JPH03129749A - Inspection apparatus of bonding state of lead at tab - Google Patents

Abstract

PURPOSE:To inspect a bonding state at a connection part of a lead to a bump in a noncontact manner, surely and at high speed by a method wherein the lead is loaded with an optical pressure and a displacement amount of the lead caused by the loaded optical pressure is detected, compared with a threshold value and judged. CONSTITUTION:A face of a lead 3 in a position adjacent to a connection part of a bump 2 of a fixed TAB to a lead 3 is irradiated, by using a radiating optical system 8, with a laser beam guided by an optical fiber 3 via an introduction optical system 6 in a direction in which a bonding of the connection part is separated. By this constitution, the lead 3 is loaded with an optical pressure; the lead 3 loaded with the optical pressure is displaced in a direction of an arrow A according to whether a bonding state to the bump 2 is normal or not. When the bonding state is normal, a displacement amount of the lead 3 is equal to zero; when the bonding state is imperfect and defective, the bonding is destroyed when a strength of the bonding is small even when one part is bonded; the lead 3 is displaced. The displacement amount of the lead 3 is detected by using an interferometer which is composed of a laser light source 9, a half mirror 10, a total-reflection mirror 11 and a photodetector 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for inspecting the bonding state of a connection between a lead in a TAB and a bump on an LSI chip.

[Prior art] Conventionally, the bonding state of the connection between the leads and the bumps on the LSI chip in TAB has been inspected visually using an optical microscope, but there are other The reality is that inspection devices that use sound waves and inspection devices that use photoacoustic effects are only at the research stage and have not yet reached the stage of practical use.

[Problem to be solved by the invention] With the increasing integration of semiconductor devices, each component in TAB,
For example, silicon chips and leads are becoming increasingly miniaturized, and at the same time, the pitch between leads is also becoming finer, resulting in higher and higher packaging densities. One of the reasons for this is that the bonding state of the high-density connection between the TAB leads and the bumps on the LSI chip is good. However, inspection of the bonding state has become increasingly difficult and time-consuming and labor-intensive due to the increasing packaging density. For example, if there is an obvious bonding defect where there is a visible gap between the lead and the bump, it can be easily detected. If it cannot be detected, it is impossible to reliably detect a bonding defect, and there is a problem in that inspection defects may occur due to oversight. Since the accuracy and efficiency of this visual inspection vary depending on the skill level and physical condition of the inspector, equipment that combines an optical microscope and a TV camera is also used to facilitate visual inspection. Although the degree of fatigue of the TAB is reduced, the above-mentioned problems caused by visual inspection are not resolved, and therefore, it is not possible to use a TAB inspection device that ensures reliability for TAB, which should automatically inspect a large number of products continuously and at high speed. There were some problems that could not be solved.

In addition, in the above-mentioned research stage devices that utilize ultrasonic waves and inspection devices that utilize photoacoustic effects, the connection part to be inspected can be easily inspected by the inspector due to energy incidence, as in the case of the optical microscope. It is necessary to be able to detect it from the outside, and it has the same problems as above.

In view of the problems of the prior art described above, the present invention displaces the leads in the TAB by optical pressure without contact.

An object of the present invention is to provide a TAB lead bonding state inspection device that can detect a bonding defect in the connection portion at high speed, reliably, and easily by detecting the amount of displacement and comparing it with a threshold value. do.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an inspection device for inspecting the bonding condition of a lead in a TAB. , a light source for applying optical pressure to the lead, and an optical fiber that introduces the light generated by the light source through an introduction optical system and guides the introduced light to a surface of the lead located close to the connection part. a light irradiation unit comprising: a light irradiation system that applies light guided by the optical fiber to apply optical pressure to the lead surface; and a displacement detection unit that detects the amount of displacement of the lead caused by the optical pressure. and a determining means that compares and determines the detected displacement amount with a threshold value.

The light irradiation means is configured to include a large number of the optical fibers, to divide the light generated in the light source into the large number of optical fibers, and to simultaneously irradiate the surfaces of the corresponding large number of leads with the divided light. is preferred.

Also, a light source to apply optical pressure to the lead.

It is preferable to use a laser light source.

[Function] The film surface of the TAB and the LSI chip are fixed to the inspection table using a method such as vacuum suction.

Light generated by a light source and guided to an optical fiber via an introduction optical system is irradiated onto the surface of a lead in the vicinity of a connection between a bump and a lead on an LSI chip in a direction in which the bond at the connection is separated. to apply optical pressure. The amount of displacement of the lead loaded with optical pressure varies depending on the state of connection with the bump. For example, the amount of displacement in a normally bonded connection portion is zero, but in an imperfectly bonded connection portion, the amount of displacement is the same amount due to the optical pressure. In this case, the film surface and L
Since the SI chip is fixed to a stand, only the leads are displaced depending on the optical pressure, so even if the amount of lead displacement is small, it can be reliably detected by the displacement detection means without being confused with the displacement of other parts. and easily detected. The detected amount of displacement is sent to a determining means, where it is compared with a threshold value, and the quality of the bonded state at the connection portion is inspected.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 shows the inspection apparatus of the present invention in "A" in FIG.
Fig. 2 is a plan view showing an example of TAB, Fig. 3 is a diagram of ■-■ in Fig. 2.
FIG.

In the figure, 1 is an LSI chip, 2 is a large number of bumps bonded on the LSI chip, and 3 is a large number of leads, which are bonded to the bumps 2 in a 1:1 ratio.

Reference numeral 4 denotes a long film that is bonded to and supports the leads 3, and is a long film that connects the top of the LSI chip and a large number of leads 3 to form one unit, which is continuous at a constant pitch. Many are placed. Reference numeral 4a denotes film feeding holes provided continuously on both edges of the film 4. 5 is a laser light source for loading the optical pressure of the laser beam onto the lead 3; 6 is an introduction optical system that introduces the laser beam generated by the laser beam [5 into the optical fiber 7; An emission optical system 8 guides the light to the surface of the lead 3 located close to the connection part between the bump 2 and the lead 3, and converts the laser light guided by the optical fiber 7 into parallel light or focused light and irradiates the lead 3. As a result of this irradiation, a light pressure is applied to the lead 3. The laser light source 5. Introduction optical system6. The optical fiber 7 and the exit optical system 8 form a light irradiation means.

Reference numeral 9 denotes a laser light source for detecting the amount of displacement of the lead 3 displaced by the applied optical pressure, and the laser light from the laser beam g9 is transmitted to the connecting portion between the bump 2 and the lead 3 via the half mirror 10. It is designed to be irradiated towards the target.

In the first construction, the laser light from the laser light source 9 is used as a half mirror 10.
A total reflection mirror that receives the light reflected by and totally reflects the light.
12 is a photodetector placed opposite to the total reflection mirror 11, and is connected to the laser light source 9. Together with the half mirror 10° total reflection mirror 11, it constitutes an interferometer, and serves as means for detecting the amount of displacement of the lead 3. The photodetector 12 is connected to determining means (not shown) that compares and determines the bonding state of the connection portion with a threshold value.

Inspection of the bonding state of the leads in TAB is performed by firmly fixing the LSI chip 1 and film 4 to an inspection table (not shown) using a method such as vacuum suction so that they do not move during the inspection. A laser beam is introduced into the surface of the lead 3 at a position close to the connection between the bump 2 of the fixed TAB and the lead 3 in a direction in which the bond at the connection is separated.The laser beam is guided to the optical fiber 7 via the optical system 6. is irradiated from the injection optical system 8.

This irradiation applies optical pressure to the lead 3, and the lead 3 loaded with the optical pressure is displaced in the direction of arrow A shown in the figure depending on whether the bonding state with the bump 2 is normal or not. That is,
If the bonding condition is normal, the amount of displacement of the lead 3 is equal to zero, but if the bonding condition is incomplete or defective, even if a portion of the bond is bonded, if the strength of the bond is small, the bond will be destroyed. As a result, lead 3 is displaced. The amount of displacement of the lead 3 is determined by the laser beam g9. Half mirror 10. Total reflection mirror 11
, is detected by an interferometer consisting of a photodetector 12. In this case, since the top of the TAB LSI chip and the film 4 are fixed to the inspection table, the displacement beam due to the optical pressure is detected.
Even if the amount of displacement of the lead 3 is small, it can be detected reliably and easily without being confused with the displacement of other parts. The amount of displacement of the lead 3 detected by the interferometer is sent to a determining means (not shown), where it is compared and determined with a threshold value, and the quality of the bonded state at the connection portion is inspected.

In the above embodiment, since a laser is used as a light source, the laser has characteristics such as high power, high directivity, and easy control. It becomes possible to displace an incompletely connected portion in a bonded state by applying a constant value of optical pressure without contact, without using a complicated mechanical structure that applies pressure to the bonded portion. It is also possible to divide the power of the laser beam and irradiate each of the leads 3, which are expected to become smaller and finer in the future, so that a large number of connections can be inspected simultaneously. Furthermore, the temperature of the entire TAB, including the leads, rises during use in actual equipment, making the bond at the connection part more likely to peel off than at room temperature; however, when using a laser beam, the lead should be heated while being inspected. Therefore, the connection part is inspected at a temperature close to the temperature at which the TAB is actually used, making it possible to conduct a highly reliable inspection. Note that the light source is of course not limited to laser light, and any light source having characteristics similar to laser light may be used.

Further, in the above embodiment, an interferometer that uses a laser light source 9 different from the light source 5 that applies optical pressure to the lead 3 is used as the displacement detection means, but the laser beam 'g9 is not used and the laser beam It may be configured to use an interferometer that utilizes the reflected light of the laser beam from the light source 5 reflected by the lead 3 and analyzes and measures changes in the interference fringes of the reflected light.

[Effects of the Invention] Since the present invention is configured as explained above, it produces the effects as described below.

By applying a light pressure to the lead, detecting the amount of lead displacement caused by the applied light pressure, and comparing it with a threshold value, it is possible to check the bonding state at the connection between the lead and the bump without contact. The light generated by the light source is split into multiple optical fibers, and the split light is irradiated onto a corresponding number of leads at the same time. Even small-sized leads can be inspected easily and at high speed.

Furthermore, by using a laser light source as the light source, the characteristics of laser light make it easier to split into the above-mentioned large number of optical fibers.On the other hand, since the leads are heated by the laser light during inspection, it is difficult to actually use them in actual equipment. TAB inside
Since the test will be performed at a temperature close to that of , the reliability of the test can be increased.

[Brief explanation of the drawing]

The figures are all explanatory diagrams of the inspection device according to the present invention, and FIG. 1 is an overall schematic diagram showing an embodiment of the inspection device for inspecting the section A'' in FIG. 3, and FIG. A plan view showing an example of TAB, and FIG. 3 is a cross-sectional view taken along line mm in FIG. 2. 1...LSI chip, 2...bump, 3...lead, 4...film, 5 ...Light source, 6...Introduction optical system, 7...Optical fiber, 8...Ejection optical system, 10
~12... Displacement detection means (interferometer).

Claims (1)

[Claims] 1. In an inspection device for inspecting the bonding state of a connection between a bump and a lead of an LSI chip in TAB, a light source for applying optical pressure to the lead and light generated by the light source are provided. an optical fiber that introduces the introduced light through an introduction optical system and guides the introduced light to the surface of the lead located close to the connection part, and irradiates the light guided by the optical fiber to apply optical pressure to the lead surface. A light irradiation means comprising an emission optical system to apply a load, a displacement detection means for detecting the amount of displacement of the lead generated by the light pressure, and a determination means for comparing and determining the detected displacement amount with a threshold value. TAB characterized by having
Lead bonding condition inspection device. 2. The light irradiation means includes a large number of the optical fibers, and is configured to divide and introduce the light generated in the light source into the large number of optical fibers, and simultaneously irradiate the surfaces of the corresponding large number of leads with the divided light. The device for inspecting the bonding state of leads in a TAB according to claim 1. 3. The device for inspecting the bonding state of leads in a TAB according to claim 1 or 2, wherein the light source is a laser light source.