JP2000260800A - Brazing evaluating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brazing evaluating apparatus capable of nondestructively evaluating the brazed condition of a brazed part and deciding the success or the failure of a joint. SOLUTION: This brazing evaluating apparatus evaluates the soldered condition of a solder ball 8 soldered to a pad of an insulation substrate 7 of a semiconductor device 4, and the semiconductor substrate 4 is mounted on a support stand 4 of a thermal image measuring part 1, and the surface temperature of the solder ball 8, when the soldered part is heated, is photographed by a thermal image measuring camera 2, and an obtained image signal is input to a thermal image analyzer 9 to calculate the increase in the temperatures the surface temperatures of the solder ball 8, and the thermal image analyzer 9 compares it with the temperature increase characteristic set previously, evaluates the solder conditions, and determines the quality of a joint.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, for example, a BGA (Ball Grid Array),
The present invention relates to a brazing evaluation apparatus suitable for evaluating a soldering state of a soldering portion of a solder ball such as FC (Flip Chip).

[0002]

2. Description of the Related Art Conventionally, the bonding condition when a solder ball is bonded to a pad provided on an insulating substrate in a semiconductor device, for example, a BGA package, is determined by measuring the bonding strength by a destructive test such as a shear test or a vertical tensile test. It was done by measuring. However, in such a test method, not only the peeling at the solder-pad surface or the bonding interface between the solder and the solder ball, but also the solder ball may be detached from the pad due to breakage of the solder itself.

[0003] Further, depending on the distribution of the bonding area and the direction of the load for applying the peeling load, the peeling load varies even in the same bonding area, so that accurate bonding strength cannot be obtained and the bonding state is correctly determined. Can not do it. In addition, in testing, wasteful members are generated because products such as semiconductor devices are destroyed, and furthermore, it is not possible to judge the bonding state of the products in the manufacturing process,
Based on the test results of test samples randomly drawn from the process, the joint state of a product manufactured in the same process is estimated.

For this reason, it is possible to non-destructively evaluate the joining state of the solder joints of the solder balls to judge the quality of the joining, and to evaluate and judge the joining state even during the manufacturing process. It is desired.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to non-destructively evaluate the brazing state of a brazing portion to determine the quality of a joint. The present invention is to provide a brazing evaluation device capable of determining the following.

[0006]

A brazing evaluation apparatus according to the present invention is a brazing evaluation apparatus for evaluating a brazing state of a brazed member brazed to a brazing portion. Heating or cooling the brazing part of the part, characterized in that the brazing state was determined based on the temperature change of the brazed member obtained by heating or cooling, further, The determination of the brazing state is performed based on a change in the surface temperature of the brazed member obtained by the thermal image, and further, the brazing part is immersed in a highly permeable liquid and , Characterized in that the liquid is heated or cooled, and the liquid is ethyl alcohol. There is a pad provided on an insulating substrate, and is characterized in that the object to be brazed member is a solder ball.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment will be described with reference to FIGS. FIG. 1 is a diagram showing a schematic configuration in a partial cross section.
FIG. 2 is a diagram showing the temperature of the solder ball, FIG. 2 (a) is a temperature rise characteristic diagram, FIG. 2 (b) is a plan view showing measurement points,
FIG. 3 is a view showing an example of a thermal image of the solder ball, and FIG. 4 is a view showing a thermal image when the solder ball is heated.
4A is a diagram showing a thermal image immediately after heat input, FIG. 4B is a diagram showing a thermal image after 24 seconds of heat input, and FIG. 4C is a diagram showing a thermal image after 44 seconds of heat input. FIG. 5 is a view showing an average temperature characteristic of a solder ball, FIG. 5A is a view showing an average temperature rise characteristic at the time of good bonding, and FIG. 5B is a view showing an average temperature rise characteristic at the time of poor bonding. FIG.

1 to 5, reference numeral 1 denotes a thermal image measuring unit. A thermal image measuring camera 2 is mounted on a camera fixing stand 3, and is mounted on an upper surface at a position facing the thermal image measuring camera 2. A support table 5 is provided, which is capable of heating and cooling the semiconductor device 4 to be measured, which is a placed object to be measured. Further, a light-shielding enclosure 6 is provided above the support table 5 so that the thermal image of the semiconductor device 4 placed and heated by the thermal image measurement camera 2 is not affected by the surroundings. ing.

On the support 5, the semiconductor device 4 is brazed to a pad (not shown) of the insulating substrate 7, which is a brazing portion, by soldering a brazing material, with the insulating substrate 7 on the lower side. The solder ball 8 as a member is placed on the upper side, and the solder ball 8 side is photographed by the thermal image measurement camera 2. The fixed base 3 is provided with a focus adjusting function for adjusting the distance between the thermal image measuring camera 2 and the support base 5 to perform focusing.

On the other hand, reference numeral 9 denotes a thermal image analyzer, which receives an image signal taken by the thermal image measuring camera 2 via a cable 10. And in the thermal image analyzer 9,
Based on the input image signal, the temperature of each part of the solder ball 8 on which focusing has been performed is calculated, a temperature distribution display or the like is displayed on the display screen 11 by color, and the average temperature of each solder ball 8 and its change. Alternatively, it is configured to calculate a temperature change at a fixed point.

Further, the thermal image analyzer 9 compares the preset temperature change with the measured temperature change, determines whether or not the difference is within a predetermined range, and determines the result as, for example, good bonding or poor bonding. Is displayed. In addition, regarding the temperature change set in advance in the thermal image analyzer 9, for a solder ball on which good soldering has been performed, the temperature change when heated is measured, and it is confirmed that good soldering is performed by a destructive test. Check and obtain data, and vice versa, prepare for defective soldering, measure the temperature change and check the soldering state, obtain the data, and input these data in advance. Have been.

[0013] With such a configuration, the support 5
The semiconductor device 4 is placed thereon and heated. Then, the temperature of the solder ball 8 soldered to the pad in the heating process is detected by the thermal image measuring camera 2, the temperature change is calculated by the thermal image analyzer 9, and the calculation result is evaluated. The evaluation at this time is, for example, as shown in FIG.
The temperature changes measured at points A to H of FIG.
As shown in the graphs, the characteristic lines of the temperature rise from the start of the heating substantially have the same tendency at the points A to G, but at the point H, the temperature immediately becomes high at the beginning of the heating, and after a certain period of time, the other temperature rises. Since a temperature rise similar to that of the point is shown, it is determined that the bonding state is defective.

As a result, the joint of the solder ball 8a is determined to be defective in a non-destructive state. Conversely, although not shown, the solder ball 8 in which the characteristic lines of the temperature rise at all the measurement points have the same tendency is judged to be good in the non-destructive state of the joint. Also, the display screen 11 of the thermal image analyzer 9
The temperature distribution display image 12 of the solder ball 8 displayed at
For example, as shown in FIG. 3, the left side is an image 12a when the bonding state is good, and the right side is an image 12b when the bonding state is bad.

In the above description, the quality of the bonding of the solder balls 8a is determined based on the characteristic line of the temperature rise at a fixed point. For example, as shown in FIG. From the temperature distribution display image 12 of the ball 8, the average temperature in the circular area S equal to the diameter of the solder ball 8 is obtained, and the rate of increase in the average temperature from immediately after the heat input to the elapse of a predetermined time is calculated to determine the quality of the joining. May be performed. That is, while the average temperature elapses as shown by the characteristic lines X and Y shown in FIGS. 5A and 5B, the temperature rise values Tdx and Tdy from the input of heat to the elapse of 24 seconds are obtained. The quality of the bonding is determined based on whether these values are larger or smaller than a predetermined reference value, or the quality of the bonding is determined based on how the temperature is compared with the temperature rise value of the other solder balls 8.

In FIG. 5, the temperature rise value Tdx of the characteristic line X shown in FIG. 5A is seen from the temperature rise value up to 24 seconds after the heat input, and the temperature rise value of the characteristic line Y shown in FIG. This is a case where the temperature rise value Tdx of the characteristic line X in FIG. 5A is smaller than the value Tdy and the junction is good, and the temperature rise value Tdy of the characteristic line Y in FIG. This is because in good bonding, heat diffuses through the bonding interface to the substrate or the like, and the temperature rise becomes gentle. Conversely, in poor bonding, heat does not diffuse through the bonding interface and the solder ball 8 Is mainly heated.

Next, a second embodiment will be described with reference to FIG. FIG. 6 is a diagram showing a schematic configuration in a partial cross section. In addition,
The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The configuration of the present embodiment that is different from the first embodiment will be described.

In FIG. 6, reference numeral 13 denotes a thermal image measuring section, in which a liquid tank 14 is arranged at a predetermined distance in opposition to the thermal image measuring camera 2 attached to the camera fixing base 3. A highly permeable liquid, for example, ethyl alcohol 15 is stored in the liquid tank 14. And the liquid tank 14
The semiconductor device 4 is arranged so that the semiconductor ball 8 is directed toward the thermal image measurement camera 2 so as to be immersed in ethyl alcohol 15.

The semiconductor device 4 in the liquid tank 14 can be heated by a heat source (not shown). Then, ethyl alcohol 15 soldered to the pad of the insulating substrate 7
The temperature of the solder ball 8 inside is photographed by the thermal image measuring camera 2, and is calculated and measured by the thermal image analyzer 9 based on the obtained thermal image. In the same manner as in the first embodiment, a color temperature distribution display or the like is performed on the display screen 11, and the average temperature of each solder ball 8 and its change, or the temperature change at a fixed point are calculated. I have.

Since the liquid tank 14 is constructed as described above,
The temperature of the solder ball 8 soldered to the pad of the semiconductor device 4 in the heating process is captured by the thermal image measurement camera 2, the temperature change is calculated by the thermal image analyzer 9, and the calculation result is evaluated. . As a result, it is possible to evaluate and judge the quality of the soldering state in a non-destructive state as in the first embodiment.

In the above embodiment, the soldering state is evaluated and judged based on the temperature rise of the solder ball 8 in the heating process. The evaluation and determination of the soldering state may be performed based on a thermal image at the time of temperature decrease due to temperature decrease or cooling.

Although not shown, the support table 5 or the liquid tank 14 is provided so as to be moved in the manufacturing process, and the thermal image measuring camera 2 is moved in synchronization with the support table 5 or the liquid tank 14 so that the solder ball 8, the temperature change is calculated by the thermal image analyzer 9, and the evaluation of the soldering state is performed based on the calculation result. Can be evaluated.

Alternatively, although not shown, the support table 5 or the liquid tank 14 is provided so as to move during the manufacturing process, and a plurality of thermal image measuring cameras 2 are arranged apart from each other in the moving direction. An image signal from the measuring camera 2 is input to the thermal image analyzer 9, a temperature change is calculated by combining the image signals from the thermal image measuring cameras 2, and a soldering state is evaluated based on the calculation result. In other words, it is possible to directly evaluate the process without using extra parts.

[0024]

As is apparent from the above description, according to the present invention, it is possible to non-destructively evaluate the brazing state of the brazing portion and to judge the quality of the joint of the brazing portion. In addition, there is an effect that there is no need to prepare an extra part for checking the brazing state.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a first embodiment of the present invention in a partial cross section.

FIG. 2 is a diagram showing a temperature of a solder ball according to the first embodiment of the present invention. FIG.
(B) is a plan view showing measurement points.

FIG. 3 is a diagram illustrating an example of a thermal image of a solder ball according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a thermal image when the solder ball according to the first embodiment of the present invention is heated, FIG. 4 (a) is a diagram showing a thermal image immediately after heat input, and FIG. FIG. 4C is a diagram illustrating a thermal image 24 seconds after heat input, and FIG. 4C is a diagram illustrating a thermal image 44 seconds after heat input.

5A and 5B are diagrams showing average temperature rise characteristics of the solder ball according to the first embodiment of the present invention, FIG. 5A is a diagram showing average temperature rise characteristics at the time of good bonding, and FIG. FIG. 9 is a diagram showing an average temperature rise characteristic at the time of defective bonding.

FIG. 6 is a view showing a schematic configuration of a second embodiment of the present invention in a partial cross section.

[Explanation of symbols]

 Reference Signs List 1, 13: thermal image measurement section 2: thermal image measurement camera 4: semiconductor device 5: support base 7: insulating substrate 8: solder ball 9: thermal image analyzer 14: liquid tank 15: ethyl alcohol

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B23K 101: 40

Claims (5)

[Claims] 1. A brazing evaluation apparatus for evaluating a brazing state of a brazed member brazed to a brazing portion, wherein the brazing portion of the brazed member and the brazing portion of the brazing portion are heated or cooled. A brazing state determination unit that determines a brazing state based on a temperature change of the brazed member obtained by heating or cooling. 2. The brazing evaluation apparatus according to claim 1, wherein the determination of the brazing state is performed based on a change in the surface temperature of the brazed member obtained from the thermal image. 3. The brazing evaluation apparatus according to claim 1, wherein the brazing portion is immersed in a highly permeable liquid, and the liquid is heated or cooled. 4. The brazing evaluation device according to claim 3, wherein the liquid is ethyl alcohol. 5. The brazing evaluation apparatus according to claim 1, wherein the brazing portion is a pad provided on the insulating substrate, and the member to be brazed is a solder ball.