding capillary capable of obtaining a high bonding strength is provided.

It is a front view showing the bonding capillary concerning this embodiment. It is an expanded sectional view expanding and showing the tip shape of the bonding capillary concerning this embodiment. It is explanatory drawing showing an example of a simulation result. It is explanatory drawing showing an example of a simulation result. It is a table | surface showing the evaluation result of a bonding capillary. It is a table | surface showing the evaluation result of a bonding capillary. It is a table | surface showing the evaluation result of a bonding capillary. It is a table | surface showing the evaluation result of a bonding capillary. It is a table | surface showing the evaluation result of a bonding capillary. It is a table | surface showing the evaluation result of a bonding capillary. It is a table | surface showing the evaluation result of a bonding capillary. It is a table | surface showing the evaluation result of a bonding capillary. It is a table | surface showing the evaluation result of a bonding capillary. It is a table | surface showing the evaluation result of a bonding capillary.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, in each drawing, the same code | symbol is attached | subjected to the same component and detailed description is abbreviate | omitted suitably.

FIG. 1 is a front view showing a bonding capillary according to this embodiment.
As shown in FIG. 1, the bonding capillary 10 includes a first main body portion 11, a second main body portion 12, a bottle neck portion 13, and an insertion hole 14.

  The bonding capillary 10 is used for ball bonding, for example. The bonding capillary 10 can be used, for example, for ball bonding using a wire containing copper. The bonding capillary 10 can be used as, for example, a bonding capillary for copper wire.

  For example, ceramic is used for each part of the bonding capillary 10. Each part of the 1st main-body part 11, the 2nd main-body part 12, the bottle neck part 13, and the penetration hole 14 is integrally formed, for example. For example, a material such as alumina is used as the material of each of the first main body portion 11, the second main body portion 12, and the bottle neck portion 13. The material of each part of the bonding capillary 10 may be, for example, a composite material containing at least one of alumina, zirconia, and chromia.

  The first main body 11 extends in the axial direction Da. The cross-sectional shape in the cross section orthogonal to the axial direction Da of the first main body 11 is a circular shape. That is, the outer shape of the first main body 11 is a cylindrical shape. The cross-sectional shape of the first main body 11 is not limited to a circular shape, and may be an elliptical shape or a polygonal shape. The outer shape of the first main body 11 is not limited to a cylindrical shape, and may be any shape extending in the axial direction Da.

  The length of the bonding capillary 10 in the axial direction Da is, for example, 11 mm (7 mm or more and 15 mm or less). The diameter (width in the direction orthogonal to the axial direction Da) of the first main body 11 is, for example, 1.6 mm (1 mm or more and 2 mm or less). Moreover, in the 1st main-body part 11, "circular shape" is a state below 0.1 mm in roundness tolerance, for example.

  The second main body 12 is provided on one end side of the first main body 11 in the axial direction Da. In other words, the second main body 12 is provided on the distal end side (lower side in FIG. 1) of the first main body 11. In this example, the second main body portion 12 is provided continuously at the tip of the first main body portion 11. In other words, the second main body 12 is in contact with the tip of the first main body 11. The cross-sectional area of the cross section orthogonal to the axial direction Da of the second main body portion 12 decreases toward the tip of the second main body portion 12 (the side opposite to the first main body portion 11). The external shape of the 2nd main-body part 12 is a cone shape. Accordingly, the diameter of the second main body portion 12 decreases toward the tip of the second portion 12. The outer shape of the second body portion 12 may be an elliptical cone shape or a pyramid shape. The cross-sectional shape of the second main body portion 12 may be an arbitrary shape corresponding to the cross-sectional shape of the first main body portion 11, for example.

  The cross-sectional area of the second main body 12 continuously decreases toward the tip of the second main body 12. The outer surface of the second main body 12 is an inclined surface that is inclined with a substantially constant inclination toward the tip of the second main body 12. The outer surface of the 2nd main-body part 12 is not restricted above, For example, you may curve in the convex curve shape or the concave curve shape. The cross-sectional area of the second main body portion 12 may decrease stepwise toward the tip of the second main body portion 12. The outer surface of the second main body portion 12 may have a stepped shape.

  The bottle neck portion 13 is provided at the end of the second main body portion 12 on the side opposite to the first main body portion 11 in the second main body portion 12. In other words, the bottleneck portion 13 is provided on the distal end side of the second main body portion 12. The bottleneck part 13 is provided continuously at the tip of the second main body part 12, for example. The “bottleneck portion” is the second body in the technical field according to the present embodiment, mainly for the purpose of avoiding interference with adjacent wires and adjusting ultrasonic transmission when the pitch between the electrodes is narrow. This is a constricted portion provided on the distal end side of the portion 12. The length of the bottle neck portion 13 in the axial direction Da is about 0.1 mm or more and 0.4 mm or less. The diameter of the bottleneck portion 13 (for example, the diameter of a first portion described later) is about 0.04 mm or more and 0.35 mm or less.

  The cross-sectional area (maximum cross-sectional area) of the cross section orthogonal to the axial direction Da of the bottle neck part 13 is smaller than the cross-sectional area (minimum cross-sectional area) of the cross section orthogonal to the axial direction Da of the second main body part 12. The diameter of the bottle neck portion 13 is smaller than the diameter of the second main body portion 12. The sectional area of each part of the bonding capillary 10 is obtained by subtracting the inner area (the area surrounded by the inner circumference) from the outer area (the area surrounded by the outer circumference) in the shape of the cross section orthogonal to the axial direction Da. It is an area.

  The insertion hole 14 extends in the axial direction Da. The insertion hole 14 passes through each of the first main body part 11, the second main body part 12, and the bottle neck part 13, and allows the wire to be inserted. The insertion hole 14 extends in a straight line along the axial direction Da and penetrates in a straight line from the base end surface of the first main body portion 11 to the distal end surface of the bottle neck portion 13.

  The cross-sectional shape of the cross section orthogonal to the axial direction Da of the insertion hole 14 is, for example, a circular shape. Further, the central axis of the insertion hole 14 is substantially coaxial with the central axes of the first main body portion 11, the second main body portion 12, and the bottle neck portion 13. That is, the 1st main-body part 11 is cylindrical shape, and the 2nd main-body part 12 is conical cylinder shape. In other words, the first main body portion 11 is a cylindrical portion. In other words, the second main body portion 12 is a conical portion (cone portion).

  The diameter of the insertion hole 14 is, for example, 15 μm (micrometer) or more and 80 μm or less. The diameter of the insertion hole 14 is set larger than the diameter of the wire to be inserted. For example, when the diameter of the wire is 25 μm, the diameter of the insertion hole 14 is set to about 30 μm.

  The cross-sectional shape of the insertion hole 14 is not limited to a circular shape, and may be an arbitrary shape. The cross-sectional shape of the insertion hole 14 may be the same as or different from the cross-sectional shape of the first main body portion 11 or the second main body portion 12.

FIG. 2 is an enlarged cross-sectional view showing an enlarged tip shape of the bonding capillary according to the present embodiment.
FIG. 2 shows a cross section taken along line A1-A2 of FIG. That is, FIG. 2 shows a cross section of the bonding capillary 10 cut along a plane parallel to the axial direction Da and passing through the central axis of each part.

  As illustrated in FIG. 2, the bottleneck portion 13 includes a first portion 21 and a second portion 22. The second portion 22 is provided on the distal end side of the first portion 21. In other words, the first portion 21 is provided between the second main body portion 12 and the second portion 22 in the axial direction Da. The first portion 21 includes a front end of the first portion 21 and a rear end of the first portion 21. The second portion 22 includes a front end of the second portion 22 and a rear end of the second portion 22. For example, the first portion 21 is provided continuously at the tip of the second main body portion 12. For example, the second portion 22 is provided continuously at the tip of the first portion 21.

  The second portion 22 has a pressing surface 22a for pressing the wire at the tip (an end portion on the opposite side to the first portion 21). In other words, the pressing surface 22a is the tip surface of the bottleneck portion 13. One end of the insertion hole 14 is provided on the pressing surface 22a.

  In the bonding capillary 10, a wire is inserted into the insertion hole 14 from the first body portion 11 side, and the tip of the wire is exposed from the pressing surface 22 a of the bottle neck portion 13. Then, a ball is formed at the tip of the wire by melting the tip of the wire by discharge or the like. At this time, the diameter of the ball is made larger than the diameter of the opening end of the insertion hole 14. The bonding capillary 10 presses the ball against the electrode with the pressing surface 22a, and bonds the ball (wire) to the electrode with heat, ultrasonic waves, and pressure. Thereby, the bonding (first bond) between the wire and the electrode of the semiconductor element is completed. When the diameter of the wire is 25 μm, the diameter of the ball after pressing is about 50 μm.

  The first portion 21 is recessed inward from the tangent line TL of the second main body portion 12. In other words, the first portion 21 is recessed inward from the extension line of the second main body portion 12. The tangent line TL is, for example, a tangent line of the second main body portion 12 on a plane parallel to the axial direction Da and passing through the central axis of the insertion hole 14. Further, the tangent line TL is, for example, a tangent line at the position where the change in the inclination with respect to the change in the position in the axial direction Da is smallest on the outer surface of the second main body 12. The tangent line TL is, for example, a tangent line at the center position in the axial direction Da of the second main body portion 12. The first portion 21 is, for example, on the plane parallel to the axial direction Da and passing through the central axis of the insertion hole 14, on the inner side of the extended line segment connecting the base end (rear end) and the distal end of the second main body portion 12. It may be recessed.

  The distinction between the front end of the first portion 21 and the rear end of the second portion 22 can be performed, for example, as follows. When the composition and the apparent density of the first portion 21 and the second portion 22 are different, for example, by SEM-EDX composition analysis or SEM cross-sectional observation, the front end of the first portion 21 and the rear end of the second portion 22 Can be distinguished. In addition, when it has a part where gradient composition and density change continuously, you may distinguish the intermediate vicinity of the area | region in an axial direction into the front-end | tip of the 1st part 21, and the rear end of the 2nd part 22. FIG. For example, as shown in FIG. 2, the rear end of the first portion may be the rear end (portion where the constriction starts) of the bottle neck portion 13.

  The cross-sectional shape in the cross section orthogonal to the axial direction Da of the first portion 21 is a circular shape. The cross-sectional shape in the cross section orthogonal to the axial direction Da of the second portion 22 is a circular shape. The first portion 21 and the second portion 22 are cylindrical. The cross-sectional shape of the first portion 21 and the cross-sectional shape of the second portion 22 are not limited to a circular shape, and may be any shape according to the cross-sectional shape of the second body portion 12 and the like. Moreover, the diameter of the 1st part 21 becomes small toward a front-end | tip. The outer shape of the first portion 21 is a truncated cone shape. The diameter of the first portion 21 may be substantially constant from the proximal end to the distal end. Further, the diameter of the second portion 22 decreases toward the tip. The outer diameter shape of the second portion 22 is a truncated cone shape. The diameter of the second portion 22 may be substantially constant from the proximal end to the distal end. The “circular shape” in the first portion 21 and the second portion 22 is, for example, a state where the roundness tolerance is 20 μm or less.

  In this example, the diameter of the bottleneck portion 13 is continuous from the first portion 21 to the second portion 22, and the cross-sectional area of the second portion 22 is equal to or smaller than the cross-sectional area of the first portion 21. For example, the diameter of the first portion 21 at the boundary B between the first portion 21 and the second portion 22 is the same as the diameter of the second portion 22 at the boundary B. In other words, the cross-sectional area of the first portion 21 at the boundary B is the same as the cross-sectional area of the second portion 22 at the boundary B. However, in the embodiment, the diameter of the bottleneck portion 13 may be discontinuous at the boundary B. For example, the maximum cross-sectional area of the second portion 22 may be larger than the minimum cross-sectional area of the first portion 21. The maximum diameter of the second part may be larger than the minimum diameter of the first part.

  The length L1 of the first portion 21 in the axial direction Da is longer than the length L2 of the second portion 22 in the axial direction Da. The length L1 of the first portion 21 is, for example, not less than 2 times and not more than 20 times the length L2 of the second portion 22.

  The length (L1 + L2) of the bottle neck part 13 in the axial direction Da is, for example, 150 μm (100 μm or more and 400 μm or less). The length L1 of the first portion 21 is, for example, 125 μm (100 μm or more and 350 μm or less). The length L2 of the second portion 22 is, for example, 25 μm (15 μm or more and 50 μm or less).

  The thermal resistance per unit length in the axial direction Da of the first portion 21 (degree / watt: ° C./W·cm) is the thermal resistance per unit length in the axial direction Da of the second portion 22 (° C./W·cm). cm). Thermal resistance per unit length in the axial direction Da of the first main body 11 (° C./W·cm), thermal resistance per unit length in the axial direction Da of the second main body 12 (° C./W·cm), The thermal resistance per unit length (° C./W·cm) in the axial direction Da of the first portion 21 is equal to the thermal resistance per unit length in the axial direction Da of the second portion 22 (° C./W·cm). Higher).

  Here, the thermal resistance (° C./W) is a coefficient representing the difficulty of heat flow in heat transfer that occurs when heat is applied to an object. More specifically, the thermal resistance per unit length in the axial direction Da of the second portion 22 gives the temperature difference between the rear end side of the second portion 22 and the front end side of the second portion 22 from the ball. This is a value obtained by dividing the value (thermal resistance) divided by the amount of heat generated by the length of the second portion 22 in the axial direction Da. The thermal resistance per unit length in the axial direction Da of the first portion 21 is a value obtained by dividing the temperature difference between the rear end side of the first portion 21 and the front end side of the second portion 22 by the amount of heat given from the ball. This is a value obtained by dividing (thermal resistance) by the length of the first portion 21 in the axial direction Da.

For example, the heat conductivity (W / mK) of the first portion 21 is lower than the heat conductivity (W / mK) of the second portion 22. Thereby, the thermal resistance per unit length in the axial direction Da of the first portion 21 can be made higher than the thermal resistance per unit length in the axial direction Da of the second portion 22. Furthermore, the thermal conductivity (W / mK) of each of the first main body part 11, the second main body part 12 and the first part 21 is lower than the thermal conductivity (W / mK) of the second part 22. Here, the thermal conductivity is the amount of heat (W / mK) that moves in the unit cross-sectional area (1 m ² ) per unit time (1 sec) when there is a temperature difference of (1 ° C.) per unit length (1 m). It is.

For example, the thermal diffusivity (square meter / second: m ² / s) in the first portion 21 is lower than the thermal diffusivity (m ² / s) in the second portion 22. Thereby, the thermal resistance per unit length in the axial direction Da of the first portion 21 can be made higher than the thermal resistance per unit length in the axial direction Da of the second portion 22. Thermal diffusivity in the first body portion 11 ^(m 2 / s), the thermal diffusivity of the second body portion 12 ^(m 2 / s), and each thermal diffusivity of the ^(m 2 / s) at the first portion 21 , Lower than the thermal diffusivity (m ² / s) in the second portion 22. The thermal diffusivity is a value obtained by dividing the thermal conductivity of an object by the density and specific heat, and may be called temperature diffusivity, temperature conductivity, or the like.

For example, when the material of the second portion 22 is substantially the same as the material of the first portion 21, the apparent density (kg / cm ³ ) of the first portion 21 is the apparent density of the second portion 22. Lower than density (kg / cm ³ ). Thereby, the thermal resistance per unit length in the axial direction Da of the first portion 21 can be made higher than the thermal resistance per unit length in the axial direction Da of the second portion 22. Furthermore, the first body portion 11, each of the apparent density of the second body portion 12 and first portion 21 (kg / cm ³⁾ is lower than the apparent density of the second portion 22 (kg / cm ³⁾ . Here, the apparent density is a density in which the volume occupied by the substance itself and the closed pores is a volume for calculation. In other words, the volume of pores on the surface of the object is excluded, but the volume of pores inside is the density obtained by including it.

Further, for example, the material of the second portion 22 is different from the material of the first portion 21, the true density of the first portion 21 (kg / cm ^3), the true density of the second portion 22 (kg / ^cm 3) Lower than. Thereby, the thermal resistance per unit length in the axial direction Da of the first portion 21 can be made higher than the thermal resistance per unit length in the axial direction Da of the second portion 22. Furthermore, the first body portion 11, each of the true density of the second body portion 12 and first portion 21 (kg / cm ³⁾ is a true density (kg / cm ³⁾ of the second portion 22 lower than. Here, the true density is a density in which only the volume occupied by the substance itself is a volume for calculation. In other words, it is a value obtained by dividing the mass of the object by the volume of the object itself excluding the surface of the object and the pores inside.

  In wire bonding, a semiconductor element is heated and diffusion bonding is performed with heat and ultrasonic waves. At this time, since the thermal resistance per unit length in the axial direction Da of the first portion 21 is higher than the thermal resistance per unit length in the axial direction Da of the second portion 22, the second portion 22 is appropriately The heat can be stopped. Thermal resistance per unit length in the axial direction Da of the first main body part 11, thermal resistance per unit length in the axial direction Da of the second main body part 12, and per unit length in the axial direction Da of the first part 21 Since each of the thermal resistances is higher than the thermal resistance per unit length in the axial direction Da of the second portion 22, heat can be appropriately retained by the second portion 22. That is, the heat retention effect at the capillary tip during bonding can be promoted. Thereby, the temperature between a wire and an electrode can be made high and joint strength can be improved. Therefore, high bonding strength can be obtained while reducing the stress applied to the semiconductor element.

  For example, when the thermal resistance is R, the area of the evaluation part is A, the thickness of the evaluation part is L, and the thermal conductivity of the evaluation part is λ, the thermal resistance is R = L / (λ × A). Can be obtained.

  The thermal conductivity can be obtained, for example, by λ = ρca, where c is the specific heat of the evaluation part, ρ is the density of the evaluation part, and a is the thermal diffusivity of the evaluation part.

  The thermal diffusivity can be calculated by, for example, a laser flash method. The measurement method of the thermal diffusivity by the laser flash method may be performed according to JISR1611, for example. Further, the thermal diffusivity may be calculated by, for example, a = λ / ρc. For the thermal conductivity at this time, for example, a value in a material database may be used.

  Since the true density is a value specific to a substance, for example, it can be obtained by identifying a material with an electron probe microanalyzer (EPMA). For example, the sample is cut into a shape that includes the first portion 21 and the second portion 22 of the bonding capillary 10. Thereafter, the prepared sample is set in EPMA, and elemental analysis is performed by comparing characteristic verification by measuring characteristic X-rays generated when the electron beam is irradiated with a constant acceleration voltage. Characteristic X-rays are emitted when the incident electrons eject the orbital electrons of the atoms that make up the sample to the outside of the atom and the electrons fall from the outer shell into the vacant orbit. X-ray. Since the energy of characteristic X-rays is a unique value for each element, elemental analysis can be performed by measuring this. Under the present circumstances, the magnification of EPMA is 5000 times -10000 times, for example. The acceleration voltage is, for example, 10 kV to 25 kV. For example, 15 kV.

  The apparent density can be calculated by, for example, the formula of true density × (1−porosity / 100). That is, the apparent density can be calculated by obtaining the true density and the porosity. The porosity is a scale representing the amount of a solid substance including spaces such as small pores, cracks, and interparticle voids, and is defined by the ratio of the volume of the space to the total volume of the substance.

  In measuring the porosity, first, a sample is cut into a shape that includes the first portion 21 and the second portion 22 of the bonding capillary 10. Thereafter, the prepared sample is set in a scanning electron microscope (for example, S-4100 manufactured by Hitachi, Ltd.), and a secondary electron image is observed with a scanning electron microscope. At this time, the magnification of the scanning electron microscope is, for example, 15000 times to 50000 times. The acceleration voltage is, for example, 10 kV to 25 kV, for example, 15 kV.

  Secondary electrons refer to those in which valence electrons of atoms constituting the sample are emitted when electrons are incident on the sample. Since the energy is very small, what is generated deep in the sample is immediately absorbed in the sample, and only what is generated near the surface of the sample is released out of the sample. In addition, the amount of emitted light is greater when the electron beam is incident obliquely than when the electron beam is incident perpendicular to the sample. Therefore, when there are closed pores (pores) in the bonding capillary 10, the luminance varies between the portion occupied by the substance and the pore portion.

After acquiring the secondary electron image, it is evaluated by image analysis software (for example, Winroof ver 6.5.1, manufactured by MITANI CORPORATION). Thereby, a histogram is obtained in which the horizontal axis represents luminance and the vertical axis represents appearance frequency. In this histogram, a region where the luminance is lower than the average value of the minimum value and the maximum value is a low luminance region, and a region where the luminance is higher than the average value is a high luminance region. A binarization process is performed by determining the low luminance region as a pore and determining a high luminance region other than the pore as a substance itself. Thereafter, the porosity can be obtained from the following formula.
Porosity (%) = integrated value of low luminance area ÷ integrated value of overall appearance frequency × 100

FIG. 3 is an explanatory diagram illustrating an example of a simulation result.
As shown in FIG. 3, in the simulation, the characteristics of the bonding capillary 10 according to the present embodiment and the bonding capillary REF1 of the reference example were compared.

  The same description as the bonding capillary 10 described with reference to FIGS. 1 and 2 can be applied to the bonding capillary 10a used in the simulation shown in FIG. In the bonding capillary 10 a, the material of the second portion 22 is the same as the material of the first main body portion 11, the material of the second main body portion 12, and the material of the first portion 21. The 1st main-body part 11, the 2nd main-body part 12, the 1st part 21, and the 2nd part 22 are comprised integrally by the same ceramic material (for example, compounds, such as an alumina).

Further, the apparent density (g / cm ³ ) of the first main body part 11, the apparent density (g / cm ³ ) of the second main body part 12, and the apparent density (g / cm ³ ) of the first part 21. each cm ^3), lower than the apparent density of the second portion 22 (g / cm ^3). In this example, the apparent density of the first main body 11, the apparent density of the second main body 12, and the apparent density of the first portion 21 are the same. For example, the porosity of the first body portion 11, the porosity of the second body portion 12, and the porosity of the first portion 21 are higher than the porosity of the second portion 22. The apparent density of each part can be adjusted by, for example, the amount of binder included in the raw material when the bonding capillary is formed.

  In the bonding capillary REF1 of the reference example, the apparent density of the second portion 22 is the apparent density of the first body portion 11, the apparent density of the second body portion 12, and the apparent density of the first portion 21, respectively. Is the same. Otherwise, the configuration of the bonding capillary REF1 of the reference example is substantially the same as the configuration of the bonding capillary 10a shown in FIG.

  The simulation was performed by CAE (Computer Aided Engineering) analysis. In this simulation, for the bonding capillary 10 according to the present embodiment and the bonding capillary REF1 of the reference example, the temperature generated between the electrode and the ball when the ball is pressed with the same pressure and an ultrasonic wave with the same strength is applied. Asked. In the simulation, a copper wire was used for the wire (ball).

  As shown in FIG. 3, in the bonding capillary REF1 of the reference example, the temperature generated between the electrode and the ball was 140.6 ° C. In contrast, in the bonding capillary 10a according to the present embodiment, the temperature generated between the electrode and the ball was 186.2 ° C.

  Thus, in the bonding capillary 10a according to the present embodiment, the temperature generated between the electrode and the ball can be made higher than that of the bonding capillary REF1 of the reference example. Thereby, in the bonding capillary 10a according to the present embodiment, the diffusion bonding can be promoted and the bonding strength can be improved as compared with the bonding capillary REF1 of the reference example.

  At the time of wire bonding, the semiconductor element is heated and diffusion bonding is performed with this heat and ultrasonic waves. Heat diffuses through the bonding capillary. At this time, in the bonding capillary 10a according to the present embodiment, the apparent density of the first body part 11, the apparent density of the second body part 12, and the apparent density of the first part 21 are the second part 22 respectively. It is presumed that heat diffusion can be suppressed and heat can be retained between the electrode and the ball by lowering the apparent density. Therefore, in the bonding capillary 10a according to the present embodiment, it is presumed that the temperature generated between the electrode and the ball could be increased as compared with the bonding capillary REF1 of the reference example.

FIG. 4 is an explanatory diagram illustrating an example of a simulation result.
In this simulation, the temperature generated between the electrode and the ball was determined for the bonding capillary 10b according to the present embodiment and the bonding capillary REF2 of the reference example, as described above.

  The same description as the bonding capillary 10 described with reference to FIGS. 1 and 2 can be applied to the bonding capillary 10b used in the simulation shown in FIG. In the bonding capillary 10 b, the material of the second portion 22 is different from the material of the first body portion 11, the material of the second body portion 12, and the material of the first portion 21. The 1st main-body part 11, the 2nd main-body part 12, and the 1st part 21 are comprised by the same ceramic material, and the 2nd part 22 is comprised by another ceramic material.

  Further, the thermal conductivity of the first main body 11 (watts / (meter · Kelvin): W / (m · K)), the thermal conductivity of the second main body 12 (W / (m · K)), and the second Each of the thermal conductivity (W / (m · K)) of the first portion 21 is lower than the thermal conductivity (W / (m · K)) of the second portion 22. In this example, the thermal conductivity of the first main body 11, the thermal conductivity of the second main body 12, and the thermal conductivity of the first portion 21 are the same.

In other words, the bonding capillary 10b is true density of the first body portion 11 (grams / cubic centimeter: g / ^cm 3), the true density of the second body section 12 (g / ^cm 3), and the first portion 21 each true density (g / cm ^3), true density less than (g / cm ³⁾ of the second portion 22. In this example, the true density of the first body portion 11, the true density of the second body portion 12, and the true density of the first portion 21 are the same.

  In the bonding capillary REF2 of the reference example, the thermal conductivity of the second portion 22 is the thermal conductivity of the first body portion 11, the thermal conductivity of the second body portion 12, and the thermal conductivity of the first portion 21, respectively. Is the same. In other words, in the bonding capillary REF2, the true density of the second portion 22 is the same as the true density of the first body portion 11, the true density of the second body portion 12, and the true density of the first portion 21. is there. Other than this, the configuration of the bonding capillary REF2 of the reference example is substantially the same as the configuration of the bonding capillary 10b shown in FIG.

  As shown in FIG. 4, in the bonding capillary REF2 of the reference example, the temperature generated between the electrode and the ball was 140.6 ° C. On the other hand, in the bonding capillary 10b according to this embodiment, the temperature generated between the electrode and the ball was 206.7 ° C.

  Thus, in the bonding capillary 10b according to the present embodiment, the thermal conductivity of the first body portion 11, the thermal conductivity of the second body portion 12, and the thermal conductivity of the first portion 21 are the second. By being lower than the thermal conductivity of the portion 22, heat can be appropriately retained in the second portion 22 during bonding. In other words, in the bonding capillary 10b, each of the true density of the first body portion 11, the true density of the second body portion 12, and the true density of the first portion 21 is lower than the true density of the second portion 22. As a result, heat can be appropriately retained in the second portion 22 during bonding. That is, the heat retention effect at the capillary tip during bonding can be promoted. Thereby, the temperature between a wire and an electrode can be made high and joint strength can be improved. Therefore, high bonding strength can be obtained while reducing the stress applied to the semiconductor element.

  In the bonding capillary 10, the length L1 of the first portion 21 in the axial direction Da is longer than the length L2 of the second portion 22 in the axial direction Da. Thereby, it is suppressed that the 2nd part 22 becomes long too much, and the spreading | diffusion of the heat | fever in a capillary tip can be suppressed. Thereby, it becomes easy to accumulate heat in the 2nd part 22, and joint strength can be raised more.

FIG. 5 is a table showing the evaluation results of the bonding capillaries.
In this evaluation, with respect to the bonding capillaries according to the present embodiment and the reference example, the apparent densities of the first main body part 11, the second main body part 12, and the first part 21 are changed, so that Examples 1 to 9 and the reference example are performed. 1-3 bonding capillaries were prepared. In each bonding capillary, the apparent density of the first body portion 11, the apparent density of the second body portion 12, and the apparent density of the first portion 21 are the same value (D1 (g / cm ³ )). It is. In the bonding capillaries of Examples 1 to 9 and Reference Examples 1 to 3, the first main body part 11, the second main body part 12, and the first part with respect to the apparent density (D 2 (g / cm ³ )) of the second part 22. The apparent density (D1 (g / cm ³ )) of 21 is different from each other (= D1 / D2).

Examples 1 to 3 and Reference Example 1 are bonding capillaries corresponding to, for example, 65 μm BPP (bond pad pitch). BPP is the distance between the centers of two adjacent bond pads. For example, the size (length or diameter) of the tip of the bonding capillary can be designed according to the size of the BPP. In Examples 1 to 3 and Reference Example 1, the apparent density (D2) of the second portion 22 is 4.19 (g / cm ³ ), and the first main body portion 11, the second main body portion 12, and the first portion. The apparent density (D1) of 21 is changed.

Examples 4 to 6 and Reference Example 2 are bonding capillaries corresponding to, for example, 85 μm BPP, and the apparent density (D2) of the second portion 22 is 4.19 (g / cm ³ ). 11, the apparent density (D1) of the 2nd main-body part 12 and the 1st part 21 is changed.
Examples 7 to 9 and Reference Example 3 are bonding capillaries corresponding to, for example, 300 μm BPP, and the apparent density (D2) of the second portion 22 is 4.19 (g / cm ³ ). 11, the apparent density (D1) of the 2nd main-body part 12 and the 1st part 21 is changed.

  Each bonding capillary was bonded a plurality of times, its bonding strength (shear strength) was measured, and the process capability index (Cpk) of the bonding strength was calculated.

In the evaluation of FIG. 5 (and FIGS. 6 to 11 described later), the process capability index (Cpk) of the bonding strength is calculated by the following equation.
Cpk = (Ave.−LSL) / 3σ
Here, Ave. Is an average value of the measured bonding strength, and σ is a standard deviation of the measured bonding strength. LSL is a lower limit specification value. LSL = 10 gram weight (gf) for 65 μm BPP, LSL = 15 (gf) for 85 μm BPP, and LSL = 40 (gf) for 300 μm BPP.

  In FIG. 5 (and FIGS. 6 and 7 described later), “◯” represents 2.0 ≦ Cpk, and “x” represents Cpk <2.0. 8 to 11 described later, “◎” represents 2.33 ≦ Cpk, “◯” represents 2.0 ≦ Cpk <2.33, and “Δ” represents 1.67 ≦ Cpk <2. 0.0 and “x” represents Cpk <1.67.

  As shown in FIG. 5, in any BPP, Cpk is “x” when D1 / D2 = 1.0 as in the reference example. On the other hand, in the embodiment, D1 / D2 <1. As shown in FIG. 5, in the embodiment, Cpk is “◯” in the range of 0.9 ≦ D1 / D2 ≦ 0.99. That is, each of the apparent density of the first body portion 11, the apparent density of the second body portion 12, and the apparent density of the first portion 21 is 0.9 times or more of the apparent density of the second portion 22. It is desirable that it is 0.99 times or less.

  When each of the apparent density of the first main body portion 11, the apparent density of the second main body portion 12, and the apparent density of the first portion 21 is excessively smaller than the apparent density of the second portion 22. As a result, the bending strength of the bonding capillary is reduced, and the bonding capillary may be damaged during bonding. On the other hand, each of the apparent density of the first main body 11, the apparent density of the second main body 12, and the apparent density of the first portion 21 is excessively larger than the apparent density of the second portion 22. In this case, the heat retention effect at the tip of the bonding capillary is reduced, and the bonding strength may be reduced. On the other hand, the apparent density of the first main body portion 11, the apparent density of the second main body portion 12, and the apparent density of the first portion 21 are each 0. By being 9 times or more, the strength of the bonding capillary can be secured. Each of the apparent density of the first main body 11, the apparent density of the second main body 12, and the apparent density of the first portion 21 is 0.99 times or less of the apparent density of the second portion 22. As a result, the heat retention effect at the tip of the bonding capillary is promoted, and the bonding strength can be improved.

6 and 7 are tables showing the evaluation results of the bonding capillaries.
In this evaluation, with respect to the bonding capillaries according to the present embodiment and the reference example, the materials of the first main body portion 11, the second main body portion 12, the first portion 21, and the second portion 22 are changed, thereby changing the structure shown in FIG. Bonding capillaries of Examples 10 to 30 and Reference Examples 4 to 18 shown in FIG. 7 and Examples 31 to 36 and Reference Examples 19 to 33 shown in FIG. 7 were prepared. The bonding capillaries of Examples 10 to 36 and Reference Examples 4 to 33 are different from each other in the combination of materials of the first main body part 11, the second main body part 12, the first part 21, and the second part 22. In each bonding capillary, the material of the first main body portion 11, the material of the second main body portion 12, and the material of the first portion 21 are the same material M1. Moreover, in FIG.6 and FIG.7, the thermal conductivity and thermal diffusivity of a material intrinsic value are shown.

In each bonding capillary shown in FIG. 6, the material M1 of the first main body part 11, the second main body part 12 and the first part 21 is any one of mullite, forsterite, steatite, cordierite, alumina and sapphire. .
Examples 10 to 16 and Reference Examples 4 to 8 are bonding capillaries corresponding to, for example, 65 μm BPP. The material M2 of the second portion 22 is alumina, and the first main body 11, the second main body 12, and the first The material M1 of the portion 21 is changed.
Examples 17 to 23 and Reference Examples 9 to 13 are bonding capillaries corresponding to, for example, 85 μm BPP. The material M2 of the second portion 22 is alumina, and the first main body 11, the second main body 12, and the first The material M1 of the portion 21 is changed.
Examples 24 to 30 and Reference Examples 14 to 18 are bonding capillaries corresponding to, for example, 300 μm BPP, and the material M2 of the second portion 22 is alumina, and the first main body 11, the second main body 12, and the first The material M1 of the portion 21 is changed.

In each bonding capillary shown in FIG. 7, the material M2 of the second portion is any one of sapphire, mullite, forsterite, steatite, and cordierite.
Examples 31 and 32 and Reference Examples 19 to 23 are bonding capillaries corresponding to, for example, 65 μm BPP, and the material M1 of the first main body part 11, the second main body part 12 and the first part 21 is made of alumina. The material M2 of the portion 22 is changed.
Examples 33 and 34 and Reference Examples 24 to 28 are bonding capillaries corresponding to, for example, 85 μm BPP, and the material M1 of the first main body part 11, the second main body part 12 and the first part 21 is made of alumina. The material M2 of the portion 22 is changed.
Examples 35 and 36 and Reference Examples 29 to 33 are bonding capillaries corresponding to, for example, 300 μm BPP, and the material M1 of the first main body part 11, the second main body part 12 and the first part 21 is made of alumina. The material M2 of the portion 22 is changed.

  The thermal conductivity of mullite, the thermal conductivity of forsterite, the thermal conductivity of steatite, and the thermal conductivity of cordierite are each lower than that of alumina. On the other hand, the thermal conductivity of sapphire is higher than that of alumina. Therefore, in Examples 10 to 14, 17 to 21, and 24 to 28 shown in FIG. 6 and Examples 31 to 36 shown in FIG. 7, the thermal conductivity of the first main body portion 11 and the thermal conductivity of the second main body portion 12. Each of the rate and the thermal conductivity of the first portion 21 is lower than the thermal conductivity of the second portion 22. On the other hand, in Reference Examples 4, 5, 8-10, 13-15, and 18 shown in FIG. 6 and Reference Examples 19 to 33 shown in FIG. 7, the thermal conductivity of the first main body portion 11 and the second main body portion 12. Each of the thermal conductivity and the thermal conductivity of the first portion 21 is equal to or higher than the thermal conductivity of the second portion 22.

  In Examples 15, 22, and 29 and Reference Examples 6, 11, and 16 shown in FIG. 6, the material M1 of the first body part 11, the second body part 12, and the first part 21 and the material M2 of the second part are used. While using alumina, the thermal conductivity of the materials M1 and M2 is made the same, and the thermal diffusivity of the material M1 is changed. In Examples 15, 22, and 29, each of the thermal diffusivity of the first main body portion 11, the thermal diffusivity of the second main body portion 12, and the thermal diffusivity of the first portion 21 is the thermal diffusivity of the second portion 22. Lower than. On the other hand, in Reference Examples 6, 11, and 16, the thermal diffusivity of the first main body 11, the thermal diffusivity of the second main body 12, and the thermal diffusivity of the first portion 21 are the heat of the second portion 22. Higher than diffusivity.

  In Examples 16, 23, and 30 and Reference Examples 7, 12, and 17 shown in FIG. 6, the material M1 of the first body part 11, the second body part 12, and the first part 21 and the material M2 of the second part are used. While using alumina, the thermal conductivity of the material M1 is changed while the thermal diffusivities of the materials M1 and M2 are the same. In Examples 16, 23, and 30, the thermal conductivity of the first body part 11, the thermal conductivity of the second body part 12, and the thermal conductivity of the first part 21 are the thermal conductivity of the second part 22. Lower than. On the other hand, in Reference Examples 7, 12, and 17, each of the thermal conductivity of the first body portion 11, the thermal conductivity of the second body portion 12, and the thermal conductivity of the first portion 21 is the heat of the second portion 22. Higher than conductivity.

  Each bonding capillary shown in FIGS. 6 and 7 was bonded a plurality of times, its bonding strength (shear strength) was measured, and the process capability index (Cpk) of the bonding strength was calculated.

  As shown in FIGS. 6 and 7, in any BPP, Cpk is “x” in the bonding capillary of the reference example. On the other hand, in the bonding capillary of the example, Cpk is “◯”. As described above, the first main body 11, the second main body 12, and the first portion 21 are made of a material having a lower thermal conductivity or thermal diffusivity than the second portion 22, so that heat retention at the tip of the bonding capillary is achieved. The effect is promoted and the bonding strength can be improved.

8 and 9 are tables showing the evaluation results of the bonding capillaries.
In this evaluation, by changing the shapes of the first portion 21 and the second portion 22 of the bonding capillary according to the present embodiment, Examples 37 to 60 shown in FIG. 8 and Examples 61 to 84 shown in FIG. A bonding capillary was prepared. In the bonding capillaries of Examples 37 to 84, the ratio of the length (L1 (μm)) of the first portion 21 in the axial direction Da to the length (L2 (μm)) of the second portion 22 in the axial direction Da (= L1 / L2) are different from each other.

In each bonding capillary shown in FIG. 8, the apparent density of the second portion 22 is 4.19 (g / cm ³ ), and the first main body portion 11, the second main body portion 12, and the first portion 21. The apparent density of each is 4.15 (g / cm ³ ). In each bonding capillary shown in FIG. 9, the second portion 22 is made of alumina, and each of the first main body portion 11, the second main body portion 12, and the first portion 21 is made of steatite. Yes.

Examples 37 to 44 and 61 to 68 are bonding capillaries corresponding to, for example, 65 μm BPP. The length (L2) in the axial direction Da of the second portion 22 is 33 (μm), and the axis of the first portion 21 is used. The length (L1) in the direction Da is changed.
Examples 45 to 52 and 69 to 76 are bonding capillaries corresponding to, for example, 85 μm BPP, and the length (L2) in the axial direction Da of the second portion 22 is 39 (μm), and the axis of the first portion 21 is used. The length (L1) in the direction Da is changed.
Examples 53 to 60 and 77 to 84 are bonding capillaries corresponding to, for example, 300 μm BPP. The length (L2) in the axial direction Da of the second portion 22 is 45 (μm), and the axis of the first portion 21 is used. The length (L1) in the direction Da is changed.

  For each of the bonding capillaries of Examples 37 to 84, bonding was performed a plurality of times, the bonding strength (shear strength) was measured, and the process capability index (Cpk) of the bonding strength was calculated.

  As shown in FIGS. 8 and 9, in any BPP, Cpk is “Δ” when 3.20 ≦ L1 / L2 ≦ 7.76, and 4.31 ≦ L1 / L2 ≦ 7.15. When Cpk is “◯”, it is “◎” when 4.69 ≦ L1 / L2 ≦ 6.47.

  Therefore, in the embodiment, the ratio (L1 / L2) of the length of the first portion 21 in the axial direction Da to the length of the second portion 22 in the axial direction Da is 3.20 or more and 7.76 or less. It is desirable to be. When L1 / L2 is 3.20 or more, the second portion 22 is suppressed from becoming excessively long, and heat diffusion at the capillary tip can be suppressed. Thereby, it becomes easy to accumulate heat in the 2nd part 22 more appropriately, and joint strength can be raised more. When L1 / L2 is 7.76 or less, it is possible to prevent the second portion 22 from becoming excessively short, and to secure a total heat storage amount at the capillary tip. Thereby, it becomes easy to accumulate heat in the 2nd part 22 more appropriately, and joint strength can be raised more.

  The ratio of the length of the first portion 21 in the axial direction Da to the length of the second portion 22 in the axial direction Da (L1 / L2) is more preferably 4.31 or more and 7.15 or less. More preferably, it is not less than .69 and not more than 6.47.

10 and 11 are tables showing the evaluation results of the bonding capillaries.
In this evaluation, the bonding capillaries of Examples 85 to 102 were prepared by changing the shape of the second portion 22 of the bonding capillaries according to this embodiment. As shown in FIGS. 10 and 11, the bonding capillaries of Examples 85 to 102 are different from each other in the roundness tolerance (μm) of the second portion 22.

  The roundness tolerance of the second portion 22 is the roundness of the outer shape (outer peripheral shape) of the second portion 22 in a cross section perpendicular to the axial direction Da. For example, the roundness calculated based on JIS B 0621 can be used.

In each bonding capillary shown in FIG. 10, the apparent density of the second portion 22 is 4.19 (g / cm ³ ), and the first main body portion 11, the second main body portion 12, and the first portion 21. The apparent density of each is 4.15 (g / cm ³ ). In each bonding capillary shown in FIG. 11, the second portion 22 is made of alumina, and each of the first main body portion 11, the second main body portion 12, and the first portion 21 is made of steatite. Yes.

  For each of the bonding capillaries of Examples 85 to 102, bonding was performed a plurality of times, and the bonding strength (shear strength) was measured. For the bonding capillaries of each example, a process capability index (Cpk) of bonding strength was calculated.

  As shown in FIGS. 10 and 11, Cpk is “Δ” when the roundness tolerance of the second portion 22 is 20 μm or less. When the roundness tolerance of the second portion 22 is 10 μm or less, Cpk is “◯”. When the roundness tolerance of the second portion 22 is 5 μm or less, Cpk is “◎”.

  Therefore, in the embodiment, the roundness tolerance of the second portion 22 is desirably 0 μm or more and 20 μm or less. By setting the roundness tolerance of the second portion 22 to 20 μm or less, it is possible to suppress the occurrence of direction dependency in the bonding strength between the wire and the electrode, and to suppress variations in the bonding strength.

  The roundness tolerance of the second portion 22 is more preferably 0 μm or more and 10 μm or less, and further preferably 0 μm or more and 5 μm or less.

12 and 13 are tables showing the evaluation results of the bonding capillaries.
In this evaluation, with respect to the bonding capillaries according to the present embodiment and the reference example, the materials of the first main body part 11, the second main body part 12, the first part 21, and the second part 22 are changed, whereby FIG. The bonding capillaries of Examples 103 to 117 and Reference Examples 34 to 42 shown in FIG. 13 and Examples 118 to 123 and Reference Examples 43 to 57 shown in FIG. The bonding capillaries of Examples 103 to 123 and Reference Examples 34 to 57 are different from each other in the material combination of the first main body part 11, the second main body part 12, the first part 21, and the second part 22. In each bonding capillary, the material of the first main body portion 11, the material of the second main body portion 12, and the material of the first portion 21 are the same material M1. 12 and 13 show the thermal resistance per unit length in the axial direction Da.

In each bonding capillary shown in FIG. 12, the material M1 of the first main body part 11, the second main body part 12, and the first part 21 is any one of mullite, forsterite, steatite, cordierite, alumina, and sapphire. .
Examples 103 to 107 and Reference Examples 34 to 36 are bonding capillaries corresponding to, for example, 65 μm BPP, and the material M2 of the second portion 22 is alumina, and the first main body 11, the second main body 12, and the first The material M1 of the portion 21 is changed.
Examples 108 to 112 and Reference Examples 37 to 39 are bonding capillaries corresponding to, for example, 85 μm BPP, and the material M2 of the second portion 22 is alumina, and the first main body 11, the second main body 12, and the first The material M1 of the portion 21 is changed.
Examples 113 to 117 and Reference Examples 40 to 42 are bonding capillaries corresponding to, for example, 300 μm BPP. The material M2 of the second portion 22 is alumina, and the first main body 11, the second main body 12, and the first The material M1 of the portion 21 is changed.

In each bonding capillary shown in FIG. 13, the material M2 of the second portion is one of sapphire, mullite, forsterite, steatite, and cordierite.
Examples 118 and 119 and Reference Examples 43 to 47 are bonding capillaries corresponding to, for example, 65 μm BPP, and the material M1 of the first main body part 11, the second main body part 12 and the first part 21 is made of alumina. The material M2 of the portion 22 is changed.
Examples 120 and 121 and Reference Examples 48 to 52 are bonding capillaries corresponding to, for example, 85 μm BPP, and the material M1 of the first main body part 11, the second main body part 12 and the first part 21 is made of alumina. The material M2 of the portion 22 is changed.
Examples 122 and 123 and Reference Examples 53 to 57 are bonding capillaries corresponding to, for example, 300 μm BPP, and the material M1 of the first main body part 11, the second main body part 12 and the first part 21 is made of alumina. The material M2 of the portion 22 is changed.

  The thermal resistance of mullite, the thermal resistance of forsterite, the thermal resistance of steatite, and the thermal resistance of cordierite are higher than the thermal resistance of alumina, respectively. On the other hand, the thermal resistance of sapphire is lower than that of alumina. Accordingly, in the embodiments 103 to 117 shown in FIG. 12 and the embodiments 118 to 123 shown in FIG. 13, the thermal resistance per unit length in the axial direction Da of the first main body 11 and the axial direction of the second main body 12. Each of the thermal resistance per unit length in Da and the thermal resistance per unit length in the axial direction Da of the first portion 21 is higher than the thermal resistance per unit length in the axial direction Da of the second portion 22. . On the other hand, in Reference Examples 34 to 42 shown in FIG. 12 and Reference Examples 43 to 57 shown in FIG. 13, the thermal resistance per unit length in the axial direction Da of the first main body 11, and the axial direction of the second main body 12. The thermal resistance per unit length in Da and the thermal resistance per unit length in the axial direction Da of the first portion 21 are each lower than the thermal resistance per unit length in the axial direction Da of the second portion 22. .

  Each bonding capillary shown in FIG. 12 and FIG. 13 was bonded a plurality of times, its bonding strength (shear strength) was measured, and the process capability index (Cpk) of the bonding strength was calculated.

  As shown in FIGS. 12 and 13, in any BPP, Cpk is “x” in the bonding capillary of the reference example. On the other hand, in the bonding capillary of the example, Cpk is “◯”. As described above, the first main body portion 11, the second main body portion 12, and the first portion 21 are made of a material having a higher thermal resistance per unit length in the axial direction Da than the second portion 22, so that a bonding capillary is formed. The heat retention effect at the tip is promoted, and the bonding strength can be improved.

FIG. 14 is a table showing the evaluation results of the bonding capillaries.
In this evaluation, the bonding capillaries of Examples 124 to 147 shown in FIG. 14 were prepared by changing the shapes of the first portion 21 and the second portion 22 of the bonding capillary according to this embodiment. In the bonding capillaries of Examples 124 to 147, the ratio of the length (L1 (μm)) in the axial direction Da of the first portion 21 to the length (L2 (μm)) in the axial direction Da of the second portion 22 (= L1 / L2) are different from each other.

In each bonding capillary shown in FIG. 14, the second portion 22 is made of steatite, and each of the first main body portion 11, the second main body portion 12, and the first portion 21 is made of alumina. Yes. The apparent density of the second portion 22 is 2.80 (g / cm ³ ), and the apparent density of each of the first main body portion 11, the second main body portion 12 and the first portion 21 is 3. 80 (g / cm ³ ).

Examples 124 to 131 are bonding capillaries corresponding to, for example, 65 μm BPP, and the length (L2) of the second portion 22 in the axial direction Da is 33 (μm), and the length of the first portion 21 in the axial direction Da. (L1) is changed.
Examples 132 to 139 are bonding capillaries corresponding to, for example, 85 μm of BPP, and the length (L2) of the second portion 22 in the axial direction Da is 39 (μm), and the length of the first portion 21 in the axial direction Da. (L1) is changed.
Examples 140 to 147 are bonding capillaries corresponding to, for example, 300 μm BPP, and the length (L2) of the second portion 22 in the axial direction Da is set to 45 (μm), and the length of the first portion 21 in the axial direction Da. (L1) is changed.

  For each of the bonding capillaries of Examples 124 to 147, bonding was performed a plurality of times, the bonding strength (shear strength) was measured, and the process capability index (Cpk) of the bonding strength was calculated.

  As shown in FIG. 14, in any BPP, Cpk is “Δ” when 3.23 ≦ L1 / L2 ≦ 7.74, and Cpk is 4.33 ≦ L1 / L2 ≦ 7.06. “◯”, and “「 ”when 4.74 ≦ L1 / L2 ≦ 6.44.

  Therefore, in the embodiment, the ratio of the length of the first portion 21 in the axial direction Da to the length of the second portion 22 in the axial direction Da (L1 / L2) is 3.23 or more and 7.74 or less. It is desirable to be. When L1 / L2 is 3.23 or more, it is possible to suppress the second portion 22 from becoming excessively long, and to suppress heat diffusion at the capillary tip. Thereby, it becomes easy to accumulate heat in the 2nd part 22 more appropriately, and joint strength can be raised more. When L1 / L2 is 7.74 or less, it is possible to suppress the second portion 22 from becoming excessively short, and to secure a total heat storage amount at the capillary tip. Thereby, it becomes easy to accumulate heat in the 2nd part 22 more appropriately, and joint strength can be raised more.

  The ratio of the length of the first portion 21 in the axial direction Da to the length of the second portion 22 in the axial direction Da (L1 / L2) is more preferably 4.33 or more and 7.06 or less. More preferably, it is not less than .74 and not more than 6.44.

  In Examples 124 to 147, the apparent density of the first portion 21 is higher than the apparent density of the second portion 22. Thus, even if the apparent density of the first portion 21 is higher than the apparent density of the second portion 22, the length L1 of the first portion 21 in the axial direction Da is set to be equal to that of the second portion 22. By making it longer than the length L2 in the axial direction Da, the bonding strength can be improved. That is, even when the apparent density of the first portion 21 is higher than the apparent density of the second portion 22, the length L1 of the first portion 21 in the axial direction Da is set to the axial direction of the second portion 22. By making it longer than the length L2 of Da, the thermal resistance per unit length in the axial direction Da of the first portion 21 is made higher than the thermal resistance per unit length in the axial direction Da of the second portion 22. be able to.

The embodiment of the present invention has been described above. However, the present invention is not limited to these descriptions. As long as the features of the present invention are provided, those skilled in the art appropriately modified the design of the above-described embodiments are also included in the scope of the present invention. For example, the shape, size, material, arrangement, and the like of each element included in the bonding capillary 10 are not limited to those illustrated, and can be changed as appropriate.
Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

  DESCRIPTION OF SYMBOLS 10 Bonding capillary, 11 1st main-body part, 12 2nd main-body part, 13 Bottle neck part, 14 Insertion hole, 21 1st part, 22 2nd part

Claims (8)

A first main body extending in the axial direction;
A second main body portion provided on one end side in the axial direction of the first main body portion, and having a cross-sectional area that decreases toward the opposite side to the first main body portion;
A bottleneck portion provided at an end of the second body portion opposite to the first body portion;
An insertion hole extending in the axial direction and penetrating the first main body portion, the second main body portion, and the bottleneck portion, and allowing insertion of a wire;
With
The bottleneck portion has a first portion and a second portion,
The first portion is provided between the second main body portion and the second portion in the axial direction,
The second part has a pressing surface that presses the wire at an end opposite to the first part,
The bonding capillary according to claim 1, wherein a thermal resistance per unit length of the first portion in the axial direction is higher than a thermal resistance per unit length of the second portion in the axial direction.   The bonding capillary according to claim 1, wherein the thermal conductivity of the first portion is lower than the thermal conductivity of the second portion.   The bonding capillary according to claim 1 or 2, wherein a thermal diffusivity of the first part is lower than a thermal diffusivity of the second part.   The bonding capillary according to claim 1, wherein an apparent density of the first portion is lower than an apparent density of the second portion.   The bonding capillary according to claim 1, wherein the true density of the first portion is lower than the true density of the second portion.   The bonding capillary according to claim 1, wherein a length of the first portion in the axial direction is longer than a length of the second portion in the axial direction.   The bonding capillary according to claim 6, wherein a ratio of a length of the first portion in the axial direction to a length of the second portion in the axial direction is 3.20 or more and 7.76 or less.   The thermal resistance per unit length in the axial direction of the first main body portion and the thermal resistance per unit length in the axial direction of the second main body portion are per unit length in the axial direction of the second portion. The bonding capillary according to claim 1, wherein the bonding capillary is higher than the thermal resistance of the bonding capillary.