Metal fusion bonding – Means to apply vibratory solid-state bonding energy to work
Reexamination Certificate
2000-08-01
2001-06-19
Dunn, Tom (Department: 1725)
Metal fusion bonding
Means to apply vibratory solid-state bonding energy to work
C228S044300, C228S044700, C228S045000, C228S110100
Reexamination Certificate
active
06247628
ABSTRACT:
BACKGROUND OF THE INVENTION
1. [Field of the Invention]
The present invention relates to an ultrasonic vibration tool for bonding overlapped portions of a plurality of members to be bonded together made from metals with ultrasonic vibration.
2. [Description of the Prior Art]
FIG. 25
shows the support structure of a tool by a holder disclosed by Japanese Patent Publication No. 2911394. In
FIG. 25
, reference numeral
251
denotes an ultrasonic horn having a length equal to the wavelength of resonance frequency (length from the maximum vibration amplitude point f
13
to the maximum vibration amplitude point f
17
),
252
bonding working portions projecting outward from the ultrasonic horn
251
at the central maximum vibration amplitude point f
15
of the ultrasonic horn
251
,
253
a round bar-like booster having a length equal to the half of the wavelength of resonance frequency (length from the maximum vibration amplitude point f
11
to the maximum vibration amplitude point f
13
),
254
a cylindrical support portion projecting outward from the booster
253
at the central minimum vibration amplitude point f
12
of the booster
253
,
255
a round bar-like booster which is symmetrical to the booster
253
and has a length equal to the half of the wavelength of resonance frequency (length from the maximum vibration amplitude point f
17
to the maximum vibration amplitude point f
19
),
256
a cylindrical support portion which is symmetrical to the support portion
254
and projects outward from the booster
255
at the central minimum vibration amplitude point f
18
of the booster
255
,
257
a transducer,
258
a holder,
259
and
260
cylindrical clamp portions which have a slit in part of the wall and project downward from both end portions of the holder
258
,
261
a mounting table placed right below the bonding working portion
252
, and
262
and
263
a plurality of members to be bonded together which are made from metals. The booster
253
and
255
are connected coaxial to both ends of the ultrasonic horn
251
by unshown headless screws, and the transducer
257
is connected coaxial to the end portion of the booster
253
by an unshown headless screw. While the support portion
254
is inserted in the inside of the clamp portion
259
and the support portion
256
is inserted in the inside of the clamp portion
260
, the clamp portions
259
and
260
are fastened by unshown bolts to narrow the widths of the slits and hold the support portions
254
and
256
from the outside, respectively. The holder
258
is attached to a piston rod which is a vertically movable output portion of a pressure unit such as an air cylinder. The member
262
and
263
to be bonded together are mounted on the mounting table
261
in such a manner that they are placed one upon the other. In this state, the holder
258
is moved down by the air cylinder, the bonding working portion
252
and the mounting table
261
hold the members
262
and
263
to be bonded together by pressure, ultrasonic vibration is transmitted from the transducer
257
to the ultrasonic horn
251
through the booster
253
, the bonding working portion
252
vibrates in a direction shown by an arrow X, this vibration is transmitted from the bonding working portion
252
to the members
262
and
263
to be bonded together, the contact portions of the members
262
and
263
to be bonded together vibrate in a horizontal direction while they are pressed by the bonding working portion
252
and the mounting table
261
, frictional heat is generated between the contact portions, and the contact portions of the members
262
and
263
to be bonded together are thereby activated and bonded together.
However, the above support structure of the prior art tool is such that the boosters
253
and
255
having a length equal to the half of the wavelength of resonance frequency are connected to both ends of the ultrasonic horn
251
which has a length equal to the wavelength of resonance frequency and the cylindrical support portions
254
and
256
of the boosters
253
and
255
are held by the cylindrical clamp portions
259
and
260
of the holder
258
, respectively. That is, since the cylindrical support portions
254
and
256
are held by the cylindrical clamp portions
259
and
260
, respectively, the distance between the support portion
254
and the other support portion
256
must be at least the total of the wavelength and the half of the wavelength of resonance frequency in order to secure as wide a working space as possible for the members
262
and
263
to be bonded together. Therefore, when the bonding working portion
252
and the mounting table
261
hold the members
262
and
263
to be bonded together by pressure, there is a possibility that the ultrasonic horn
251
and the boosters
253
and
255
may bend upward in an arc form with the support portions
254
and
256
as joints. If they bend, the vibration state, that is, resonance state goes wrong, thereby causing a bonding failure. To solve this problem, the present applicant developed a plate-like ultrasonic horn
271
shown in FIG.
26
and used it in place of the above ultrasonic horn
251
. However, when the members
262
and
263
to be bonded together are a semiconductor chip and a circuit board and the semiconductor chip is surface mounted on the circuit board by ultrasonic vibration bonding, the basic weight to be applied to each bump (electrode) of the semiconductor chip is limited. Since the number of bumps is small, it is difficult to control the bonding weight at the time of bonding when the bonding weight (weight required for bonding) which is obtained by multiplying the number of bumps of the semiconductor chip by the basic weight is lower than the total weight of the boosters
253
and
255
and the ultrasonic horn
271
. On the other hand, when the number of bumps is large and the bonding weight is high, there may occur a bonding failure that the ultrasonic horn
251
and the boosters
253
and
255
bend and some of the bumps of the semiconductor chip are not bonded to the pads (electrodes) of the circuit board properly.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an ultrasonic vibration bonding tool which can be made light in weight and can reduce the distance between support portions.
According to a first aspect of the present invention, there is provided an ultrasonic vibration bonding tool for bonding overlapped portions of a plurality of members to be bonded together made from metals by ultrasonic vibration, which comprises a square bar-like horn body, bonding working portions which are provided on the upper and lower surfaces of the horn body at the central maximum vibration amplitude point of the horn body, and crooked support portions which project from the front and rear surfaces of the horn body at the two minimum vibration amplitude points which are separate the same distance from the bonding working portions on both sides. According to the present invention, since the two surfaces on which the bonding working portions are provided of the square bar-like horn body are perpendicular to the two surfaces on which the support portions are provided of the square bar-like horn body, a wide working space can be secured for the members to be bonded together without being narrowed by the support portions even when the support portions are provided on the square bar-like horn body at the closest two minimum vibration amplitude points which are separate the same distance from the bonding working portions on both sides. When the tool is held by the holder at both sides, the distance between the support portions can be set equal to or shorter than the wavelength of resonance frequency. Since the length of the tool can be set to the wavelength of resonance frequency, the tool becomes small in size and light in weight.
According to a second aspect of the present invention, there is provided an ultrasonic vibration bonding tool, wherein each of the support portions co
Nakai Seiya
Sato Shigeru
Dunn Tom
Pittman Zidia
Sughrue Mion Zinn Macpeak & Seas, PLLC
Ultex Corporation
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