JPH0917929A - Bonding post and its selector - Google Patents

Abstract

PURPOSE: To provide a bonding post small in heat fatigue and a selector capable of deciding a front face or a reverse face of a bonding post without erroneous decisions. CONSTITUTION: With the use of a Fe-Ni alloy plate 4 as a mother material, on a side face of a bonding post 1 punched by a press die, a fractured plane (non-glossy part) 2 or a shear face (glossy part) 3 of width 0.3mm or more is formed, to decide a front face or a reverse face by detecting by an optical sensor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding post used in a thick-film hybrid integrated circuit and an apparatus for selecting the same.

[0002]

2. Description of the Related Art Generally, a bonding post is fixed on a substrate of a thick film hybrid integrated circuit to eliminate irregularities in height with a surface to which an Al wire is bonded such as a semiconductor chip.
It is used as a buffer for cutting the bonded Al wire. 5A to 5C are a top view, a side view, and a sectional view taken along line BB of a conventional bonding post.

A conventional bonding post 1A is shown in FIG.
As shown in (a) to (c), an aluminum (Al) plate 7 having a thickness of about 0.8 mm is used as a base material, and a thickness of about 5 mm is formed on one surface.
A Cu (or Ni) layer 8 of 10 to 10 μm is provided by plating or the like,
Further, a composite material having a solder layer 6 of about several tens to 100 μm provided thereon is punched into a shape having a diameter of 2 mm by a press die.

This composite material has a Vickers hardness H _V = 40 to
Since it is soft at about 60, a large roundness is formed at the edge of the sheared surface (glossy portion) 3 as shown in FIG. The opposite fracture surface (matte portion) 2 is flat. Therefore, by utilizing this difference in shape, the front and back of the bonding post are discriminated by the inclination angle and the vibration of the selection device shown in FIG.

As shown in FIG. 6, a bonding post sorting apparatus includes a spirally-formed first transfer section 9A provided on a rotary vibrating section 10 and a straight line connected to the first transfer section 9A. And a second conveyance section 9B having a shape of
The bonding post 1A placed on the bottom portion of the first transfer portion 9A is rotated and vibrated to be transferred to the upper portion. At the end portion of the first transfer portion 9A, for example, only the bonding post having the back surface as the upper portion is transferred to the second transfer portion 9. It is supposed to be sent.

[0006] As shown in FIG. 7A, a step 1 is provided at the end of the first transport section 9A for selecting the bonding post 1A.
9 is provided, and when the bonding post 1 </ b> A is sent with the large rounded back side down, the step 1 is formed.
It falls at the part of 9 and is excluded. On the other hand, the bonding post 1A sent with the flat surface down is shown in FIG.
As shown in (b), since the friction is large, it is sent to the second transport section without falling over the step 19, and is automatically taped by a taping machine, for example.

FIG. 8 shows a case where the bonding post 1A is applied to a thick film hybrid integrated circuit. As shown in FIG. 8, a semiconductor chip 23 and a bonding post 1A are soldered on a thick film conductor 22 such as Ag-Pd or Ag-Pt having a thickness of 8 to 15 μm, which is formed by printing and firing on an alumina ceramic substrate 21. 6 and the like, and the semiconductor chip 23
And the bonding post 1A are connected by an Al wire 24 having a diameter of 50 to 500 μm.

[0008]

In this conventional bonding post, the punching shape changes due to the adjustment of the thickness and composition of the composite material and the press die, and the surface roughness of the composite material changes. Of the transfer unit became unstable, and a problem of about 0.5% occurred in the determination of the front and back sides by the inclination angle and the vibration of the transport unit. Therefore, there has been a problem that front and back mounting errors occur during automatic mounting on an alumina ceramic substrate.

Further, a bonding post 1A made of aluminum as a base material on a thick film conductor of an alumina ceramic substrate.
There is a large difference in the coefficient of thermal expansion in the hybrid integrated circuit device that is connected by soldering, so that the thermal stress of the actual use causes thermal stress at the connection part between the alumina ceramic substrate and the bonding post, causing the connection deterioration. There was also.

As a countermeasure against this, for example, Japanese Patent Laid-Open No. 61-15 / 1986
As disclosed in Japanese Patent No. 0359, if the material of the bonding post is changed to, for example, an iron-nickel alloy,
To become hard and Vickers hardness H _V = 100 to 150 nm, when punched by a press die, roundness of the edge portion of the bonding post is reduced, since the same as the shape of the opposite surface, in the sorting apparatus of conventional bonding post However, there is a problem that it is impossible to distinguish between front and back.

A first object of the present invention is to provide a bonding post which can reduce thermal fatigue when mounted.

A second object of the present invention is to provide a bonding post sorting apparatus capable of distinguishing between front and back sides without erroneous determination.

[0013]

According to a first aspect of the present invention, there is provided a bonding post formed by pressing a composite material having an Fe-Ni alloy plate as a base material, an Al layer on one surface and a solder layer on the other surface. In a bonding post formed by punching with a mold, a shearing surface or a fractured surface having a width of at least 0.3 mm is provided around the entire periphery of the side surface by punching.

According to a second aspect of the present invention, there is provided an apparatus for sorting bonding posts, comprising: a first transport section formed in a spiral shape and feeding the bonding posts upward by vibration; and a second linear transport section connected to the first transport section. A bonding post sorting apparatus that aligns the surface of the bonding post and sends a front / back discrimination means including an optical sensor for detecting a sheared surface or a broken surface of the bonding post at an end of the first transport unit. It is characterized by having.

[0015]

Next, embodiments of the present invention will be described with reference to the drawings. FIGS. 1A to 1C are a top view, a side view, and a cross-sectional view taken along line AA of a bonding post according to a first embodiment of the present invention.

1 (a) to 1 (c), a bonding post 1 is made of a 0.8 mm thick Fe-Ni alloy plate 4 as a base material, and has a 10-15 μm thick Al (or Al-
Si) layer 5 and a solder layer 6 having a thickness of 30 to 50 μm on the back surface.
Is formed by punching out a composite material to which a surface is applied with a press die. In particular, a fracture surface 2 or a shear surface 3 having a width of 0.3 mm or more is provided around the entire side surface.

FIG. 2 is a sectional view of a die for punching out the bonding post 1 of the first embodiment. In order to form the fractured surface 2 or the sheared surface 3 around the entire side surface of the punched bonding post 1, it is necessary to adjust the clearance 1 between the punch 16 and the die 17. The width t of the fractured surface 2 and the clearance l are proportional to the thickness T of the bonding post 1 as shown in FIG. Therefore, clearance l
Can be set to a desired value for the width t of the fractured surface 2.

For example, in FIG. 2, the diameter of the punch 16 is 1.98 to 1.99 mm, the clearance 1 between the punch 16 and the die 17 is 10 to 20 μm, and the thickness is about 0.8 mm.
When the bonding post 1 having a diameter of 2 mm is formed by punching out the composite material 15 of
A fracture surface 2 and a shear plane 3 of mm are formed. When the value of the clearance 1 is other than 10 to 20 μm, the width of the fracture surface 2 or the shear surface 3 increases.

FIGS. 4 (a) and 4 (b) are block diagrams of a bonding post selection apparatus according to a second embodiment of the present invention, and particularly show a state when the bonding posts are selected. This will be described with reference to FIG.

Referring to FIGS. 4 (a), 4 (b) and 6, the bonding post sorting apparatus comprises a first transfer section 9A which is formed in a spiral shape and feeds the bonding post 1 upward by vibration, and the first transfer section 9A. An optical sensor including a light-emitting element and a light-receiving element, which are provided at the end of the first transfer section 9A and detect a fractured surface 2 or a shear plane 3 of the bonding post 1 provided at the end of the first transfer section 9A. A comparing unit 12 for comparing the value of the light amount detected by the optical sensor 11 with a reference value stored in advance;
A compressor control unit for controlling the compressor by a signal from the control unit 2;
Air 18 for removing bonding post 1 on A
It mainly comprises a compressor 14 for feeding to a hole 20 formed in the conveying section. Hereinafter, the operation of the sorting device will be described.

Due to the vibration, the step 1 at the end of the first transfer section 9A
When the bonding post 1 is sent to the position 9, light is emitted from the optical sensor 11 to the lower portion of the side surface, and the reflected light is detected. For example, when the bonding post 1 having the lower surface is selected and sent to the second transport unit 9B, the comparison unit 12 determines whether or not the reflected light is from the fractured surface (matte portion) 2. If it is from the shear surface (glossy portion) 3, as shown in FIG.
Is sent to the hole 20 to remove the bonding post 1. On the other hand, as shown in FIG. 4B, if the reflected light from the bonding post 1 is from the fracture surface 2, the bonding post 1 is sent to the second transport section 9B as it is and is moved to the next step.

Assuming that the diameter of the light beam emitted from the optical sensor 11 is 0.1 to 0.2 mm, the width of the fracture surface 2 or the shear surface 3 formed on the side surface of the bonding post 1 is 0.3 m.
m or more is desirable. When the thickness is 0.3 mm or less, an error occurs in the detection of reflected light due to a variation in the width of the fractured surface 2 or the sheared surface 3, and the sorting accuracy of the bonding post 1 is reduced.

As described above, since the bonding post of the present invention has a fractured surface or a cross-section having a width of 0.3 mm or more formed on the side surface thereof, the bonding post can be accurately selected by a selection device having an optical sensor. Further, unlike the conventional bonding post 1A shown in FIG. 5, since it is not necessary to form a large roundness on the back surface, the base material of the bonding post is changed to the coefficient of linear expansion of the ceramic substrate (about 2.0 × 10 ⁻⁶ / ° C.). ) Can be obtained (approximately 5.0 × 10 ⁻⁶ / ° C.). Therefore, as shown in FIG. 8, even when the bonding post 1 is connected to the ceramic substrate 21 and the thermal cycle is performed, the thermal stress is small.
Can suppress thermal fatigue and prevent connection deterioration.

In the second embodiment, a case has been described in which the front and back of the bonding post 1 are discriminated, and then the bonding post is removed using air. However, the present invention is not limited to this. A bonding post may be used to remove the bonding post.

[0025]

As described above, according to the present invention, a fracture surface (matte portion) or a shear surface (glossy portion) having a width of 0.3 mm or more is formed on the side surface of a bonding post formed by punching with a press die. By optically detecting the gloss difference with an optical sensor, the front and back of the bonding post can be determined without erroneous determination. Therefore, erroneous mounting due to mounting on an integrated circuit device can be reduced from 0.5% in the past to 0%.

Further, since a material having a thermal expansion coefficient equivalent to that of an alumina ceramic substrate can be applied to the bonding post, when applied to a thick film hybrid integrated circuit, deterioration of a connection portion due to thermal fatigue in a cooling / heating cycle can be reduced. There is also an effect.

[Brief description of the drawings]

FIG. 1 is a plan view, a side view, and a cross-sectional view taken along line AA of a bonding post of the present invention.

FIG. 2 is a cross-sectional view of a mold for forming a bonding post.

FIG. 3 is a diagram showing a relationship between a ratio of a width of a fractured surface to a thickness of a bonding post and a clearance of a mold.

FIG. 4 is a configuration diagram of a bonding post selection device of the present invention.

FIG. 5 is a plan view, a side view, and a cross-sectional view taken along line BB of a conventional bonding post.

FIG. 6 is a sectional view of a conventional sorting device.

FIG. 7 is a cross-sectional view for explaining a conventional bonding post selection method.

FIG. 8 is a cross-sectional view of a hybrid integrated circuit on which a conventional bonding post is mounted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1A Bonding post 2 Breaking surface 3 Shear surface 4 Fe-Ni alloy plate 5 Al layer 6 Solder layer 7 Al plate 9 Cu layer 9A 1st conveyance part 9B 2nd conveyance part 10 Rotation vibration part 11 Optical sensor 12 Comparison part 13 Compressor control unit 14 Compressor 15 Composite material 16 Punch 17 Die 18 Air 19 Step 20 Hole 21 Alumina ceramic substrate 22 Thick film conductor 23 Semiconductor chip 24 Al wire

Claims (2)

[Claims] 1. A bonding post formed by punching a composite material having a Fe—Ni alloy plate as a base material, an Al layer on one surface thereof, and a solder layer on the other surface thereof, being punched by a press die. A bonding post, characterized in that a shear surface or a fracture surface having a width of at least 0.3 mm is provided all around the side surface. 2. A first transfer section which is formed in a spiral shape and feeds a bonding post upward by vibration, and a second linear transfer section connected to the first transfer section. An apparatus for sorting bonding posts to be sent together, wherein front and back discriminating means including an optical sensor for detecting a sheared surface or a broken surface of the bonding posts is provided at an end portion of the first transport unit. apparatus.