Adhesive bonding and miscellaneous chemical manufacture – Surface bonding means and/or assembly means therefor – With work feeding or handling means
Reexamination Certificate
1998-09-10
2001-05-01
Osele, Mark A. (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Surface bonding means and/or assembly means therefor
With work feeding or handling means
C156S558000, C156S566000, C156S578000, C428S118000, C428S126000, C228S006200
Reexamination Certificate
active
06223800
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a die bonding apparatus and, more particularly, to a die bonding apparatus for selectively performing LOC (lead on chip) die bonding and normal die bonding through regulation of a simple control function when bonding semiconductor chips of a memory device from a wafer to lead frames, thereby to increase efficiency in use of equipment and reduce the cost for equipment.
2. Discussion of Related Art
A semiconductor lead frame is one of the core elements constructing a semiconductor package together with a wafer.
It has been well known that the lead frame serves as both a lead for connecting the inside of the semiconductor package and the outside, or the circuit board, and a frame for supporting a semiconductor chip.
This semiconductor lead frame is made in such a manner of forming a predetermined shape out of thin film material using a press dies sequentially transferred or through an etching step utilizing chemicals.
The semiconductor lead frame manufactured through the ways as illustrated above is put together with the other components including a chip of a memory device through an assembly process and, more specifically, constructs the semiconductor package through die bonding and wire bonding.
On the thin film are formed a plurality of unit lead frames which are arranged in all directions, and adhesive tape for the mounting of the chip is applied to the bottom surface, thus forming unit lead frame members.
Each unit lead frame members where the adhesive tape is applied is arranged on a rail through vacuum adsorption and then the die bonding step is performed.
For the die bonding step, a die is picked up through suction by a nozzle from a silicon wafer where multiple dice are formed, each die being a unit device, and then transferred to a predetermined site to be mounted on. Subsequently, each die is transferred below the arranged lead frame and mounted thereon. The bonding is, in turn, performed using things like a thermo-compression bonding machine.
After this bonding step, the lead frame is transferred to passing through the next wire bonding step. During the wire bonding, each lead is connected to the circuit of the die through a metal wire, such as gold or silver having excellent conductivity.
In other words, adhesive tape
2
for the bonding of a chip is applied to the multiple unit lead frames
1
formed out of the thin film in a taping process as illustrated FIG.
1
. The lead frame where the adhesive tape
2
applied is then transferred facing downward and the die
3
, such as a chip of a memory device, is mounted on the lead frame from below. At the next wire bonding step, the nodes of the die and the lead frame are bonded through the wire
4
by way of LOC die bonding widely used, as shown in
FIG. 2
a.
Alternatively, adhesive Ag epoxy is applied to the top surface of a lead frame
5
and a die
7
is directly mounted down on the lead frame from above before bonding the nodes of the die
7
to the lead frame
5
using a wire
8
in normal die bonding, as shown in
FIG. 2
b
, which is often used due to its operation efficiency.
At the early stage of development where the size of the die is large, the LOC die bonding is primarily used because an overall package can be reduced, but when it is not necessary to reduce the size of the overall package due to the small size of the die, the normal bonding is used much more frequently than the LOC die bonding.
However, according to the conventional die bonding apparatus, separate apparatus must be used for each LOC die bonding step and normal die bonding step because operations for each step are different, so additional production facilities must be installed. In addition, there is a drawback that the facilities are left and not used because the apparatus for the LOC die bonding or normal die bonding cannot used for other processes.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a die bonding apparatus that substantially obviates one or more of the limitations and disadvantages of the related art.
An object of the present invention is to provide a die bonding apparatus for selectively performing LOC die bonding and normal die bonding through regulation of a simple control function when bonding semiconductor chips of a memory device from a wafer to lead frames, thereby to increase efficiency in use of equipment and reduce the cost for equipment.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure as illustrated in the written description and claims hereof, as well as the appended drawings.
To achieve these and other advantages, and in accordance with the purpose of the present invention as embodied and broadly described, a die bonding apparatus includes: a lead frame supply station for accommodating a plurality of lead frames; a frame transferring device for transferring the lead frame piled up in the lead frame supply station to an Ag epoxy application table or transferring it to a traveling rail; a frame fixing station for fixing the lead frame transferred by the frame transferring device to the Ag epoxy application table through suction power of a vacuum pump and moving the lead frame back and forth through actuation of a motor; an Ag epoxy supply station for applying a predetermined amount of Ag epoxy which is an adhesive bonding agent to a site of the lead frame fixed by the frame fixing station, the site will being in contact with a die; a moving device for moving the lead frame on the traveling rail, which is transferred by the frame transferring device after the application of the Ag epoxy at the Ag epoxy supply station, to a preheating station in front using a pushing piece; a wafer supply station for sequentially supplying semiconductor wafers externally and manually supplied thereto; a wafer placement station for transferring the wafers sequentially supplied from the wafer supply station to a predetermined location while rotating about a shaft; a die transferring device for picking up the semiconductor wafers (chips) placed at the predetermined location in the wafer placement station one by one and transferring each chip to a work site for the die bonding; a die bonding station for precisely bonding the die transferred by the die transferring device to a bottom surface where an adhesive tape is stuck in the lead frame which has been fed from the preheating station via a traveling rail; and a stocker for accommodating the lead frames to which each die of the semiconductor device has been bonded at the die bonding station while moving an internal magazine up and down.
It is preferable to form the lead frame supply station as a loading box so as to accommodate a plurality of lead frames therein.
The frame transferring device includes: a vacuum suction for picking up the lead frames which are piled up in the lead frame supply station; an up-and-down shifter for raising or putting down the lead frame by moving the vacuum suction up and down; and a right and left shifter for transferring the lead frame to the traveling rail or to the Ag epoxy application table by moving the vacuum suction and up-and-down shifter to the right and left.
The frame fixing station of the present invention includes: a vacuum pump for fixing the lead frame carried by the frame transferring device to the precise site on the Ag epoxy application table by adsorbing the lead frame from below; and a motor for moving the lead frame back and forth.
The Ag epoxy supply station includes: a nozzle for ejecting the predetermined amount of Ag epoxy on the site where the die will be placed in the lead frame which is temporarily fixed to the Ag epoxy application table; a pumping device connected to the upper portion of the nozzle, for pumping the predetermined amount of the Ag epoxy at a time with
Kim Seong-bong
Yeom Myeong-Kyu
Burns Doane Swecker & Mathis L.L.P.
Osele Mark A.
Purvis Sue A.
Samsung Electronics Co,. Ltd.
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