Method and apparatus for circuit board continuity test, tool for continuity test, and recording medium
AssigneeOHT Inc.
InventorShuji Yamaoka
Life of this patent
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Abstract
The present invention provides an apparatus and method for inspecting electrical continuity of a circuit board, capable of decreasing the impedance in a current path as an inspection object to achieve enhanced SN ratio. A coupling capacitance is formed at one of terminals of a pattern wire on a board as an inspection object in a non-contact manner, and an inductance (450) and a lead wire are connected to this capacitance. An AC inspection signal is applied to the other terminal through the lead wire in a contact manner. A resonance circuit is defined by the capacitance, inductance and pattern wire, and thereby an output signal can be detected with lowering the impedance.
Claims22
A continuity inspection apparatus for inspecting electrical continuity between first and second terminals of a pattern wire formed on a board, said continuity inspection apparatus comprising:
- capacitive coupling means to be capacitively coupled with said first terminal in a non-contact manner to provide a coupling capacitance therebetween;
- an inductive element connected to said capacitive coupling means to form a resonance circuit in conjunction with the capacitance yielded by said capacitive coupling means in order to inspect said electrical continuity under a low resistance;
- a first lead wire connected to said inductive element;
- probe means connected to a second lead wire and to be contacted with said second terminal;
- signal inputting means for inputting an inspection signal including an AC component into one of said first and second lead wires;
- and
- signal detecting means for detecting an output of said inspection signal at the other of said first and second lead wires.
A continuity inspection method for inspecting electrical continuity between first and second terminals of a pattern wire formed on a board, said continuity inspection method comprising steps of:
- positioning a given electrode close to said first terminal to form a coupling capacitance, and connecting a given inductive element to said electrode, followed by connecting a first lead wire to said inductive element and connecting a second lead wire to said second terminal, so as to form a resonance circuit by said first lead wire, inductive element, electrode, coupling capacitance, first terminal, pattern wire, second terminal and second lead wire in order to inspect said electrical continuity under a low resistance;
- applying an inspection signal including an AC component to one of said first and second lead wires;
- and
- detecting an output of said inspection signal at the other of said first and second lead wires.
A continuity inspection apparatus for inspecting electrical continuity between first and second terminals of a pattern wire formed densely on a board, said continuity inspection apparatus comprising:
- a sensor electrode having a dimensional size so as to provide a coupling capacitance falling within the range of 50 fF to 1 pF with said pattern wire;
- an inductive element connected in parallel or series with said sensor electrode, to form a resonance circuit said inductive element having a constant ranging from 20 mH to 25 μH in order to inspect said electrical continuity under a low resistance;
- and
- an oscillator oscillating at a reference frequency falling within the rang of 5 MHz to 10 MHz, said oscillator being adapted to change the frequency thereof in a given range from said reference frequency.
Dependencies are inferred from the claim text.