JPH07159380A - Connecting part inspecting method in mounting lsi chip, etc. - Google Patents

Abstract

PURPOSE:To perform the direct, accurate detection of the connecting state of electrodes and a conductive particle by casting infrared rays on the conducting particle as the modulation light from the outside, oscillating the particle, and detecting the difference in oscillating mode. CONSTITUTION:Infrared rays 7 transmitted through an Si chip 4 are condensed on a chip electrode 5 by a condenser lens, and a conductive particle 3 is irradiated. Then, the particle 3 receives periodic energy, and thermal oscillation occurs. When the frequency of the infrared rays is matched with the natural oscillation of the particle 3, the large steady-state oscillation occurs in the particle 3. At this time, the oscillation mode and the resonant frequency are different depending on the sufficient/insufficient connection between the substrate-side electrode 2 and the electrode 5, and the particle 3. Then, the modulating frequency of the light is adequately changed, and the quality of the connection of the particle 3 with the electrodes 2 and 5 can be detected. In this way, the defective conduction of the connecting part, when the electric connection between the electrodes is carried out through the conductive particle, can be directly detected in high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a connection portion in face-down mounting of an LSI or other electronic device in which electrodes are connected via conductive particles.

[0002]

2. Description of the Related Art Conventionally, in a so-called bare chip LSI mounting technique in which a chip is directly mounted on a substrate, when an anisotropic conductive connection method is used which realizes electrical connection by interposing conductive particles between electrodes, Since the conductive particles are not in sufficient contact with the upper and lower electrodes, poor conduction may be caused.

In this connection, as shown in FIG. 6, the Si chip 4 is mounted face down, and the Si chip 4 and the substrate 1 are electrically connected to each other through the conductive particles 3 while facing each other. Therefore, the joint is optically opaque and invisible from the outside. In addition, 2 is a substrate side electrode, 11
Is an adhesive. In such a connection structure, for example, in the case shown in FIG. 7, the particle size of the conductive particles 3 varies, and the conductive particles having a small diameter are not connected to the upper chip electrode 5. I can't find it. In addition, 6 is a passivation film.

[0004]

Therefore, an electrical check is generally performed. That is, the inspection is performed by bringing the probe into contact with each terminal, but it is necessary to secure a space for hitting the probe, and
There is a problem that it is difficult to find an initial defect such as insufficient bonding between the terminal and the conductive particles.

In addition, a method based on acoustic microscopy is also known (TO858A ProcIEEE / CHMT).
Int Electron Manuf Techn
ol Symp VOL. 9th PAGE. 92
-97 1990) adopts a method in which vibration is transmitted from the outside with an ultrasonic microscope, so that a signal in which information of all transmission paths is mixed is obtained, and there is a problem in detection accuracy.

The present invention has been made in view of the above points, and in face-down mounting of an LSI chip or the like,
It is an object of the present invention to provide a connection evaluation method capable of directly and accurately detecting a conduction failure in a connection portion when electrically connecting electrodes by interposing conductive particles.

[0006]

According to the present invention, firstly, a connection portion when an electrode such as an LSI chip and a substrate-side electrode are electrically connected face down with conductive particles interposed A method for inspecting a connection portion in mounting an LSI chip or the like, characterized in that the conductive particles are vibrated, and a bonding state between the electrode and the conductive particles is detected by a difference in vibration mode. .

Secondly, in the above, the vibration of the conductive particles is performed by transmitting infrared light as modulated light from the back surface of the chip and irradiating the electrode portion of the joint portion. A method for inspecting a connection part in mounting the same is provided.

Thirdly, in the above description, the vibration of the conductive particles is performed by irradiating the conductive particles with modulated excitation light by using the substrate side extraction electrode as a reflection plate. A connection inspection method in packaging is provided.

Fourthly, in the above description, the vibration of the conductive particles is elastically synthesized by irradiating the back surface of the LSI chip with modulated light and changing the irradiation position with time to obtain the elastic combination based on the relationship between the scanning speed and the ultrasonic wave propagation speed. Provided is a method for inspecting a connection portion in mounting an LSI chip or the like, which is performed by generating a wave front and vibrating conductive particles in an LSI electrode portion.

Fifth, in the above, there is provided a method for inspecting a connection portion in mounting an LSI chip or the like, characterized in that the vibration of the conductive particles is performed by detecting an elastic wave transmitted to an extraction electrode.

Sixth, in the method of inspecting the connection portion when the electrodes of the LSI chip and the electrodes on the substrate side are electrically connected by the faying with the conductive particles interposed, heat is applied from the periphery of the connection portion to conduct electricity. Provided is a method for inspecting a connection portion in mounting an LSI chip or the like, which detects heat transmitted through a conductive particle and detects a bonding state between the electrode and the conductive particle based on a difference in thermal conductivity.

[0012]

In the first connection portion inspection method, the conductive particles are vibrated and the bonding state between the electrode and the conductive particles is detected by the difference in the vibration mode, so that the bonding state can be directly detected. Moreover, as compared with the case of performing an electrical check, it is also possible to perform a joint shortage that cannot be found by an initial resistance value check and to observe the state of other joints.

In the second method for inspecting a connecting portion, since the conductive particles are vibrated by irradiating the conductive particles from outside with infrared light as modulated light, the LSI mounted face down. Then, the electrode portion can be irradiated from the back surface of the LSI chip, and the vibration of the conductive particles in contact therewith can be performed efficiently and accurately.

In the third method for inspecting a connecting portion, the conductive particles are vibrated by irradiating the conductive particles with modulated excitation light by using the substrate-side extraction electrode as a reflection plate. In comparison with the second method, the conductive particles can be easily irradiated directly with the excitation light, and the vibration can be efficiently performed.

In a fourth method for inspecting a connecting portion, the vibration of the conductive particles is irradiated to the back surface of the LSI chip with modulated light, and the irradiation position is changed with time to obtain the relationship between the scanning speed and the ultrasonic wave propagation speed. Since the elastic synthetic wavefront is generated and the conductive particles of the LSI electrode portion are vibrated, the wavefront can be focused and vibrated even to the conductive particles on the opposite side of the optically opaque LSI. .

In the fifth method of inspecting a connecting portion, the conductive particles are vibrated by detecting the elastic wave transmitted to the extraction electrode. Therefore, the vibration of the conductive particles can be easily performed without damaging the mounting structure. It can be measured from the outside.

In contrast to the sixth inspection method for connecting parts, in which the above-mentioned first inspection method vibrates the conductive particles, the difference in vibration modes is detected and the joining state is known.
It applies heat to the periphery of the connection part, detects the heat transmitted through the conductive particles, and tries to know the bonding state by the difference in the thermal conductivity. Even conductive particles on the opposite side of the optically opaque LSI can be The information on the joint can be obtained directly and more quickly.

[0018]

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of a method for inspecting a connecting portion by detecting a difference in vibration mode according to the present invention. This embodiment corresponds to the method described in the above first or second. In FIG. 1, 1 is an electrode 2 made of Cu or the like
Substrate such as a polyimide film on which is formed, 3 is conductive particles obtained by plating resin particles with Ni or Au, and 4
Is a semiconductor chip of Si having an electrode 5 and a passivation film 6 formed around the electrode 5, and 7 and 8 are infrared light (modulated light) and a lens, respectively. As shown in FIG. 1, when infrared light 8 transmitted through the Si chip 7 is used, the infrared light (modulated light) 7 is condensed on the junction electrode 5 by the condenser lens 8, and the conductive particles 3 are irradiated, the irradiation is performed. The generated conductive particles 3 receive periodic energy (heat) and generate thermal vibration. When the frequency of the modulated light 7 is adjusted to the natural vibration of the conductive particle 3, the conductive particle 3 causes a large steady vibration. Therefore, the conductive particles that are in sufficient contact with the electrodes 2 and 5 and the conductive particles that are poorly bonded have different vibration modes and different resonance frequencies. Therefore, by appropriately changing the modulation frequency of light, the electrodes 2, It is possible to detect the difference between the conductive particles 3 that are in sufficient contact with the conductive particles 3 and the conductive particles 3 that are insufficiently bonded. According to this example, the electrode portion 5 can be irradiated from the back side with the LSI chip 4 mounted in a phase-down manner, and the conductive particles 3 in contact therewith can be vibrated efficiently and accurately.

Next, FIG. 2 is a diagram showing a second embodiment of the present invention. This example corresponds to the method described in the first or third. As shown in FIG. 2, the extraction electrode 2 on the side of the substrate 1 is used as a mirror, and a light beam that passes through the adhesive 11 is irradiated from a predetermined angle to be incident from the end of the bonding layer 11 and the conductive particle 3 is irradiated with light. Apply heat to cause vibration. According to this example, the conductive particles can easily be directly irradiated with the excitation light, and the vibration can be efficiently performed.

FIG. 3 is a diagram showing a third embodiment of the present invention. This example corresponds to the method described in the first or fourth.
LSI chip 4 face down as shown in FIG.
By irradiating the light beam 20 from the outside and moving the irradiation position, a synthetic wave 22 of elastic waves is generated and the elastic waves are focused on the electrode portion 5. According to this example, the optically opaque LS
The wavefront is also focused on the conductive particles 3 on the opposite side (inner side) of the I-chip 4 to give vibration.

FIG. 4 is a diagram showing a fourth embodiment of the present invention. This example corresponds to the method described in the first or fifth.
As shown in FIG. 4, when the conductive particles 3 at the joint are vibrated, the contact efficiency between the conductive particles 3 and the electrodes 2 and 5 causes different propagation efficiency when the vibration is transmitted to the substrate electrode 2. By detecting the elastic wave signal of the electrode 2, the contact condition between the conductive particle 3 and the electrodes 2 and 5 can be known. For the detection, for example, a piezoelectric element 30 or the like may be brought into close contact with the substrate electrode 2 or the substrate 31 may be irradiated with the optical micro 31 to optically detect the vibration. According to this example, it is possible to easily measure from the outside without breaking the mounting structure of the conductive particles 3.

The above is the method of vibrating the conductive particles and detecting the difference between the vibration modes to know the bonding state (holding state of the conductive particles). For that purpose, it is effective to make the modulation frequency when intensity-modulating light variable so as to match the natural vibration frequency of vibration.

FIG. 5 is a diagram showing another embodiment of the connection portion inspection method of the present invention. This example corresponds to the method described in the sixth. As shown in FIG. 5, heat is applied from the top surface of the chip 4 or from the electrode 2 on the substrate side (for example, light energy may be converted by irradiating light), and the heat 42 is conducted and the conductivity of the bonding portion is increased. Heat 4 transferred to the other via particle 3
When 3 is detected, the heat conduction efficiency is naturally different when the adhesive 11 is present in the joint portion of the conductive particles 3 and the detected amount of heat is different. Measurement of heat quantity Non-contact temperature measurement methods such as thermo-viewers are effective. According to this example, even in the case of the electrically conductive particles 3 on the opposite side of the optically opaque LSI chip, the information on the bonded portion can be obtained more quickly.

[0025]

As described above, according to the present invention, the LSI
It is possible to directly detect the bonding state of electrodes and conductive particles in the face-down mounting of chips, etc., and moreover, it is possible to accurately detect bonding shortages that cannot be detected by the initial resistance value check as compared with electrical checks. Can be detected.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of a connection portion inspection method according to the present invention.

FIG. 2 is a diagram illustrating another example of the connection portion inspection method according to the present invention.

FIG. 3 is a diagram illustrating still another example of the connection portion inspection method according to the present invention.

FIG. 4 is a diagram illustrating still another example of the connection portion inspection method according to the present invention.

FIG. 5 is a diagram illustrating an example of another connection portion inspection method according to the present invention.

FIG. 6 is a diagram showing a bare chip face-down mounting structure.

FIG. 7 is a diagram illustrating a defective joint in a bare chip face-down mounting structure.

[Explanation of symbols]

 1 Substrate 2 Substrate Side Electrode 3 Conductive Particle 4 Si Chip 5 Chip Electrode 6 Passivation Film 7 Infrared Light (Modulated Light) 8 Condensing Lens 10 Excitation Light 11 Adhesive 20 Light Beam 21 Ultrasonic Wave 22 Synthetic Wave 30 Piezoelectric Element 31 Light Micro 41 Light irradiation 42,43 Heat conduction

Claims (6)

[Claims] 1. A method of inspecting a connecting portion when electrodes such as an LSI chip and electrodes on a substrate side are electrically connected by face down with conductive particles interposed therebetween. An LS characterized by detecting a bonding state between the electrode and the conductive particle based on a mode difference
A method for inspecting a connection portion in mounting an I chip or the like. 2. The vibration of the conductive particles is performed by transmitting infrared light as modulated light from the back surface of the chip and irradiating the electrode portion of the bonding portion.
5. A method for inspecting a connection part in mounting an LSI chip or the like as described in. 3. The LSI chip according to claim 1, wherein the conductive particles are vibrated by using the substrate-side extraction electrode as a reflector and irradiating the conductive particles with modulated excitation light. Inspection method for connection in mounting. 4. The vibration of the conductive particles irradiates the back surface of the LSI chip with modulated light and changes the irradiation position with time to generate an elastic composite wavefront based on the relationship between the scanning speed and the ultrasonic wave propagation speed. The L according to claim 1, which is performed by vibrating the conductive particles of the LSI electrode portion.
A method for inspecting a connection portion in mounting an SI chip or the like. 5. The method for inspecting a connection portion in mounting an LSI chip or the like according to claim 1, wherein the vibration of the conductive particles is performed by detecting an elastic wave transmitted to an extraction electrode. 6. A method for inspecting a connection portion when an electrode of an LSI chip or the like and a substrate-side electrode are electrically connected by faying with conductive particles interposed therebetween, wherein heat is applied from the periphery of the connection portion so that the conductivity is reduced. A method for inspecting a connection portion in mounting an LSI chip or the like, which comprises detecting heat transmitted through particles and detecting a bonding state between the electrode and the conductive particles based on a difference in thermal conductivity.