JPH0580006A - Method and device for inspecting internal defect of ic package - Google Patents

Abstract

PURPOSE:To obtain a method and device for inspecting an internal defect of an IC package which performs a heat-resistance test of the IC package without any contact. non-destructively, and in real time. CONSTITUTION:An IC package 1 as a sample is fitted to a heating device 2 and is heated. At this time, a surface temperature of the IC package 1 is measured two-dimensionally as a heat radiation light intensity of a surface of the IC package 1 by an infrared rays camera which consists of a lens 3 and an infrared rays image pickup element 4. A structural abnormality within the heated IC package l is detected, by means of a computer 5, based on temperature values and the distribution thereof on the surface of the IC package 1 which are obtained by the infrared rays camera and a two-dimensional distribution of the surface temperature of the IC package 1 or a defect detection result is displayed on a video monitor 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC package internal defect inspection method and apparatus, and more particularly to an IC package internal defect inspection method and apparatus for detecting structural abnormality inside a heated IC package. ..

[0002]

2. Description of the Related Art Recently, since an IC package is rapidly overheated during solder reflow, there is a problem that peeling or cracking occurs inside. For this reason, measures have been taken to carry out a thermal endurance test on the IC package before shipping, and to guarantee the quality that cracks will not occur inside even if it is heated.

At this time, a method of observing the internal state using x-rays or observing the internal state using ultrasonic waves is adopted. It can be said that such a method using x-rays or ultrasonic waves is suitable for non-destructively observing the internal state in detail.

[0004]

However, the above conventional method has a problem that accurate measurement cannot be performed unless the measurement environment is prepared.

For example, when observing the inside with ultrasonic waves, it is necessary to bring a piezoelectric element for generating / detecting ultrasonic waves into close contact with the test sample. However, since these elements have low resistance to heat, they cannot be used in a situation where the test sample is heated.

In addition, the method using x-rays requires a large-scale apparatus, and strict radiation measures are required to prevent x-rays from leaking to the outside. Therefore, the inside of the IC package must be observed in an environment different from the thermal durability test,
It is common to remove the IC package from the device during or after the thermal endurance test and observe the inside of the IC package in another environment.

Therefore, in order to know at what temperature, for example, cracks are generated inside by a method using x-rays, the IC package is taken out from the thermal endurance test device at each temperature and inserted into the measuring device each time. It is very inefficient because it requires internal observation.

An object of the present invention is to solve the above problems and to provide an IC package internal defect inspection method and apparatus capable of noncontact, nondestructive, real-time and efficient thermal endurance test of an IC package. Especially.

[0009]

In order to solve the above problems, in the present invention, an internal defect inspection method and apparatus for an IC package for detecting a structural abnormality inside an IC package heated in a thermal endurance test. At IC
The temperature of the surface of the package was two-dimensionally measured using an infrared camera, and a structure for detecting the structural abnormality inside the heated IC package from the temperature value of the surface of the IC package and its distribution was adopted.

[0010]

According to the above construction, the IC package is heated, the state of heat distribution on the surface of the sample is measured by using an infrared camera, and the infrared radiation intensity of the IC package obtained by the infrared camera is obtained. Structural abnormalities inside the heated IC package can be detected from the temperature value on the surface of the package and its distribution.

[0011]

EXAMPLE In the present invention, an infrared thermography method is used for conducting a thermal durability test of an IC package. In this method, the surface temperature of an object is observed using an infrared camera, and internal defects are measured non-destructively, in non-contact, and in real time due to abnormal changes in temperature.

By the way, as described above, when the IC package is heated, there is a problem that cracks are generated inside, but it has been recently clarified that the cause of the problem is the moisture contained in the IC package. It was

That is, if moisture is contained in the heated IC package, the moisture causes thermal expansion and pushes up the package from the inside. At this time, if there is a structurally concentrated stress, the stress will accumulate there and eventually cause a crack.

On the other hand, when the test sample is heated using a heat source, the thermal image of the sample surface can be captured by using an infrared camera which two-dimensionally detects the thermal radiation intensity. It goes without saying that the state of heat distribution of the sample largely depends on the thermal conductivity of the sample.

When a crack or peeling occurs inside the IC package, the thermal conductivity at that portion becomes lower than that at other places. Therefore, by detecting the change in the heat distribution as described above. Internal defects can be detected.

In this method, it is necessary to heat the IC package, but in the thermal endurance test, the heat source necessary for heating has already been prepared, so it can be said to be the optimum measurement environment. In addition, this method allows real-time inspection of thermal internal changes in IC packages undergoing thermal endurance testing. For this reason,
For example, it is possible to easily know at which temperature the peeling or cracking occurred inside during the heat durability test.

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

FIG. 1 shows a schematic structure of an IC package internal defect inspection apparatus adopting the present invention.

In the figure, reference numeral 1 is an IC as an inspection sample.
As a package, the IC package 1 is mounted on the heating device 2. At this time, the IC package 1 is preferably attachable to the heating device 2 via an IC socket or the like.
The heating device 2 has an inlet 2a and an outlet 2b for circulating the warm air heated by an appropriate heat source (such as an infrared light source) inside.

The temperature distribution on the surface of the IC package 1, that is, a thermal image is detected by the infrared imaging device 4 via the lens 3. The lens 3 and the infrared imaging device 4 are composed of a known infrared video camera or the like.

When the IC package 1 is heated, a temperature distribution associated with the package structure occurs. When the IC package 1 has heat, thermal radiation light having an intensity corresponding to the surface temperature is emitted. The intensity of the emitted light increases as the surface temperature of the sample rises, but at the same time, the wavelength simultaneously shifts to the short wavelength side.

Therefore, in the infrared camera composed of the lens 3 and the infrared imaging element 4, only the wavelength band corresponding to the temperature of the sample heated in the thermal endurance test is transmitted by the infrared transmission filter, and the thermal radiation light is further transmitted. It is detected by an infrared light receiving element and converted into an electric signal. An infrared lens is preferably used as the lens 3 in order to efficiently receive the heat radiation light from the sample.

A lens is arranged at a position where the sample surface is imaged on the light receiving element. Here, in order to measure the two-dimensional distribution of the heat radiation light emitted from the sample surface, a method of scanning the optical axis two-dimensionally or arranging the light-receiving elements two-dimensionally is used.

In this way, the infrared camera including the lens 3 and the infrared image pickup device 4 captures the heat temperature distribution on the sample surface as an electric signal. Since the intensity of the electric signal converted by using the light receiving element depends on the intensity of thermal radiation light radiated from the sample surface, if the electric signal is displayed on the monitor, I
The intensity and spatial distribution of heat radiated from the C package 1 can be visualized as the brightness on the screen. That is, the infrared camera can be used to output the relative temperature distribution of the sample to the image monitor.

During the test, the sample is heated by using the thermal endurance test device while monitoring the temperature distribution of the sample as described above. At this time, the temperature distribution state of the sample depends on the structure of the package.

A semiconductor device is hermetically sealed in the center of the inside of the package. Since this has a high thermal conductivity, the central part of the package becomes hotter than other parts in the overheated state.
Moreover, the temperature of the sample rises with heating. However, when peeling or cracking occurs in the IC package due to the increase in heat, the thermal conductivity changes rapidly at that portion, and at this time, the thermal image obtained as described above shows an abnormal distribution. ..

The thermal image of the IC package 1 is converted into an electric signal by using an infrared camera, the electric signal is input to the computer 5 and image processing is performed, and the resulting image is displayed on the video monitor 6 as a monitor display.

In order to detect an abnormal change in the thermal image caused by the occurrence of cracks, for example, in the computer 5, the thermal radiation intensity is differentiated with time as shown in FIG.
The upper part of FIG. 2 shows changes in the intensity of thermal radiation light of a certain pixel detected by the infrared imaging element 4 during heating of the IC package 1.

When a crack occurs inside the IC package 1 at a position corresponding to this pixel, an abnormal rate of change of the intensity of heat radiation occurs, which can be detected by performing time differentiation as shown in the lower part of FIG. If the time differentiation processing is performed for each pixel, a time-differentiated image can be output.

For example, by visually recognizing the change in the image, the timing of crack occurrence and the position inside the IC package 1 can be determined.

Further, by obtaining the heat temperature from the intensity of the heat radiation light, it is possible to easily know at which temperature the crack has occurred. When the time differential value becomes large, the image can be observed later by recording it in a new memory.

According to the above-mentioned embodiments, at the same time as the thermal endurance test of the IC package is performed, the state in which structural abnormality such as crack or peeling has occurred inside the IC package is prevented without disturbing the thermal endurance test. Moreover, it becomes possible to observe in real time. As a result, compared to the conventional method,
Internal defect inspection can be performed in a much faster time and easily.

Further, according to this internal inspection method, I
Even if there are many C packages, if all the samples are heated under the same conditions, all the samples can be observed at the same time. This is the right method.

In the above, the crack occurrence is detected by the inspector visually observing the change of the thermal image displayed on the video monitor 6, but the time differentiation is performed as shown in FIG.
It is also possible to automatically detect the crack generation timing or position by detecting a change in the differential signal of a predetermined value or more by the computer 5. As the heating device, a known heating furnace or the like can be used.

It goes without saying that the present invention is not limited by the circuit built in the IC package 1.

[0036]

As is apparent from the above, according to the present invention, an IC package internal defect inspection method or apparatus for detecting a structural abnormality inside an IC package heated in a thermal endurance test, is provided. The temperature of the surface was measured two-dimensionally using an infrared camera, and the temperature of the surface of the IC package and its distribution were used for heating I
Since the structure that detects the structural abnormality inside the C package is adopted, an excellent IC package internal defect inspection method capable of non-contact, non-destructive, and real-time and efficient thermal endurance test of the IC package. And a device can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of an internal defect inspection apparatus for an IC package according to the present invention.

FIG. 2 is a diagram showing a crack detection method in the method and apparatus of the present invention.

[Explanation of symbols]

 1 IC Package 2 Heating Device 3 Lens 4 Infrared Imaging Device 5 Computer 6 Video Monitor

Claims (5)

[Claims] 1. An internal defect inspection method for an IC package, which detects a structural abnormality inside an IC package heated in a thermal endurance test, wherein the temperature of the surface of the IC package is measured by an infrared camera.
A method for inspecting an internal defect of an IC package, which comprises dimensionally measuring and detecting a structural abnormality inside the heated IC package from a temperature value on the surface of the IC package and its distribution. 2. The internal structure of the IC package is determined from the timing of occurrence of structural abnormality inside the IC package through the temporal change of temperature information obtained by the infrared camera, and from the spatial position where the change occurs. The method for inspecting an internal defect of an IC package according to claim 1, wherein a position where a physical abnormality is generated is detected. 3. An internal defect inspection apparatus for an IC package, which detects a structural abnormality inside an IC package heated in a thermal endurance test, wherein the surface temperature of the IC package is two-dimensionally measured as the heat radiation intensity of the surface of the IC package. IC for measuring structurally inside the heated IC package based on the temperature value of the surface of the IC package and its distribution obtained by the infrared camera. Package internal defect inspection system. 4. The internal structure of the IC package is determined from the timing of occurrence of structural abnormality inside the IC package through the temporal change of temperature information obtained by the infrared camera, and from the spatial position where the change occurs. The internal defect inspection apparatus for an IC package according to claim 3, wherein a position where a physical abnormality is generated is detected. 5. The temperature value and its distribution on the surface of the IC package obtained by the infrared camera, or means for two-dimensionally displaying the detection result by the processing means is provided. Item 5. An internal defect inspection apparatus for an IC package according to Item 4.