JP4139020B2 - Capillary for wire bonding - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a capillary for wire bonding used when bonding an electrode of a semiconductor element and an electrode pad of a package, or electrode pads of a semiconductor element with a wire made of gold or the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a semiconductor device in which a semiconductor element such as an IC or LSI is accommodated in a package, the conductive connection between the electrode of the semiconductor element and the electrode pad in the package and between the electrodes of the semiconductor element is performed by bonding wires. And when performing wire bonding, in order to draw and guide the wire which consists of a fine diameter gold wire etc., the capillary (fine tube) is used.
[0003]
Various materials such as ceramic, metal, plastic, and glass have been prototyped as the material of the capillary, but most of them are made of ceramic at present. Because ceramics have high processing accuracy, the tolerance of the inner and outer diameters of capillaries can be processed with a high accuracy of 0.1 μm or less, and because ceramics have a small friction coefficient, insertion of wires into capillaries, capillary This is because it is easy to deliver from the surface, has a high rigidity and a low coefficient of thermal expansion, is stable against external stress and temperature change, and has excellent corrosion resistance.
[0004]
In recent years, alumina (Al ₂ O ₃ ) ceramic and zirconia (ZrO) ceramic have been used as the ceramic for such capillaries.
[0005]
[Problems to be solved by the invention]
However, although ceramics generally have a smaller coefficient of thermal expansion than metals, the coefficients of thermal expansion of alumina ceramics and zirconia ceramics at 10 to 40 ° C. are 5 × 10 ⁻⁶ / ° C. and 10 × 10 ⁻⁶ / ° C., respectively. Therefore, it was insufficient for the recent demand for high form accuracy on the order of submicrons. For example, there has been a problem that deformation due to expansion and contraction is caused by a change in ambient temperature, resulting in poor connection with other members and connection loss.
[0006]
On the other hand, cordierite (2MgO · 2Al ₂ O ₃ · 5SiO ₂ ) is conventionally known as a ceramic material having a low coefficient of thermal expansion, but cordierite has a very narrow firing temperature range, so it is densely sintered. When using a capillary made of a non-dense material such as cordierite, the capillary itself is damaged due to insufficient strength, or the wire is broken due to poor surface smoothness. It was.
[0007]
Therefore, the present invention has been completed in view of the above circumstances, and its purpose is to provide a capillary made of a material having a predetermined small coefficient of thermal expansion and high density, so that it has excellent shape accuracy and other members. It is intended to prevent the occurrence of connection failures and connection losses, and to prevent damage to the capillary itself and wire breakage.
[0008]
[Means for Solving the Problems]
The capillary for wire bonding of the present invention has a composite oxidation of Mg, Al, and Si having a coefficient of thermal expansion at 10 to 40 ° C. of 2 × 10 ⁻⁶ / ° C. or less and a density of 2.3 g / cm ³ or more. The composite oxide has a molar ratio of xMgO.yAl ₂ O ₃ .zSiO ₂ (where x = 10 to 40 mol%, y = 10 to 40 mol%, z = 20 to 80 mol%, x + y + z = 100 mol%), and the main crystal phase is cordierite, and mullite, protoenstatite, clinoenstatite, forsterite, cristobalite, tridymite or safarin is precipitated as the other crystal phases. It is characterized by comprising a dielectric ceramic composition.
[0009]
According to the above configuration, the present invention can be made of a dense dielectric ceramic composition having a smaller coefficient of thermal expansion than conventional alumina ceramics and zirconia ceramics. By being made of a small and dense material, it is possible to obtain high-precision joining accuracy, suppress the occurrence of connection failure and connection loss, and prevent damage to the capillary itself and wire breakage.
[0010]
In the capillary for wire bonding of the present invention, the molar ratio of the composite oxide is xMgO.yAl ₂ O ₃ .zSiO ₂ (where x = 10 to 40 mol%, y = 10 to 40 mol%, z = 20 to 80 mol%, x + y + z = 100 mol%), and the main crystal phase is cordierite, and the other crystal phases are mullite, protoenstatite, clinoenstatite, forsterite, cristobalite, tridymite. Or it consists of a dielectric ceramic composition in which safarin is deposited. Thereby, it becomes possible to make it more excellent in terms of thermal expansion coefficient and denseness.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The wire bonding capillary of the present invention will be described below. 1 and 2 are a cross-sectional view and a perspective view schematically showing a wire bonding capillary according to the present invention. In these drawings, 1 is a wire bonding capillary (hereinafter referred to as a capillary), 1a is a capillary 1 A through hole 1b is formed in the direction of the central axis for inserting and delivering a wire, 1b is a conical portion for facilitating the insertion of the wire, 1c formed at the end of the through hole 1a on the wire insertion side. Is a taper portion which is a guide surface of the wire formed on the outer surface of the capillary 1 on the wire delivery side, and 1d is a conical portion which is formed on the wire delivery side and controls the capacity and shape of the metal of the wire to be bonded. 1e is a cylindrical maximum diameter part.
[0012]
As shown in FIG. 1, the capillary 1 of the present invention is configured by a cylindrical maximum diameter portion 1 e and a conical tapered portion 1 c on the tip side continuous with the maximum diameter portion 1 e. It is not necessary to have the shape and the conical shape, and it may be a polygonal column shape such as a quadrangular prism shape and a quadrangular pyramid shape, a polygonal pyramid shape, and the like. In general, the length of the entire capillary 1 is about 10 mm, the outer diameter of the maximum diameter portion 1e is about 0.8 to 3 mm, and the inclination angle of the conical tapered portion 1c with respect to the surface of the maximum diameter portion 1e is about 30 °. The through hole 1a has a diameter of 25 to 40 μm, the inclination angle of the conical portion 1b and the conical portion 1d is about 60 °, and the diameter of the wire is about 25 to 30 μm.
[0013]
The dielectric ceramic composition which is the material of the capillary 1 of the present invention is xMgO.yAl ₂ O ₃ .zSiO ₂ (where x = 10 to 40 mol%, y = 10 to 40 mol%, z = 20 to 80 mol) %, X + y + z = 100 mol%).
[0014]
The reason why the composition ratio of the main component of the dielectric ceramic composition for the capillary 1 of the present invention is limited to the above range is as follows. That is, x indicating 10% by mole of MgO is set to 10 to 40% by mole. If it is less than 10% by mole, a good sintered body cannot be obtained and the density is lowered, and if it exceeds 40% by mole, the coefficient of thermal expansion is large. Become. In particular, x is preferably 15 to 35 mol% in that the coefficient of thermal expansion is 1.5 × 10 ⁻⁶ / ° C. or less.
[0015]
Further, the y representing 10% by mole of Al ₂ O ₃ was set to 10 to 40% by mole because when y was smaller than 10% by mole, a good sintered body could not be obtained and the density was lowered. It is because a thermal expansion coefficient will become large when it exceeds%. In particular, 17 to 35 mol% is desirable in that the coefficient of thermal expansion is 1.5 × 10 ⁻⁶ / ° C. or less.
[0016]
The reason why the SiO ₂ mol% is 20 to 80 mol% is that when z is less than 20 mol%, the coefficient of thermal expansion increases, and when it exceeds 80 mol%, a good sintered body cannot be obtained and the density is low. This is because it tends to decrease. In particular, 30 to 65 mol% is desirable in that the coefficient of thermal expansion is 1.5 × 10 ⁻⁶ / ° C. or less.
[0017]
These x, y, and z, which indicate the mol% of MgO, Al ₂ O ₃ , and SiO ₂ , are specified by an analysis method such as an EPMA (Electron Probe Micro Analysis) method or an XRD (X-ray Diffraction) method. it can.
[0018]
In the present invention, the coefficient of thermal expansion at 10 to 40 ° C. is set to 2 × 10 ⁻⁶ / ° C. or less. If the coefficient of thermal expansion exceeds 2 × 10 ⁻⁶ / ° C., a high precision joining accuracy of submicron order is obtained. This is because connection loss and connection failure are likely to occur. A method with a small coefficient of thermal expansion is desirable, but it is particularly desirable that the coefficient of thermal expansion at 10 to 40 ° C. is 1.5 × 10 ⁻⁶ / ° C. or less.
[0019]
In the dielectric ceramic composition for the capillary 1 of the present invention, the main crystal phase is cordierite (3MgO · 2Al ₂ O ₃ · 5SiO ₂ ), and the other crystal phase is mullite (3Al ₂ O ₃ · 2SiO). ₂ ), Protoenstatite {a kind of steatite mainly composed of magnesium metasilicate (MgO · SiO ₂ )}, Clinoenstatite {a kind of steatite mainly composed of magnesium metasilicate (MgO · SiO ₂ )} , Forsterite (2MgO · SiO ₂ ), cristobalite {a kind of silicic acid (SiO ₂ )}, tridymite {a kind of silicic acid (SiO ₂ )}, safarin (a kind of silicate of Mg and Al), etc. are deposited. However, the precipitation phase differs depending on the composition.
[0020]
The dielectric ceramic for the capillary 1 of the present invention is manufactured as follows. For example, MgCO ₃ powder, Al ₂ O ₃ powder, and SiO ₂ powder are used as raw material powders, weighed at a predetermined ratio, wet-mixed and then dried, and this mixture was calcined at 1100 to 1300 ° C. in the atmosphere. ,Smash. An appropriate amount of a binder is added to the obtained powder and molded, and the molded body is fired at 1300 to 1450 ° C. in the atmosphere.
[0021]
The main component of the dielectric ceramic composition for the capillary 1 of the present invention is composed of Mg, Al, Si as metal elements, and has a coefficient of thermal expansion of 2 × 10 ⁻⁶ / ° C. or less at 10 to 40 ° C. In addition to the above elements, other components may be contained for the purpose of mixing impurities in the pulverized ball and raw material powder, controlling the sintering temperature range, and improving the mechanical strength. For example, rare earth element compounds, Ba, Sr, Ca, Ni, Co, In, Ga, Zr, Ti, Nb, Ta, Cr, Mo, W, Mn, Cu, Zn, B, Ge, Sn, and other oxides, Or it is non-oxides, such as nitrides, such as silicon nitride, and carbides, such as silicon carbide. These may be contained alone or in combination.
[0022]
Thus, the present invention can be made of a dense dielectric ceramic composition having a smaller coefficient of thermal expansion than conventional alumina ceramics and zirconia ceramics. By being made of such a material, it is possible to obtain high-precision joining accuracy, to suppress the occurrence of connection failure and connection loss, and to prevent the capillary 1 itself from being damaged and the wire from being broken.
[0023]
Since the capillary 1 of the present invention has a hollow shape with a sharp tip as described above, it can be applied to other applications as long as it has a dense and low thermal expansion property. For example, it can be applied to various applications such as pipette tip parts, syringes, vacuum tweezers tip parts, and the like.
[0024]
In addition, this invention is not limited to the said embodiment, A various change may be performed within the range which does not deviate from the summary of this invention.
[0025]
【Example】
Examples of the present invention will be described below.
[0026]
(Example)
The capillary 1 of FIGS. 1 and 2 was configured as follows. As raw material powders, 99 wt% of MgCO _3, purity 99.7 wt% _Al 2 _{O 3,} with a purity of 99.4 wt% of SiO ₂ powder, in Table 1 when the form these sintered bodies The mixture was weighed so as to have a composition ratio, wet-mixed for 15 hours, then dried, and the mixture was calcined in the atmosphere at 1200 ° C. for 2 hours and then pulverized. In Table 1, MgCO ₃ is in terms of MgO, and the thermal expansion coefficient in Table 1 is at 10 to 40 ° C.
[0027]
An appropriate amount of a resin binder is added to the obtained powder and granulated, and this is molded, and the sintered product as the final product has an overall length of 10 mm and an outer diameter of the cylindrical maximum diameter portion 1e of 0. 8 mm, the diameter of the through hole 1a is 30 μm, the inclination angle of the conical portion 1b is 60 °, and the inclination angle of the conical portion 1d is 60 °. This molded body was sintered at 1300 to 1450 ° C. for 2 hours to prepare a capillary 1.
[0028]
[Table 1]
[0029]
According to Table 1, the dielectric ceramic composition for the capillary 1 of the present invention has a small coefficient of thermal expansion of 2 × 10 ⁻⁶ / ° C. or less at 10 to 40 ° C., and the density is 2.3 g / cm ^3. As described above, connection failure with other members and occurrence of connection loss can be suppressed, and occurrence of breakage of the capillary 1 itself and breakage of the wire is remarkably reduced.
[0030]
【The invention's effect】
The capillary for wire bonding of the present invention has a composite oxidation of Mg, Al, and Si having a coefficient of thermal expansion at 10 to 40 ° C. of 2 × 10 ⁻⁶ / ° C. or less and a density of 2.3 g / cm ³ or more. The composite oxide has a molar ratio of xMgO.yAl ₂ O ₃ .zSiO ₂ (where x = 10 to 40 mol%, y = 10 to 40 mol%, z = 20 to 80 mol%, x + y + z = 100 mol%), and the main crystal phase is cordierite, and mullite, protoenstatite, clinoenstatite, forsterite, cristobalite, tridymite or safarin is precipitated as the other crystal phases. A dielectric material having a smaller coefficient of thermal expansion than that of conventional alumina ceramics and zirconia ceramics. Made of porcelain composition, as a result, thermal deformation due to ambient temperature is small, high accuracy of joining accuracy is obtained, connection failure and connection loss can be suppressed, and damage to the capillary itself and wire breakage can be prevented It has the effect of.
[0031]
In the capillary for wire bonding of the present invention, the molar ratio of the composite oxide is xMgO.yAl ₂ O ₃ .zSiO ₂ (where x = 10 to 40 mol%, y = 10 to 40 mol%, z = 20 to 80 mol%, x + y + z = 100 mol%), and the main crystal phase is cordierite, and the other crystal phases are mullite, protoenstatite, clinoenstatite, forsterite, cristobalite, tridymite. Or it can be made more excellent in terms of coefficient of thermal expansion and denseness by comprising a dielectric ceramic composition in which safarin is deposited.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a capillary of the present invention.
FIG. 2 is a perspective view of a capillary of the present invention.
[Explanation of symbols]
1: Capillary 1a: Through hole 1b: Conical part 1c: Tapered part 1d: Conical part 1e: Maximum diameter part

Claims (1)

A composite oxide of Mg, Al, and Si having a coefficient of thermal expansion at 10 to 40 ° C. of 2 × 10 ⁻⁶ / ° C. or less and a density of 2.3 g / cm ³ or more, in the molar ratio _{xMgO · yAl 2 O 3 · zSiO} 2 ( where, x = 10 to 40 mol%, y = 10 to 40 mol%, z = 20 to 80 mol%, x + y + z = satisfies 100 mol%) And a dielectric ceramic composition in which the main crystalline phase is cordierite and the other crystalline phases are precipitated as mullite , protoenstatite, clinoenstatite, forsterite, cristobalite, tridymite or safarin. A wire bonding capillary characterized by the above.