Inspection apparatus and inspection method for inspecting a wiring board

Patent metadata

Field	Value
Publication number	US-9476934-B2
Application number	US-201414261480-A
Country	US
Kind code	B2
Filing date	Apr 25, 2014
Priority date	Jun 21, 2013
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

An inspection apparatus for inspecting a wiring board having an opposing electrode facing an upper face of the wiring board, a capacitance meter electrically connected to the opposing electrode and the multi-layer wiring, and measuring capacitance between the opposing electrode and the multi-layer wiring, ground, a switch box that is connected to the ground wirings, the opposing electrode, and the ground, and switches to select between a first connection state, in which all the ground wirings are electrically connected to the opposing electrode, and a second connection state, in which one ground wiring is electrically connected to the ground. A control unit extracts a capacitance value by calculating difference between a first capacitance and a second capacitance, wherein capacitance in units of layers of the multi-layer wiring are measured based on the capacitance value extracted by the control unit.

First claim

What is claimed is:

1. An inspection apparatus for inspecting a wiring board that includes multiple layers of wiring including electrically connecting wirings of a plurality of mutually-different layers, from an uppermost layer to a lowermost layer, and at least one ground wiring electrically insulated from the multiple layers of wiring and located at a position, wherein distance between one ground wiring and a wiring of the uppermost layer of the multiple layers of wiring is longer than distance between the one ground wiring and another wiring, with the exception of the wiring of the uppermost layer of the multiple layers of wiring, the inspection apparatus comprising:
an opposing electrode locatable facing a surface of the wiring board closest to the wiring of the uppermost layer;
a capacitance meter that is electrically connected to the opposing electrode and the multiple layers of wiring and measures capacitance between the opposing electrode and the multiple layers of wiring;
a ground;
a switch box that is connected to the at least one ground wiring, the opposing electrode, and the ground, and switching between a first connection state and a second connection state, wherein
when there is only one ground wiring, in the first connection state the one ground wiring is electrically connected to the opposing electrode, and, in the second connection state, the one ground wiring is electrically connected to the ground, and
when there is a plurality of ground wirings, in the first connection state, all ground wirings are electrically connected to the opposing electrode, and, in the second connection state, a ground wiring is electrically connected to the ground; and

a control unit extracting a capacitance value by calculating difference between a first capacitance that is measured in the first connection state by the capacitance meter, and a second capacitance that is measured in the second connection state by the capacitance meter, wherein capacitance in units of layers of the multiple layers of wiring is obtained based on the capacitance value extracted by the control unit.

2. The inspection apparatus according to claim 1 , wherein the control unit is connected to the capacitance meter and stores capacitances measured using the capacitance meter.

3. The inspection apparatus according to claim 1 , wherein the control unit is connected to the switch box and controls switching of the switch box between the first connection state and the second connection state.

4. The inspection apparatus according to claim 1 , wherein
the wiring board includes a plurality of the ground wirings, each ground wiring is electrically insulated from the multiple layers of wiring, is located at a position, wherein distance between each ground wiring and the wiring of the uppermost layer of the multiple layers of wiring is longer than distance between each ground wiring and each of the multiple layers of wiring, with the exception of the wiring of the uppermost layer of the multiple layers of wiring,
the second connection state includes a plurality of connection states in which one ground wiring is electrically connected to the ground, and all other ground wirings are electrically connected to the opposing electrode,
the switch box switches between the first connection state and the second connection state,
wherein the second connection state is a state selected from a plurality of connection states in which each ground wiring electrically connected to the ground is mutually different, and
the control unit extracts the capacitance value by calculating difference between the first capacitance and a capacitance that is measured by the capacitance meter in the second connection that is selected from among a plurality of connection states.

5. The inspection apparatus according to claim 1 , wherein
the multiple layers of wiring of the wiring boarder have a two-layer wiring structure that includes a lower layer wiring and an upper layer wiring, and one ground wiring disposed at a position, wherein distance between the ground wiring and the upper layer wiring is longer than distance between the ground wiring and the lower layer wiring,
in the first connection state, one ground wiring is electrically connected to the opposing electrode,
in the second connection state, the one ground wiring is electrically connected to the ground, and
the control unit extracts the capacitance value by calculating difference between the first capacitance that is measured in the first connection state and the second capacitance that is measured by the capacitance meter in the second connection state.

6. A method of inspecting a wiring board that includes multiple layers of wiring including electrically connecting wirings of a plurality of mutually-different layers, from an uppermost layer to a lowermost layer, and at least one ground wiring electrically insulated from the multiple layers of wiring, and located at a position, wherein distance between one ground wiring and a wiring of the uppermost layer of the multiple layers of wiring is longer than distance between the one ground wiring and another wiring with the exception of the wiring of the uppermost layer of the multiple layers of wiring, the method comprising:
disposing an opposing electrode to face a surface of the wiring board closest to the wiring of the uppermost layer;
switching between a first connection state and a second connection state, wherein
when there is only one ground wiring, in the first connection state, the one ground wiring is electrically connected to the opposing electrode, and, in the second connection state, the one ground wiring is electrically connected to the ground; and
when there is a plurality of ground wirings, in the first connection state, all ground wirings are electrically connected to the opposing electrode, and, in the second connection state, a ground wiring is electrically connected to the ground;

measuring a first capacitance in the first connection state;
measuring a second capacitance in the second connection state; and
obtaining capacitance in units of layers of the multiple layers of wiring by extracting a capacitance value by calculating difference between the first capacitance and the second capacitance.

7. The method according to claim 6 , wherein the wiring board includes a plurality of the ground wirings, and each ground wiring is electrically insulated from the multiple layers of wiring, is located at a position, wherein distance between each ground wiring and the wiring of the uppermost layer of the multiple layers of wiring is longer than distance between each ground wiring and each of the multiple layers of wiring, with the exception of the wiring of the uppermost layer of the multiple layers of wiring,
the second connection state includes a plurality of connection states in which one ground wiring is electrically connected to the ground, and all other ground wirings are electrically connected to the opposing electrode,
switching between the first connection state and the second connection state, wherein the second connection state is a state selected from a plurality of connection states in which each ground wiring electrically connected to the ground is mutually different,
the second capacitance is measured for each one of the second connection states in which each ground wiring electrically connected to the ground is mutually different, by switching, and obtaining a plurality of the second capacitances, and
extracting a plurality of the capacitance values using the first capacitance and each one of the second capacitances, and obtaining capacitance in units of layers of the multiple layers of wiring based on the plurality of the capacitance values extracted.

8. The method acc

Assignees

• Nihon Micronics Kk

Inventors

• Fukami Yoshiyuki

Classifications

• G01R31/2801

  Testing of printed circuits, backplanes, motherboards, hybrid circuits or carriers for multichip packages [MCP] (G01R31/318508 takes precedence; contactless testing G01R31/302; testing contacts or connections G01R31/66) · CPC title

• G01R31/2812

  Checking for open circuits or shorts, e.g. solder bridges; Testing conductivity, resistivity or impedance (of connections G01R31/66) · CPC title

• G01R31/2822 Primary

  of microwave or radiofrequency circuits (of attenuation, gain, e.g. using network analyzers G01R27/28) · CPC title

• G01R31/2805

  Bare printed circuit boards · CPC title

• G01R31/2808

  Holding, conveying or contacting devices, e.g. test adapters, edge connectors, extender boards (probe, multiprobe, probe manipulator or probe fixture G01R1/067) · CPC title