JPH11204176A - Conductive rubber sheet - Google Patents

Abstract

(57) [Summary] [PROBLEMS] When inspecting a surface mount LSI or an electronic circuit board, it is placed on a test board at a position facing an electrode of a test object,
Provided is a conductive rubber sheet having elasticity for electrically connecting to a surface mount LSI or an electronic circuit board, and a connector using the same and a jig for electrical inspection of a circuit board. A conductive rubber sheet having a plurality of conductive portions in an electrically insulating material, wherein at least one conductive portion has an area of a conductive portion on one surface of an anisotropic conductive rubber sheet and the other. The ratio with the area of the conductive part on the surface is
A conductive rubber sheet having a thickness of 1.05 or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The object of the present invention is to provide a surface mounting LSI or an electronic circuit board at a position facing an electrode of a test object on an inspection board at the time of inspection, and to electrically connect to the surface mounting LSI or an electronic circuit board. The present invention relates to a conductive rubber sheet having elasticity and a jig for electrical inspection of a connector and a circuit board using the conductive rubber sheet.

[0002]

2. Description of the Related Art When inspecting a surface mount LSI or an electronic circuit board, a conductive rubber sheet having a conductive portion penetrating in an electrical insulating material in a thickness direction is placed on an inspection substrate, and the conductive portion of the conductive rubber sheet is removed. Inspects the surface mounting LSI or electronic circuit board electrode, which is the inspection object, and sandwiches it between the inspection substrate and the inspection object. While maintaining the compressed state, it is electrically connected to the surface mounting LSI or electronic circuit board for inspection. There are known ways to do this.

In recent years, the size of electrodes has been required to be reduced due to the progress of miniaturization of surface-mount LSIs and electronic circuit boards to be inspected. There has been a demand for smaller diameters. Along with this, the conductive rubber sheet and the inspection substrate on the jig side have also been required to be finer and smaller in diameter of the conductive portion in response to these finer and higher densities.

To give a specific example, in a jig-side inspection board, the size between electrodes is reduced by miniaturization, and the number of wirings between the electrodes is increased due to packaging and higher density. The result was a reduction in electrode dimensions. For this reason, a conductive rubber sheet which takes a conductive contact from the inspection substrate on the jig side is also required to respond, and accordingly, the conductive rubber sheet also tends to reduce the inter-electrode dimension and the electrode dimension. However, with a conductive rubber sheet with a reduced electrode size and a smaller electrode diameter, positioning with the conventional inspection jig structure at the time of inspection becomes difficult in establishing electrical continuity with the surface mount LSI or electronic circuit board to be inspected. It has been found that there may be situations where sufficient conduction cannot be ensured. This is because, in the conventional inspection jig structure, positioning based on the outer shape is mainstream in a package type IC of a surface mount LSI, which is an object to be inspected, and positioning using positioning guide pins is generally used in an electronic circuit board. On the other hand, when compared with the permissible accuracy of alignment with the conductive portion of the conductive rubber sheet, the surface mount LSI has a large variation in the external dimensions and the like,
Also, the processing accuracy of the guide pins in the electronic circuit board is due to insufficient conduction.

[0005] As described above, the surface mounting LSI to be inspected is
In addition, the conductive rubber sheet tends to reduce the inter-electrode dimension and the electrode dimension in response to the miniaturization and higher density of electronic circuit boards, so that it is difficult to secure conduction. On the other hand, in both methods of inspecting the object, the technology to reduce the positional deviation compared to the conventional manufacturing method has not changed significantly, so the external accuracy of the package and the processing accuracy of the positioning guide pin holes on the electronic circuit board Have a greater dependence on the positioning accuracy. Therefore, BGA (ball
In grid array) type packages, attention has been paid to positioning using balls, which are electrodes, from external alignment.On electronic circuit boards, a mechanism has been introduced that shifts from external hole alignment using pins to alignment using an optical system to ensure reliable positioning. It is getting. However, both methods have complicated mechanisms and devices, and are expensive.

[0006]

When inspecting an object to be inspected, such as a surface-mounted LSI or an electronic circuit board, a BGA (ballgrid) is used as a mechanism capable of securely positioning the conductive rubber sheet and ensuring conduction. In an (array) type package, positioning using a ball as an electrode can be considered, and in an electronic circuit board, positioning using an optical system can be cited. However, both methods have complicated mechanisms and devices, and are expensive. Therefore, by improving the conductive rubber sheet to be connected to the electrodes of the object to be inspected, the processing accuracy for positioning the surface-mounted LSI or the electronic circuit board as the object to be inspected can be maintained at the conventional accuracy and at a low cost. An object of the present invention is to develop a conductive rubber sheet that can easily secure conduction.

[0007]

According to the present invention, as a means for solving these conventional problems, for example, even when an electrically insulating material having high hardness is used, a conductive portion penetrates through the electrically insulating material in the thickness direction. It has been found that by using a specific conductive rubber sheet, it is possible to obtain a conductive rubber sheet that has sufficient elasticity and excellent durability due to repeated compression and the like while having a high density of conductive portions. The invention has been reached. That is, the present invention is a conductive rubber sheet having a plurality of conductive portions in an electrically insulating material, and in at least one conductive portion, the area of the conductive portion on one surface of the conductive rubber sheet and the other When the ratio with the area of the conductive portion on the surface is 1.0
It is intended to provide a conductive rubber sheet having a number of 5 or more. Further, the present invention is a conductive rubber sheet having a plurality of conductive portions in an electrically insulating material, wherein the area of at least one conductive portion on one surface is such that the thickness of the anisotropic conductive rubber sheet is R And the value of R ² π / 4 is 1
An object of the present invention is to provide the above conductive rubber sheet characterized by the above. Further, the present invention provides a connector made of the conductive rubber sheet and a jig for electrical inspection of a circuit board using the conductive rubber sheet.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The conductive rubber sheet of the present invention is a conductive rubber sheet having a plurality of conductive portions in an electrically insulating material, wherein at least one of the conductive portions has one of the anisotropic conductive rubber sheets. Wherein the ratio of the area of the conductive portion on the surface to the area of the conductive portion on the other surface is 1.05 or more. The ratio of the areas is preferably 1.1 or more, more preferably 1.15 to 10, and particularly preferably 1.2 to 3. The conductive rubber sheet of the present invention is a conductive rubber sheet having a plurality of conductive portions in which conductive particles are arranged in a thickness direction in an electrically insulating material, and an area of at least one conductive portion on one surface thereof. However, when the thickness of the anisotropic conductive rubber sheet is R, the value of R ² π / 4 is preferably 1 or more.
The value of R ² π / 4 is preferably 1 or more, more preferably 1.1 to 10, further preferably 1.2 to 5, and particularly preferably 1.3 to 3. The thickness R of the conductive rubber sheet is the total thickness of the conductive rubber sheet when the conductive rubber sheet is, for example, a multilayer sheet, and excludes the conductive rubber sheet when there is an intermediate layer such as a circuit board in the middle. This is the total thickness of the sheet. At least one such conductive portion is provided in the conductive rubber sheet, but it is preferable that a plurality of such conductive portions be a group. In such a case, the conductive rubber sheet may be scattered or continuously arranged over the entire surface or a partial range of the conductive rubber sheet.

The conductive rubber sheet according to the present invention is arranged such that the conductive rubber sheet is disposed on a test substrate and is positioned at a position facing the electrode of the test object when inspecting the electrical conductivity and electrical characteristics of the test object. Place, sandwich between the inspection board and the inspection object, and maintain the compressed state as necessary, and electrically secure the electrodes of the inspection object and the electrodes of the inspection substrate via the conductive portion of the conductive rubber sheet. Can be connected to Examples of the object to be inspected include various circuit boards, for example, surface mount LSI, electronic circuit board, BGA, CSP, various package boards, and the like.

According to the conductive rubber sheet of the present invention, the width of the conductive portion on the surface of the conductive rubber sheet with respect to the interval (pitch) between adjacent conductive portions, that is, the distance from the center of the adjacent conductive portion to the center. Since the size can be increased, a circuit board, a board on which an LSI or the like is mounted, an electrode such as a CSP or a BGA can be reliably contacted with the conductive portion, and a reliable connection can be achieved even if the positions thereof are slightly shifted. For this reason, surface mount LSI
Even if the mounting substrate such as CSP or the electrode such as CSP or BGA is fine, and the pitch of the electrodes is small and the density is high, reliable connection is possible. Further, in the case of connection with a circuit board or the like, when the conductive portion of the conductive rubber sheet is compressed by the electrode of the circuit board or the like, the conductive portion is supported by the electrically insulating material portion around the conductive portion. Is small, distortion is suppressed, and stable conduction is obtained.

FIG. 1 shows an example of the configuration of the conductive rubber sheet of the present invention. In FIG. 1, a conductive rubber sheet 1 having a large area of a conductive portion 3 includes an insulating portion 4 made of an electrically insulating material such as silicone rubber as a base material, and nickel particles or gold-plated particles of silicon rubber or the like. And a conductive portion 3 in which conductive particles such as the above are blended.
Similarly, the conductive rubber sheet 2 having a small area of the conductive portion 3 is also composed of an insulating portion 4 made of an electrically insulating material such as silicone rubber as a base material and nickel particles or silicon-plated particles of silicon rubber or the like. The conductive portion 3 is formed by blending conductive particles. It is preferable that the conductive portion has a structure in which conductive particles are oriented in the conductive rubber sheet and are electrically conductive in the thickness direction. The conductive rubber sheets 1 and 2 may be laminated in two or more layers, or may be formed integrally, with their conductive portions being aligned so that the conductive portions overlap each other.

In the conductive rubber sheet of the present invention, the thickness of the large-area conductive portion may be equal to the thickness of the small-area conductive portion as shown in FIG. The conductive portion having a small thickness and a small area may have a large thickness. FIG.
The thickness of the conductive portion having a large area may be large and the thickness of the conductive portion having a small area may be small. Further, as shown in FIG. 4, the conductive part having a large area and the conductive part having a small area may have a taper. Further, as shown in FIG. 5, three or more layers may be stacked. Alternatively, a conductive metal 7 may be joined as shown in FIG. The contact surface of the metal with the object to be inspected may be flat, may be triangular or hemispherical as shown in FIG. 7 when viewed in a cross section along the conduction direction, and there is no particular limitation on other shapes.

The conductive rubber sheet can be manufactured, for example, by the following method. A composition in which magnetically conductive particles are mixed into an insulating rubber-like polymer is produced, and the composition is formed into a sheet and sandwiched between magnets as shown in FIG. 8, and a magnetic field is applied in the thickness direction. Then, the conductive particles are oriented and cured to hold and fix the particles serving as the conductive portion. A composition containing the above-described conductive particles is laminated on the conductive rubber sheet thus obtained, and an anisotropic conductive rubber sheet is produced and laminated in the same manner as described above to obtain an objective heterogeneous rubber sheet. A conductive rubber sheet can be manufactured. This lamination may be repeated two or more times. When a parallel magnetic field is applied, by using a magnetic pole plate having portions with different magnetic field strengths, the conductive particles in the cured sheet are brought into a dense state so that the conductive portion and the insulating portion exist. Sheet can be formed.

As another method, a composition in which the above-mentioned conductive particles are blended is laminated on both the upper and lower surfaces of a previously manufactured conductive sheet, and a magnetic field is applied in the thickness direction to orient the conductive particles. Then, the conductive sheet can be manufactured by curing. Further, as shown in FIG. 3, a composition containing the above-described conductive particles is laminated between two previously manufactured anisotropic conductive sheets, and a magnetic field is applied in the thickness direction to orient the conductive particles. Then, the conductive sheet can be manufactured by curing. A composition in which conductive particles having magnetism are mixed with an insulating rubber-like polymer is formed into a sheet, sandwiched between magnets as shown in FIG. 8, and a magnetic field is applied in the thickness direction thereof to apply the conductive particles. When orienting the layers, the area of the upper ferromagnetic portion and the area of the lower ferromagnetic portion may be changed. For example, the conductive rubber sheet of the present invention as shown in FIG. 4 may be manufactured by increasing the area of the upper ferromagnetic member and decreasing the area of the lower ferromagnetic member.

[0015] As another method, the conductive rubber sheets separately manufactured can be combined and manufactured by a method of bonding together in the presence or absence of an adhesive. Silicone rubber or the like can be suitably used as the adhesive. Further, a circuit board or the like may be provided as an intermediate layer between two conductive rubber sheets. Although the spacing between the conductive portions in each layer of the anisotropic conductive rubber sheet of the present invention may be the same, the spacing between the conductive portions may be changed for each layer.

In the conductive rubber sheet of the present invention, the hardness of each layer of the conductive rubber sheet is not particularly limited, and may be appropriately changed. Also, the diameter and pitch of the conductive portion can be individually responded to by the shape and arrangement of the electrode portions of the surface mount LSI and the electronic circuit board. The conductive rubber sheet of the present invention may be formed by stacking conductive rubber sheets of the same quality, but it is also effective to stack conductive rubber sheets of different types. For example, the hardness and elastic modulus of the first and second layers are changed, the hardness and strength of the outer layer are changed to three or more layers, or the durability, heat resistance and weather resistance are changed by changing the type of the rubbery polymer. And the like, or the outer layer can be made softer than the inner layer to prevent the electrodes of the substrate to be inspected from being damaged.

Examples of the rubbery polymer include polybutadiene, natural rubber, polyisoprene, conjugated diene rubbers such as SBR and NBR and hydrogenated products thereof, styrene butadiene diene block copolymer, styrene isoprene block copolymer and the like. And hydrogenated products thereof, chloroprene, urethane rubber, polyester rubber, epichlorohydrin rubber, silicone rubber, ethylene propylene copolymer, ethylene propylene diene copolymer and the like. When weather resistance is required, a rubber-like polymer other than a conjugated diene rubber is preferred, and silicone rubber is particularly preferred in terms of moldability and electrical properties.

Here, the silicone rubber will be described in more detail. As the silicone rubber, one obtained by crosslinking or condensing a liquid silicone rubber is preferable. The liquid silicone rubber preferably has a viscosity of 105 poise or less at a strain rate of 10-1 sec and may be any of a condensation type, an addition type, and a type containing a vinyl group or a hydroxyl group. Specific examples include dimethyl silicone raw rubber, methyl vinyl silicone raw rubber, and methylphenyl vinyl silicone raw rubber. Among these, as the vinyl group-containing silicone rubber, usually, dimethyldichlorosilane or dimethyldialkoxysilane is subjected to hydrolysis and condensation reaction in the presence of dimethylvinylchlorosilane or dimethylvinylalkoxysilane. By performing the separation by

The molecular weight (weight average molecular weight in terms of standard polystyrene) of this component is preferably 10,000 to 40,000. The molecular weight distribution index of the rubbery polymer (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 2 from the viewpoint of heat resistance of the obtained conductive elastomer.
The following is preferred.

As the conductive particles, for example, nickel,
Magnetic particles such as iron and cobalt, or particles of alloys of these or particles containing them, containing noble metals, or those core particles coated with noble metals by plating, etc., non-magnetic metal particles or glass Core particles made of inorganic particles or polymer particles such as beads and containing or coating a conductive magnetic material such as nickel or cobalt and coated with a noble metal, or particles coated with both a conductive magnetic material and a noble metal. Can be mentioned. Precious metals include gold, silver, palladium,
Rhodium and the like are preferable, and gold and silver are preferable. Among these, particles in which nickel particles are used as core particles and the surface of which is coated with a noble metal such as gold or silver are preferred. Also,
A combination of both gold coating and silver coating is preferred.
The method of coating the surface of the core particles with the noble metal is not particularly limited, but can be performed by, for example, chemical plating, electroless plating, or the like.

The particle size of the conductive particles is 1 to 1000 μm.
Is more preferable, more preferably 2 to 500 μm,
More preferably 5-300μm, particularly preferably 10-200μ
m. The particle size distribution (Dw / Dn) of the conductive particles is preferably 1 to 10, more preferably 1.01 to 1.01.
To 7, more preferably 1.05 to 5, particularly preferably 1.1 to 4. The moisture content of the conductive particles is preferably 5% or less, more preferably 3% or less, more preferably 2% or less, and particularly preferably 1% or less. The shape of the conductive particles is not particularly limited, but may be spherical, star-shaped, or agglomerated aggregates of the above-mentioned components (a) and (b) because of the ease of dispersion in the component or a mixture thereof. preferable.

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 this proportion is less than 30 parts by weight, the obtained conductive rubber sheet does not have a sufficiently low electric resistance even during use, and therefore does not have a good connection function, and also exceeds 1,000 parts by weight. The cured elastomer becomes brittle, making it difficult to use as a conductive rubber sheet. The conductive rubber sheet of the present invention 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 rubber sheet after curing is improved. .

[0023]

The present invention will now be described by way of examples. Example 1 [Production of a conductive rubber sheet] Silicone rubber having a hardness of 40 degrees was used as an electrically insulating material, and particles of 3 were formed on the particle surface.
By weight, gold-plated nickel particles were mixed at a ratio of 7% by weight to prepare a molding material composition. The average particle size of the nickel particles was 40 μm. Next, using a mold as shown in FIG. 6, the molding material composition prepared in the above ratio was poured between the molds. This mold has a ferromagnetic part 2 with a pattern corresponding to the electrode part of a surface mount LSI or electronic circuit board
5 and the other non-magnetic body 26 are a pair of flat magnetic pole plates 21 composed of opposed magnetic poles of the upper mold 22 and the lower mold 23, and have spacers 24 according to the thickness required for the conductive rubber sheet. is there. Next, after defoaming under vacuum, an upper mold was placed thereon, and molding was performed by applying a pressing force and a parallel magnetic field by an electromagnet in the thickness direction of the molded product. The molding was carried out at room temperature under a parallel magnetic field of 4000 Gauss in the thickness direction at 100 ° C. for 1 hour to prepare a first conductive rubber sheet.

Next, the conductive rubber sheet of the first layer is removed from the mold, and an upper mold and a lower mold having larger areas of the respective magnetic parts than the mold are prepared. Moved to production of rubber sheet. First, a composition is prepared by mixing silicone rubber and conductive magnetic particles in the same ratio as in the first layer. This composition is spread in a sheet form on a first-layer conductive rubber sheet placed on a lower mold and subjected to vacuum demolding. Thereafter, a laminated conductive rubber sheet was produced in the same manner as in the first layer. The pitch of the conductive portions of the conductive rubber sheet is 1.27 mm, the thickness is 1 mm, the upper conductive portion of the conductive rubber sheet is a circle having a diameter of 1 mm, and the lower conductive portion has a diameter of 0 mm. It was a circle of 0.5 mm.

FIG. 9 shows an example of using the conductive rubber sheet manufactured as described above. The conductive rubber sheet 1 manufactured as described above was sandwiched and fixed between the surface mounting LSI 14 and the inspection substrate 11 by aligning the electrodes. This was held in a state where it was pressurized and compressed, and conduction was conducted from the electrode 12 of the inspection substrate 11 to the electrode 13 of the surface mounted LSI 14 through the conductive portion 3 of the conductive rubber sheet 1, and an electrical operation test of the surface mounted LSI 14 was performed. As a result, electrical continuity and short-circuit inspection were performed with sufficient performance. In addition, although it was used for a long time, there was no conduction failure or deterioration, and the inspection could be repeatedly performed for a long time.

[0026]

The conductive rubber sheet of the present invention has a surface mount
In the case of electrical connection with an LSI or an electronic circuit board, an electrically stable connection can be obtained with a low compression load, and durability against compression connection is excellent even in repeated compression.
In addition, a conductive rubber sheet in which a plurality of conductive portions are closely spaced and densely arranged can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of the configuration of a conductive rubber sheet of the present invention.

FIG. 2 is a schematic view showing an example of the configuration of the conductive rubber sheet of the present invention.

FIG. 3 is a schematic view showing an example of the configuration of the conductive rubber sheet of the present invention.

FIG. 4 is a schematic view showing an example of the configuration of the conductive rubber sheet of the present invention.

FIG. 5 is a schematic view showing an example of the configuration of the conductive rubber sheet of the present invention.

FIG. 6 is a schematic view showing an example of the configuration of the conductive rubber sheet of the present invention.

FIG. 7 is a schematic view showing an example of the configuration of the conductive rubber sheet of the present invention.

FIG. 8 is a schematic view showing an example of a mold used for producing the conductive rubber sheet of the present invention.

FIG. 9 is a schematic diagram showing an example of the configuration of an electrical inspection of an LSI or the like using the conductive rubber sheet of the present invention.

[Explanation of symbols]

 1, 2 conductive rubber sheet 3 conductive part 4 insulating part 12, 13 electrode 21 magnetic plate 22 upper die 23 lower die 24 spacer 25 ferromagnetic material part 26 nonmagnetic material part 31 Inspection object (LSI)

Claims (4)

[Claims] 1. A conductive rubber sheet having a plurality of conductive portions in an electrically insulating material, wherein at least one conductive portion has an area of the conductive portion on one surface of the anisotropic conductive rubber sheet and the other. The ratio of the surface to the area of the conductive portion is 1.0
A conductive rubber sheet having a particle size of 5 or more. 2. A conductive rubber sheet having a plurality of conductive portions in an electrically insulating material, wherein at least one conductive surface has
The area of the two conductive parts determines the thickness of the anisotropic conductive rubber sheet as R.
^2. The conductive rubber sheet according to claim 1, wherein the value of R ² π / 4 is 1 or more. 3. A conductive rubber sheet having a plurality of conductive portions in an electrically insulating material, wherein at least one of the conductive portions has an area of the conductive portion on one surface of the anisotropic conductive rubber sheet and the other. The ratio of the surface to the area of the conductive portion is 1.0
A connector made of a conductive rubber sheet, wherein the number is 5 or more. 4. A conductive rubber sheet having a plurality of conductive portions in an electrically insulating material, wherein at least one conductive portion has an area of the conductive portion on one surface of the anisotropic conductive rubber sheet and the other. The ratio of the surface to the area of the conductive portion is 1.0
A jig for electrical inspection of a circuit board using a conductive rubber sheet, wherein the number is 5 or more.