JPH06140484A - Probe card - Google Patents

Abstract

PURPOSE:To provide an inspection jig which can be used for inspecting the high-speed and high-frequency areas of an IC mounted on a package containing input-output terminals arranged in an array-like state. CONSTITUTION:This card is provided with a ceramic substrate 1 and wiring layer 5 formed on the substrate 1 and the layer 5 is composed of a resin insulating layer 2, ground layer 4 formed in the film 2, and lead-out signal lines 3 formed so that their characteristic impedances can be controlled to the thickness of the film 2 to the layer 4. Then connection pads 6 which are formed on the surface of the wiring layer 5 and connected to the input-output terminals of an IC to be inspected are electrically connected to probe pads 7 which are formed on the surface of the substrate 1 and become input-output terminals for signals for inspection through the signal lines 3. In addition, thin film resistances 9 for termination and thin film by-pass capacitors 10 for reducing noise are formed on the surface of the wiring layer 5 or substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe card which is an IC inspection jig mounted on a package in which input / output terminals are arranged in an array.

[0002]

2. Description of the Related Art An outline of an IC mounted in a package in which input / output terminals are arranged in an array is shown in FIGS.
Will be explained. FIG. 3A shows a pin grid array (P) having input / output terminals 11 in which pins are arranged in an array.
GA) IC12 mounted in a package, as shown in FIG.
FIG. 3B is an upside-down view of FIG.
FIG. 4 shows the shape of the IC 32 mounted in a pad grid array (PGA) package using pads as input / output terminals 31 instead of pins. FIG. 4B is an upside-down view of FIG. 4A. Since the structure is the same as that of the IC (hereinafter referred to as PGA-IC) 12 mounted in a pin grid array (PGA) package having the pins as the input / output terminals 11 of FIG. 3, the pins will be used in the following description. Figure 3) is represented by the type.

A conventional PGA-IC electrical characteristic inspection method will be described with reference to FIG. The PGA-I is attached to the connection pad 22 of the probe card using the printed wiring board 13 as shown in FIG.
The C12 is mounted on the printed wiring board 13 using bumps or the like, the inspection pad 15 and the probe connector are electrically contacted, and a DC power supply, a pulse generator, a pulse waveform observation device, etc. are connected, and an electrical characteristic inspection is performed. It is carried out. PGA-IC1 in the high frequency range where the clock exceeds several tens MHz
In the inspection of No. 2, it is necessary to match the characteristic impedance of the signal line 14 in the expanded portion of the wiring to suppress the reflection distortion of the signal. Further, it is necessary to mount the terminating chip resistor 16 and the noise reducing bypass capacitor 17 on the printed wiring board.

FIG. 6 shows an outline of the PGA-IC12 having 364 terminals as an example of the case of inspecting the actual PGA-IC12.
It shows in (a). In addition, FIG. 6B shows the PGA-IC1.
2 shows a state in which a lead wire 43 is formed on the printed wiring board 13 to develop the second terminal. In the printed wiring board 13, as shown in FIG. 6B, the arrangement of one pin between the through holes in the zigzag arrangement of 1.27 mm is almost the limit. Therefore, it is difficult to further reduce the terminal pitch of the PGA-IC12 to 1 mm or less.
Cannot be miniaturized. Further, in order to inspect the PGA-IC 12 having 364 terminals shown in FIG. 6A, if the signal terminal 41 is surrounded by the ground (GND) terminal 42 as shown in FIG. Requires 3 layers. If a stripline structure is used to control the characteristic impedance, seven or more layers including the GND layer are required. If the number of signal terminals increases, the pitch must be expanded or the number of layers must be increased, which is not practical. Specifically, it is considered possible to develop the lead-out signal lines by applying the limits of the current printed wiring board manufacturing technology to the pitch between the lead-out lines, and using multiple layers, but it is necessary to install the necessary number of terminals. The area is so large that it is not practical.

In addition, since the printed wiring board 13 cannot be finely processed, the thickness between layers cannot be made thin and uniform, so that the characteristic impedance cannot be controlled with high precision.

In addition, disadvantageously, the terminating chip resistor 16 and the bypass capacitor 17 are soldered to the front surface or the back surface of the printed wiring board, and their dimensions are as large as several mm square. For this reason, since the size is as large as several mm square, it cannot be placed in the immediate vicinity of the PGA-IC 12, so PGA-
Not only wiring for connecting the IC and the chip components 16 and 17 is required, but also a bonding pad 18, a bonding wire 19 and the like are required, and unnecessary inductance,
Capacitance is added, resulting in deterioration of high frequency characteristics. Therefore, the lead wire 1 of the printed wiring board 13
In Nos. 4 and 43, the electrical characteristics that affect high-speed signal propagation cannot be controlled with high precision, so even if a coaxial probe capable of observing a pulse waveform up to several Gb / s is used for inspection, The pulse waveform is greatly distorted during propagation, and only DC or pulse waveforms up to about 100 Mb / s can be observed.

[0007]

As described above, the conventional technique has a problem that the pad pitch of the inspection jig cannot be made small, so that the PGA-IC package cannot be made small in order to secure a space for development. Also, when inspecting a PGA-IC with a relatively small number of terminals, 10
It was difficult to inspect a high frequency region of 0 Mb / s or more.

An object of the present invention is to solve the above-mentioned problems in the prior art and to provide an inspection jig capable of inspecting a PGA-IC in a high speed / high frequency region.

[0009]

In order to achieve the above object, in the present invention, a probe card which is an IC inspection jig mounted in a package in which input / output terminals are arranged in an array. In, a ceramic substrate,
A wiring layer formed on the substrate, wherein the wiring layer is formed by a resin insulation film, a ground layer formed in the film, and a characteristic impedance controlled by the resin insulation film thickness up to the ground layer. Connection lead pad formed on the surface of the wiring layer and connected to the input / output terminals of the IC to be inspected, and the input of the inspection signal formed on the surface of the wiring layer or the ceramic substrate. A probe pad serving as an output terminal is electrically connected by the lead-out signal line, and a thin film resistor for termination and a thin film bypass capacitor for noise reduction are formed on the surface of the wiring layer or the ceramic substrate. To do.

[0010]

According to the present invention, in a PGA-IC inspection jig, a stripline structure, a microstripline structure, or a coplanar structure, which uses an input / output terminal for signals and the like and a resin insulating film for electrically connecting the two, is used. Construction,
Alternatively, it is composed of a signal line that controls the characteristic impedance of these mixed structures and a power supply line that supplies the voltage required for the PGA-IC, and also has a built-in thin film terminating resistor that matches the characteristic impedance and has good high-frequency characteristics. In addition, the probe card is characterized by having a built-in thin film bypass capacitor for reducing power supply noise with good high-frequency characteristics in the required parts. It is a high-density, multi-terminal PGA-IC high-speed / high-frequency region electrical characteristic test. Can be easily performed.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the probe card according to the present invention. FIG. 1A is a plan view and FIG. 1B is a sectional view. However, in FIG. 1B, for convenience of illustration, the positions of the pads, the input / output terminals and the like are changed from those in FIG. 1A. The probe card 8 is a wiring layer 5 having a stripline structure including a resin insulating film 2 formed on a ceramic substrate 1, lead-out signal lines 3 and a ground layer 4.
And a connection pad 6 formed on the surface of the wiring layer 5 and a probe pad 7 serving as an input / output terminal for an inspection signal or the like, and the connection pad 6 and the probe pad 7 have a strip line structure. Are electrically connected by.
Using this probe card 8, the input / output terminal 11 of the PGA-IC is directly connected to the connection pad 6 by using a bump or the like, and the coaxial probe pin is electrically contacted with the probe pad 7 for inspection. At this time, press PGA-I
C and the probe card 8 may be fixed.

In this embodiment, a polyimide resin having a low dielectric constant is used as the resin insulating film of the wiring layer 5, and copper having a low resistivity is used as the signal line conductor. The copper polyimide wiring, thin film resistor, and thin film capacitor are formed by photolithography. For example, a wiring layer using a polyimide resin insulating film can form a high-density wiring having a signal line width of 25 μm and a signal line gap of 75 μm, so that a high-density multi-terminal PGA-IC can be inspected. Further, the characteristic impedance of the signal line 3 can be easily controlled to an arbitrary value and highly accurately. FIG. 2 shows the relationship between the polyimide resin insulation film thickness (gap between the signal line and the ground layer) and the characteristic impedance when the width of the signal line is 30 μm and the thickness is 5 μm. By controlling the film thickness of the resin insulating film 2 as compared with the conventional technique, a desired characteristic impedance can be obtained with high accuracy without depending on the material, the width of the lead-out signal line 3, and the like. Further, since the probe pads 7 are also formed by photolithography similarly to the wiring layer 5, the probe pads 7 can be arranged with a narrow interval pitch with high accuracy. Further, the probe card 8 can be formed in an arbitrary size without depending on the shape of the PGA-IC, and the probe pad 7 can be arranged on the entire surface of the probe card 8 excluding the PGA-IC mounting region. In addition, a thin film termination resistor 9 matching the characteristic impedance of the signal line is formed on the ceramic substrate 1, and a PGA-IC terminal (pin or pad) that requires a termination resistor for the purpose of reducing signal reflection distortion. The connection pad 6 for connection with the thin film termination resistor 9 is connected with the signal line 3. In the present invention, the thin film terminating resistor 9 is also formed by photolithography similarly to the wiring layer 5, so that the thin film terminating resistor 9 can be formed on the ceramic substrate, and the connecting pad 6 and the ground layer 4 can be formed in a compact and shortest distance. Since it can be inserted between them, unnecessary inductance and capacitance can be reduced to a negligible level, and impedance matching with the signal line can be achieved with high accuracy. Further, since a resistance of about 50Ω can be formed in a square of several 100 μm, the thin film termination resistor 9 can be formed with high density. Since it is possible to reduce the reflection distortion of the signal that interferes with the measurement in the high speed / high frequency region, it is possible to control the characteristic impedance of the signal line with higher accuracy during the PGA-IC operation.

Further, the ceramic substrate 1 has wiring for power supply, and supplies a required voltage to the PGA-IC through a power supply line (not shown) formed in the wiring layer 5. A thin film bypass capacitor 10 for reducing power source noise is formed on the power supply line on a wiring layer or on a ceramic substrate. Here, the bypass capacitor 10 is PGA-
It is important to insert the IC in the immediate vicinity of the connection pad 6 of the IC, but in the present invention, the bypass capacitor 10 can be formed by photolithography similarly to the wiring layer 5 and can be formed by 1 mm.
Since the capacitance of several hundred pF is possible at each corner, the thin film bypass capacitor 10 can be formed on the wiring layer or the ceramic substrate with high density and can be inserted between the connection pad 6 and the ground layer 4 in the shortest distance. Therefore, a small-sized, high-density and large-capacity bypass capacitor can be easily formed, and the power supply noise that has hindered the measurement in the high speed / high frequency region can be reduced.

The above-described technique of forming the copper polyimide wiring, the thin film resistor, the thin film capacitor and the like by photolithography enables the inspection of the small multi-terminal PGA-IC in the high speed / high frequency region.

In the embodiment of FIG. 1 described above, the connection pad 6 and the probe pad 7 are electrically connected by using the one-layer signal line 3 having a stripline structure whose characteristic impedance can be easily controlled. A signal line having a multilayer stripline structure may be used, and a microstripline structure which is another structure capable of controlling characteristic impedance,
Alternatively, a signal line such as a coplanar structure may be used,
Furthermore, the stripline structure and the microstripline structure may be mixed or the stripline structure and the coplanar structure may be mixed.

Further, although the probe pad 7 is arranged on the front surface of the probe card in this embodiment, it may be arranged on the rear surface of the ceramic substrate 1 via the wiring (and the via) in the ceramic substrate 1. Further, a coaxial connector may be arranged instead of the probe pad 7 on the edge portion or the back surface of the ceramic substrate, and the coaxial cable may be directly connected to be connected to the inspection system device. Further, Teflon or the like having a low dielectric constant may be used as the resin insulating film 2, and metal such as gold or Ni may be used as the conductor material of the signal line 3 or the like. In addition, although the above-mentioned embodiment explained the case for PGA-IC inspection, the present invention is not limited to QF
It can also be applied to the inspection of an IC in a mounting form such as a P-IC.

[0018]

INDUSTRIAL APPLICABILITY In a PGA-IC inspection jig, a connection pad connected to a terminal of a PGA-IC mounted on a wiring board, an input / output terminal for signals, etc. are electrically connected to each other. By using a probe card composed of a stripline structure using a resin insulating film, a microstripline structure, a coplanar structure, or a signal line whose characteristic impedance is controlled in a structure in which these are mixed, a PGA-IC High-speed PGA-IC with multiple terminals, independent of terminal shape, layout, etc.
It becomes possible to easily perform the electrical characteristic inspection in the high frequency region. Further, since the PGA-IC can be inspected in the form of being mounted on the wiring board, the inspection close to that in practical use is possible.

[Brief description of drawings]

FIG. 1A is a plan view showing an embodiment of the present invention, FIG.
(B) is a sectional view.

FIG. 2 is a diagram showing a relationship between a resin insulation film thickness and a characteristic impedance of a lead-out signal line.

FIG. 3 (a) of a PGA-IC having pins as input / output terminals
Is a perspective view, and (b) is a perspective view showing (a) inverted upside down.

FIG. 4A is a perspective view of a PGA-IC using pads as input / output terminals, and FIG. 4B is a perspective view of FIG.

5A and 5B are diagrams showing a conventional probe card, in which FIG. 5A is a plan view and FIG. 5B is a sectional view.

6A and 6B are diagrams showing a terminal arrangement example of a PGA-IC having 364 terminals, FIG. 6A is a plan view, and FIG. 6B is an enlarged view showing a state in which the terminals are developed into lead lines.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ceramic substrate 2 ... Resin insulating film 3 ... Lead-out signal line 4 ... Ground layer 5 ... Wiring layer 6 ... Connection pad 7 ... Probe pad 8 ... Probe card 9 ... Thin film termination resistor 10 ... Thin film bypass capacitor 11 ... Input / output terminal 12 ... PGA-IC 13 ... Printed wiring board 14 ... Lead-out signal line 15 ... Inspection pad 16 ... Termination chip resistor 17 ... Bypass capacitor 18 ... Bonding pad 19 ... Bonding wire 20 ... Ground terminal 21 ... Ground wire 22 ... Connection Pad 31 ... Input / output terminal 32 ... PGA-IC 41 ... Signal terminal 42 ... Ground terminal 43 ... Development lead wire

Claims (1)

[Claims] 1. A probe card, which is an IC inspection jig mounted in a package in which input / output terminals are arranged in an array, comprises a ceramic substrate and a wiring layer formed on the substrate. The wiring layer includes a resin insulating film, a ground layer formed in the film, and a lead-out signal line formed by controlling the characteristic impedance by the resin insulating film thickness up to the ground layer, The lead-out signal includes the connection pad formed on the surface of the wiring layer and connected to the input / output terminal of the IC to be inspected, and the probe pad formed on the surface of the wiring layer or the ceramic substrate and serving as the input / output terminal of the inspection signal. A thin film resistor for termination and a thin film bypass capacitor for noise reduction, which are electrically connected by wires, are formed on the surface of the wiring layer or ceramic substrate. , A probe card characterized by the following.