JP5624716B2 - Probe pin and insulation method thereof - Google Patents

Description

  The present invention relates to a probe pin, and more particularly to a probe pin insulated with a high heat resistance and high withstand voltage insulating coating, and an insulation treatment method thereof.

Semiconductor devices and electrical / electronic components are always required to have higher-density mounting in order to achieve cost reduction as well as reduction in size and weight. Usually, before and after the mounting process of the circuit board and the semiconductor element mounted at high density, a DC resistance value measurement and an energization inspection are performed using a prober (inspection machine). Dozens or hundreds of probe pins are attached to the tip of the current-carrying inspection jig connected to the prober. The probe pins are pressed against the circuit board or semiconductor device electrodes and electrode pads, and the prober inspects the probe. An energization test for supplying current to the circuit is performed. Along with the high density of circuits, the number of electrodes and electrode pads of circuit boards and semiconductor elements has become very large, and the wiring interval between them has become extremely small. Therefore, the number of probe pins attached to the inspection jig is increasing, while the distance between the probe pins is becoming smaller. Therefore, when pressing a probe pin against an electrode or electrode pad to ensure a connection, it is difficult to avoid contact between adjacent probes, and therefore the probe pin body has a flexible and strong electrical insulation. Formation of a protective coating is required.
For example, Patent Document 1 (Japanese Patent Laid-Open No. 2006-17455) uses an enamel film made of a polyurethane resin, a polyester resin, a polyesterimide resin, or a polyamideimide resin as an insulating film. Further, in Patent Document 2 (Japanese Patent Laid-Open No. 2002-168879), the body portion of the probe pin is insulatively coated with a normal cationic or anionic electrodeposition coating solution as an insulating coating.
On the other hand, as semiconductor elements and electrical / electronic components are often used in high-temperature environments such as in-vehicle applications, current inspection of these semiconductor elements and mounted circuit boards is performed at a high temperature of 150 ° C. or higher. It has become necessary to do this. The insulation coating of the probe pin in such applications is not sufficient with the conventional insulation coating, and even when used in a high temperature atmosphere, electrical insulation is ensured and there is a possibility of contact between adjacent probes. However, an insulation coating that does not cause defects such as fusion and film peeling has been demanded.
JP 2006-17455 A JP 2002-168879 A Japanese Patent Laid-Open No. 2005-162954

In order to cover the probe pin with a heat-resistant insulating film, it is possible to form a heat-resistant insulating film with a very uniform film thickness around the thin wire without causing defects such as pinholes. Desired.
Patent Document 3 discloses a solution containing, as a resin component, a specific block copolymerized polyimide having a siloxane bond as an electrodeposition coating composition that can form a highly insulating coating that is unlikely to be peeled off or cracked on a member to be insulated and protected. A type of electrodeposition coating composition is disclosed. It is described that this electrodeposition coating composition can form an electrodeposition coating (insulating layer) that is not only excellent in adhesion to the member and flexibility of the coating, but also has good heat resistance and voltage resistance.

  However, since many probe pins of tens to hundreds are simultaneously pressed against the electrodes of the circuit to be inspected, in addition to the uniformity of the film thickness in the longitudinal direction and the circumferential direction for each probe pin, Uniform film thickness between the probe pins is required. In particular, in the inspection in a high temperature atmosphere, if the uniformity of the film thickness is insufficient, the probe pin is bent at the thin portion of the probe pin when pressed, and the probe pin and the electrode There may be insufficient electrical connection between the two. Therefore, even if the probe pins come into contact with each other in a high-temperature atmosphere, the insulation property does not deteriorate, the film thickness between the probe pins is uniform, and the film thickness in the longitudinal direction and the circumferential direction for each probe pin However, in order to achieve a uniform insulation coating, further improvements were necessary.

  As a result of intensive studies to solve the above problems, the present inventors have found that a block copolymer polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule has a relatively large particle size. It has been found that a suspension type paint dispersed as precipitated particles can be made into a paint. Furthermore, the obtained suspension-type paint can form an electrodeposition film with high uniformity in film properties, and the formed electrodeposition film has a very high level of heat resistance and voltage resistance, The inventors have found that an extremely uniform electrodeposition film can be formed in a wide film thickness range of 1.5 μm to 50 μm, and have completed the present invention.

（式中、４つのＲは、それぞれ独立して、アルキル基、シクロアルキル基、フェニル基又は１個乃至３個のアルキル基若しくはアルコキシル基で置換されたフェニル基を表し、ｌ及びｍはそれぞれ独立して１〜４の整数を表し、ｎは１〜２０の整数を表す。）
［２］該被膜が、該ブロック共重合ポリイミドからなるポリイミド粒子を含むサスペンジョン型電着塗料組成物を該金属細線の胴部に電着することで形成された被膜である上記［１］のプローブピン。
［３］該被膜が、ＪＩＳ Ｃ３００３に準拠した温度指数評価法での温度指数が２００℃以上を示す絶縁被膜である上記［１］または［２］のプローブピン。
［４］該被膜が、層厚みが１０μｍのときのＡＣ耐電圧が１ｋＶ以上、層厚みが２０μｍのときのＡＣ耐電圧が２ｋＶ以上、層厚みが３０μｍのときのＡＣ耐電圧が３ｋＶ以上を示す絶縁被膜である上記［１］または［２］のプローブピン。
［５］該一般式（Ｉ)中の４つのＲが、それぞれ独立して、炭素数１〜６のアルキル基、炭素数３〜７のシクロアルキル基、フェニル基又は１個乃至３個の炭素数１〜６のアルキル基若しくは炭素数１〜６のアルコキシル基で置換されたフェニル基を表す、上記［１］または［２］のプローブピン。
［６］該アニオン性基が、カルボキシル基若しくはその塩、及び／又は、スルホン酸基若しくはその塩である上記［１］または［２］のプローブピン。
［７］該ブロック共重合ポリイミドが、ジアミン成分の１つとして、芳香族ジアミノカルボン酸を含む上記［１］または［２］のプローブピン。
［８］全ジアミン成分中、該分子骨格中にシロキサン結合を有するジアミンの割合が５〜９０モル％、該芳香族ジアミノカルボン酸の割合が１０〜７０モル％（ただし、両者の合計は１００モル％以下であり、第３のジアミン成分を含んでいてもよい）である上記［７］のプローブピン。
［９］プローブピンの絶縁被覆方法であって、
金属細線からなるプローブピンの胴部に、ブロック共重合ポリイミドからなるポリイミド粒子を含むサスペンジョン型電着塗料組成物を電着して絶縁被膜を形成する工程を含み、
該ブロック共重合ポリイミドは、分子骨格中にシロキサン結合を有し、分子中にアニオン性基を有し、かつ、ジアミン成分の１つとして、分子骨格中にシロキサン結合を有するジアミンを含み、
該分子骨格中にシロキサン結合を有するジアミンが、ビス(４−アミノフェノキシ)ジメチルシラン、１，３−ビス(４−アミノフェノキシ)−１，１，３，３−テトラメチルジシロキサン、及び下記の一般式（Ｉ）で表される化合物よりなる群から選ばれる１種又は２種以上である、
ことを特徴とするプローブピンの絶縁被覆方法。

（式中、４つのＲは、それぞれ独立して、アルキル基、シクロアルキル基、フェニル基又は１個乃至３個のアルキル基若しくはアルコキシル基で置換されたフェニル基を表し、ｌ及びｍはそれぞれ独立して１〜４の整数を表し、ｎは１〜２０の整数を表す。）
［１０］該サスペンジョン型電着塗料組成物が、粒子径が０．１〜１０μｍ、粒子径の標準偏差が０．１〜８μｍで分散されているポリイミド粒子を含む組成物である上記［９］のプローブピンの絶縁被覆方法。 That is, the present invention is as follows.
[1] A probe pin in which a body of a fine metal wire is covered with an insulating film,
The coating contains a block copolymerized polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule,
The block copolymerized polyimide contains a diamine having a siloxane bond in the molecular skeleton as one of the diamine components,
The diamine having a siloxane bond in the molecular skeleton is bis (4-aminophenoxy) dimethylsilane, 1,3-bis (4-aminophenoxy) -1,1,3,3-tetramethyldisiloxane, and A probe pin, which is one or more selected from the group consisting of compounds represented by formula (I).

(In the formula, four R's each independently represents an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxyl groups, and l and m are each independently And represents an integer of 1 to 4, and n represents an integer of 1 to 20.)
[2] The probe according to [1], wherein the coating is a coating formed by electrodeposition of a suspension type electrodeposition coating composition containing polyimide particles made of the block copolymerized polyimide on the body of the thin metal wire. pin.
[3] The probe pin according to [1] or [2], wherein the coating is an insulating coating having a temperature index of 200 ° C. or higher according to a temperature index evaluation method in accordance with JIS C3003.
[4] The coating film exhibits an AC withstand voltage of 1 kV or more when the layer thickness is 10 μm, an AC withstand voltage of 2 kV or more when the layer thickness is 20 μm, and an AC withstand voltage of 3 kV or more when the layer thickness is 30 μm. The probe pin according to [1] or [2] above, which is an insulating film.
[5] Four Rs in the general formula (I) are each independently an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, a phenyl group, or 1 to 3 carbon atoms. The probe pin according to [1] or [2] above, which represents a phenyl group substituted with an alkyl group having 1 to 6 carbon atoms or an alkoxyl group having 1 to 6 carbon atoms.
[6] The probe pin according to the above [1] or [2], wherein the anionic group is a carboxyl group or a salt thereof, and / or a sulfonic acid group or a salt thereof.
[7] The probe pin according to [1] or [2], wherein the block copolymerized polyimide contains an aromatic diaminocarboxylic acid as one of the diamine components.
[8] In all diamine components, the proportion of diamine having a siloxane bond in the molecular skeleton is 5 to 90 mol%, and the proportion of aromatic diaminocarboxylic acid is 10 to 70 mol% (however, the total of both is 100 mol) % Or less, and may contain a third diamine component).
[9] A probe pin insulation coating method,
Including the step of electrodepositing a suspension-type electrodeposition coating composition containing polyimide particles made of block copolymerized polyimide on the body of a probe pin made of a fine metal wire to form an insulating coating;
The block copolymer polyimide has a siloxane bond in the molecular skeleton, an anionic group in the molecule, and a diamine having a siloxane bond in the molecular skeleton as one of the diamine components,
The diamine having a siloxane bond in the molecular skeleton is bis (4-aminophenoxy) dimethylsilane, 1,3-bis (4-aminophenoxy) -1,1,3,3-tetramethyldisiloxane, and One or more selected from the group consisting of compounds represented by formula (I),
An insulating coating method for a probe pin.

(In the formula, four R's each independently represents an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxyl groups, and l and m are each independently And represents an integer of 1 to 4, and n represents an integer of 1 to 20.)
[10] The above-mentioned [9], wherein the suspension-type electrodeposition coating composition is a composition containing polyimide particles dispersed with a particle size of 0.1 to 10 μm and a standard deviation of the particle size of 0.1 to 8 μm. Insulation method for probe pins.

  The probe pin of the present invention is insulatively coated with a very uniform electrodeposition coating, and since the variation in the film thickness between the probes is small, when pressed against the inspection electrode under a constant pressure, The bendability between the probe pins becomes uniform, and a high contact pressure to the inspection electrode is ensured. In addition, stable energization inspection can be performed even in a high-temperature atmosphere without causing mutual fusion of the insulating films.

  In the probe pin of the present invention, an extremely high heat-resistant insulating film whose heat-resistant species in the temperature index evaluation method according to JIS C3003 indicates C type is firmly adhered to the surface of the fine metal wire, and the insulating film is cracked. Therefore, high heat resistance and high reliability can be realized.

  The probe pin of the present invention has an AC withstand voltage of 1 kV or more when the layer thickness is 10 μm on the surface of the thin metal wire, an AC withstand voltage of 2 kV or more when the layer thickness is 20 μm, and a layer thickness of 30 μm. Insulation coating with extremely high voltage resistance with an AC withstand voltage of 3 kV or higher is firmly adhered, and cracking of the insulation coating hardly occurs, so that high insulation and high reliability can be realized. it can.

  Further, the probe pin of the present invention has the above-mentioned insulating film having extremely high heat resistance and voltage resistance firmly adhered to the surface of the fine metal wire, and the insulating film is not easily cracked. It is possible to realize a highly reliable probe pin that is protected not only from insulation protection and heat resistance protection but also from damage.

  With the probe pin insulation coating method of the present invention, a heat-resistant insulating film can be formed on the probe pin with a uniform thickness in a short time.

Hereinafter, the present invention will be described with reference to the drawings according to an embodiment.
FIG. 1 is a perspective view showing an example of a probe pin. The probe pin 10 is composed of a fine metal wire 11, and the fine metal wire 11 has a probe pin tip 12 for making contact with an electrode of a specimen and a connection end 14 for connecting to a probe jig (not shown). The body of the fine metal wire 11 is covered with a suspension type electrodeposition coating (insulating coating) 13. FIG. 2 is a conceptual diagram showing a state in which the probe pins 10 a to 10 d are pressed against the inspection electrode 21 provided on the circuit board 20. In FIG. 2, the probe interval is shown as being spaced apart, but in actual use, the probe pin pitch P may be as small as 20 μm. 1 and 2, the tip 12 of the probe pin has a simple round shape, but the shape of the tip can be arbitrarily processed according to the inspection object.

  The metal material of the probe pin is not particularly limited, but a metal wire having high conductivity and high elastic modulus is used. In general, the metal wire is made of a hard and elastic copper alloy such as beryllium copper, tungsten, rhenium tungsten, steel, or the like.

  The thin metal wire 11 has an outer diameter of 20 to 500 μm according to the dimension of the pitch P, has a high straightness in the length direction and a roundness of the outer diameter, and a uniform outer diameter in the longitudinal direction. It is preferable that the property is high.

  The probe pin 10 of the present invention is characterized by an insulating coating 13 formed on the body of the fine metal wire 11. The insulating coating 13 has a suspension-type electrodeposition coating composition containing a block copolymerized polyimide having a siloxane bond (—Si—O—) in the molecular skeleton (that is, the main chain of the polyimide) and an anionic group in the molecule. It is formed using things.

  In the present invention, “an electrodeposition coating containing a block copolymerized polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule” specifically refers to “having a siloxane bond in the molecular skeleton. , An electrodeposition coating obtained by electrodeposition of a suspension-type electrodeposition coating composition in which a block copolymerized polyimide having an anionic group in the molecule is dispersed as precipitated particles having a relatively large particle size " The “suspension type electrodeposition coating composition” is measured using a particle size analyzer ELS-Z2 (manufactured by Otsuka Electronics Co., Ltd.) with an electrophoretic light scattering method (Laser Doppler method), and the measurement result is cumulant. This is a suspension type electrodeposition coating composition in which the polyimide particles analyzed by the analysis method have a particle size of 0.1 to 10 μm and a standard deviation of the particle size of 0.1 to 8 μm.

  The “block copolymerized polyimide” in the “block copolymerized polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule” is an imide formed by heating tetracarboxylic dianhydride and diamine. An oligomer is formed (first stage reaction), and then reacted with a tetracarboxylic dianhydride that is the same as or different from the tetracarboxylic dianhydride or / and a diamine different from the diamine (second stage reaction). ) Means a copolymerized polyimide obtained by preventing random copolymerization caused by an exchange reaction occurring between amic acids.

  In the “block copolymer polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule” in the present invention, the siloxane bond in the main chain is a siloxane bond derived from a tetracarboxylic dianhydride component. May be a siloxane bond derived from a diamine component, but is preferably a siloxane bond derived from a diamine component, and usually a siloxane bond (—Si—O—) is added to the molecular skeleton in at least a part of the diamine component. It is a block copolymerized polyimide obtained by using a diamine compound (hereinafter sometimes referred to as “siloxane bond-containing diamine”).

  The siloxane bond-containing diamine is not particularly limited as long as it can be imidized with tetracarboxylic dianhydride. For example, bis (4-aminophenoxy) dimethylsilane, 1,3-bis ( 4-aminophenoxy) -1,1,3,3-tetramethyldisiloxane and the general formula (I):

(Wherein, each of four R's independently represents an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxyl groups, and l and m are each Independently represents an integer of 1 to 4, and n represents an integer of 1 to 20.). The compound represented by the general formula (I) includes a single compound in which n is 1 or 2, and polysiloxane diamine.

  In four R in the formula (I), the alkyl group and the cycloalkyl group preferably have 1 to 6 carbon atoms, and more preferably 1 to 2 carbon atoms. In the phenyl group substituted with 1 to 3 alkyl groups or alkoxyl groups, 1 to 3 alkyl groups or alkoxyl groups may be the same or different when they are 2 or 3 May be. Moreover, as for an alkyl group and an alkoxyl group, C1-C6 is respectively preferable, and 1-2 are more preferable.

  In the compound represented by the general formula (I), four Rs in the formula are preferably the same alkyl group (particularly a methyl group) or a phenyl group, and in the formula, l and m are 2 to 3, A polysiloxane diamine in which n is 5 to 15 is preferred.

  Preferred examples of the polysiloxane diamine include bis (γ-aminopropyl) polydimethylsiloxane (in the formula (I), l and m are 3 and 4 R are methyl groups), bis (γ-amino). Propyl) polydiphenylsiloxane (in the formula (I), l and m are 3, and four R are phenyl groups).

  In the present invention, the siloxane bond-containing diamine may be a single compound or a combination of two or more compounds. Moreover, you may use a commercial item and can use what is sold from Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Co., Ltd., and Chisso Corporation as it is. Specifically, KF-8010 (bis (γ-aminopropyl) polydimethylsiloxane: amino group equivalent of about 450), X-22-161A (bis (γ-aminopropyl) polydimethyl, manufactured by Shin-Etsu Chemical Co., Ltd.) Siloxane: amino group equivalent of about 840) and the like, and these are particularly preferred.

  In the “block copolymer polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule” in the present invention, the anionic group is a group that becomes an anion in the solvent (described later) of the electrodeposition composition. Preferably, it is a carboxyl group or a salt thereof, and / or a sulfonic acid group or a salt thereof. The anionic group may be contained in a siloxane-containing diamine or a tetracarboxylic dianhydride component, but it is preferable to use a diamine having an anionic group as one of the diamine components. Such an anionic group-containing diamine is preferably an aromatic diamine in order to improve the heat resistance of the polyimide, the adhesion to the electrodeposit, and the degree of polymerization. That is, aromatic diaminocarboxylic acid and / or aromatic diaminosulfonic acid is preferable. Examples of the aromatic diaminocarboxylic acid include 3,5-diaminobenzoic acid, 2,4-diaminophenylacetic acid, 2,5-diaminoterephthalic acid, 3,3′-dicarboxy-4,4′-diaminodiphenylmethane, 3,5-diaminoparatoluic acid, 3,5-diamino-2-naphthalene carboxylic acid, 1,4-diamino-2-naphthalene carboxylic acid and the like can be mentioned, and aromatic diaminosulfonic acid includes 2,5-diamino Examples thereof include benzenesulfonic acid, 4,4′-diamino-2,2′-stilbene disulfonic acid, o-tolidine disulfonic acid, and the like. Among these, 3,5-diaminobenzoic acid is particularly preferable. Such anionic group-containing aromatic diamines can be used alone or in combination of a plurality of types. When the siloxane bond-containing diamine has an anionic group, the diamine component may be only the siloxane bond-containing diamine.

  As the diamine component, in addition to the above-described siloxane bond-containing diamine and diaminocarboxylic acid, another diamine may be further contained. As such a diamine, an aromatic diamine is usually used in order to improve the heat resistance of the polyimide, the adhesion to the electrodeposit, and the degree of polymerization. Examples of such aromatic diamines include m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 4,4′-diamino-3,3′-dimethyl-1,1′-biphenyl, 4, 4'-diamino-3,3'-dihydroxy-1,1'-biphenyl, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, 4,4'-diamino Diphenylsulfone, 4,4′-diaminodiphenyl sulfide, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 1,3-bis (4-aminophenoxy) ) Benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) bif Nyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, bis [4- (3-aminophenoxy) Phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, 2,6-diaminopyridine, 2,6-diamino-4-methylpyridine, 4,4 ′-(9-fluorenylidene) dianiline, α, α-bis (4-aminophenyl) -1,3-diisopropylbenzene can be mentioned, among which bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] Sulfone is more preferred.

  In the total diamine component, the proportion of the siloxane bond-containing diamine is preferably 5 to 90 mol%, more preferably 15 to 50 mol%. When the siloxane bond-containing diamine unit is less than 5 mol%, the electrodeposition coating film of polyimide is inferior in elongation and it is difficult to obtain sufficient flexibility, so that peeling and cracking are liable to occur. Moreover, it is preferable that the ratio of aromatic diaminocarboxylic acid or its salt is 10-70 mol% (however, the sum total of siloxane bond containing diamine and aromatic diaminocarboxylic acid or its salt is 100 mol% or less, and , May contain a third diamine component as described above).

  On the other hand, as a tetracarboxylic dianhydride component in polyimide, aromatic tetracarboxylic dianhydride is usually used from the viewpoint of heat resistance of polyimide and compatibility of polysiloxane diamine. For example, pyromellitic dianhydride 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride , Bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride Products, 3,3 ′, 4,4′-biphenylsulfonetetracarboxylic dianhydride, and the like. Among these, heat resistance of polyimide, adhesion to an electrodeposit, polysiloxane di From the viewpoint of amine compatibility and polymerization rate, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 3,3 ′, 4 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride and the like are particularly preferable. These exemplary tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  In the present invention, “a block copolymerized polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule” is soluble in a water-soluble polar solvent (for example, N-methyl-2-pyrrolidone (NMP ) Exhibits solubility at a concentration of 5% by weight or more, preferably 10% by weight or more.) Block copolymerized polyimide. The block copolymerized polyimide and the production method thereof are already known (for example, International Publication No. 1999/19771 pamphlet), and the polyimide used in the present invention is a known method using the diamine component and tetracarboxylic dianhydride. Can be manufactured by application. A water-soluble polar solvent is used for the polymerization reaction. Specifically, N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP) , Γ-butyrolactone (γBL), anisole, tetramethylurea, and sulfolane, and NMP is preferable. In such a water-soluble polar solvent, tetracarboxylic dianhydride and diamine are added in an approximately equimolar amount (preferably in a molar ratio of 1: 0.95 to 1.05) and heated in the presence of a catalyst to perform a dehydration imidization reaction. To produce a polyimide solution directly. The catalyst is a two-component composite catalyst composed of a lactone and a base or a crotonic acid and a base. The lactone is preferably γ-valerolactone, and the base is preferably pyridine or N-methylmorpholine. The mixing ratio of the lactone or crotonic acid and the base is from 1: 1 to 5 (molar equivalent), preferably from 1: 1 to 2 (molar equivalent). In the presence of water, it acts as an acid-base double salt, exhibits catalytic action, completes imidization, and water comes out of the reaction system (preferably, a polycondensation reaction is performed in the presence of toluene, and water produced is When it is removed from the reaction system together with toluene, the catalytic action is lost. The amount of the catalyst used is usually 1/100 to 1/5 mol, preferably 1/50 to 1/10 mol, relative to tetracarboxylic dianhydride. The mixing ratio (acid / diamine) of tetracarboxylic dianhydride and diamine to be subjected to the imidization reaction is preferably about 1: 0.95 to 1.05 in molar ratio as described above. The concentration of the acid dianhydride in the entire reaction mixture at the start of the reaction is preferably about 4 to 16% by weight, the concentration of lactone or crotonic acid is preferably about 0.2 to 0.6% by weight, and the concentration of the base Is preferably about 0.3 to 0.9% by weight, and the concentration of toluene is preferably about 6 to 15% by weight. The reaction temperature is preferably 150 ° C to 220 ° C. Moreover, reaction time is not specifically limited, Although it changes with the molecular weight etc. of the polyimide which is going to manufacture, it is about 180 to 900 minutes normally. Moreover, it is preferable to perform reaction under stirring.

  An acid dianhydride and a diamine are heated in a water-soluble polar solvent in the presence of the above-mentioned two-component acid catalyst to form an imide oligomer, and then an acid dianhydride or / and a diamine are added to the second diamine oligomer. A polyimide can be produced by a stepwise reaction. By this method, random copolymerization due to an exchange reaction occurring between amic acids can be prevented. As a result, a block copolymerized polyimide can be produced. The solid concentration at this time is preferably 10 to 40% by weight, more preferably 20 to 30% by weight.

  The polyimide preferably has an inherent logarithmic viscosity (25 ° C.) of 5,000 to 50,000 mPas, more preferably 5,000 to 15,000 mPas, in a 20 wt% NMP solution.

  Further, the weight average molecular weight (Mw) of the block copolymerized polyimide used as the resin component is preferably 20,000 to 150,000, particularly preferably 45,000 to 90,000 in terms of polystyrene. When the weight average molecular weight of the polyimide is less than 20,000, the heat resistance of the electrodeposition coating film tends to decrease, the coating film surface becomes rough, and the withstand voltage characteristic tends to decrease. On the other hand, when the weight average molecular weight is larger than 150,000, the polyimide resin has water repellency with respect to water and easily causes gelation in the electrodeposition liquid (paint) manufacturing process.

  Moreover, about a number average molecular weight (Mn), 10,000-70,000 are preferable in polystyrene conversion, More preferably, it is 20,000-40,000. When the number average molecular weight is less than 10,000, the electrodeposition efficiency tends to decrease, and the heat resistance and voltage resistance may decrease. Here, the molecular weight of the polyimide is a polystyrene-equivalent molecular weight measured by GPC, and the value measured using a SKGel Super-H-RC as a GPC apparatus using HLC-8220 manufactured by Tosoh Corporation. It is.

  In the suspension-type electrodeposition coating composition used in the present invention, the average particle diameter of the particles made of block copolymerized polyimide is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm. When the average particle size is less than 0.1 μm, the Coulomb efficiency is lowered and the withstand voltage performance is lowered due to overvoltage. On the other hand, if it exceeds 10 μm, the coulombic efficiency is controlled and the leakage current is increased due to the increase in particles, thereby causing a decrease in withstand voltage performance. Therefore, the particle size range in which the control of the coulomb efficiency and the maintenance of the withstand voltage performance are balanced is preferably 0.5 to 5 μm.

  The production of the suspension-type electrodeposition coating composition used in the present invention is specifically performed as follows. First, a post-polymerization composition containing a block copolymerized polyimide obtained through the above polymerization reaction (that is, containing a block copolymerized polyimide and a water-soluble polar solvent, and the content of the block copolymerized polyimide is 15 to 25 wt. % Composition) is heated and melted. The heating temperature here is usually about 100 to 180 ° C, preferably about 120 to 160 ° C. When the heating temperature is less than 100 ° C, the block copolymerized polyimide does not dissolve and tends to be difficult to disperse with other solvents, and when it exceeds 180 ° C, hydrolysis tends to occur and the molecular weight tends to decrease.

  Next, after adding a basic compound to the composition after heating and melting, and neutralizing the block copolymerized polyimide, the composition is cooled to 40 ° C. or lower, and a poor solvent and water for the block copolymerized polyimide are further added. Add, mix and stir to prepare suspension.

  In the manufacturing process of such a coating composition, when the temperature after cooling of the composition after neutralizing the block copolymerized polyimide exceeds 40 ° C., the polyimide tends to be decomposed by the neutralizing agent. The cooling temperature of the composition is more preferably 30 ° C. or lower. If the cooling temperature of the composition is too low, solidification tends to start again, so the lower limit of the cooling temperature is preferably 20 ° C. or higher.

  The basic compound is not particularly limited as long as it can neutralize the anionic group of the block copolymerized polyimide, but a basic nitrogen-containing compound is preferable, for example, N, N-dimethylaminoethanol, triethylamine, and the like. Primary amines such as triethanolamine, N-dimethylbenzylamine and ammonia, secondary amines and tertiary amines. Also, nitrogen-containing five-membered heterocyclic compounds such as pyrrole, imidazole, oxazole, pyrazole, isoxazole, thiazole, isothiazole, and nitrogen-containing six-membered heterocyclic compounds such as pyridine, pyridazine, pyrimidine, pyrazine, piperidine, piperazine, morpholine And nitrogen-containing heterocyclic compounds such as In addition, since many aliphatic amines have a strong odor, nitrogen-containing heterocyclic compounds are preferred from the viewpoint of low odor. In consideration of the toxicity of the paint, piperidine and morpholine having low toxicity are preferable among the nitrogen-containing heterocyclic compounds. The basic compound may be used in such an amount that the acidic group in the polyimide is stably dissolved or dispersed in the aqueous solution, and is usually about 30 to 200 mol% of the theoretical neutralization amount.

  Examples of the poor solvent for the block copolymer polyimide include alcohols or ketones having a phenyl group, a furfuryl group, or a naphthyl group. Specifically, acetophenone, benzyl alcohol, 4-methylbenzyl alcohol, 4- Examples include methoxybenzyl alcohol, ethylene glycol monophenyl ether, phenoxy-2-ethanol, cinnamyl alcohol, furfuryl alcohol, and naphthyl carbinol. An aliphatic alcohol solvent is preferred because of its low toxicity, and an aliphatic alcohol solvent having an ether group is particularly preferred. For example, as the aliphatic alcohol solvent, 1-propanol, isopropyl alcohol, ethylene glycols, and propylene glycols can be used. Examples of ethylene glycols and propylene glycols include dipropylene glycol, tripropylene glycol, ethylene glycol monoethyl ether, propylene glycol monomethyl ether (1-methoxy-2-propanol), propylene glycol methyl ether acetate, and the like. These poor solvents can use 1 type (s) or 2 or more types.

  The blending amount of the poor solvent is preferably 10 to 40% by weight and more preferably 10 to 30% by weight with respect to the total amount of the composition. The amount of water is preferably 10 to 30% by weight, more preferably 15 to 30% by weight, based on the total amount of the composition.

  In addition to the poor solvent and water of the block copolymer polyimide, an appropriate amount of a water-soluble polar solvent or an oil-soluble solvent may be added for the purpose of adjusting the viscosity and electrical conductivity of the composition. Here, specific examples of the water-soluble polar solvent include the same water-soluble polar solvent used for the polymerization reaction of the block copolymerized polyimide, and examples of the oil-soluble solvent include N-methylpyrrolidone and γ-butyrolactone. It is done. In addition, when adding an oil-soluble solvent, the quantity is 15 weight% or less with respect to the composition whole quantity.

  The solid concentration of the suspension-type electrodeposition coating composition used in the present invention is preferably 1 to 15% by weight, more preferably 5 to 10% by weight. The content of the water-soluble polar solvent is preferably 25 to 60% by weight, more preferably 35 to 55% by weight, based on the total amount of the composition.

The block copolymerized polyimide dispersed in the suspension type electrodeposition coating composition used in the present invention preferably has a particle size of 0.1 to 10 μm and a standard deviation of the particle size of 0.1 to 8 μm. Furthermore, it is more preferable that the average particle diameter is 0.5 to 5 μm and the standard deviation of the particle diameter is 0.3 to 3 μm. The inherent logarithmic viscosity of the suspension type electrodeposition coating composition is preferably 5 to 100 mPas.
By using this suspension type electrodeposition coating composition, an insulating film having a uniform thickness of about 1.5 μm to about 50 μm, more preferably 3 μm to 30 μm is formed around a fine metal wire having an outer diameter of 20 to 500 μm. be able to.
For example, when electrodeposition is performed using a copper wire having a diameter of 1.0 mm and a length of 20 cm using the suspension-type electrodeposition coating composition used in the present invention, a polyimide film having a thickness of 15 to 250 μm per coulomb is formed. be able to.

  In the probe pin of the present invention, a suspension type electrodeposition coating composition containing a block copolymer polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule as a resin component is electrodeposited. By forming an electrodeposited film, the electrodeposited film adheres firmly to the fine metal wire (electrodeposit) and is excellent in flexibility in that it does not easily crack, and has extremely high heat resistance. Then, the temperature index in the temperature index evaluation method based on JIS C3003 is 200 ° C. or higher (that is, the heat resistance classification indicates C type or higher). The electrodeposited film has extremely high voltage resistance. When the layer thickness is 10 μm, the AC withstand voltage is 1 kV or more, when the layer thickness is 20 μm, the AC withstand voltage is 2 kV or more, and the layer thickness is 30 μm. This is an insulating film having an AC withstand voltage of 3 kV or more. Such a high heat resistance and a high withstand voltage have the above-described suspension-type electrodeposition coating composition having a high electric conductivity during the growth process of the coating film, and on the surface of the thin metal wire (electrodeposit). This is thought to be for the purpose of growing a highly uniform film having film properties.

As described above, the suspension-type electrodeposition coating composition used in the present invention forms a thin film having a uniform thickness of about 1.5 μm to about 50 μm, more preferably 3 μm to 30 μm and having excellent insulating properties. Is possible.
In addition, the above suspension-type electrodeposition coating composition is difficult to achieve with conventional polyimide electrodeposition compositions because the dispersed particles (precipitated particles) of the block copolymerized polyimide are likely to deposit (adhere) on the surface of the fine metal wires. An electrodeposited film having a thickness exceeding 20 μm can be grown. By forming a film having a thickness of more than 20 μm, it is possible to realize an insulation-coated probe pin that is protected not only from insulation protection and heat resistance but also from damage protection. That is, according to the probe pin of the present invention, the insulating film having a thickness of more than 20 μm having extremely high heat resistance and voltage resistance is firmly adhered to the surface of the fine metal wire, and the insulating film It is difficult for cracks to occur. As a result, according to the present invention, not only insulation protection and heat protection but also damage protection can be achieved by an insulating coating having a wide film thickness of about 1.5 μm to about 50 μm, more preferably 3 μm to 30 μm, depending on the application. In addition, a high-performance and highly reliable probe pin can be realized.

  The electrodeposition coating composition described in Patent Document 3 has the siloxane bond in the molecular skeleton and contains a block copolymerized polyimide having an anionic group in the molecule as a resin component. This is similar to the suspension type electrodeposition coating composition. However, as described above, the electrodeposition coating composition described in Patent Document 3 is a solution-type composition, and has the highest heat resistance classification according to the temperature index evaluation method based on JIS C3003. Insulating film) can only be formed, and the AC withstand voltage when the layer thickness is 10 μm shows only about 0.3 kV at the maximum. Even if the electrodeposition conditions are variously changed, it is difficult to form an electrodeposition film (insulating film) having a thickness exceeding 20 μm.

  The probe pin of the present invention is an electrodeposition operation in which a fine metal wire (electrodeposit) is immersed in the above-described suspension-type electrodeposition coating composition, and a polyimide coating is grown on the fine metal wire through an electric current using the fine metal wire as an anode. And the obtained film is dried by heating (baking).

  Electrodeposition can be performed by the constant current method or the constant voltage method. For example, in the case of the constant current method, the conditions of current value: 1.0 to 200 mA, DC voltage: 5 to 200 V (preferably 30 to 120 V) are used. Can be mentioned. The electrodeposition time varies depending on the electrodeposition conditions, the thickness of the electrodeposition film to be formed, etc., but is generally selected from the range of 10 to 120 seconds, preferably 30 to 60 seconds. Moreover, the composition temperature at the time of electrodeposition is 10-50 degreeC normally, Preferably it is 10-40 degreeC, More preferably, it is 20-30 degreeC. If the electrodeposition voltage is lower than 5V, it tends to be difficult to form a coating film by electrodeposition. If the electrodeposition voltage is higher than 200V, the generation of oxygen from the coated material becomes intense and a uniform coating film cannot be formed. . Also, if the electrodeposition time is shorter than 10 seconds, the coating film is difficult to grow even if the electrodeposition voltage is set high, so that pinholes are likely to occur, and the withstand voltage performance of the electrodeposition film is significantly reduced. Yes. On the other hand, if it exceeds 120 seconds, the thickness of the coating film becomes thicker than necessary, and it is not economical. Further, when the composition temperature is lower than 10 ° C., it is difficult to form a coating film by electrodeposition, and when it is higher than 50 ° C., temperature management is required, which increases the production cost.

  Baking is performed at 70 to 110 ° C. for 10 to 60 minutes in the first stage, then at 160 to 180 ° C. for 10 to 60 minutes in the second stage and further at 200 to 220 ° C. for 30 to 30 minutes. It is preferable to perform a third stage baking process for 60 minutes. By performing such a three-stage baking process, it is possible to form a sufficiently dried polyimide film that adheres to the fine metal wires (electrodeposits) with high adhesion.

When producing a probe pin, the electrodeposition and baking operations of the above suspension-type electrodeposition coating composition can be performed, for example, with an apparatus as shown in FIG. That is, the thin metal wire 31 wound around the thin metal wire roll 30 is pulled out and passed through the electrodeposition tank 32 filled with the electrodeposition coating composition 33 in a state of being connected to the anode side of the AC power source. In the electrodeposition tank 32, a cathode plate 34 is disposed, and when the above-described voltage is applied when the fine metal wire 31 passes, the potential difference between the fine metal wire 31 serving as the anode and the negative electrode plate 34 serving as the cathode causes the polyimide to become the fine metal wire. It is deposited almost uniformly on the surface 31. After the electrodeposition bath 32, the fine metal wire 31 passes through the drying device 35. In the drying device 35, the water in the polyimide deposited on the conductor wire 31 evaporates. After passing through the drying device 35, an insulating film made of polyimide is formed by passing through a baking furnace 36, and the insulated conductor is wound up by a roll 37. By performing electrodeposition and baking operations of the electrodeposition coating composition with such an apparatus, it is possible to continuously produce an insulated coated wire.
In addition, insulation coating is performed over the full length on the metal fine wire 31 by this method. Therefore, in order to process into the necessary probe pin shape, after cutting the coated fine metal wire, the coating at both ends may be removed, and the tip of the probe pin may be processed into an arbitrary shape. Alternatively, electrodeposition can be applied in a state where portions other than those requiring insulation coating are masked with tape or the like in advance.
Furthermore, probe pins that have been processed into a required length and shape in advance may be individually electrodeposited.

  The electrodeposition coating of the suspension-type electrodeposition coating composition containing a block copolymerized polyimide having a siloxane bond in the molecular skeleton and an anionic group in the molecule as a resin component used in the present invention is a thin metal wire. The probe pin has excellent process resistance that is resistant to peeling and cracking of the insulating coating (electrodeposition coating) during tip processing and mounting to an inspection jig because it is firmly adhered and excellent in flexibility. It will have.

  In the probe pin of the present invention, the thickness of the electrodeposition coating (insulating coating) varies depending on the shape of the probe pin, the pitch of the probe pin, the type of the fine metal wire, etc., and is not particularly limited, but is generally 1.5 to 50 μm. Is selected within the range. That is, in the present invention, an electrodeposition coating (insulating coating) having a thickness exceeding 30 μm can be formed, but from the viewpoint of film thickness uniformity and productivity, the upper limit of the thickness is usually preferably about 50 μm. The probe pin of the present invention has a very thin film thickness of about 3 μm and can ensure uniform and high insulation, and even in a thick film exceeding 20 μm, it is uniform in both the circumferential direction and the longitudinal direction. Thickness can be realized. In this respect, it can be said that an insulating coating suitable for probe pin applications in which many wires are used at the same time and contact between adjacent portions is often achieved has been realized.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples.
[Example]
[Preparation of suspension-type electrodeposition coating composition]
A 2-liter separable three-necked flask equipped with a stainless steel vertical stirrer was equipped with a ball condenser equipped with a water separation trap. The flask was charged with 58.84 g (200 mmol) of 3,3′4,4′-biphenyltetracarboxylic dianhydride, 43.25 g (100 mmol) of bis- [4- (4-aminophenoxy) phenyl] sulfone, γ -After charging 4.0 g (40 mmol) of valerolactone, 6.3 g (80 mmol) of pyridine, 531 g of N-methyl-2-pyrrolidone (NMP) and 50 g of toluene, the mixture was stirred for 10 minutes at 180 rpm in a nitrogen atmosphere at room temperature. The mixture was heated to 180 ° C. and stirred for 2 hours. During the reaction, toluene-water azeotrope was removed. Next, the mixture was cooled to room temperature, and 64.45 g (200 mmol) of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride and 83.00 g of KF-8010 (manufactured by Shin-Etsu Chemical Co., Ltd.) were obtained. Mmol), 30.43 g (200 mmol) of 3,5-diaminobenzoic acid, 531 g of NMP and 50 g of toluene were added and reacted for 8 hours while stirring at 180 ° C. and 180 rpm. By removing the refluxed product out of the system, a 20 wt% polyimide solution (20% polyimide varnish) was obtained. The number average molecular weight and weight average molecular weight of the obtained polyimide were 24,000 and 68,000, respectively.

  The obtained polyimide varnish was applied on a glass plate with a wet film thickness of 50 μm using a bar coater. Then, after drying at 90 ° C./30 minutes, 180 ° C./30 minutes, 220 ° C./30 minutes with a hot air drier, peel from the glass plate and measure the mechanical elongation according to JIS C2151. A 21.8% polyimide coating was obtained. The thermal decomposition temperature was 420 ° C.

  100 g of the 20% polyimide varnish obtained above was stirred at 160 ° C. for 1 hour in a nitrogen atmosphere, and then rapidly cooled to 30 ° C., 59.4 g of N-methylpyrrolidone and 2.2 g of piperidine (neutralization rate 200 mol%) And stirred vigorously. Thereafter, the mixture was stirred while adding 129 g of propylene glycol monomethyl ether, and 67 g of water was added dropwise to prepare a suspension type electrodeposition coating composition. Using a particle size analyzer ELS-Z2 (manufactured by Otsuka Electronics Co., Ltd.), when the particle size and standard deviation of the dispersed particles in the electrodeposition solution were measured, precipitation with a particle size of 0.7 μm and a standard deviation of 0.5 μm was obtained. A suspension having particles (solid particles) was formed. In addition, it was a black turbid liquid with a solid content concentration of 6.0%, pH of 8.7, and electric conductivity of 7.3 mS / m. The intrinsic log viscosity was 50 mPas.

[Insulation coating of probe pins]
Using the suspension type electrodeposition liquid composition, an electrodeposition film was formed on the outer periphery of a circular tungsten wire having a distance between the cathode plate and the tungsten wire of 50 mm, an electrodeposition voltage of 30 V, φ70 μm, and a length of 20 mm. By controlling the energization amount in the range of 0.2 to 2.1 millicoulombs (mC), seven types of circular insulating tungsten wires having different electrodeposition coatings (insulating coatings) (number of samples per type = 5) Prepared. At this time, the electrodeposition current was in the range of 0.01 to 200 mA, and the electrodeposition time was in the range of 0.5 to 30 seconds. The tungsten wire after electrodeposition was taken out from the electrodeposition bath, washed with water, and baked at 90 ° C. for 30 minutes, further at 170 ° C. for 30 minutes, and further at 220 ° C. for 30 minutes. With respect to the obtained circular insulated tungsten wire, the electrodeposition property (film forming property) of the electrodeposition liquid, the thickness of the electrodeposition film, the AC withstand voltage and the heat resistance life were evaluated by the following test methods. The results are shown in Table 1.

  When processing the probe pin, an insulation-coated tungsten wire was cut out with a length of 20 mm, peeled and removed from the both ends with an electrodeposition film having a length of 2 mm, and both ends were rounded. After washing the exposed part of the tungsten wire, electroless plating is performed on a commercially available nickel plating solution and using a gold plating solution thereon to form a nickel plating layer (1.5 μm) and a gold plating layer (0.2 μm). Thus, a probe pin according to an embodiment of the present invention was produced.

1. Uniformity of coating In accordance with JIS C3003, the presence or absence of pinholes was investigated.

2. The thickness of the electrodeposition coating was measured using a micrometer (minimum scale: 0.001 mm). The thickness at five locations per sample was measured, and the average value was taken as the measurement result for that sample. Table 1 shows the maximum thickness and the minimum thickness in five samples.

3. AC breakdown voltage of electrodeposited coating In accordance with JIS C3003, AC breakdown voltage was measured by the B method metal foil method. That is, 1 cm of tin foil was wound around the probe pin and measured between the conductor and tin foil. Then, an AC voltage generator was connected to each plate, the voltage was increased at a rate of 100 V per second, and the short-circuited voltage (leakage current value of 10 mA or more) was taken as the breakdown voltage. Table 1 lists the average values and variations of five samples for each of the seven types of film thickness.

4). Heat-resistant life of electrodeposited film A sample having an electrodeposition film thickness of 21 to 23 μm was prepared on a 1.0 mmφ copper wire by the method of the example. With respect to this sample, the heat resistance of the probe pin (heat resistant life of the electrodeposition coating) was evaluated in accordance with the temperature index evaluation method described in JIS C3003. That is, according to the method of the example, two copper wire samples each having an electrodeposition coating having a thickness of about 21 to 23 μm were twisted to obtain a test piece. This test piece was heat-treated in an oven set at a temperature of 290 to 320 ° C. at intervals of 10 ° C. (290 ° C., 300 ° C., 310 ° C., 320 ° C.), and each was destroyed by applying a voltage of 500 V × 1 second. The time to reach was measured. The temperature index was calculated from a heat resistant life graph in which the measurement results at temperatures of 290 ° C., 300 ° C., 310 ° C., and 320 ° C. were Arrhenius plotted. According to the example, the electrodeposition film formed on the copper wire has a heat resistant temperature (that is, temperature index) corresponding to a lifetime of 20,000 hours of 240 ° C., and the heat resistant classification corresponds to C type of 200 ° C. or higher. It was a thing. In this test, a copper wire was used instead of a beryllium copper wire or a tungsten wire because the test was conducted by twisting two wires according to the standard.

[Comparative example]
After 100 g of a semisolid composition containing 20% by weight of the block copolymerized polyimide (resin component) obtained in the examples was heated and melted to 160 ° C., 70 g of NMP was added, 55 g of anisole, 45 g of cyclohexanone and N-methylmorpholine. 2.6 g (neutralization rate: 200 mol%) was added, and 30 g of water was added dropwise with stirring to obtain an electrodeposition liquid composition having a solid content concentration of 6.6% and pH 7.8. The particle size and standard deviation of the dispersed particles in the electrodeposition coating composition were measured using a particle size analyzer ELS-Z2 (manufactured by Otsuka Electronics Co., Ltd.), but the precipitated particles having a particle size of 0.1 μm or more were observed. Not in solution. Using this solution-type electrodeposition coating composition, the distance between the cathode plate and the tungsten wire was 50 mm, the electrodeposition voltage was 100 V, and the energization amount was controlled to 2 to 14 mC. At this time, the electrodeposition current was in the range of 0.01 to 200 mA, and the electrodeposition time was 0.5 to 120 seconds. Under the above conditions, as in the examples, electrodeposition was performed on a 70 μm tungsten wire, and thereafter, in the same manner as in the examples, circular insulated copper wires having electrodeposition coatings (insulating coatings) of various thicknesses (Number of samples per electrodeposition condition = 5). And by the above-mentioned test method, the electrodeposition property (film formation property) of the solution type electrodeposition coating composition, the thickness of the electrodeposition film, and the AC withstand voltage were evaluated. Table 2 shows the results of evaluating five samples each for seven types of film thickness. Further, in the comparative example, when the heat resistant life of the electrodeposited film having a thickness of about 19 to 21 μm formed on the 1 mmφ copper wire was measured by the above method, the temperature index was 180 ° C. and the heat resistance classification was H type. .

[Evaluation]
As is apparent from a comparison between Table 1 and Table 2, it can be seen that the film formation proceeds with a small amount of current even at the same voltage by the method of forming a film according to the example. For example, in the comparative example, an energization amount of 10.0 mC is necessary to obtain a film thickness of 14.9 μm, whereas in order to obtain a film thickness of 14.5 μm in the example, an energization of 1.0 mC is required. The amount was sufficient. As described above, since a necessary film can be formed with an energization amount of about 1/10 as compared with the conventional case, it is possible to reduce the manufacturing time and the electric power required for manufacturing. Further, in the comparative example, a film thickness of 20 μm or more could not be obtained at 30 V, whereas in the example, even a film thickness of 30 μm can be formed in proportion to the energization amount. The excellent features of the present invention were confirmed.

  Table 3 and FIG. 4 show characteristic lines of the relationship between the thickness of the electrodeposited film (horizontal axis) and the AC withstand voltage (vertical axis) on the circular insulated tungsten wires (diameter 70 μm) obtained in the examples and comparative examples. The comparison is shown. In FIG. 4, the data of the example is plotted with (●), and the data of the comparative example is plotted with (■). From Table 3 and FIG. 4, the insulation-coated tungsten wire of the example obtained by electrodeposition of the suspension type paint composition is in proportion to the film thickness (μm) in the range of a thin film of less than 3 μm to a thick film of about 30 μm. Thus, the AC withstand voltage (kV) increases. From 3 μm to 30 μm, the variation in AC withstand voltage at the same film thickness was very small, indicating that a uniform and strong insulating coating was formed. In contrast, in the case of the comparative example using the solution-type electrodeposition liquid composition, the AC withstand voltage is about 0.3 to 0.6 kV lower than that of the example when the film thickness is about 3 μm to about 20 μm. became.

  In addition, when the AC withstand voltage variation is compared with a film thickness of about 10 μm, the average AC withstand voltage of the comparative example varies from 0.76 kV up and down with respect to 0.66 kV. More than 100% was scattered. On the other hand, in the example, when the film thickness was about 10 μm, the variation was 0.20 V up and down with respect to the average value of 1.25 kV, and the variation ratio with respect to the average value was as small as 16%. . This result shows that the embodiment of the present invention is very excellent in film thickness and film quality uniformity as compared with the prior art.

From the above results, the probe pin of the present invention that is insulation-coated using the suspension-type paint composition has any film thickness range compared to the probe pin that is insulation-coated using the conventional solution-type electrodeposition paint. Even so, it was shown that the AC withstand voltage is high and the variation in the AC withstand voltage is small.
That is, the probe pin of the present invention has a higher film growth rate at the time of electrodeposition and superior AC withstand voltage per unit thickness of the film compared to a probe pin using a conventional solution-type paint composition. Therefore, a sufficient withstand voltage can be secured even with a thin film of several μm, and the electrodeposition coating (insulating coating) can be thickened to 30 μm or more.

FIG. 1 is a perspective view showing an embodiment of the probe pin of the present invention. FIG. 2 is a perspective view for explaining the state of an energization test using probe pins. FIG. 3 is a schematic view of an apparatus showing an embodiment of an electrodeposition process for applying an insulating coating to the probe pin of the present invention using a suspension type electrodeposition liquid composition. FIG. 4 is a graph showing the relationship between the thickness of the electrodeposited coating (insulating coating layer) and the AC withstand voltage.

Explanation of symbols

10 Probe Pin 11 Metal Thin Wire 12 Probe Pin Tip 13 Suspension Type Electrodeposition Coating (Insulation Coating)
DESCRIPTION OF SYMBOLS 14 Jig connection front-end | tip part 10a-10d Probe pin 20 Circuit board 21 Inspection electrode 30 Roll for metal fine wires 31 Metal fine wire 32 Electrodeposition tank 33 Electrodeposition coating composition 34 Cathode plate 35 Drying device 36 Baking furnace 37 Roll for insulation coating wires

Claims (2)

A probe pin insulation coating method comprising:
Including a step of electrodepositing a suspension-type electrodeposition coating composition containing solid particles of block copolymerized polyimide on the body of a probe pin made of a fine metal wire to form an insulating coating;
The block copolymerized polyimide has a siloxane bond in the molecular skeleton, an anionic group in the molecule, and a diamine having a siloxane bond in the molecular skeleton as one of the diamine components,
The diamine having a siloxane bond in the molecular skeleton is bis (4-aminophenoxy) dimethylsilane, 1,3-bis (4-aminophenoxy) -1,1,3,3-tetramethyldisiloxane, and One or more selected from the group consisting of compounds represented by formula (I),
The particle size of the solid particles of the block copolymerized polyimide in the suspension-type electrodeposition coating composition is 0.1 to 10 μm, and the standard deviation of the particle size is 0.1 to 8 μm.
The metal thin wire is connected to the anode side of an AC power source, and the amount of current flowing between the cathode plate and the metal thin wire is controlled in the range of 0.2 to 2.1 mC to perform electrodeposition of the suspension type electrodeposition coating composition. A method for insulating the probe pin.

(In the formula, four R's each independently represents an alkyl group, a cycloalkyl group, a phenyl group, or a phenyl group substituted with 1 to 3 alkyl groups or alkoxyl groups, and l and m are each independently And represents an integer of 1 to 4, and n represents an integer of 1 to 20. An insulating coating method for a probe pin according to claim 1, wherein the insulating coating formed on the body of the probe pin is baked through the method. Manufacturing method .

Images