JPH07221152A - Migration tester - Google Patents

Abstract

PURPOSE:To provide a migration tester, which improves the reproducibility of a water section area over between electrodes and can measure accurately an migration even in a practical substrate. CONSTITUTION:A frame 3 which is mounted at a migration measurement site on a substrate 2, power terminals 5 and 6 formed of an insoluble metal and a hot plate 1 for keeping the temperature of the substrate 2 constant are provided. Accordingly, a measurement of a migration can be made accurately in a practical substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a test for a migration phenomenon in which a dendrite-like metal extending mainly from the cathode side is often generated on a substrate such as a printed wiring board used in electronic equipment when a voltage is applied. Regarding vessels. More specifically, the migration phenomenon testing method includes a method of applying a voltage by dropping a water droplet on a substrate and a method of applying a voltage by placing the substrate in a high temperature and high humidity atmosphere, but the present invention belongs to the former.

[0002]

2. Description of the Related Art Conventionally, for example, 0 or 2 cc of distilled water is dropped on a test-dedicated substrate having a Y-shaped conductor with an electrode interval of 0 and 32 mm, and a constant DC voltage of 1 or 5 V is applied to measure a leak current. Alternatively, the migration phenomenon was tested by a method in which a DC constant current of 40 microamperes was applied and the drop voltage was measured. The purpose of the test-dedicated board with the Y-type conductor is to purposely prevent the metal that composes this terminal from electrochemically eluting when the terminal that applies the DC power to the board conductor gets wet with water. It was used as a conductor of and was connected at a remote place so as not to get wet with water. Conventionally, a tester for migration phenomenon by a method of applying a voltage by dropping a water drop on a substrate has not been commercially available.

[0003]

When carrying out a migration test by applying a water drop voltage, the cross-sectional area of water between electrodes becomes more important than the amount of water drops. That is, in the constant voltage migration test, the voltage drop, which is the ohmic loss between the electrodes, is the product of the current and the liquid resistance, but the liquid resistance is inversely proportional to the cross-sectional area of water between the electrodes. That is, ohmic loss is inversely proportional to the cross-sectional area of water. Therefore, even if a certain amount of water is dropped, a substrate that is easily wetted by water will spread widely and the cross-sectional area of water will become small. Therefore, in order to perform a reproducible migration test, it is necessary to make the cross-sectional area of water constant. In addition, if the Y-shaped conductor 7 is used, it can be connected at a remote place so as not to get wet with water. However, as a practical matter, when performing a migration test by applying a water drop dripping voltage on a practical substrate used for ordinary electric equipment, There is a possibility that the terminal portion may get wet with water, and if the terminal portion gets wet with water, the terminal metal may be electrochemically eluted and an accurate test cannot be performed.
Needless to say, it is more accurate to carry out the test at the same temperature.

[0004]

The present invention has been proposed in order to solve the above-mentioned problems, and it is natural to make the dropping amount constant with a pipette or the like, but before dropping water. In advance, a frame formed of a non-conductive, water-impermeable, non-leakable material is mounted on the substrate. Further, the terminal needle is formed of an insoluble metal that electrochemically does not elute metal ions. Further, a hot plate capable of heating the test substrate to a constant temperature is provided.

[0005]

[Function] Before the water is dropped, a frame made of a non-conductive, water-impermeable, non-leakable material is mounted on the substrate in advance, and a certain amount of water is dropped into the frame. Spreads almost uniformly over the water and the cross-sectional area of water is almost constant. In addition, since the terminal needle is made of an insoluble metal that electrochemically does not elute metal ions, even if a voltage is applied to both terminals even if the terminals are continuously connected with water, No metal ions are eluted from the needle.
Furthermore, by providing a hot plate under the test substrate that can be heated to a constant temperature, the test substrate temperature becomes a constant temperature during the test.

[0006]

EXAMPLE As shown in FIG. 2, a substrate 2 is first placed on a hot plate 1 which can be heated to a constant temperature, and then a rubber frame 3 is mounted on the substrate 2. To mount the frame, an adhesive or an adhesive may be applied to the back surface of the frame in advance and the frame may be attached to the substrate, or the frame may be pressed by a spring, a clamp, or another method. A certain amount of water is injected into the inside of this frame with the pipette 4. Next, the platinum-plated power supply terminal needles 5 and 6 on titanium are fixed in contact with the electrode portions 8 and 9 inside or outside the frame. Next, a power supply is applied, and in the case of a constant voltage, the leak current is measured, and in the case of a constant current, the voltage drop is measured and recorded by a recorder.

[0007]

EFFECTS OF THE INVENTION After a frame 3 made of a non-conductive, non-water-permeable and non-leakable material is mounted on the substrate 2 before dropping water, a predetermined amount of water is dropped. Spreads almost uniformly within this frame, and the cross-sectional area of water is almost constant at all times. Therefore, the reproducibility of the ohmic loss between the electrodes 8 and 9 is improved, and accurate measurement is possible. In addition, since the terminal needles 5 and 6 are formed of an insoluble metal that electrochemically does not elute metal ions, voltage is applied to both terminals 5 and 6 even when the terminal needles 5 and 6 are continuously connected with water. Since metal ions do not elute from both terminal needles 5 and 6 when applied or applied, the terminal needles 5 and 6 cannot be used on a practical substrate or the like.
It is also possible to immerse them in water and bring them into contact with each other, and a migration test can be performed on any substrate. Further, since the hot plate 1 that can be heated to a constant temperature is provided below the test substrate 2, the temperature of the test substrate 2 becomes a constant temperature during the test, so that accurate measurement is possible.

[Brief description of drawings]

FIG. 1 is a Y-shaped conductor diagram in the case of performing a conventional water drop dropping voltage application migration test.

FIG. 2 is a perspective view of an embodiment of the present invention.

[Explanation of symbols]

1 Hot Plate 2 Test Substrate 3 Frame 4 Pipette 5 Platinum Plated Power Terminal Needle (Anode Side) 6 Platinum Plated Power Terminal Needle (Cathode Side) 7 Y-type Conductor 8 Electrode (Anode Side) 9 Electrode (Cathode side)

Claims (3)

[Claims] 1. A device provided with a frame, which is made of a non-conductive, water-impermeable and non-leakable material, mounted on a substrate and which can inject a fixed amount of water into the inside of the frame. Constant voltage type and constant current type migration tester characterized by 2. A constant voltage, characterized in that two needles made of an insoluble metal that does not elute metal ions electrochemically when used as an anode are brought into contact with two conductors on a substrate. And constant current migration testers 3. The migration tester according to claim 1, further comprising a heating device provided below the test substrate to keep the temperature of the test substrate constant.