Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – With vibration step
Reexamination Certificate
2000-01-14
2003-07-01
Chaudhuri, Olik (Department: 2823)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
With vibration step
C438S612000, C438S613000
Reexamination Certificate
active
06586278
ABSTRACT:
BACKGROUND
The present invention relates to a method for mounting electronic components and structures having mounted thereon electronic components, and more particularly, the invention relates to a method for mounting electronic components and structures having mounted thereon electronic components in which electrodes of the electronic components are mounted by connecting the electrodes to wiring electrodes of substrates via bumps.
FIG. 7
shows an example of a structure where an electronic component is mounted on a substrate (a substrate used for mounting) via bumps by a conventional method. In such a structure, the top portions of Au bumps (protruding bumps)
53
are on surfaces of electrodes
52
. The bumps
53
disposed on electrodes
52
are formed on a surface of an electronic component
51
. The bumps
53
are connected to wiring electrodes (substrate pads)
55
of a substrate
54
by a conductive adhesive (a conductive paste)
56
. An insulating bonding resin
57
fills a gap between the electronic component
51
and the substrate
54
, and mounts the electronic component
51
on the substrate
54
.
In the above-described method for mounting the electronic component, the conductive adhesive
56
(the conductive paste) is applied at the top portions of the Au bumps (the protruding bumps)
53
formed on the electronic component
51
through wire bonding technology. The insulating bonding resin
57
is applied to the wiring electrode
55
of the substrate
54
. Then, the conductive paste
56
is temporarily hardened. After this, while pressing the electronic component
51
on the substrate
54
, heat is applied to connect the Au bumps
53
of the electronic component
51
and the wiring electrodes
55
of the substrate
54
, which hardens the conductive adhesive (the conductive paste)
56
and the bonding resin
57
to mount the electronic component.
In the above-described method for mounting an electronic component, there are some problems:
(1) A material (a conductive paste) whose conductive component (filler) is formed of Ag or an alloy of Ag is typically used as the conductive adhesive, which leads to an increase in cost;
(2) although the bonding resin is used to enhance the bonding strength, since bonding only by applying small amounts of conductive adhesives at the top portions of the Au bumps is not strong enough, there is insufficient strength, and no moisture resistance; and
(3) when the electronic component is mounted by pressing on the substrate and hardening the conductive adhesive (the conductive paste) and the bonding resin, since the Au bumps formed by using wire bonding have protruding configurations, the substrate, (which is typically formed of resin), flush against the lower side of the wiring electrode, is deformed. The deformation affects the connection reliability, and particularly, the moisture resistance.
SUMMARY OF THE INVENTION
Accordingly, the present invention is aimed at solving the above-described problems. It is an object of the present invention to provide a highly reliable method for mounting an electronic component and structure having mounted thereon an electronic component, in which the electronic component can be efficiently mounted on a substrate without expending significant cost.
To this end, according to one aspect of the present invention, there is provided a method for mounting an electronic component by connecting an electrode of the electronic component to a wiring electrode on the substrate via a bump, the method including the steps of:
disposing the top portion of an ultrasonic-wave applying unit (a collet) flush against the electronic component;
positioning the electronic component on the wiring electrode of the substrate, which is heated, via the bump,
applying ultrasonic oscillation to the electronic component under a condition in which the oscillating amplitude of the top portion of the collet is larger than the oscillating amplitude of the electronic component, where the oscillating amplitude of the electronic component is 0.20 &mgr;m or larger, and
metallically bonding the bump, and the electrode of the electronic component or the wiring electrode on the substrate, which are objects to be connected, so as to mount the electronic component on the substrate via the bump.
In this case, while disposing the top portion of the collet flush against the electronic component and positioning the electronic component on the wiring electrode of the substrate, which is heated, via the bump, the ultrasonic oscillation is applied to the electronic component under the condition in which the oscillating amplitude at the top portion of the collet is larger than the oscillating amplitude of the electronic component, where the oscillating amplitude of the electronic component is 0.20 &mgr;m or larger. As a result, without using an expensive conductive adhesive (a conductive paste), the bump, and the electrode of the electronic component or the wiring electrode on the substrate, which are objects to be connected, can be metallically bonded to reliably connect the bump and the electrode of the electronic component or the wiring electrode on the substrate.
In other words, with frictional heat caused by the ultrasonic oscillation, where the oscillating amplitude of the top portion of the collet is larger than the oscillating amplitude of the electronic component, and heat provided by heating, it is possible to produce a sufficient atomic diffusion between the bump and the electrode of the electronic component or the wiring electrode on the substrate. As a result, it is possible to obtain a sufficiently reliable connection, and moisture resistance, by metallically bonding the bump and the electrode of the electronic component or the wiring electrode on the substrate.
In addition, in the method for mounting an electronic component in accordance with the present invention, since the bump and the electrodes are metallically bonded while applying ultrasonic oscillation, it is possible to provide the heat energy necessary to perform metallic bonding at relatively low temperatures to avoid deforming the substrate. Accordingly, the deformation of a substrate, which occurs in a conventional mounting method, can be suppressed or prevented.
Furthermore, in the method for mounting an electronic component in accordance with another aspect of the invention, the bump is formed by plating and is made of a material including gold (Au) as a main component.
Although the present invention can also be applied in the cases of bumps formed by various methods and formed of various materials, when a plated bump flatly formed on a surface of an electrode is used, it is generally possible to suppress deformation of the substrate that occurs in the case of a bump with a protruding configuration. Thus, this is advantageous in improving characteristics such as moisture resistance. At the same time, the bonding strength can be improved since a large area for bonding can be provided. In addition, in the case of the bump plated by the material including gold (Au) as the main component, it is possible to metallically bond the bump to the electrode of the electronic component or the wiring electrode of the substrate by heating while applying the ultrasonic oscillation, with the result that the electrode of the electronic component can be reliably connected to the wiring electrode of the substrate via the bump.
Furthermore, in the method for mounting an electronic component in accordance with another aspect of the invention, the thickness of the substrate is 0.2 mm or less.
When the thickness of the substrate is increased, the substrate absorbs the ultrasonic oscillation. As a result sufficient frictional heat cannot be generated between the bump and the electrode of the electronic component or the wiring electrode of the substrate. However, when the thickness of the substrate is 0.2 mm or less, the substrate can be prevented from absorbing the ultrasonic oscillation so that sufficient frictional heat can be generated between the bump and the electrodes.
Furthermore, in the met
Minami Masaaki
Okamura Mototsugu
Osaka Takeshi
Chaudhuri Olik
Keating & Bennett LLP
Lee Hsien-Ming
Murata Manufacturing Co. Ltd.
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