Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With rotor
Reexamination Certificate
1999-06-22
2001-10-16
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With rotor
C324S757020, C324S755090
Reexamination Certificate
active
06304073
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an IC testing apparatus for testing one or more semiconductor integrated circuit devices and other various electric devices (hereinafter referred to as an “IC” or “ICs” to represent them), more particularly relates to an IC testing apparatus which excels in attaining a uniformity of a pressing force against a contact portion of an IC to be tested.
2. Description of the Related Art
An IC testing apparatus called a “handler” conveys a large number of ICs held on a tray to the inside of a testing apparatus where the ICs are made to electrically contact a test head, then the IC testing unit is made to perform the test. When the test is ended, the ICs are conveyed out from the test head and reloaded on trays in accordance with the results of the tests so as to sort them into categories of good ICs and defective ones, etc.
In an IC testing apparatus of the related art, the trays for holding the DUTs (Devices under test) to be tested or the tested DUTs (hereinafter referred to as “customer trays”) and the trays conveyed circulated inside the IC testing apparatus (hereinafter referred to as the “test trays”) are different in type. In this type of IC testing apparatus, the ICs are switched between the customer trays and the test trays before and after the test. In the test process where the ICs are tested by being brought into contact with the test head, the ICs are pushed against the test head in the state held on the test trays.
In test processing of an IC testing apparatus of the related art, an IC to be tested is pressed against contact pins by lowering a press mechanism called pusher. The lowering limit of the pusher is decided by a stopper which makes the distance between the pusher and the contact portion a predetermined distance.
However, there exists not a small production error between a thickness of an IC to be tested itself (the error is defined as &Dgr;X), a production dimension of the stopper on the pusher side and the pusher surface (the error is defined as &Dgr;Y), and a production dimension of the stopper on the contact portion side and tips of the contact pins (the error is defined as &Dgr;Z), and the multiplied amount of &Dgr;X to &Dgr;Z normally becomes as much as about ±0.1 to ±0.2 mm.
Therefore, when the multiplied error of &Dgr;X to &Dgr;Z becomes, for example, +0.04 mm, as shown in a pusher stroke-load curve in
FIG. 13
, a load of 45 gf/1 ball is actually acted on the IC to be tested for the reference load of 25 gf/1 ball (in this case, it is sufficient if the pusher stroke is set at 0.18 mm). This causes a fear that the IC is damaged or broken. Contrary to this, when the multiplied error of &Dgr;X to &Dgr;Z varies, for example, by −0.1 mm to the minimum side, it is liable that a sufficient press force cannot be obtained and the test cannot be carried out.
Though the total error can be reduced by improving respective dimension precision of the pusher and the contact portion, there is a certain limit to attaining such dimension precision. Moreover, since dimension precision of a package mold is quite rough in chip size packages (CSP), etc., the production error &Dgr;X becomes large when an IC to be tested is a CSP chip. Therefore, only attaining higher precision of the pusher and contact portion is not enough as a countermeasure.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an IC testing apparatus which excels in giving a unified press force to a contact portion of an IC to be tested.
(1) According to the present invention, there is provided an IC testing apparatus for testing by pressing input/output terminals of DUTs to a contact portion of a test head, comprises a pusher base provided movably and close to but away from the contact portion, a pusher block provided on the pusher base for pressing the DUTs by contacting the same from the opposite side of the contact portion, and an elastic part for giving an elastic force to the pusher block in the direction of pressing the DUTs.
In an IC testing apparatus of the present invention, when the input/output terminal of the IC to be tested is pressed against the contact portion of the test head, the pusher base is made close to the contact portion and the IC is pressed against the contact portion side by a pusher block.
At this time, positional relationship of the pusher base and the contact portion is regulated/controlled to be a reference dimension by a mechanical mechanism of the stopper, etc. and an electric mechanism of an electric motor, etc. However, when an error arises in the positional relationship of the pusher base and the contact portion, the pusher block absorbs the error while biasing an elastic force on the IC to be tested by an elastic part. Accordingly, it can be prevented that an excessive press force acts on the IC, or the press force of the pusher is insufficient oppositely, etc. Namely, in the IC testing apparatus of the present invention, the press force to the IC is unified not by controlling strokes of the pusher but by controlling the load by the pusher block.
The elastic part according to the present invention is not specifically limited and a variety of elastic bodies and actuators, such as a coil spring, can be used. Also, the elastic part can be provided to any parts other than the pusher base.
As a main error arisen in the positional relationship of the pusher base and the contact portion, a thickness of an IC to be tested itself &Dgr;X, a production dimension of the stopper on the pusher side and the pusher surface &Dgr;Y, and a production dimension of the stopper on the contact portion side and tips of the contact pins &Dgr;Z can be considered, and as explained in the above, the multiplied amount of &Dgr;X to &Dgr;Z becomes as much as about ±0.1 to 0.2 mm. However, when considering a case of using, for example, a coil spring as the elastic part, the error of the press force acting on the IC to be tested becomes about ±3 gf/1 ball with respect to the reference load of 25 gf/1 ball, for example, even when an error of 2 mm arises. Therefore, there is no disadvantage of an excessive load not a load shortage.
(2) In the IC testing apparatus of the present invention, the form of transferring the IC to be tested to the contact portion is not specifically limited, and it also includes a type of pressing the IC to the contact portion by a suction head while carrying the IC by suction and a type of pressing the IC to the contact portion while carrying the IC on a tray. Especially in the latter type, since a large number of ICs are simultaneously pressed for testing a large number of ICs simultaneously, an error is easy to be arisen in the positional relationship of the pusher and the contact portion. Accordingly, a type of pressing the IC to the contact portion in the state the ICs are carried by trays is preferably applied in the present invention.
(3) In an elastic part according to the present invention, it is not specifically limited, but it is preferable that the elastic force of the elastic part is made variable.
The variability of the elastic force means that the elastic force given to the pusher block in the direction of pressing the IC to be tested is made changeable, and specific means is not specifically limited.
For example, making the elastic force variable by exchanging a plurality of kinds of elastic part having a different elastic modulus, or making the elastic force variable by using the same elastic part and changing a reference length thereof can be mentioned.
By making the elastic force of the elastic part variable, even if the reference load (press force) changes in accordance with test conditions of an IC to be tested and others, it becomes possible to flexibly deal with the changes, therefore, the IC testing apparatus becomes more general purpose.
(4) To attain the above object, according to another aspect of the present invention, there is provided an IC testing apparatus for testing one or more semiconductor devices
Advantest Corporation
Birch & Stewart Kolasch & Birch, LLP
Deb Anjan K
Metjahic Safet
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