Metal fusion bonding – With means to juxtapose and bond plural workpieces – Wire lead bonder
Patent
1988-02-18
1989-11-07
Godici, Nicholas P.
Metal fusion bonding
With means to juxtapose and bond plural workpieces
Wire lead bonder
228 62, 228101, B23K 3700
Patent
active
048786098
DESCRIPTION:
BRIEF SUMMARY
The present invention is directed to an apparatus for manual wire bonding as specified in the preamble of claim 1.
In microelectronics, bonding generally means the interconnection of components by cementing or welding as compared to normal soldering, in which the connections are made by means of solder (mostly a tin-lead alloy). One distinguishes between chip (die) bonding methods for mounting a component on a supporting substrate and wire bonding methods for connecting the component terminals to the substrate or, respectively, the contact pads of component and substrate by means of fine wires.
The present invention deals with the last-mentioned method, in which the so-called thermocompression bonding or ultrasonic wedge bonding is used. The bonding wires used are gold or aluminum wires of greater or smaller size. For certain cases, thermocompression bonding and ultrasonic bonding are combined. In that case one speaks of thermosonic bonding, as it is called, in which mostly gold wire is used which, similar to ball bonding, is melted off to form a ball, and welding or bonding takes place at a moderate heat (150.degree. to 160.degree. C.) by means of ultrasonic energy. This method can be well controlled and well automated. The use of aluminium wire is a further development of the thermosonic method. Melting-off takes place under forming gas so as to obtain an oxide-free surface. The use of the one or other bonding method depends substantially on the type and volume of the respective circuit design.
The above-mentioned bonding methods are mostly carried out by fully automatic bonding apparatus. But the hardware and software required therefor is highly complex and is not necessary in many cases.
It is therefore the object of the present invention to provide an apparatus for manual wire bonding which, while causing relatively little design effort, is easy to handle, operates accurately and can be adapted to a variety of external conditions.
In accordance with the invention the specified object is solved by the characterizing features of patent claim 1 and one or several of the further claims, respectively.
The significance of the invention resides in the variability and therefore the wide variety of possible applications while being extremely easy to handle, so that such an apparatus can also be successfully used in threshold countries. Moreover, the apparatus according to the invention is especially suited for performing bonding tests and pull tests. With the apparatus according to the invention it is also possible in an extremely simple way to determine the bonding conditions which must be observed for automated bonding. This applies especially to the movements to be performed by the bonding head in respect of distance and speed and the matching of empirical compression and/or ultrasonic and/or heating periods with the sequence of motions of the bonding head. At the same time, the control of the wire clamp can readily be matched with the movement of the bonding head. The function feedback provided in accordance with the invention is of particular significance. Every single function of the bonding head is checked for proper execution. When the counter-check indicates that the function has not been executed, the bonding operation is interrupted and must be restarted manually. Prior to restarting, the source of error can be checked and eliminated. Thereby it is also possible to considerably reduce the rate of rejects, which has so far been practically impossible with manual wire bonding.
For moving the bonding head and controlling the movements thereof a d.c. motor is especially suited, which is due to the characteristic of said motor. Basically, of course, other drive units such as stepping motors could also be used. But in all cases the counter-check of the movements performed by the bonding head and the movable units associated therewith, for instance wire clamp or vibration damping means, is important. Thus, the apparatus according to the invention is not only intended to be easily and individually adjustabl
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Emhart Industries Inc.
Godici Nicholas P.
Skillman Karen
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