JPH11211800A - Probing device for ic package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the probing of an IC package, especially a VLSI package with remarkably high density and high speed and at the same time measure a signal accurately by arranging a near magnetic field probe so that it is in the same arrangement as the lead terminal of the IC package. SOLUTION: The single substance probe of a group of near magnetic field probes is placed on a substrate 1, and a coil 2, a lead wire 3, and a pad 4 are formed by a conductive thin film. The single substance probe is allowed to correspond to the pitch of a lead 10 of an LSI package 9, and the chip of a probe array 8 that is formed while being arranged in a plurality of arrays is applied to a support 8 so that it corresponds to the lead 10. The lower edge of the support 8 is engaged to the lead 10 of the VLSI package 9 for mounting, and each near magnetic field probe on the support 8 is electrically connected to such measuring instrument as a spectrum analyzer and an oscilloscope for measurement. In this manner, since a non-contact-type near field magnetic field is used, a current signal can be measured accurately without being affected by a load effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic copying machine, a facsimile,
When detecting electric signals of various electric and electronic equipment systems such as printing presses, personal computers and other office electronic equipment, home electric equipment, industrial equipment, etc., especially when performing operation check and failure analysis of IC packages such as VLSI packages, This is a so-called near-magnetic field probe that performs current detection by approaching the lead wire of an IC package, and can perform accurate signal measurement by eliminating the effect of the load effect of the probe when probing high-frequency signals. It is.

[0002]

2. Description of the Related Art Packaging technology for ICs, especially VLSIs, has been developed and spread due to demands for high reliability, high speed, high density, and heat dissipation, and various forms of packages have been developed depending on applications. These VLSI packages are mounted on portable equipment, personal computers, home appliances, and office equipment, etc. In order to realize miniaturization, weight reduction, and multi-functionality, the number of pins of input / output terminals is increased and the pitch of pins is narrowed. ing. QFP
(Quad Flat Package), MCM (Multi Chip Modul)
As shown in e) and the like, there are many VLSI package leads having a 0.5 mm pitch or 0.3 mm pitch, and a number of pins of 100 to 300 or more. When a circuit system is assembled on a printed circuit board using these package components, it becomes necessary to analyze the operation of the circuit system. However, as described above,
The lead pitch of the SI package is becoming very narrow, and in order to perform motion analysis, it is necessary to repeatedly perform the inoperable work of measuring the probe by contacting it with the very thin lead of the package. did not become. To this end, various probing accessories are provided by various companies (for example, HP E5331A of Hewlett-Packard Co., Ltd.) in order to make the above operation easier and save time required for operation analysis and countermeasures.

[0003]

However, since these conventional probes are all contact-type probes, when probing a high-frequency signal, a problem that the waveform of the measured signal is distorted due to a load effect becomes apparent. It will become. Therefore, it is very difficult to perform accurate signal measurement and operation analysis, and when accurate evaluation is required,
Complicated measures were required, such as the need to correct the measurement results. In view of the above, the present invention provides
An object of the present invention is to devise a probing method so that a C package, in particular, a VLSI package having a remarkably high density and high speed can be easily probed and an accurate signal measurement can be easily realized. .

[0004]

[Means for Solving the Problems]

A first solution for solving the above-mentioned problem employs a so-called near-field probe which detects a magnetic field generated by a current flowing through a lead in a non-contact manner.
That is, they are arranged in the same arrangement as the lead terminals of the C package.

[0005]

A second solution is to form a near-magnetic field probe in the first solution by forming a thin film or a thick film on a substrate.

[0006]

A third solution is to form the near-magnetic field probe by forming a thin film or a thick film on an insulating substrate, and the probe surface has the same arrangement as the lead terminals of the IC package. That is, a plurality of such layers are stacked.

[0007]

The present invention employs a so-called near-field probe which detects a magnetic field generated by a current flowing through a lead in a non-contact manner, so that a current flowing through the lead in a non-contact manner can be measured. Therefore, it is possible to obtain an accurate signal waveform without causing a problem of waveform distortion due to a load effect, which is inevitable with a conventional contact-type probe (measuring voltage), and is required for operation analysis and measures. You can save time. Moreover, since the near-field probes are arranged in the same arrangement as the lead terminals of the IC package, the near-field probe can be easily and reliably positioned with respect to each lead, and accurate signal measurement can be performed.

Further, by forming a probe with a thin film or a thick film, a minute coil and a transmission line can be formed, so that it is possible to cope with a narrow pitch of leads of an IC package.

Further, a near-field probe is formed by a thin film or a thick film on an insulating substrate, and the probe surface is formed by an IC.
By stacking a plurality of near-field probes in the same arrangement as the lead terminals of the package, the pitch of the near-field probes can be further reduced as compared with a case where the near-field probes are arranged on the same plane, and further increase in the lead terminals It is possible to cope with a narrow pitch. When the near-field probes are arranged on the same plane, the probe area is restricted by the lead pitch. In this case, the probe area is perpendicular to the lead terminal surface, so that the probe area is , The area of the coil (in the case of a magnetic field sensor such as an MR element, the area of the magneto-sensitive surface) can be increased, and higher-sensitivity measurement can be performed.

[0010]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a single probe of a group of near-magnetic field probes used in the probing apparatus of the present embodiment. This probe is provided on a substrate 1 with a coil 2 for detecting a magnetic field generated from a current flowing through a lead. , Lead lines 3 and pads 4 are formed of a conductive thin film. In this embodiment, the transmission line constituted by the lead wire 3 is formed by a coplanar guide in order to obtain impedance matching in a high frequency region.

In the production of a probe, in particular, VLSI
It is necessary to use photolithography technology and thin film patterning technology when forming a fine probe corresponding to a lead with a narrowed pitch like a package. However, depending on the lead pitch of the IC package, a screen may be appropriately used. A thick film forming technique such as printing can also be used.

In this embodiment, a photolithography technique and a thin-film patterning technique are used to obtain a 525 μm thick film.
An Al film having a thickness of about 1 μm was formed on a quartz substrate having a thickness of m 2 by a sputtering method or a vacuum heating evaporation method. The substrate only needs to have an insulating property, and the film material may be a conductive material such as Cu and Pt in addition to Al.

Thereafter, a resist layer is formed on the substrate for patterning the coil and the lead wire. The resist of a desired pattern portion is left by photolithography, and the resist is removed using an RIE (Reactive Ion Etching) apparatus.
Dry etching is performed using a chlorine-based gas such as Cl ₃ or CCl ₄ . When performing etching such films, large minimum line width of the formed pattern, when the side etching is not an _{issue, H3PO 4 + HNO 3 + CH} 3 C
It may be formed by wet etching using OOH + H ₂ O. After the etching, the remaining resist is removed by an ashing device, and then SiO ₂ is formed by sputtering to form an insulating film of about 1 μm. Of course, the process of forming the insulating film is performed by CVD (Chemical Vapor Deposition).
Depending on the device.

Next, a pattern is formed by photolithography in the same manner as described above, and RIE (Reactive Ion Etchi
ng) Using a fluorine-based gas such as CF _{4 in the} device,
The window frame is opened to remove the SiO ₂ from the pad portion and obtain an electrical connection. In this embodiment, the transmission line is formed by a coplanar guide in order to obtain impedance matching in a high frequency region. The combination of the size of the center conductor of the coplanar guide and the distance between the ground conductor and the center conductor is appropriately determined according to the dielectric constant, thickness, and the like of the substrate.

The above is the structure and method of forming a single probe. In the probing apparatus of the present embodiment, the single probe is connected to an IC package such as VL as shown in FIG.
A plurality of arrays are formed so as to correspond to the leads of the SI package. That is, a plurality of thin-film single probes 5 composed of coils, lead wires, and pads are formed in an array on the substrate 6 so as to correspond to the lead pitch of the VLSI package.

Specifically, the patterns of the single probes described above are formed in an array in a photolithography process. In the present embodiment, the pitch of the probe array was 0.5 mm for a lead of 0.5 mm pitch, and the probe array was formed on a quartz substrate. This probe array is diced into a desired size to form a chip.

As shown in FIG. 3, a chip of a probe array 7 formed by arranging a plurality of thin film single probes 5 on a substrate 6 in an array is used as a VLSI package, for example, a QFP (Quad Flat Package). ) Is attached to the support 8 so as to correspond to the lead of ()). The lower end of the support 8 is connected to a lead 10 so as to be in close contact with the VLSI package 9.
, Such as a comb-like or saw-tooth-like structure, and adopts a structure in which a chip-shaped probe array comes close to a lead.

As shown in FIG. 4, the lower end of the support is
The support is attached to the VLSI package by engaging the leads of the I package, and each near-magnetic field probe on the support is electrically connected to a measuring instrument such as a spectrum analyzer or an oscilloscope to perform measurement.

In the conventional adapter using a contact probe, there is a problem such as ringing caused by a phase shift of each frequency component caused by a load effect of the probe.
It was difficult to accurately analyze the signal waveform, and even when taking countermeasures, it had to rely on know-how correction. According to the probing apparatus of the present embodiment, since the non-contact type near-field probe is used, accurate measurement of the current signal can be performed without being affected by the load effect. Also,
Since the probing apparatus of this embodiment is closely attached to the VLSI package, it is a non-contact type probe.
Since the positional relationship between the current source (lead of the package) and the coil of the probe can be very accurately reproduced, the current value flowing through one lead can be measured with high accuracy by appropriately performing calibration.

FIGS. 5 and 6 show another embodiment of the present invention.
In the probing apparatus of this embodiment, a thin-film probe is formed on an insulating substrate, and a plurality of thin-film probes are stacked so that the probe surface has the same arrangement as the lead terminals of the IC package.

A so-called flexible printed wiring board using a material such as glass cloth epoxy or polyimide can be easily obtained with a substrate film thickness of about 0.1 mm. In this embodiment, a wiring board made of a BT resin glass cloth base material having a thickness of 0.2 mm is used.

As shown in FIG. 5, fine coils 12 and lead wires 13 are formed on the substrate 11 by etching in the same manner as in the previous embodiment, and the surface is covered with a solder resist except for the land portions 14. I do. The area of the coil is
0.5 mm square.

The probe thus formed on the substrate is VL
As many as the number of leads of the SI package are produced, and these are stacked and bonded as shown in FIG. A pre-grig 15 having an appropriate thickness is sandwiched between the substrates 11, and heated and pressed. The coil and the lead wire are accurately overlapped, and a large number of holes are made in a blank portion of the substrate so that there is no displacement due to melting of the pre-grig at the time of bonding, and bonding is performed by penetrating pins. Through this step, the coils are formed so that the pitch between the superposed coils becomes 0.3 mm. Therefore,
By arranging the probing apparatus including the probe array in which the probes are stacked in such a manner that the probe surface on which each coil is formed is perpendicular to the lead terminal surface of the VLSI package, the lead pitch is 0.3 mm.
Of the VLSI package can be performed. In this case, the probe array may be placed in contact with the lead terminal on the side surface of the VLSI package, or may be placed in contact with the top surface of the VLSI package and at a position where each coil comes as close to the lead terminal as possible. In any case, it is preferable to provide a guide member for positioning the probe array with respect to the VLSI package.

By appropriately setting the thickness and the shape of the pre-grig, the probing device including the probe array of the present embodiment can be formed into a shape that engages with the leads of the VLSI package, as in the previous embodiment. Also in this case, the probe surface on which each coil is formed is a VLSI
The probe array is engaged with and fixed to the leads of the VLSI package so as to be perpendicular to the lead terminal surface of the package.

In the above embodiment, since the probes are arranged in a line on the same plane, the size of the coil and the lead wire is limited by the pitch of the leads of the VLSI package. Since the coils are formed on the surface perpendicular to the lead surface by laminating the probes, the limitation on the size of the coil and the lead wire is greatly eased. In addition, since the electromotive force induced in the coil is proportional to the area and frequency, if the coil is miniaturized, sensitivity cannot be obtained at low frequencies, so a probe having a large coil diameter is required. Such a probe can meet such a demand.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made. For example, although the example in which the coil has one turn has been described, a coil having a plurality of turns may be used. In addition, a magnetic field sensor such as an MR element (magnetoresistive element) or a GMR element (giant magnetoresistive element) may be used as a magnetic field detecting element other than the coil. Further, the probe array is not limited to the one corresponding to one side of the VLSI package. For example, in the case of QFP, as a probing device in which four probe arrays of the respective embodiments are combined and integrated so that four side lead terminals can be simultaneously probed. Is also good.

[0027]

The effects produced by the present invention are as described in the section of the operation and the section of the embodiment, and the summary is as follows. That is, by employing a non-contact type probe called a near magnetic field probe, the VL
An accurate signal waveform can be obtained without the problem of waveform distortion caused by the load effect of the probe on the current of the lead of the SI package, and the time required for operation analysis and countermeasures can be saved.

Further, by forming a probe with a thin film or a thick film, a magnetic field sensor such as a minute coil and a transmission line can be formed, and it is possible to cope with a narrow pitch of VLSI package leads. Furthermore, by forming microprobes on an extremely thin insulating substrate, and laminating them, and forming a near-magnetic field probe device so that the probe surface is arranged in the same arrangement as the lead terminals of the IC package, the lead terminals can be further narrowed. It is possible to cope with the pitch, and it is possible to ease the restriction that the area of the coil (the area of the magnetic sensing surface in the case of the magnetic field sensor) must be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a single probe of a near-magnetic field probe group used in a probing apparatus according to an embodiment of the present invention.

FIG. 2 is a view showing a probe array in which the single probes of FIG. 1 are arranged.

FIG. 3 is a view showing a probe support.

FIG. 4 is a block diagram of a measurement system.

FIG. 5 is a diagram showing a single probe of a near-magnetic field probe group used in a probing apparatus according to another embodiment of the present invention.

FIG. 6 is a diagram showing a probe array in which the single probes of FIG. 5 are stacked.

[Explanation of symbols]

 1: Substrate 2: Micro coil 3: Lead wire 4: Pad opening 5: Single probe 6: Quartz substrate 7: Probe array 8: Support 9: VLSI package 10: Lead 11: BT resin glass wiring board 12: Micro coil 13: Lead wire 14: Land part 15: Pre-grig

Claims (4)

[Claims] 1. A probing apparatus for an IC package, comprising a group of near-field probes having the same arrangement as the lead terminals of the IC package. 2. The probing apparatus for an IC package according to claim 1, wherein said near-magnetic field probe is formed by forming a thin film or a thick film on a substrate. 3. A near-magnetic field probe is formed by forming a thin film or a thick film on an insulating substrate, and a plurality of such near-field probes are stacked so that the probe surface is arranged in the same arrangement as the lead terminals of the IC package. I according to claim 1, characterized in that:
Probing device for C package. 4. A probing device for an IC package according to claim 1, 2 or 3 so that a probe surface of a near-field probe is perpendicular to a lead terminal surface of the IC package, and a signal is measured. Probing method of IC package to be performed.