JP2001291748A - Probe card - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the ground structure of probes to be grounded and also to hardly peel the probes and to shorten the length between the probes and the ground plane on the surface of a printed wiring board in a probe card. SOLUTION: A conducting layer (35) is formed extending over the inner peripheral surface (23), holding surface (24) and outer peripheral surface (25) of a holding stand (22) provided on the rear of a printed wiring board (20). A ground pin (27) and the outer surface conductors of coaxial pins (29) are secured on the holding surface (24) with a conductive bonding agent (36). The inner peripheral surface (23) and a ground plane (38) on the surface of the wiring board (20) are connected with each other through conductor (39).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe card for use in testing the electrical characteristics of an electronic circuit die formed on a semiconductor wafer.

[0002]

2. Description of the Related Art An electronic circuit die formed on a wafer is inspected for quality by a prober and a tester. The probe card used for the prober includes an electronic circuit die. A plurality of probe needles are provided for electrical connection to the electrodes. The probe needle includes a power needle for supplying power to the circuit, a signal needle for obtaining test data, a ground needle for a common potential, and the like. A coaxial needle is used in which an insulating layer made of Teflon (registered trademark) or polyimide is formed around the needle and a conductor is provided on the outer surface for the high frequency signal.

Of the probe needles, the outer conductor of the coaxial needle and the ground needle are grounded on the ground surface formed on the printed wiring board of the probe card.
In order to improve the transmission characteristics, it is desired that the length between the tip of the needle and the ground portion be as short as possible. Therefore, conventionally, for example, a grounding structure as shown in FIG. 5 has been adopted. In the figure, a printed wiring board (1) in which wiring patterns for connecting to respective probe needles are formed in multiple layers.
An annular holding base (2) is provided on the back surface of the base. The holding base (2) has a grounding needle (3), a signal needle (not shown), a power needle, etc. It is fixed in 4). At this time, the probe needles are arranged side by side and fixed with a single resin layer, or the probe needles are dispersed in a plurality of layers in a laminated state and the probe needles are arranged, and a resin layer is provided for each layer and fixed. .
Then, a substantially triangular plate-shaped copper foil (5) having a sharp tip is formed, and a tip (6) of the copper foil (5) is protruded into a center hole (7) of the printed wiring board (1). Solder (8) to the shaft part of (3) and attach the base end (9) of the copper foil (5) to the ground plane (10) on the surface of the printed wiring board (1).
Was soldered (11).

[0004] As described above, the operation of soldering a copper foil having a substantially triangular plate shape with a sharp tip to each ground needle or the like involves a large number of ground needles, about 8% of the total number of probe needles. In addition, since a large number of probe needles are arranged in parallel at a very small interval, it must be performed with great care so as not to come into contact with other probe needles. Soldering to the like tends to be uncertain. In particular, when the probe needles are arranged in a plurality of layers, the ground needles are sometimes interrupted by the signal needles, the power supply needles, and the like located above, and it is sometimes impossible to reinforce the ground with copper foil. In addition, the shaft portion of the ground needle protruding into the center hole of the printed wiring board moves up and down when the needle tip hits the electrode during measurement and the needle pressure is applied. The portion became more easily peeled off, causing poor mechanical reliability.

[0005]

The problem to be solved by the present invention is as follows.
As described above, a probe car having a plurality of probe needles
In the probe, the grounding structure of the probe needle to be grounded can be easily manufactured, the soldered part is hardly peeled off, the reliability can be improved, and the length between the needle tip and the grounding part can be shortened. It is possible to reduce the ground impedance, improve the transmission characteristics of the coaxial needle with respect to high frequency, and reinforce the ground even with a multi-layered ground needle or the like that could not be conventionally reinforced. The purpose of the present invention is to provide a probe card as described above.

[0006]

According to the present invention, a conductive layer is formed on the inner peripheral surface on the center hole side of the annular holder provided on the printed wiring board, the holding surface for holding the probe needle, and the outer peripheral surface. The probe needle to be formed and grounded is fixed to the conductive layer on the holding surface with a conductive adhesive, and the conductive layer on the inner peripheral surface and the ground surface on the surface of the printed wiring board are connected by a conductor. The above-mentioned problem is solved by providing a probe card characterized by the following.

[0007]

FIG. 1 shows an embodiment of the present invention. In the drawing, a printed wiring board (20) has a wiring pattern and a through hole for connection to respective probe needles. However, those components are omitted in the figure. The printed wiring board (20) has a central hole (21) for projecting each probe needle as is well known, and is used to hold the probe needle facing the central hole (21). An annular holding base (22) is provided.

The holding table (22) is made of an insulating material such as ceramics, but may be made of a conductive material such as a metal material. The holding table (22) has an inner peripheral surface (23) on the side of the central hole (21) and a holding surface (24) inclined inward for holding the tip of the probe needle downward. ) And outer peripheral surface
(25) and the mounting surface to be mounted on the printed wiring board (20)
(26).

The ground needle (2) held on the holding surface (24)
7) Probe needles such as a power needle (28), a coaxial needle (29), a signal needle (30) are arranged radially in parallel with the holding surface (24) and an insulating resin such as an epoxy resin material. When the layers are fixed by the layer (31), they are provided in multiple layers with their phases changed in the vertical direction so that they do not contact each other, but one cross section shown in FIGS. 1 and 2 shows one ground needle. The needles that should not be conducted can be arranged in a single layer by covering them with an insulating film. The coaxial needle (2
9) As shown in FIG. 3, an insulating layer (33) such as Teflon or polyimide is formed outside the needle shaft (32), and a conductor (34) such as a copper pipe is provided on the outer surface. As is well known, it is suitably used as a probe for a high-frequency signal.

The inner peripheral surface (23) of the holding table (22) and the holding surface (2)
4), a conductive layer (35) is formed on the entire peripheral surface of the holder over the outer peripheral surface (25) and the mounting surface (26). This conductive layer (35)
The surface of the holding table (22) formed of a ceramic material or the like is formed in a thin film by nickel plating, copper, silver or other suitable conductive material by metal plating or sputtering. Can also be applied. Further, if the holding table is formed of a metal material having good conductivity, the surface itself can be used as a conductive layer without forming a thin film or the like separately.

[0011] Among the probe needles, the probe to be grounded
Needle, the ground needle (27) and the coaxial needle (2
The outer surface conductor (34) of (9) is fixed to the conductive layer (35) of the holding surface (24) with a conductive adhesive (36), for example, an epoxy-based adhesive containing silver powder. At this time, an annular receiving groove (37) may be formed on the holding surface (24) so that the adhesive (36) accumulates. In the embodiment shown in FIG. 1, the ground needle (27) and the like are electrically connected to the conductive layer (35) via the conductive adhesive (36), but are shown in FIG. As described above, the holding surface portions on either side of the receiving groove (37) or any one of the portions (not shown) may be connected to the conductive layer (35).

The conductive layer (35) on the inner peripheral surface (23) and the ground surface (38) formed on the surface of the printed wiring board (20) are made of a conductor, in the figure, a strip-shaped copper foil ( 39) are connected by soldering (40) between them. The conductor may be provided at a position corresponding to each ground needle, coaxial needle, or the like, may be provided in an appropriate number in an appropriate position, or may be formed by applying a conductive paint instead of a copper foil.

A base end of the ground needle (27) is connected to a ground surface (41) provided on the printed wiring board (20).
Also, the conductive layer (35) on the outer peripheral surface (25) and the ground surface (4
Although the conductive adhesive (42) is filled and connected between 1), the conductive adhesive (42) may be connected with a conductive paint or another conductor.

FIG. 4 shows an embodiment of ground reinforcement when probe needles are dispersed and fixed in a plurality of layers. As shown in FIG. 3B, on the lower surface of the conductive layer (35) of the holding table (22), the first, second, third, and fourth resin layers ( 31a), (31b), (31c), and (31d) are provided, and prong needles are arranged and fixed to each resin layer. And
For example, a ground needle (2) to be grounded to the second resin layer (31b)
5), in the conventional structure as shown in FIG. 5, it is difficult for the signal needle (30), the power needle (28) and the like existing in the upper part of FIG. In such a case, a cut is made in the third resin layer (31c) as shown in the figure.
(43), the conductive adhesive in the fourth resin layer (31d)
The conductive adhesive (36) may be provided to the second resin layer (31b) through the cut (43) so as to conduct with the (36).
At this time, if the conductor (44) such as a metal piece is embedded in the cut (43), the conductivity of the conductive adhesive can be increased.

[0015]

The present invention is constituted as described above,
A conductive layer is formed on the inner peripheral surface, the holding surface and the outer peripheral surface of the holding table for holding the probe needle, and a probe needle to be grounded is fixed to the conductive layer on the holding surface with a conductive adhesive, and The conductive layer on the surface and the ground plane on the surface of the printed wiring board are connected by a conductor, so that the troublesome work of soldering the tip of copper foil to the shaft part of the ground needle etc. as in the past has been done. It is not necessary to carry out the process, the production is simple, and it has become possible even for a needle which cannot conventionally be ground-reinforced.
Also, since the structure is not soldered to the movable part of the needle, there is no danger that the soldered part will peel off.In addition, since the inner peripheral surface and the ground surface are directly connected by a conductor, the grounding structure is reinforced and The length between the needle protruding from the center hole of the printed wiring board and the ground plane can be shortened, the ground impedance of the ground needle can be reduced, the transmission characteristics of the coaxial needle for high frequencies are improved, and When the ground surface of the printed wiring board is made conductive, more excellent characteristics can be obtained and the measurement can be performed efficiently.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention and is a partially cutaway perspective view of a probe card.

FIG. 2 is a partially cutaway perspective view showing a probe card according to another embodiment of the present invention.

FIG. 3 is a sectional view of a coaxial needle.

4A and 4B are explanatory views showing a state in which probe needles are arranged in multiple layers, wherein FIG. 4A is a perspective view in which a resin layer is omitted, and FIG.

FIG. 5 is a partially cutaway perspective view of a probe card, showing a conventional example.

[Description of Signs] 20 Printed Wiring Board 22 Holder 23 Inner Peripheral Surface
24 Holding surface 25 Outer peripheral surface 26 Mounting surface 27 Ground needle 28 Power needle 29 Coaxial needle 30 Signal needle
35 Conductive layer 36,42 Conductive adhesive 38,41 Ground plane 43 cut

Claims (4)

[Claims] An annular holding base is provided on a printed wiring board for holding probe needles, and holds the inner peripheral surface of the holding base on the center hole side of the printed wiring board and the probe needles. A conductive layer is formed over the holding surface and the outer peripheral surface to be grounded, a probe needle to be grounded is fixed to the conductive layer on the holding surface with a conductive adhesive, and the conductive layer on the inner peripheral surface and the surface of the printed wiring board are fixed. A ground plane connected by a conductor. 2. The probe card according to claim 1, wherein an outer peripheral surface of said holding table and a ground surface of said printed wiring board are connected by a conductive adhesive. 3. The probe needles are arranged in multiple layers on the holding surface of the holding table, and the probe to be grounded exists in each layer.
2. The probe card according to claim 1, wherein the probe needles are electrically connected by a conductive adhesive provided between the layers. 4. The probe card according to claim 3, wherein a conductor is inserted in a conductive portion provided by a conductive adhesive provided over the layers.