JPH11258294A - Apparatus and method for inspection of circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an apparatus and a method in which the electric continuity between electrodes can be inspected easily and surely by a method wherein an insulating sheet on which electric continutiy parts are dotted in the thickness direction and a conductive plate as an electric good conductor are arranged on the side opposite to a probe with reference to a circuit board. SOLUTION: An elastic body sheet 6 which is set to electric continuity in the thickness direction is arranged under a circuit board 5. A probe head 2 is moved to an electrode (a through hole) 4. A probe is brought into contact with the electrode 4. The electric continuity of the circuit board 5 is inspected. When the continuity between the surface electrode of the circuit board 5 and its rear-side electrode is inspected, a conductor layer such as a copper-clad plate 7 is installed at the elastic body sheet 6, and it is sufficient to inspect the continuity between the layer 7 and the probe head 2. When a part between electrodes on the surface side of the board 5 is inspected, an insulating layer is arranged under the elastic body sheet 6, and it is sufficient to inspect the part between the electrodes on the surface side. As the elastic body sheet 6, a sheet in which conductive particles such as nickel particles whose surface is covered with gold or silver are contained in an elastic insulator such as silicone rubber or the like is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for inspecting electrical continuity of a circuit wiring board such as a printed circuit board.

[0002]

2. Description of the Related Art In the case of performing an electrical continuity test on a circuit board such as a printed wiring board by contacting a probe, conventionally, as shown in FIG. Prepare and arrange them in such a way that one pin is in contact with each electrode on the back of the circuit board, and one or more probes are brought into contact with each electrode from the front side of the circuit board. A method of performing an electrical continuity test is known.

[0003]

However, in the conventional pin probe continuity inspection method, for example, a method in which a circuit board is set up vertically and a probe is brought into contact with electrodes on both sides of a through hole or the like by means of a probe, the accuracy is reduced due to the deflection of the board. This makes it difficult to make contact, and it has been difficult to conduct an electrical continuity test on a thin and flexible circuit board. Also, place the circuit board horizontally, place a pin jig consisting of a plurality of pins at positions corresponding to the electrodes on the back surface of the circuit board, and contact one or more probes from the front side of the circuit board to make electrical contact. In the method of conducting electrical continuity inspection, it is necessary to prepare a pin jig in which pins are arranged at positions corresponding to each electrode of the circuit board for each of different types of circuit boards, and labor and manufacturing for manufacturing the pin jig for each circuit board are required. There was a problem that time and cost became extremely large. The present invention provides an easy and reliable method for performing an electrical continuity test between electrodes of a circuit board, even if the number of through holes and the like is minute and large, and the distance between each electrode is small and large. It is an object of the present invention to provide an inspection device and an inspection method for performing an electrical continuity inspection of a device.

[0004]

SUMMARY OF THE INVENTION The present invention relates to an apparatus for inspecting electrical continuity of a circuit board using a probe, which is electrically connected to a circuit board to be inspected in a thickness direction on a side opposite to the probe. An object of the present invention is to provide an inspection apparatus for a circuit board, wherein an insulating sheet having conductive portions interspersed therein and a conductive plate which is an electrically good conductor are arranged. Further, the present invention is characterized in that, in the electrical continuity inspection of a circuit board using a probe, an insulating sheet in which conductive portions electrically conducting in the thickness direction are interspersed and arranged on the circuit board to be inspected. And a circuit board inspection method.

[0005]

FIG. 2 shows an example of an embodiment of the present invention. Hereinafter, the present invention will be specifically described with reference to FIG.
In FIG. 2, an elastic sheet 6 that is electrically conductive in the thickness direction is disposed under a circuit board 5 such as a printed wiring board, and the probe head 2 is driven on each electrode 4 serving as an inspection point by using a driving device. Then, the probe 3 is moved downward and brought into contact with the electrodes to perform an electrical continuity test on the circuit board. With this configuration, for example, when conducting an electrical continuity test between the electrodes on the front side and the electrodes on the back side of the circuit board, a conductor such as a copper-clad plate 7 is formed on the elastic sheet 6 as shown in FIG. And the electrical conductivity between the conductor layer 7 and the probe head 2 may be inspected. Also, when testing the insulation or continuity between the electrodes on the front side of the circuit board,
As shown in FIG. 3, the insulating layer 10 may be disposed below the elastic sheet 6 and the electrical insulation or conductivity between the electrodes on the front side may be inspected.

As the elastic sheet 6 electrically conducting in the thickness direction, a sheet having conductivity and elasticity is preferable.
In particular, a sheet in which conductive portions that are electrically conductive in the thickness direction when pressurized are scattered in a nonconductive portion formed of an insulating sheet is preferable. As such a conductive portion, a conductive portion which is electrically conductive in a thickness direction when pressurized is preferable, and a conductive and elastic portion is preferable. In particular, a material in which conductive particles are contained in an elastic insulator is preferable.

As the elastic insulator, a rubber-like polymer is preferable. Examples of the rubbery polymer include conjugated diene rubbers such as polybutadiene, natural rubber, polyisoprene, SBR and NBR, and hydrogenated products thereof, and block copolymers such as styrene butadiene diene block copolymer and styrene isoprene block copolymer. Examples include coalesced and hydrogenated products thereof, chloroprene, urethane rubber, polyester rubber, epichlorohydrin rubber, silicone rubber, ethylene propylene copolymer, and ethylene propylene diene copolymer. If weather resistance is required, a rubbery polymer other than the serving diene rubber is preferred,
In particular, silicone rubber is preferable from the viewpoint of moldability and electrical characteristics. Examples of the insulator having high rigidity include a glass fiber reinforced epoxy resin and a polyimide resin.

Here, the silicone rubber will be described in more detail. As the silicone rubber, one obtained by crosslinking or condensing liquid silicone rubber is preferable. Preferably it has the following 10 ⁵ poise at a liquid silicone rubber is the viscosity of the strain rate of 10 ^{over 1} sec, condensation type, addition type, may be any of vinyl group and a hydroxyl group-containing type. Specific examples include dimethyl silicone raw rubber, methyl vinyl silicone raw rubber, and methylphenyl vinyl silicone raw rubber. Among these, as a vinyl group-containing silicone rubber, usually, dimethyldichlorosilane or dimethyldialkoxysilane, in the presence of dimethylvinylchlorosilane or dimethylvinylalkoxysilane,
It can be obtained by hydrolysis and condensation, followed by fractionation by repeated dissolution-precipitation.

In the case of those containing a vinyl group at both terminals, a cyclic siloxane such as octamethylcyclotetrasiloxane is anionically polymerized in the presence of a catalyst, and the polymerization is terminated by using a terminal terminator to form a polymer. When obtaining, it can be obtained by using, for example, dimethyldivinylsiloxane as a terminal stopper, and appropriately selecting reaction conditions (eg, the amount of the cyclic siloxane and the amount of the terminal stopper). Here, examples of the catalyst include alkalis such as tetramethylammonium hydroxide and n-butylphosphonium hydroxide or silanolate solutions thereof, and the like.
The reaction temperature is, for example, 80 to 130 ° C.

The hydroxyl group-containing silicone rubber is usually prepared by converting dimethyldichlorosilane or dimethyldialkoxysilane into a hydrosilane compound such as dimethylhydrochlorosilane, methyldihydrochlorosilane or dimethylhydroalkoxysilane.
It can be obtained by hydrolysis and condensation, followed by fractionation by repeated dissolution-precipitation. In addition, when the cyclic siloxane is anionically polymerized in the presence of a catalyst and the polymerization is terminated using a terminal stopper to obtain a polymer, the reaction conditions (for example, the amount of the cyclic siloxane and the amount of the terminal stopper) are selected. Can be obtained by using dimethylhydrochlorosilane, methyldihydrochlorosilane or dimethylhydroalkoxysilane as a terminal stopper. Here, examples of the catalyst include alkalis such as tetramethylammonium hydroxide and n-butylphosphonium hydroxide and silanolate solutions thereof, and the reaction temperature is, for example, 80 to 130 ° C.
Is mentioned.

The molecular weight (weight average molecular weight in terms of standard polystyrene) of the rubbery polymer is preferably 10,000 to 40,000. The molecular weight distribution index of the rubbery polymer component (the ratio of the weight average molecular weight in terms of standard polystyrene to the number average molecular weight in terms of standard polystyrene (hereinafter referred to as "Mw / Mn"))
Is preferably 2 or less from the viewpoint of the heat resistance of the obtained conductive rubber.

Examples of the conductive particles include known single conductive metal particles such as iron, copper, zinc, chromium, nickel, gold, silver, cobalt, and aluminum, and alloys or composites of two or more of these metal elements. Conductive metal particles, carbon black, and the like. Of these, carbon black, nickel, iron,
Conductive particles such as copper are preferable in terms of economy and conductive characteristics, and particularly preferably nickel particles whose surface is coated with gold or silver.

When silicon rubber is used as the insulator, the coverage of the conductive particles with the silane coupling agent is preferably 5% or more, and more preferably 7 to 5.
It is 100%, more preferably 10 to 100%, particularly preferably 20 to 100%. The particle size of the conductive particles is preferably 1 to 1000 μm, more preferably 2 to 500 μm, more preferably 3 to 300 μm, and particularly preferably 5 to 100 μm. In particular, in the vicinity of the uneven portion of the conductive rubber sheet, it is necessary that the conductive particles are sufficiently filled in the convex portion, and the particle size of the conductive particles is preferably 1 to 200 μm, more preferably 2 to 150 μm, and particularly preferably. 5 to 100 μm. In the case where the conductive rubber sheet has a surface having no irregularities, the conductive particles in the vicinity of the surface may have a particle diameter of 1 to 1000 μm. In addition, the particle size distribution (Dw / D
n) is preferably 1 to 10, more preferably 1.01 to 7, more preferably 1.05 to 5, and particularly preferably 1.
1 to 4. The water content of the conductive particles is preferably 5% or less, more preferably 3% or less, and more preferably 2% or less.
%, Particularly preferably 1% or less. According to the conductive particles having a particle diameter in such a range, in the obtained conductive rubber, sufficient electrical contact between the conductive particles can be obtained during use. The shape of the conductive particles is not particularly limited, but is preferably spherical or star-shaped from the viewpoint of easy dispersion in the above-mentioned silicon rubber or the like.

The nickel particles whose surfaces are preferably coated with gold, which are particularly preferably used as the conductive particles in the present invention, are those obtained by plating the surfaces of the nickel particles with gold by, for example, electroless plating. Thus, the nickel particles having a gold coating on the surface have extremely low contact resistance. When coating gold by plating, the film thickness is 10
It is preferably at least 00 angstroms. Also,
The plating amount is preferably 1% by weight or more of the particles, more preferably 2 to 10% by weight, and particularly preferably 3 to 7% by weight.

In the present invention, the conductive particles are used in an amount of 30 to 1,000 parts by weight, preferably 50 to 100 parts by weight, per 100 parts by weight of the rubbery polymer.
Used in proportions of up to 750 parts by weight. When the proportion is less than 30 parts by weight, the obtained conductive rubber does not have a sufficiently low electric resistance value during use, and thus does not have a good connection function. The used conductive rubber becomes brittle, and it becomes difficult to use the conductive rubber as the conductive rubber. The composition for conductive rubber containing the rubbery polymer and the conductive particles described above may contain, if necessary, an inorganic filler such as ordinary silica powder, colloidal silica, airgel silica, and alumina. By including such an inorganic filler, the thixotropy at the time of uncuring is secured, the viscosity is increased, and the dispersion stability of the conductive particles is improved, and the strength of the conductive rubber after curing is improved. .

The amount of the inorganic filler used is not particularly limited, but if used in an excessively large amount, the conductive rubber becomes brittle. The viscosity of the composition for conductive rubber is 25 ° C.
It is preferably in the range of 100,000 to 3,000,000 cp at ° C. The composition for a conductive rubber has a function as a conductive rubber due to the formation of a conductive rubber having a large elasticity through a crosslinking or condensation reaction and the addition of a specific conductive particle component.

The composition for conductive rubber can use a curing catalyst for curing. Examples of such a curing catalyst include an organic peroxide, a fatty acid azo compound, a hydroxylation catalyst, and radiation. Examples of the organic peroxide include benzoyl peroxide, bisdicyclobenzoyl peroxide, dicumyl peroxide, and ditertiary butyl peroxide. Examples of the fatty acid azo compound include azobisisobutyronitrile. Specific examples of the catalyst that can be used as a catalyst for the hydrosilylation reaction include chloroplatinic acid and salts thereof, a siloxane complex containing a platinum-unsaturated group, a complex of vinyl siloxane and platinum, and a complex of platinum and 1,3-divinyl tetra. Known ones such as a complex with methyldisiloxane, a complex of triorganophosphine or phosphite with platinum, an acetylacetonate platinum chelate, and a complex of cyclic diene and platinum can be mentioned.

The method of adding the curing catalyst is not particularly limited. However, it is preferable that the curing catalyst is preliminarily mixed with the main component, from the viewpoints of storage stability and prevention of uneven distribution of the catalyst when mixing the components. It is preferable to use an appropriate amount of the curing catalyst in consideration of the balance between the actual curing speed and the pot life. Further, a hydrosilylation reaction control agent such as an amino group-containing siloxane or a hydroxy group-containing siloxane, which is usually used for controlling the curing rate and the pot life, can be used in combination.

The insulating sheet used in the present invention may be a sheet made of a rigid material, but is preferably an insulating material having elasticity. Among them, those having a rigid body layer and an elastic body layer are preferred, and a laminate of the rigid body layer and the elastic body layer is particularly preferred. When using a highly elastic insulator layer and a highly rigid insulator layer together, it is preferable to use the laminated sheets of the insulator, and when laminating,
Apply a primer on one insulator surface in advance,
The adhesiveness of the interface can be improved. Further, by adding a coupling material to one of the insulator materials, the adhesiveness of the interface at the time of bonding can be improved.

The insulating sheet used in the present invention is an insulating sheet having conductive portions scattered in the thickness direction, and preferably an insulating sheet having an elastic layer and a hard layer. And a conductive sheet made of an elastic body that is electrically conductive in the thickness direction. The insulating sheet used in the present invention may be a single layer as shown in FIGS. 12 and 13 as described above, or may be a multilayer as shown in FIG. The insulating sheet used in the present invention,
For example, it can be manufactured by the following method. (1) A method in which a hole is formed in a sheet of rubber or resin where a conductive portion is to be formed, and a conductive material is filled therein. (2) Conductive magnetic particles such as nickel are blended in a fluid base material such as silicone rubber or epoxy prepolymer, and then placed in a mold having a small magnetic pole where a conductive portion is to be formed. A method in which the magnetic force lines in the thickness direction are concentrated on that portion to collect and cure the magnetic particles. (3) A hole is formed in a rubber or resin sheet where a conductive part is to be formed, and a conductive material such as nickel is provided in a fluid base material such as silicone rubber or epoxy prepolymer. A method of filling a conductive material containing particles, applying a magnetic field in the thickness direction to orient and cure the magnetic particles.

In particular, in the insulating laminate having the elastic layer and the hard layer, a sheet in which conductive portions made of an elastic material electrically conductive in the thickness direction are interspersed is, for example, as follows. It can be manufactured by a method. That is, as shown in FIGS. 4 to 11, it can be manufactured by the following three steps. Step (1) An elastic rubber material layer is applied to one surface of a metal foil (FIG. 4), and then the elastic rubber material layer applied to the metal is applied to both surfaces of a rigid insulating material sheet. The surfaces were laminated (FIG. 5), and the rubber material layer was hardened by applying heat under pressure as the case may be, and the metal foil, rubber layer, rigid insulating material sheet, rubber layer, and metal foil were laminated in this order. Step of forming a laminate (FIG. 6). Step (2) A through hole is formed in the laminate (FIG. 7), and the hole is filled with a conductive material composed of a rubber material and metal particles (FIG. 8), and the conductive material is cured to form a conductive portion. (FIG. 10). Step (3) A step of removing the copper foil from the laminate on which the conductive portion is formed (FIG. 11).

The probe head 2 may be installed in correspondence with the electrodes of the circuit board, but one or a plurality of them can be freely moved in the horizontal (vertical and horizontal) direction and the vertical direction. It is preferable to use a so-called flying probe which can be moved to a contact with an electrode. The layer 7 of the conductor is not particularly limited, but a plate, a foil, a laminate, or the like such as copper or copper plated with gold or the like is preferably used. The probe 3 may be in direct contact with the electrode of the printed circuit board 5, but a connector electrically conductive in the thickness direction between the probe 3 and the electrode of the printed circuit board 5, preferably It is also preferable to dispose an elastic sheet or the like, for example, an insulating sheet (elastic sheet 6) used in the present invention.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One example of a specific embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a diagram illustrating one embodiment of an electrical continuity inspection method using an insulating sheet 6 having a conductive portion having conductivity in a thickness direction and having electrical continuity. FIG.
The insulating sheet 6 having the electrically conductive portion of
It was manufactured as follows. The size is 300mm long and 300m wide
Two pieces of a copper foil 21 having a thickness of 18 μm and a liquid room temperature-curable silicone rubber 30B applied to one surface of a copper foil 21 with a coater were prepared. See FIG. As shown in FIGS. 5 and 6, this copper foil 21 is 330 mm long and 330 m wide.
m, glass fiber reinforced epoxy sheet 2 with a thickness of 200μ
0 was heated and pressed at a temperature of 100 ° C. under a total pressure of 8 kg for 30 minutes to form a laminate 6A. Next, a copper foil opening having a diameter of 200 μm is formed by photolithography and an etching method containing ferric chloride as a main component in a portion where the conductive portion of the laminate is to be formed. Laser irradiates the opening of the copper foil to form a through hole 2
5H was formed. See FIG.

In this through hole 25H, as shown in FIG.
A room temperature curing type liquid silicone rubber is filled with a conductive part forming material 25B in which nickel particles P having an average particle diameter of 40 μ are blended so as to have a volume content of 30% by a coater, and this sheet is electromagnetized as shown in FIG. After being cured by heating at 100 ° C. for 30 minutes while applying a magnetic field in the thickness direction under a parallel magnetic field device 53/55 of 2000 gauss, spray etching using an etching solution containing ferric chloride as a main component. Then, the copper foil was removed to form an insulating sheet 6 having a conductive portion electrically conducting in the thickness direction of FIG.

Next, as shown in FIG. 2, the conductive plate 14 connected to the conductive wire 1 and the conductive plate 7 having the gold-plated copper plate 13 conductive on both sides at the through holes 8 are electrically connected in the thickness direction. An insulating sheet 6 having a conductive part to be inspected is disposed, a printed circuit board 5 to be inspected is disposed thereon, a movable probe head 2 is disposed thereon, and the probe head 2 and the conductor 1 are electrically connected. It was configured to be connected to a continuity inspection device. In the electrical continuity test of the printed wiring circuit board, the probe head 2 is moved to the position of each electrode 4 such as a through hole of the wiring board 5 using a driving device in such a configuration, and the probe 3 is lowered to The printed circuit board was easily and reliably tested for electrical continuity as a result of the electrical continuity test between the electrodes on the front side and the back side of the wiring board 5 being brought into contact.

As for the electrical short between the wiring lines of the printed wiring circuit board, for example, between the wiring line and the through hole, as shown in FIG. 3, the elastic body electrically connected to the conductive plate 7 of FIG. Insulating sheet 10 between sheet 6
And an inspection was performed using a configuration using two probe heads 2. That is, the position data of the electrode to be inspected is
Input to the NC control unit of the inspection machine body in advance, and make two probe heads 2 contact each electrode at the same time,
As a result of the inspection for the electrical short between the electrodes, the electrical short between the wirings of the printed circuit board was easily and reliably inspected. .

[0027]

According to the present invention, when conducting an electrical continuity test between the electrodes of the circuit board, the number of through holes and the like may be small and large, and the spacing between the electrodes may be small and large. In addition, an electrical continuity test between the electrodes can be easily and reliably performed.

[Brief description of the drawings]

FIG. 1 is a side view illustrating a configuration of a conventional example.

FIG. 2 is a side view showing an embodiment of the configuration of the present invention.

FIG. 3 is a side view showing an embodiment of the configuration of the present invention.

FIG. 4 is an explanatory view showing a state in which a rubber material is applied to a copper foil in Examples.

FIG. 5 is an explanatory diagram showing a state before lamination of a laminate in an example.

FIG. 6 is an explanatory diagram showing a configuration of a laminated body in an example.

FIG. 7 is an explanatory view showing a state in which a through-hole is formed in the laminate in the example.

FIG. 8 is an explanatory view showing a state in which a conductive portion material is filled in a through hole of a laminate in an example.

FIG. 9 is an explanatory view showing a state in which the conductive portion material of the through-hole of the laminated body is arranged under a parallel magnetic field in the example.

FIG. 10 is an explanatory view showing a state in which the conductive portion material of the through-hole of the laminated body is cured in the example.

FIG. 11 is an explanatory diagram showing a state in which an insulating sheet having a conductive portion that is electrically conductive is formed in the example.

FIG. 12 is an explanatory view showing a state in which an insulating sheet having a conductive portion that is electrically conductive is formed in the example.

FIG. 13 is an explanatory view showing a state in which an insulating sheet having a conductive portion that is electrically conductive is formed in the example.

[Description of Signs] 1, lead wire 2, probe head 3, probe 4, through hole 5, printed circuit board 6, electrically conductive elastic sheet 6A, laminated body 6C, perforated laminated body 6B, conductive part formation Laminated body 7 filled with material, conductive plate 8, through hole 9, wiring 10, insulating sheet 11, pin 12, pin board 13, gold-plated copper plate 14, conductor plate 15, 17, land 16, short-circuit portion 20, rigid insulating sheet 21, metal foil 25, conductive part 25B, conductive part forming material 25H, drill hole 30B for conductive part formation, rubber material layer 30, rubber layer 40, anisotropic conductive elastomer layer E, elastic polymer substance P, conductive particles 53, magnetic pole plate 55, magnetic pole plate

Claims (3)

[Claims] An apparatus for inspecting electrical continuity of a circuit board using a probe, wherein conductive parts electrically conducting in a thickness direction are scattered on a side opposite to the probe with respect to the circuit board to be inspected. An inspection apparatus for a circuit board, comprising an insulating sheet and a conductive plate that is electrically good. 2. The insulating sheet according to claim 1, wherein conductive portions made of an elastic material electrically conductive in a thickness direction are scattered in an insulating laminate having an elastic material layer and a hard material layer. The circuit board inspection apparatus according to claim 1. 3. An electrical continuity test for a circuit board using a probe, wherein an insulating sheet having conductive portions scattered in a thickness direction is arranged on the circuit board to be tested. Circuit board inspection method.