Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2002-04-04
2004-03-16
Sells, James (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S073100, C156S073500, C156S358000, C156S580000, C156S580100, C228S112100, C228S002100
Reexamination Certificate
active
06706130
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a friction bonding method and apparatus and a holding tool used for the friction bonding apparatus, and relates to a friction bonding method and apparatus and a holding tool used for the friction bonding apparatus suitable for manufacturing an electronic circuit board and a suspension head by mounting an electronic component on a base member such as a semiconductor element on, for example, a circuit board or a magnetic reading suspension head with metallic bonding when metallically bonding the objects to be bonded to each other.
BACKGROUND ART
For example, with an increasing number of functions of electronic equipment and an increasing number of electronic components, electronic circuit boards tend to receive miniaturized electronic components at increasing mounting densities, and the flip chip mounting technology for mounting electronic components by providing metallic bumps on electrodes formed on a semiconductor wafer and metallically bonding the metallic bumps with a wiring pattern formed on a circuit board is also used for manufacturing an electronic circuit board. This can easily cope with the miniaturization, the fine structure, and the increase in mounting densities of electronic components and connection routes.
The metallic bonding is achieved typically by friction bonding utilizing ultrasonic vibrations. Of course, being not limited to this, the metallic bonding can also be achieved generally by frictional contact with a relative movement.
However, a comparatively strong frictional contact by pressurization and vibratory relative movement is needed for the metallic bonding by frictional contact between minute metallic bonding portions. However, as the semiconductor element becomes more minute, the metallic bumps formed on the element become very small, and the electrodes and wiring portions of the circuit pattern to be metallically bonded to this also become thin. Therefore, the frictional contact is prone to be excessive, possibly damaging the metallic bumps and the circuit pattern, causing a short-circuit as a consequence of the excessive collapse of the metallic bumps striding over the fine circuit pattern and causing defective sealing as a consequence the failure in the entry of the sealant of an excessively reduced gap between the circuit board and the semiconductor element due to the excessive collapse of the metallic bumps. If the frictional contact is reduced in order to avoid the above troubles, then the metallic bonding becomes insufficient, and the semiconductor element, which has been estimated to be bonded, subsequently falls off to make the electronic circuit board defective or causes a failure at an early stage.
Lately, there has been known the technology of using a suspension head
400
b
constructed of a thin leaf spring for reading a magnetic disk
400
a
as shown in FIG.
15
. The suspension head
400
b
is supported so that its base portion can be pivoted by a rotary shaft
400
c
, and read is executed by scanning the magnetic disk
400
a
with a reading portion
400
d
located at its tip portion in an arc in the radial direction and rotating the magnetic disk
400
a
around a spindle
400
e
. A number of sensing terminals are arranged in the read portion
400
d
of the suspension head
400
b
, and a semiconductor element
400
f
for read is bonded onto wiring lines extended from the sensing terminals to the base portion side of the suspension head
400
b.
The semiconductor element
400
f
is bonded to the base portion side of the suspension head
400
b
where the width is comparatively large and the wiring interval is increased, and connected to the wiring pattern by way of a bonded wire
400
g.
However, with increasing in the read speed, the semiconductor element
400
f
for read use are demanded to be bonded to a portion in the vicinity of the read portion
400
d
located at the tip portion of the suspension head
400
b
. However, since the tip portion of the suspension head
400
b
is thin and has very small intervals of wiring, it is difficult to perform bonding by wire connection according to the wire bonding method. If it is attempted to cope with this by replacement with the metallic bonding of the semiconductor element
400
f
provided with metallic bumps, then the semiconductor element
400
f
is required to have a very small size of not larger than 2-mm square according to circumstances, and a positional accuracy of not greater than 0.3&mgr; is needed for the bonding. Moreover, if foreign materials (particles) adhere to the read portion and the wiring lines of the suspension head
400
b
as a consequence of the occurrence of silicon powder from the semiconductor element
400
f
when ultrasonic vibrations are applied to the semiconductor element
400
f
during friction bonding via a suction tool that sucks and holds the element
400
f
or for another reason, then the read characteristics of the element are often impaired, reducing the yield.
Such foreign materials are generated not only in the case of a silicon semiconductor element but also in the case of a GaSi semiconductor element. Moreover, the same thing can be said for LiTa, LiNb, and the like used for a SAW (Surface Acoustic Wave) element, and it is also generated in the case of crystal. The foreign materials generated from these materials mean the scrapes, scratches, and chipping of the back surface of the semiconductor element
400
f
itself, which leads to the roughness and smear of the back surface, solely causing a reduction in quality after bonding. Furthermore, with an increase in the frequency of repetition of bonding by the suction tool, those foreign. materials adhere to the suction surface of the suction tool and gradually accumulate. This also causes the further roughness of the back surface of the semiconductor element
400
f
to be bonded, worsening the quality of the semiconductor element
400
f
, and further reducing the yield because of easy occurrence of chipping and cracking of the element inclusive of the electrodes.
In order to cope with this, it is attempted to reduce the ultrasonic output from the normal value of 1 W to 0.1 W or reduce the friction bonding time by ultrasonic waves from the normal value of 0.5 sec to 0.1 sec. However, this attempt tends to cause defective bonding. It is also attempted to clean the suction surface of the suction tool by periodic polishing, the required extra work degrades the productivity, and there is another issue that the operating life of the suction tool is shortened by the abrasion due to polishing.
When bonding the semiconductor elements
400
f
to the suspension head
400
b
, a number of suspension heads
400
b
are arranged parallel so as to integrally extend from a frame portion to the inside of the frame portion, allowing the whole body to be handled as one plate-shaped member. Therefore, the heads can be handled similarly to the circuit board to which electronic components are bonded.
However, each suspension head
400
b
has its base portion connected to the frame portion by two narrow connecting portions. According to the experiments carried out by the present inventors, the head is thin and easily deformed, and if the head is deformed even a little bit, it is difficult to correct the deformation, leading to a defective product and reduced yield. In particular, it has been difficult to reliably bond the semiconductor element
400
f
to the suspension head
400
b
by the friction bonding performed conventionally without the troubles of damage and so on.
The present inventors, who repetitively carried out various experiments and examinations in order to solve this issue, discovered that the proper method was to temporarily reduce or stop the friction bonding operation for metallic bonding partway.
The object of the present invention is to provide a friction bonding method and apparatus capable of performing metallic bonding just enough without damage on the objects to be bonded to each other and a holding tool used for the friction bonding apparatus, on the basi
Kanayama Shinji
Minamitani Shozo
Shida Satoshi
Ueno Yasuharu
Matsushita Electric - Industrial Co., Ltd.
Sells James
Wenderoth , Lind & Ponack, L.L.P.
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