JP2000304801A - Electronic part reliability evaluation device and electronic part reliability evaluation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a defect without feeding excessively high current and confirm the defect in an early stage by providing a load resistor between a terminal of an electronic part with insulation resistance to be measured and a power source and measuring a voltage between both terminals of the load resistor. SOLUTION: A reliability evaluation testing device evaluating a terminal insulation resistance for a printed circuit board 2 and the like is provided with a load resistor 5 connected to a power source 1 and the circuit board 2 in series and a voltmeter 6 connected in parallel between both terminals of the resistor 5. A predetermined voltage is applied between terminals 2C, 2D from the power source 1, and a voltage always monitored by the voltmeter 6 is recorded by a pen recorder 7, for example. A defect such as a short circuit is detected when a voltage between both terminals 2C, 2D is increased. As the insulation resistance of an evaluated object such as the circuit board 2, an insulation resistance of about 100 KΩ is necessary, and an insulation resistance of about 1000 KΩ is desirable. When a resistance value of the resistor 5 is 1/1000 or less to a minimum value of the insulation resistance, measurement can be facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reliability evaluation apparatus for an electronic component and a reliability evaluation method for a printed wiring board, and more particularly to a reliability evaluation method for a printed wiring board using multilayer wiring and the reliability therefor. It relates to an evaluation device.

[0002]

2. Description of the Related Art In recent years, semiconductor devices have become highly integrated and sophisticated, and a large number of connection terminals are required in comparison with the dimensions of the semiconductor device. On the other hand, in electronic devices mounted with a semiconductor device, miniaturization of the device is rapidly progressing, and miniaturization of a semiconductor device and electronic components to be used is required.

[0003] Under these circumstances, printed wiring boards used for mounting semiconductor devices and the like are required to have higher wiring densities, and printed wiring boards using multilayer wiring are required to have thinner interlayer insulating layers. Evolving. Also, with the rapid spread of electronic devices such as mobile phones, price reduction of devices is rapidly progressing, and there is a great demand for smaller and lower price printed wiring boards. Further, in markets such as mobile phones, changes in product standards are extremely frequent. With such technology and demand trends, it has become important to confirm in a short time how long-term reliability is secured when a printed wiring board is densified and thinned. That is, without significant cost increase,
There is a need for an evaluation method for easily and quickly determining the quality of a printed wiring board.

In order to meet these requirements, a printed circuit board is manufactured by applying a voltage between insulated wires and measuring a decrease in insulation resistance by using a reliability evaluation pattern of a fixed shape as a standard. Evaluation tests have been conducted to confirm reliability.

A conventional method for evaluating a printed wiring board will be described below with reference to FIG. FIG. 5A is a schematic diagram when the printed wiring board 2 for evaluation is connected to the power supply 1, and FIG. 5B is a schematic diagram when the printed wiring board 2 is connected to the insulation resistance meter 4. is there. As shown in the schematic surface views of FIGS. 5A and 5B, the printed wiring board 2 prepared for evaluation is spaced apart from the outermost surface by a certain distance to form a comb-like shape. A test pattern 2A in which a wiring portion is formed and all the wiring portions are converged at one end thereof, and a central portion between the adjacent comb tooth-shaped wiring portions of the test pattern 2A,
A test pattern 2B formed in substantially the same shape as the test pattern 2A so that a similar comb tooth-shaped wiring portion is located.
Are formed. The test patterns 2A and 2B have terminal portions 2C and 2D, respectively, in which all wiring portions are converged, and these portions can be electrically connected to the outside.

Each terminal 2 of test patterns 2A and 2B
C and 2D are connected to the + and-electrodes of the power supply 1, respectively. In this state, the power supply 1 applies a working voltage of the printed wiring board between the terminal portions 2C and 2D for a certain period of time (for example, by applying 5.5 V to a high-temperature and high-humidity atmosphere of 85 ° C. and 85% for 10 V).
00 hours). Incidentally, in order to prevent an excessive current from flowing when a short circuit occurs between the test patterns 2A and 2B, a current limiter is set for the power supply 1 and the current limiter is set to 0.01 A.
The above current is prevented from flowing.

After 1000 hours, FIG.
As shown in (B), instead of the power supply 1, an insulation resistance meter 4 is connected between the terminals 2C and 2D, a voltage of 5 V to 50 V is applied for about 60 seconds, and the insulation resistance during this period is measured. By comparing with the resistance value before application, the quality of the printed wiring board can be determined from the magnitude of the change. In addition, even if 1000 hours is added, 100 hours, 5 hours
Even in the middle stage after the lapse of about 00 hours, the characteristics can be measured in the same manner and the defect can be confirmed at an early stage.

By using such a method, if the withstand voltage between adjacent test patterns is insufficient, a short circuit occurs between the adjacent test patterns 2A and 2B at the lowest withstand voltage during voltage application, and FIG. When the resistance value between the terminal portions 2C and 2D is significantly reduced at the time of the measurement shown in (B), a defect of the printed wiring board can be confirmed. In addition, even if there is no significant fluctuation, the insulation resistance usually decreases due to the application of a voltage. Therefore, it is possible to set a lower limit of the insulation resistance value and take measures to determine that the insulation resistance value is lower than the lower limit.

[0009]

However, the above evaluation method has the following problems. That is, in the conventional method for evaluating a printed wiring board, an evaluation time of about 1000 hours is required to perform an evaluation with a sufficient margin with respect to a product standard. 10 if a defect occurs in the middle stage
A defect can be detected by measuring at a predetermined time of about 0 hour or 500 hours, but there is no means for confirming the occurrence of the defect during the evaluation time. Increasing the number of evaluations further
It was not realistic considering the working time required for the measurement. For this reason, the design change of the printed wiring board is delayed,
Prototyping of the improved product was delayed. Such a delay in prototype evaluation could be a fatal injury in product development in the market for mobile terminals with a short product life.

Further, as shown in a schematic surface view (enlarged view) of FIG. 4, a short-circuit defect is generated at a black discolored portion 11B which is scorched black over a wide width between wirings adjacent to the defective portion.
In many cases, it was difficult to identify the location where the failure occurred and to estimate the cause of the failure. Further, there is a case where a plurality of defective locations are scorched black and the number of defective locations is unknown. In the worse case,
The printed wiring board sometimes burned.

In a printed wiring board in which such a defect has occurred, when a voltage having a measurement rating of 5 V to 50 V is applied when measuring the resistance by the method shown in FIG.
At this voltage, a large current of about 0.3 A at the maximum flows, causing variations in the measured resistance value, and the spread of black scorch, which makes it more difficult to identify the location of the failure and to estimate the cause of the failure.

[0012]

SUMMARY OF THE INVENTION An electronic component reliability evaluation apparatus and an electronic component reliability evaluation method according to the present invention have been made to solve the above problems, and have the following features. An electronic component reliability evaluation device according to the present invention is an electronic component reliability evaluation device that evaluates insulation resistance between terminals of an electronic component, and is connected to a terminal of the electronic component whose insulation resistance is to be measured. A power supply capable of applying a voltage between its terminals, a load resistance connected between the power supply and the electronic component, and voltage measuring means for measuring a voltage between both terminals of the load resistance; The insulation resistance between terminals of the electronic component to be connected to the power supply is 100 kΩ or more, and the resistance value of the load resistance is 1/1000 or less of the insulation resistance between terminals of the electronic component to be connected to the power supply. I do.

[0013] Also, the present invention is characterized in that the inter-terminal insulation resistance value of the electronic component is 1000 kΩ or more, and the resistance value of the load resistance is 1/10000 or less of the inter-terminal insulation resistance value of the electronic component.

Further, the method for evaluating the reliability of an electronic component according to the present invention is a method for evaluating the reliability of an electronic component using variation in insulation resistance between terminals, wherein the resistance of the electronic component is smaller than the resistance between terminals of the electronic component. Connecting a load resistance having a value in series to apply a voltage between the terminals, measuring a resistance value variation between both ends of the load resistor, and when the resistance value variation reaches a desired value, And stopping the addition.

Further, the method for evaluating the reliability of an electronic component according to the present invention is a method for evaluating the reliability of an electronic component using a variation in insulation resistance between terminals, wherein the resistance is smaller than the resistance between terminals of the electronic component. A step of connecting a load resistance of a value in series between the terminals of the electronic component to continuously apply a voltage between the terminals, and a step of continuously applying the voltage, simultaneously with the step of applying the voltage, the resistance value between both ends of the load resistor. Continuously measuring, wherein the load resistance is 1/1000 of the inter-terminal resistance of the electronic component.
It is characterized by the following.

[0016]

Embodiments of the present invention (hereinafter, abbreviated as embodiments) will be described in detail with reference to the drawings. (First Embodiment) FIG. 1A is a schematic diagram when a printed wiring board is connected to a printed wiring board evaluation device (electronic component evaluation device) according to a first embodiment of the present invention.

In FIG. 1A, a printed wiring board 2 for evaluation and a resistance (load resistance) 5 of 10 kΩ are connected in series to a power supply 1. A voltmeter 6 is connected in parallel between the two terminals of the resistor 5 so that the voltage can be monitored at all times. The voltage monitored by the voltmeter 6 is constantly monitored by a pen recorder connected to the voltmeter 6. Has been recorded. FIG.
The printed wiring board 2 whose schematic surface view is shown in (A) is a multilayer printed board prepared for evaluation, and has a comb-shaped wiring portion formed on the outermost surface thereof at a certain distance from each other,
Test pattern 2A where all wiring parts are converged at one end
And a test pattern 2B having the same shape as the test pattern 2A so that a wiring portion similarly formed in the shape of a comb is located at the center between adjacent comb tooth-shaped wiring portions of the test pattern 2A. Is formed. Test pattern 2A,
2B has terminal portions 2C and 2D in which all the wiring portions are converged, and these portions can be electrically connected to the outside. The test pattern 2A and the test pattern 2B are each formed of a copper wiring layer having a thickness of 18 microns. The wiring width of the comb teeth of the test patterns 2A and 2B is 100 microns, and the distance between the wirings between the adjacent test patterns 2A and 2B is also 100 microns.

FIG. 1B is a schematic sectional view of a section of the printed wiring board 2 along AA '. As shown in FIG. 1B, the printed wiring board 2 is a four-layered multi-layer substrate including three interlayer insulating films 21, 22, 23 and four wiring layers. 22 and 23 are thickness 6 in order
It is an organic insulating material of 0 micron, 250 micron, and 60 micron. In the present embodiment, BT resin is used as the organic insulating material. This is PPE, FR-
It may be 4 or the like. Further, among these materials, different materials may be laminated and used. The wiring layer is made of copper. In the printed wiring board 2, test patterns 2A and 2B having the same shape as described above are formed at equal intervals on each of the four wiring layers, and the test patterns 2A and 2B of each wiring layer are substantially equal to each other. They are formed at the same position. The test patterns 2A and 2B of each wiring layer are connected to each other at terminal portions 2C and 2D by through holes penetrating all layers (not shown).

The terminal portions 2C of the test patterns 2A, 2B,
2D is connected to the + electrode and-electrode of the power supply 1, respectively. In this state, the power supply 1 applies a working voltage of the printed wiring board between the terminal portions 2C and 2D for a certain period of time (for example, 8
In a high temperature and high humidity atmosphere of 5 ° C. and 85%, 5.5 V is applied to 1000
Add time). In order to prevent an excessive current from flowing when a short circuit occurs, a limiter is set in the power supply 1 so that a current of 0.01 A or more does not flow.

Next, a method for evaluating the reliability of a printed wiring board using this evaluation apparatus will be described. First, figure
1 A voltage of 5.5 V was applied between the terminal portions 2C and 2D of the printed wiring board 2 by the power supply 1 in the state of FIG. On this occasion,
The voltage between both terminals of the resistor 5 was almost 0V. In addition, the terminal portions 2C of the printed wiring board 2 which were confirmed prior to the evaluation,
The resistance between 2D was about 10 ¹¹ Ω to 10 ¹³ Ω, which was sufficiently larger than the resistance 5 of 10 kΩ (10 ⁴ Ω).

Next, a printed wiring board 2 is connected to this apparatus in FIG.
As shown in (A), when the voltage application of 5.5 V was continued while connected, the voltage between both terminals of the resistor 5 (the voltage monitored by the pen recorder 7) increased in the application time of about 10 hours. There was something to start. This voltage almost reached 5.5 V in a relatively short time of 1 second or less or about 1 hour after the start of the voltage rise. Here, when the printed wiring board 2 was removed and the resistance between the terminal portions 2C and 2D was measured, it was found that the resistance dropped to 100Ω or less.
Many were reduced to about 10 ⁵ Ω. Even when the terminal portions 2C and 2D are connected by the copper wiring having the above-described wiring width, the terminal portions 2C and 2D have a resistance of about 100Ω.

Here, according to the method described in the prior art, when the resistance between the terminal portions 2C and 2D decreases, the short-circuited portion of the printed wiring board 2 is set to, for example, 0.
A current of 01A flows. However, if the device described in the present embodiment is used, 10
Since a resistor of kΩ is connected, a current of about 500 μA or more does not flow in the short-circuited portion of the printed wiring board 2.

By using the evaluation method according to the present embodiment, if the voltage monitored by the pen recorder 7 is constantly checked, the occurrence of a defect in the printed wiring board can be checked at an early stage, and the printed wiring board can be checked. Failure analysis and design changes can be started early.

In the present embodiment, a voltage limiter is connected in place of the pen recorder or in parallel with the pen recorder, and when a constant voltage is reached, the power is cut off and the power is turned off. It is possible to output a signal. With such a configuration, it is possible to confirm the occurrence of a defect earlier and even during unattended operation, and stop the voltage application.

In this embodiment, the method for evaluating a printed wiring board has been described. However, the object to be evaluated is not limited to a printed wiring board, but may be any electronic component that requires insulation resistance. At this time, a resistance having a resistance value of 1/100 or less is required as the resistance 5 with respect to the lowest value of the insulation resistance of the device to be evaluated. is there. In the present embodiment, about 1 /
It was 10,000. Further, in order to monitor the voltage change with the pen recorder 7 or the like, the resistance 5 must be at least 1 kΩ or more.

From the above, the insulation resistance of the device to be evaluated is at least 10
A value of about 0 kΩ is required, and is preferably 1000 kΩ or more. Further, in order to detect a change in the insulation resistance value with high sensitivity, it is desirable that the insulation resistance of the device under test when it becomes defective is reduced to about 1/1000 or less of the initial resistance value.

When the applied voltage condition is different, it is necessary to adjust the value of the resistor 5 so that the maximum current does not become too large. For example, if the applied voltage is 60
In the case of Ω, the resistor 5 may use 100 kΩ so that the maximum current is suppressed to 500 μA.

(Second Embodiment) Next, a second embodiment of the present invention will be described. The evaluation device used in the present embodiment is the same as the device used in the first embodiment, and a description thereof will be omitted.

In the present embodiment, in order to analyze a short circuit failure of the printed wiring board, the pen recorder 7 uses 5.5V.
Immediately after confirming the occurrence of a small voltage fluctuation, the voltage application was stopped, and the resistance between the terminals 2C and 2D of the printed wiring board 2 was measured.

The resistance between the terminal portions 2C and 2D is about 10 ⁷ Ω, which does not progress as much as the short circuit described in the first embodiment, but is larger than the initial resistance (10 ^-4 times to 10 times). ^{(About -6} times).

As shown in FIG. 2, the printed wiring board 2 was irradiated with light 15 from a light source 14 and the transmitted light 16 was observed by being incident on an objective lens 13 of an optical microscope. As shown in FIG. Black discolored portions 11 that short-circuit between 2A and 2B were observed. The magnification in FIG. 3 is the same as the magnification in FIG. The blackened portion 11 is the wiring 2
The wirings 2A and 2B are formed to be connected between the wirings 2A and 2B while branching between the A and 2B and branching into a tree-like black discolored portion 11A while bending. In addition, there are various cases where these black discolored portions 11 are on the surface of the printed wiring board 2, are slightly inside, or are formed between internal wiring layers. It should be noted that even when there is a blackened portion between the internal wiring layers, the BT
Since the resin was light-transmitting, the same blackening could be observed by adjusting the depth of focus of the optical microscope.

In many cases, cavities 12 were formed around these blackened portions 11. Although the cause of these cavities 12 is not clear, it was presumed that the surrounding BT resin was volatilized and formed due to the temperature rise of the black discolored portions 12.

When the next portion near the blackened portion 12 was sampled and subjected to infrared spectroscopy, it was found that some cellulose components were detected. It was presumed that this cellulose component was mixed from the fibers used in the process jig when the BT resin of the multilayer printed wiring board 11 was laminated. Similarly, in some cases, metals such as iron were detected by XMA analysis of the surface near the blackened portion. These were presumed to be from the manufacturing process of parts and materials.

As described above, by using the present embodiment, the occurrence of a short-circuit failure can be confirmed at an early stage, and it becomes easy to specify the location of the failure and to estimate the cause of the failure. In addition, it has become possible to promptly give feedback to the process management, thereby making it possible to solve problems in the process at an early stage.

Further, it was found from the recording of the pen recorder 7 that there were several patterns in the occurrence of defects. That is, 1) those which fluctuate suddenly from the start of voltage fluctuation to around 5.5 V and stabilize as they are, and 2) those which fluctuate to 5.5 V instantly and return to around 0 V immediately. 3) Although it fluctuates instantaneously and returns to its original state in almost the same manner as in 2 above,
In addition, those which show an instantaneous fluctuation similarly after several minutes to several tens of hours. And so on. Of these, the defects described in the above 2 and 3 have extremely short change times, and often cannot be sufficiently followed even by using a high-speed pen recorder capable of following 1 msec. In addition, there are cases in which a defect such as the above 1 occurs after several times of the fluctuation shown in the above 3 are shown. For each of these failures, the cause of the failure was confirmed and countermeasures could be taken. For each of the defects mentioned above,
Even if only a very short-term fluctuation is seen like
Black discoloration as described in the second embodiment was observed at any location on the printed wiring board, even if it was slight. Such a minute change cannot be detected by the conventional evaluation method, and it has been found that continuous voltage monitoring using a pen recorder or the like is extremely effective.

As described above, by using the first and second embodiments of the present invention, a short circuit failure of a printed wiring board can be confirmed at an early stage. Along with this, the design change of the printed wiring board can be performed in a short time.

In each of the above embodiments, BT resin was used as the organic insulating layer.
4, a resin such as PPE may be used. These resins are also light-transmissive, so that short-circuits occurring in the inner-layer wiring portion can be visually confirmed. In addition, even if the resin is a light-impermeable resin,
It is possible to confirm a short circuit by observing the surface, and the effects of the present invention can be enjoyed. Furthermore, although a copper wiring layer is used as a wiring layer in each of the above embodiments, it is needless to say that the conductive layer is not limited to copper.

Further, the wiring board is not limited to a printed wiring board, but may be any substrate to which the above-described configuration can be applied, and may be a ceramic multilayer board or the like. In addition, the basic configuration of the present application is not limited to the evaluation of a wiring board, but can be applied to a semiconductor element, an electronic component, and the like in which a withstand voltage may decrease.

[0039]

As described above, the use of the apparatus of the present invention makes it possible to detect a short-circuit failure of a printed wiring board without causing an excessive current to flow. Further, by using the method of the present invention as described above, a short circuit failure of a printed wiring board can be confirmed at an early stage. Along with this, the design change of the printed wiring board can be performed in a short time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a printed wiring board and a device for evaluating the same according to a first embodiment of the present invention.

FIG. 2 is a schematic view showing a method for observing a defective portion of a printed wiring board with a microscope.

FIG. 3 is an enlarged surface view of a short-circuit failure portion of the printed wiring board generated by the method for evaluating a printed wiring board according to the present invention.

FIG. 4 is an enlarged surface view of a short-circuit failure location of a printed wiring board generated by a conventional printed wiring board evaluation method.

FIG. 5 is a schematic view showing a conventional method for evaluating a printed wiring board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Power supply 2 ... Printed wiring board 2A, 2B ... Test pattern 2C, 2D ... Terminal part 4 ... Insulation resistance measurement meter 5 ... Resistance (load resistance) 6 ... Voltmeter 7 ... Pen recorder 10 ... Short part 11 ... Black discoloration part DESCRIPTION OF SYMBOLS 12 ... Cavity 13 ... Objective lens 14 ... Light source 15 ... Light (incident light) 16 ... Transmitted light 21, 22, 23 ... Interlayer insulating film

Continued on the front page (72) Inventor Kimiaki Hoizumi 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant Co., Ltd. In-plant F-term (reference) 2G014 AA03 AA15 AB59 AC09 AC15 2G028 AA02 BB11 BC01 CG03 DH03 FK02 LR01 LR07 MS05 5E346 GG34 HH31

Claims (4)

[Claims] An electronic component reliability evaluation device for evaluating insulation resistance between terminals of an electronic component, wherein the reliability evaluation device is connected to a terminal of the electronic component whose insulation resistance is to be measured and a voltage is applied between the terminals. A power supply to be obtained, a load resistance connected between the power supply and the electronic component, and voltage measuring means for measuring a voltage between both terminals of the load resistance. An electronic component reliability evaluation device, wherein an insulation resistance value is 100 kΩ or more, and a resistance value of the load resistance is 1/1000 or less of an insulation resistance value between terminals of an electronic component to be connected to the power supply. 2. An electronic component having an insulation resistance between terminals of 100.
2. The reliability evaluation device for an electronic component according to claim 1, wherein the resistance value of the load resistance is 0 kΩ or more, and the resistance value of the load resistance is 1/10000 or less of an insulation resistance value between terminals of the electronic component. 3. 3. A method for evaluating the reliability of an electronic component using variation in insulation resistance between terminals, the method comprising: connecting a load resistance having a resistance value smaller than the resistance value between terminals of the electronic component in series to connect between the terminals. A step of applying a voltage, a step of measuring a resistance value variation between both ends of the load resistor, and a step of stopping the voltage application when the resistance value variation reaches a desired value. To evaluate the reliability of electronic components. 4. A method for evaluating the reliability of an electronic component using variation in insulation resistance between terminals, wherein a load resistance having a resistance value smaller than a resistance value between terminals of the electronic component is connected in series between terminals of the electronic component. A step of continuously applying a voltage between the terminals, and a step of continuously measuring the resistance value across the load resistor simultaneously with the step of continuously applying the voltage,
The load resistance is 1/1 of the resistance between terminals of the electronic component.
000 or less, a method for evaluating the reliability of electronic components.