Electronic component

Abstract

An electronic component includes at least a contact member having, on a surface of a contact portion adapted to come into contact with another contact member, at least an undercoat plating layer and a main plating layer formed on the undercoat plating layer. A coating containing a fluorine-based oil is provided on the main plating layer, and the coating has a dry coating weight per unit area on the main plating layer of greater than or equal to 0.011 mg/cm.sup.2.

Claims

1. An electronic component comprising: at least a contact member having, on a surface of a contact portion adapted to come into contact with another contact member, at least an undercoat plating layer and a gold-containing main plating layer formed on the undercoat plating layer, wherein the contact portion further has a coating containing a fluorine-based oil on the main plating layer, and a lower limit value of a dry coating weight per unit area of the coating, determined in relation to the thickness of the main plating layer, is: 0.011 mg/cm.sup.2 when a thickness of the main plating layer is greater than or equal to 0.4 m, 0.04 mg/cm.sup.2 when a thickness of the main plating layer is greater than or equal to 0.2 m and less than 0.4 m, 0.07 mg/cm.sup.2 when a thickness of the main plating layer is greater than or equal to 0.1 m and less than 0.2 m, and 0.25 mg/cm.sup.2 when a thickness of the main plating layer is less than 0.1 m.

2. The electronic component according to claim 1, wherein the undercoat plating layer is one of a Ni plating layer, a NiP plating layer, a PdNi plating layer, and a composite plating layer of a Ni plating layer and a PdNi plating layer.

3. The electronic component according to claim 1, wherein the fluorine-based oil is a perfluoropolyether oil (PFPE oil).

4. The electronic component according to claim 2, wherein the fluorine-based oil is a perfluoropolyether oil (PFPE oil).

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a perspective diagram showing a connector from a bottom side according to an embodiment of the present invention.

(2) FIG. 2 is a perspective diagram showing a housing of the connector of FIG. 1.

(3) FIG. 3 is a perspective diagram showing a contact of the connector of FIG. 1.

(4) FIG. 4 is a cross section at a contact portion of the contact constituting the connector of FIG. 1.

(5) FIG. 5 shows photographic images of surfaces of contacts of connectors of Samples 1 to 32 and Samples 39 to 72 after a test.

(6) FIG. 6 shows photographic images of contacts of connectors of Samples 33 to 38 and Samples 73 to 75 after a test.

(7) FIGS. 7A and 7B show the result of a salt spray test, in which FIG. 7A is a photographic image showing a part of the surface condition observation result of the contacts after the salt spray test, and FIG. 7B is a graph indicating a contact resistance value before and after the salt spray test.

(8) FIGS. 8A and 8B show the result of a two-gas mixture test, in which FIG. 8A is a photographic image showing a part of the surface condition observation result of the contacts after the two-gas mixture test, and FIG. 8B is a graph indicating a contact resistance value before the test, a contact resistance value after 500 times of insertion and extraction, and a contact resistance value after exposure to a two-gas mixture flow.

(9) FIG. 9 is a photographic image showing a part of the surface condition observation result of the contacts after a nitric acid vapor test.

(10) FIG. 10 is a schematic diagram showing a first step of a corrosion occurrence mechanism in the three-gas mixture test.

(11) FIG. 11 is a schematic diagram showing a second step of a corrosion occurrence mechanism in the three-gas mixture test.

(12) FIG. 12 is a schematic diagram showing a third step of the corrosion occurrence mechanism in the three-gas mixture test.

(13) FIG. 13 is a schematic diagram showing a fourth step of the corrosion occurrence mechanism in the three-gas mixture test.

(14) FIG. 14 is a schematic diagram showing a fifth step of the corrosion occurrence mechanism in the three-gas mixture test.

(15) FIG. 15 is a schematic diagram showing a sixth step of the corrosion occurrence mechanism in the three-gas mixture test.

(16) FIG. 16 is a schematic diagram showing a seventh step of the corrosion occurrence mechanism in the three-gas mixture test.

(17) FIG. 17 is a schematic diagram showing an eighth step of the corrosion occurrence mechanism in the three-gas mixture test.

(18) FIG. 18 is a schematic diagram showing how a void is formed in a Ni plating layer as a result of the three-gas mixture test.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(19) Preferred embodiments of the present invention will be described below in detail with reference to the attached drawings. Note that a connector for an interface is taken as an example of an electronic component in the description, but the present invention is not limited thereto, and is applicable to various kinds of electronic component having a contact member such as a relay or a switch. Also, the present invention is not only applicable to a connector for an interface, but is applicable to various kinds of connectors such as connectors for FPC/FFC or SIM cards.

(20) As shown in FIG. 1, a connector (plug) 10 of the present embodiment includes a housing 12 and a plurality of contacts 14 as a contact member held by the housing 12.

(21) As shown in FIG. 2, the housing 12 is formed of electrically insulating plastic and may be fabricated by a known injection molding technique. The material is appropriately selected in consideration of dimensional stability, workability, cost, and the like, and generally selected from polybutylene terephthalate (PBT), polyamide (66PA, 46PA), a liquid crystal polymer (LCP), polycarbonate (PC), polytetrafluoroethylene (PTFE) or a synthetic material thereof.

(22) The housing 12 is provided with a desired number of insertion holes 121 through which the contact 14 are to be inserted and a fitting opening in which FPC or FFC is inserted. In the present embodiment, the contacts 14 are held in the housing 12 by welding, but the contacts 14 may be held in the housing 12 by a known technique such as press fitting or engaging.

(23) As shown in FIG. 3, each of the contacts 14 includes a contact portion 141 that is adapted to come into contact with a connector (receptacle), which is an object to be connected, not shown, and a connecting portion 143 adapted to be connected to a substrate or a cable, and the contacts 14 can be fabricated by a known processing method such as pressing or machining.

(24) Also, as schematically shown in FIG. 4, the contact portion 141 of the contact includes an undercoat plating layer 147 stacked on a surface portion of a conductive substrate 145 and a main plating layer 149 on the undercoat plating layer 147. A coating 16 is shown on a surface of main plating layer 149.

(25) It is preferable that conductive substrate 145 is made of known various kinds of metal, e.g., made of copper or made of a copper alloy. The copper alloy may be phosphor bronze, beryllium copper, brass, or the like, and it is preferable that it is made of phosphor bronze when corrosion resistance is of importance.

(26) It is preferable that the main plating layer 149 is one of Au-containing plating, Ag-containing plating, Pd-containing plating, PdNi plating, Sn plating and Sn-based alloy plating. This is because contact stability, corrosion resistance and solder wettability are good. Also, it is preferable that the main plating layer 149 is an Au-containing plating when corrosion resistance is of particular importance.

(27) It is preferable that the main plating layer 149 has a thickness of 0.03 m to 6.0 m, although it depends on the material of the main plating. For example, in a case where the main plating layer 149 is an Au-containing plating layer, it is desirable that the thickness is about 0.1 m to 1.0 m for a portion where electric reliability is necessary (contact portion) and about 0.03 m to 0.20 m for a portion where reliability of the soldering is necessary. Also, in a case where the main plating layer 149 is a Pd-containing plating or a PdNi plating, it is similarly desirable to be about 0.1 m to 1.0 m for a portion where electric reliability is necessary and about 0.03 m to 0.20 m for a portion where reliability of the soldering is necessary. Further, in order to improve corrosion resistance, the main plating layer 149 comprising an Au-containing plating layer or a Pd-containing plating layer may have a thickness of greater than 1.0 m, but considering the cost, it is preferable that a thickness is less than or equal to 1.0 m, and it is more preferable that a thickness is less than or equal to 0.4 m. On the other hand, in a case of an Ag-containing plating, Sn plating and Sn-based alloy plating, the thickness is preferably 2.0 m to 6.0 m to ensure good electrical reliability and soldering reliability.

(28) It is preferable that the undercoat plating layer 147 is one of a NiP plating layer, a Ni plating layer, a PdNi plating layer, and a composite plating layer of a Ni plating layer and a PdNi plating layer. When corrosion resistance is of particular importance, it is preferable that the undercoat plating layer 147 is a NiP plating layer. In this case, it is preferable that P density is 2.0 weight % to 18 weight %. This is because when P concentration is less than 2.0 weight %, corrosion resistance might decrease, and when P concentration is greater than 18 weight %, ductility is poor and could cause breaks such as cracks. It is preferable that the NiP plating layer has a thickness of 0.5 m to 6.0 m. This is because, in a case where the thickness is less than 0.5 m, corrosion resistance might decrease due to diffusion of copper, zinc, etc., that are included in the copper alloy, and when it is greater than 6.0 m, ductility is poor and could cause breaks such as cracks.

(29) The NiP plating layer can be formed, for example, by an electroplating method using a Watts bath or a sulfamate bath. Particularly, it is preferable to be formed by an electroplating method using a bath based on sulfuric acid in which phosphorous acid is added to a Watt bath. This is because it is possible to form a layer in which crystals are dense, a surface activity is high, and an interface reactivity with the main plating layer 149 such as Au of the upper layer is good.

(30) Further, in order to achieve higher corrosion resistance, the connector 10 includes a coating 16 containing a fluorine system oil on at least the surface of the contact portion 141 on the main plating layer 149 of the contact 14. The coating 16 for improving corrosion resistance needs not only protect the contact 14 from oxygen, moisture, and corrosive gas, but also not to inhibit electricity property. Further, it is required to have heat resistance such that detaching or resolving does not occur at a mounting temperature (up to 260 C.), have lubricity, have a small surface tension and an improved uniform dispersibility (self-recovery capacity), and further inert to chloride ions and sulfate ions.

(31) The fluorine-based oil may include perfluoropolyether-based oils (PFPE oils), and among these, it is particularly preferable to use a perfluoropolyether-based oil (PFPE) which is a polymeric fluorine-based compound having a skeleton of [CF.sub.2O], a surface tension (25 C.) of less than or equal to 25 mN/m, and a mean molecular weight of 500 to 15,000. Perfluoropolyether-based oils may be those having structural formulae indicated in Table 1 below.

(32) TABLE-US-00001 TABLE 1 SURFACE TENSION No. STRUCTURAL FORMULA (mN/m) at 20 C. 1 17-20 2 16-17 3 18-20 4 14-20 5 19-20 6 18-19 7 25 8 23

(33) For example, for such PFPE oil, SANKOL ZZS-202 (SANKOL ZZS-202) (product name) available from Sankei Kagaku Co., Ltd. (SANKEIKAGAKU CO., LTD.) can be appropriately used.

(34) As a method of forming the coating on the main plating layer 149 includes, for example, immersing the contact 14 in a solution (coating liquid) obtained by diluting a fluorine system oil with a solvent for a few to several seconds (one or more seconds) and evaporating the solvent to form the coating 16 on the surface of the contact 14. For example, HFE described below evaporates instantly in about a few to several seconds and thus only PFPE can be remained on the surface of the contact 14. Such an application work can be performed continuously by a reel to reel method.

(35) As for the solvent, a fluorine-based solvent which has a good dispersibility with the fluorine-based oil is preferable, and, for example, it is preferable to use hydrofluoroether (HFE). Hydrofluoroether may be those having structural formulae indicated in Table 2 below.

(36) TABLE-US-00002 TABLE 2 STRUCTURAL VAPOR PRESSURE SURFACE No. FORMULA (kPa, 25 C.) TENSION (mN/m) 1 28 13-14 2 0 16 13-14 3 6 14-15

(37) For example, for such HFE, SANKOLCFD diluent Z (SANKOL CFD DILUENT Z) (product name) which is available from Sankei Kagaku Co., Ltd. (SANKEIKAGAKU CO., LTD.) can be appropriately used.

(38) It is to be noted that if an analytical curve of concentration of the fluorine-based oil to the solvent in the coating liquid and the dry coating weight per unit area of the coating 16 attached on a surface of the contact 14 is made in advance, the coating 16 of a desired dry coating weight can be readily formed on the surface of contact 14 simply by adjusting the concentration of the coating liquid. As an exemplary method of forming a coating using a PFPE oil and HFE, the relationship between the concentration of the PFPE oil to HFE and the dry coating weight of the coating was examined using a test piece including a Ni plating layer and an Au plating layer formed on a pure copper plate, and the results are indicated in Table 3 below.

(39) TABLE-US-00003 TABLE 3 CONCEN- DRY COATING TRATION TOTAL DRY TEST PIECE WEIGHT PER OF PFPE COATING SURFACE UNIT AREA (wt %) WEIGHT (mg) AREA (cm.sup.2) (mg/cm.sup.2) 0.1 0.20 40.5 0.005 0.2 0.35 31.5 0.011 0.5 0.51 17 0.019 0.8 0.72 22.5 0.032 1 0.8 22.5 0.04 3 2.0 18 0.11 5 3.2 18 0.18 7 3.4 13.5 0.25 10 5.0 13.5 0.37 12 5.8 13.5 0.43 15 8.9 13.5 0.66 17 10.4 13.5 0.77 20 19.0 13.5 1.41 24 29.5 13.5 2.19

(40) Now, corrosion resistance can be improved by forming the coating 16 containing fluorine-based oil on the surface of the contact 14, but in order to obtain corrosion resistance to such an extent to conform with a corrosion resistance test under a severe condition by the four-gas mixture flow while attempting to reduce the thickness of the main plating layer 149, it is essential that the dry coating weight per unit area of the coating 16 is greater than or equal to 0.011 mg/cm.sup.2. If the dry coating weight per unit area of the coating 16 is less than 0.011 mg/cm.sup.2, it is difficult to obtain desired corrosion resistance in the corrosion resistance test under such a severe condition stated above, unless the main plating layer 149 is formed with a considerable thickness. This is because an effect of protecting the undercoat plating layer 147 by cooperation of the main plating layer 149 and the coating 16 cannot be obtained sufficiently.

(41) If the dry coating weight of the coating 16 is greater than or equal to 0.25 mg/cm.sup.2, it is preferable since a good corrosion resistance can be obtained in a broader thickness region of the main plating layer 149. In order to achieve both the reduced thickness and the corrosion resistance simultaneously for the main plating layer 149 at a higher dimension, it is preferable that: in a case where the main plating layer 149 has a thickness of greater than or equal to 0.4 m, the dry coating weight per unit area of fluorine-based-oil-containing coating 16 on the main plating layer 149 is greater than or equal to 0.011 mg/cm.sup.2; in a case where the main plating layer 149 has a thickness of greater than or equal to 0.2 m and less than 0.4 m, the dry coating weight of the coating 16 is greater than or equal to 0.04 mg/cm.sup.2; in a case where the main plating layer 149 has a thickness of greater than or equal to 0.1 m and less than 0.2 m; the dry coating weight of coating 16 is greater than or equal to 0.07 mg/cm.sup.2; and in a case where the main plating layer 149 has a thickness of less than 0.1 m, the dry coating weight of the coating 16 is greater than or equal to 0.25 mg/cm.sup.2.

(42) According to the contact 10 of the present embodiment described above, the coating 16 deposited by an appropriate amount can protect the contact 10 from oxygen, corrosive gas, moisture, etc., by cooperating with the main plating layer 149, high corrosion resistance can be obtained. The fluorine-based oil composing a coating 16 is, because of its fluidity, pushed away into micro recesses in the surface when the contacts come into contact with each other, and thus does not affect conductivity and thus a stable conductivity can be obtained. Particularly, with the main plating layer 149 having a thickness of less than or equal to 0.4 m, an amount used of an expensive material (gold plating) can be reduced and a large cost cut is possible.

EXAMPLES

(43) Tests carried out to verify the effects of the present invention will be described below.

First Example

Examples

(44) As Sample 1, a conductive substrate formed of phosphor bronze (Cu: remaining mass %, Sn: 6 weight % to 9 weight %, P: 0.3 weight % to 0.35 weight % and incidental impurities) machined into a predetermined contact shape was prepared, and, the conductive substrate was subjected to alkali cathode electrolytic degreasing under the condition of: sodium orthosilicate concentration of 50 g/l; bath temperature of 55 C.; cathode current density of 10 A/dm.sup.2; and duration of electrolysis of 30 seconds, rinsed with water, and thereafter subjected to acid cleaning under the condition of: hydrochloric acid concentration of 10 vol %; bath temperature of 20 C., and immersion duration of 10 seconds. After rinsing with water, a Ni plating layer was formed on a surface portion of phosphor bronze under the condition of: bath composition of a sulphate bath (Watts bath); pH of 4.0; bath temperature of 50 C.; and current density of 10 A/dm.sup.2, and, further, on this Ni plating layer, an Au plating layer was formed under the condition of: bath composition of gold (I) potassium cyanide (KAu(CN).sup.2) 12.5 g/l; cobalt sulfate (CoSO.sub.47H.sub.2O) of 400 ppm; additive of 12.5 ml/l; bath temperature of 50 C.; and current density of 3 A/dm.sup.2. Thereafter, on the Au plating layer, a coating liquid in which PFPE oil is diluted with HFE to a predetermined concentration was applied to form a coating containing PFPE. Thereafter, the contact was assembled to the housing shown in FIG. 1 to provide a connector of Sample 1. The thickness of the Ni plating layer, the thickness of the Au plating layer, and the dry coating weight of the PFPE-containing coating are as indicated in Table 3. Note that Sankol ZZS-202 (SANKOL ZZS-202) (product name) available from Sankei Kagaku Co., Ltd. (SANKEIKAGAKU CO., LTD.) was used as the PFPE. Also, SANKOLCFD diluent Z (SANKOL CFD DILUENT Z) (product name) which is available from Sankei Kagaku Co., Ltd. (SANKEIKAGAKU CO., LTD.) was used as the solvent.

(45) Similarly, connectors of samples 2 to 33 that are different from sample 1 merely in their thickness of the Ni plating layer, thickness of the Au plating layer and dry coating weight of the PFPE-containing coating were fabricated. The thickness of the Ni plating layer, the thickness of the Au plating layer and the dry coating weight of the PFPE-containing coating are as indicated in Table 4.

(46) A connector of sample 34 was fabricated with a method similar to a method for sample 1 except that the Ni plating layer was replaced with an electrolysis NiP plating layer formed under the condition of: bath composition of sulphate bath (phosphorous acid component); pH of 2.5; bath temperature of 60 C.; and current density of 10 A/dm.sup.2. The thickness of the Ni plating layer, thickness of the Au plating layer and the dry coating weight of the PFPE-containing coating are as shown in Table 4.

(47) Connectors of samples 35 to 37 were fabricated with a method similar to a method for sample 1 except that a PdNi plating layer was formed between the Ni plating layer and the Au plating layer under a condition of: bath composition of a low ammonia bath; PH of 7.5; bath temperature of 45 C.; and current density of 10 A/dm.sup.2. The thickness of the PdNi/Ni plating, thickness of the Au plating and the dry coating weight of the PFPE-containing coating are as shown in Table 4.

(48) A connector of sample 38 was fabricated with a method similar to a method for sample 1 except that the Au plating layer was replaced with a Ag plating layer under a condition that: bath composition of a cyanidation bath; PH of 12; bath temperature of 15 C. to 25 C.; and current density of 2 A/dm.sup.2. The thickness of the Ni plating layer, the thickness of the Ag plating layer and the dry coating weight of the PFPE-containing coating are as shown in Table 4.

Comparative Examples

(49) Connectors of samples 39 to 72 were fabricated with a method similar to a method for sample 1 except that the thickness of the Au plating layer and the dry coating weight of PFPE-containing coating were out of scope of the present invention.

(50) A connector of sample 73 was fabricated with a method similar to a method for sample 1 except that the PFPE-containing coating was replaced with a benzothiazole-based water-soluble corrosion preventing agent applied on the Au plating layer.

(51) A connector of sample 74 was fabricated with a method similar to a method for sample 73 except that an electrolysis NiP plating layer was formed in place of the Ni plating layer.

(52) A connector of sample 75 was fabricated with a method similar to a method for sample 73 except that a thiol solvent-based corrosion preventing agent of was applied on the Au plating layer in place of the benzothiazole-based water-soluble corrosion preventing agent.

(53) (Corrosion Resistance Test by Four-Gas Mixture Flow)

(54) A corrosion resistance test was conducted by steps (a) to (e) below.

(55) (a) Measurement of initial contact resistance value (measured by direct current four-probe method)

(56) (b) 50 times of insertion and extraction

(57) (c) Measurement of contact resistance value

(58) (d) Exposure to four-gas mixture flow (168 hours, unmated)

(59) (e) Measurement of contact resistance value.

(60) Note that, the four-gas mixture test complies with EIA standard (EIA-364-65A), and type and density of gases are: H.sub.2S 105 ppb; SO.sub.2 10020 ppb; NO.sub.2 20050 ppb; Cl.sub.2 103 ppb; temperature 30 C.; and humidity 75% RH.

(61) (Evaluation Method)

(62) When a contact resistance value after exposure to a four-gas mixture flow was less than 25 m, which is approximately equal to an initial contact resistance value, it was evaluated as having an excellent corrosion resistance and satisfying the S-ATA standard, which is denoted by . When the contact resistance value was greater than or equal to 25 m and less than 45, it was evaluated as having a good corrosion resistance, but not as good as and satisfying the S-ATA standard, which is denoted by . Further, when a contact resistance value was greater than or equal to 45 m and less than 200 m, it was evaluated that the corrosion resistance is not sufficient and does not satisfy the S-ATA standard, which is denoted by . Further, when a contact resistance value was greater than or equal to 200 m, it was evaluated as having a low corrosion resistance, which is denoted by x. Evaluation results are indicated in Tables 4-1 to 4-4.

(63) TABLE-US-00004 TABLE 4-1 UNDERCOAT PLATING LAYER MAIN PLATING LAYER DRY COATING WEIGHT OF ANTI- SAMPLE THICKNESS THICKNESS PFPE-CONTAINING COATING CORROSION No. TYPE (m) TYPE (m) (mg/cm.sup.2) TREATMENT EVALUATION 1 Ni 2.5 Au 0.4 0.011 N/A 2 Ni 2.5 Au 0.4 0.019 N/A 3 Ni 2.5 Au 0.4 0.032 N/A 4 Ni 2.5 Au 0.4 0.04 N/A 5 Ni 2.5 Au 0.4 0.07 N/A 6 Ni 2.5 Au 0.4 0.11 N/A 7 Ni 2.5 Au 0.4 0.18 N/A 8 Ni 2.5 Au 0.4 0.25 N/A 9 Ni 2.5 Au 0.4 0.37 N/A 10 Ni 2.5 Au 0.4 0.43 N/A 11 Ni 2.5 Au 0.2 0.04 N/A 12 Ni 2.5 Au 0.2 0.07 N/A 13 Ni 2.5 Au 0.2 0.11 N/A 14 Ni 2.5 Au 0.2 0.18 N/A 15 Ni 2.5 Au 0.2 0.25 N/A 16 Ni 2.5 Au 0.2 0.37 N/A 17 Ni 2.5 Au 0.2 0.43 N/A

(64) TABLE-US-00005 TABLE 4-2 UNDERCOAT PLATING LAYER MAIN PLATING LAYER DRY COATING WEIGHT OF ANTI- SAMPLE THICKNESS THICKNESS PFPE-CONTAINING COATING CORROSION No. TYPE (m) TYPE (m) (mg/cm.sup.2) TREATMENT EVALUATION 18 Ni 2.5 Au 0.1 0.07 N/A 19 Ni 2.5 Au 0.1 0.11 N/A 20 Ni 2.5 Au 0.1 0.18 N/A 21 Ni 2.5 Au 0.1 0.25 N/A 22 Ni 2.5 Au 0.1 0.37 N/A 23 Ni 2.5 Au 0.1 0.43 N/A 24 Ni 2.5 Au 0.05 0.25 N/A 25 Ni 2.5 Au 0.05 0.37 N/A 26 Ni 2.5 Au 0.05 0.43 N/A 27 Ni 2.5 Au 0.03 0.25 N/A 28 Ni 2.5 Au 0.03 0.37 N/A 29 Ni 2.5 Au 0.03 0.43 N/A 30 Ni 2.5 Au 0.01 0.25 N/A 31 Ni 2.5 Au 0.01 0.37 N/A 32 Ni 2.5 Au 0.01 0.43 N/A 33 Ni 2.5 Au 0.005 0.25 N/A 34 NiP 2.5 Au 0.1 0.25 N/A 35 PdNi/Ni 0.5/2.5 Au 0.1 0.04 N/A 36 PdNi/Ni 0.5/2.5 Au 0.1 0.18 N/A 37 PdNi/Ni 0.5/2.5 Au 0.1 0.25 N/A 38 Ni 2.5 Au 2 0.25 N/A

(65) TABLE-US-00006 TABLE 4-3 UNDERCOAT PLATING LAYER MAIN PLATING LAYER DRY COATING WEIGHT OF ANTI- SAMPLE THICKNESS THICKNESS PFPE-CONTAINING COATING CORROSION No. TYPE (m) TYPE (m) (mg/cm.sup.2) TREATMENT EVALUATION 39 Ni 2.5 Au 0.4 0.005 N/A X 40 Ni 2.5 Au 0.2 0.005 N/A X 41 Ni 2.5 Au 0.2 0.011 N/A X 42 Ni 2.5 Au 0.2 0.019 N/A X 43 Ni 2.5 Au 0.2 0.032 N/A X 44 Ni 2.5 Au 0.1 0.005 N/A X 45 Ni 2.5 Au 0.1 0.011 N/A X 46 Ni 2.5 Au 0.1 0.019 N/A X 47 Ni 2.5 Au 0.1 0.032 N/A X 48 Ni 2.5 Au 0.1 0.04 N/A 49 Ni 2.5 Au 0.05 0.005 N/A X 50 Ni 2.5 Au 0.05 0.011 N/A X 51 Ni 2.5 Au 0.05 0.19 N/A X 52 Ni 2.5 Au 0.05 0.032 N/A X 53 Ni 2.5 Au 0.05 0.04 N/A X 54 Ni 2.5 Au 0.05 0.07 N/A X 55 Ni 2.5 Au 0.05 0.11 N/A X 56 Ni 2.5 Au 0.05 0.18 N/A

(66) TABLE-US-00007 TABLE 4-4 UNDERCOAT PLATING LAYER MAIN PLATING LAYER DRY COATING WEIGHT OF ANTI- SAMPLE THICKNESS THICKNESS PFPE-CONTAINING COATING CORROSTION No. TYPE (m) TYPE (m) (mg/cm.sup.2) TREATMENT EVALUATION 57 Ni 2.5 Au 0.03 0.005 N/A X 58 Ni 2.5 Au 0.03 0.011 N/A X 59 Ni 2.5 Au 0.03 0.019 N/A X 60 Ni 2.5 Au 0.03 0.032 N/A X 61 Ni 2.5 Au 0.03 0.04 N/A X 62 Ni 2.5 Au 0.03 0.07 N/A X 63 Ni 2.5 Au 0.03 0.11 N/A X 64 Ni 2.5 Au 0.03 0.18 N/A X 65 Ni 2.5 Au 0.01 0.005 N/A X 66 Ni 2.5 Au 0.01 0.011 N/A X 67 Ni 2.5 Au 0.01 0.019 N/A X 68 Ni 2.5 Au 0.01 0.032 N/A X 69 Ni 2.5 Au 0.01 0.04 N/A X 70 Ni 2.5 Au 0.01 0.07 N/A X 71 Ni 2.5 Au 0.01 0.11 N/A X 72 Ni 2.5 Au 0.01 0.18 N/A X 73 Ni 2.5 Au 0.8 N/A BENZOTHIAZOL X 74 NiP 2.5 Au 0.8 N/A BENZOTHIAZOL X 75 Ni 2.5 Au 0.8 N/A THIOL X

(67) Table 5 shows the above evaluation results that are summarized based on the relationship between the thickness of the main plating layer and the dry coating weight of the PFPE-containing coating.

(68) TABLE-US-00008 TABLE 5 THICKNESS OF MAIN DRY COATING WEIGHT OF PFPE-CONTAINING COATING (mg/cm.sup.2) PLATING LAYER (m) 0.005 0.011 0.019 0.032 0.04 0.07 0.11 0.18 0.25 0.37 0.43 0.01 X X X X X X X X (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- PLE 65) PLE 66) PLE 67) PLE 68) PLE 69) PLE 70) PLE 71) PLE 72) PLE 30) PLE 31) PLE 32) 0.03 X X X X X X X X (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- PLE 57) PLE 58) PLE 59) PLE 60) PLE 61) PLE 62) PLE 63) PLE 64) PLE 27) PLE 28) PLE 29) 0.05 X X X X X X X (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- PLE 49) PLE 50) PLE 51) PLE 52) PLE 53) PLE 54) PLE 55) PLE 56) PLE 24) PLE 25) PLE 26) 0.10 X X X X (SAM- (SAM- (SAM- (SAM- (SAM- SAM- (SAM- (SAM- (SAM- (SAM- (SAM- PLE 44) PLE 45) PLE 46) PLE 47) PLE 48) PLE 18) PLE 19) PLE 20) PLE 21) PLE 22) PLE 23) 0.20 X X X X (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- PLE 40) PLE 41) PLE 42) PLE 43) PLE 11) PLE 12) PLE 13) PLE 14) PLE 15) PLE 16) PLE 17) 0.40 X (SAM- SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- (SAM- PLE 39) PLE 1) PLE 2) PLE 3) PLE 4) PLE 5) PLE 6) PLE 7) PLE 8) PLE 9) PLE 10)

(69) Further, photographic images of surfaces of the contacts of the connectors of samples 1 to 32 and samples 39 to 72 after the test are shown in FIG. 5. Further, photographic images the contacts of the connectors of samples 33 to 38 and samples 73 to 75 after the test are shown in FIG. 6.

(70) As can be seen in Tables 4 and 5, it was verified that, with the dry coating weight of the PFPE-containing coating of greater than or equal to 0.011 mg/cm.sup.2, good corrosion resistance can be obtained even if the thickness of the main plating layer was decreased to 0.4 m. Also, it was verified that, with dry coating weight of the PFPE-containing coating of greater than or equal to 0.25 mg/cm.sup.2, good corrosion resistance was obtained in a broader thickness region of the main plating layer.

(71) On the other hand, as for the samples of comparative examples, as can be seen in Tables 4 and 5, it was verified that the contact resistance values did not meet the standard, and sufficient corrosion resistance was not obtained for severe corrosion resistance tests.

(72) From these results, it was verified that both the reduced thickness of the main plating layer and the corrosion resistance are achieved simultaneously by applying the present invention.

Second Example

(73) Performance for tests other than the four-gas mixture resistant test by the present invention was examined and will be described below. Note that, for each of the following tests, a connector (sample 76) having a configuration the same as the configuration of the connector of sample 8 used in the first embodiment was used. That is to say, with the connector of sample 76, the thickness of the Au plating layer formed on the contact was 0.4 m and the dry coating weight of the PFPE-containing coating was 0.25 mg/cm.sup.2. Also, for each test, a surface condition of the contact before and after the test was observed and also contact resistance value was measured using a milli-ohm meter (manufactured by HIOKI: 3560 AC m HiTESTER).

(74) (Salt Spray Test)

(75) A salt spray test complying with JIS H8502 was carried out with a sample being mated with a counterpart connector (receptacle connector) and under a condition of: temperature 35 C.; salt water concentration 5%; test duration 48 hours. FIG. 7A shows an example of the surface condition observation result of the contacts after the salt spray test, and generation of a corrosion product due to the salt spray test was not clearly observed. FIG. 7B shows contact resistance values before and after the test, and it can be seen that there was almost no increase in contact resistance due to the salt spray test and it was within the standard (twice the initial contact resistance value or less). Therefore, it became clear that the connector to which the present invention was applied had a high corrosion resistance to the salt spray test.

(76) (Two-Gas Mixture Test)

(77) A two-gas mixture test was conducted by steps (a) to (e) below.

(78) (a) Measurement of initial contact resistance value (measured by direct current four-probe method)

(79) (b) 500 times of insertion and extraction

(80) (c) Measurement of contact resistance value

(81) (d) Exposure to two-gas mixture flow (96 hours, mated with a counterpart connector)

(82) (e) Measurement of contact resistance value

(83) Note that, the two-gas mixture test satisfies conditions standardized among electronic equipment set manufacturers, and type and density of gases are: H.sub.2S 3 ppm; SO.sub.2 10 ppm; temperature of 40 C.; and humidity of 75% RH. FIG. 8A shows an exemplary surface condition observation result of contacts after the two-gas mixture test, and although the two-gas mixture test is partially an atmosphere that was more severe than a three-gas mixture test and a four-gas mixture test (gas concentration of an order of a few to several ppm, and 500 times of insertion and extraction), a corrosion product was not clearly produced. Also, FIG. 8B shows contact resistance values for before the test, after 500 times of insertion and extraction, and after the exposure to the two-gas mixture flow, but there was almost no increase in the contact resistance, and it was within the standard (twice the initial contact resistance value or less). Therefore, it became clear that the connector to which the present invention is applied also had a high corrosion resistance to the two-gas mixture test.

(84) (Nitric Acid Vapor Test)

(85) A nitric acid vapor test complying with an EIA standard (EIA-364-53B) is carried out unmated with a counterpart connector and under a condition of: temperature 23 C.; nitric acid 300 ml (specific gravity 1.42); desiccator volume 6 L; and test duration of 75 minutes. Note that, for a nitric acid vapor test, there is no standard for measurement of a contact resistance value and thus only surface observation was performed. A method of counting corrosion products is as shown in Table 6 below. For example, in a case where the size of the corrosion product is 0.05 mm or smaller, the corrosion product is counted as zero. FIG. 9 shows a result of the surface evaluation, and it was clear that no corrosion products were produced in the nitric acid vapor test, and, the count was less than or equal to 1. Therefore, it became clear that the connector to which the present invention is applied had a high corrosion resistance to the nitric acid vapor test.

(86) TABLE-US-00009 TABLE 6 SIZE OF CORROSION ALLOTTED EVALUATION PRODUCT (DIAMETER) COUNT CRITERIA 0.05 mm 0 PASS >0.05 mm, <0.51 mm 1 0.51 mm 2 FAIL REGARDLESS OF SIZE. 20 CORROSION OCCURS IN A RANGE EXCEEDING 50% OF THE MEASURING REGION

(87) From the above-mentioned test result, it was verified that the electronic components to which the present invention is applied have performance that can meet to all existing corrosion resistance tests and standards.

(88) At last, various techniques for verifying the PFPE oil-based lubricating oil applied on the surface of the plated metal by an analysis will be described. An example thereof is shown below. Basically, since it is a method of detecting C (carbon), F (fluorine) and O (oxygen) constituting a PFPE oil to identify a substance, a perfect identification (substance identification) is difficult except for some techniques. However, if specific F (fluorine) is detected at an electrical contact position, it can be determined that at least a fluorine-based compound is applied. Also, substance identification is possible by analysis methods described below or by combinations with other methods.

(89) (1) A Case in which PFPE Concentration is Greater than or Equal to 0.5 wt %

(90) (i) Surface Analysis by EPMA (Electron Beam Micro Analyzer)

(91) Since PFPE oil is composed primarily of C (carbon) and F (fluorine), these elements are surely detected by using an electron beam micro analyzer. Other than this, although the resolution is lower, detection is possible by EDX (energy dispersed type).

(92) (ii) Surface Analysis by FT/IR (Fourier Transformation Infrared Spectrophotometer)

(93) Since the PFPE oil is composed primarily of C (carbon), F (fluorine) and O (oxygen), and it is a polymeric compound having a CF.sub.2O skeleton, infrared absorption peaks originating from bonds between them appear. That is, an absorption peak of a high intensity will appear at 1300 to 1000 cm.sup.1 for a fluorine-based compound. Also, the PFPE oil includes an ether linkage (COC), and thus an absorption peak originating from this also appears (it does not appear for polytetrafluoroethylene or the like). In addition, in a case where a CH group is included, an absorption peak appears around 3000 to 2800 cm.sup.1 about.

(94) (2) In a Case where PFPE Concentration is Less than 0.5 wt %

(95) Surface Analysis by XPS (X-Ray Photoelectron Spectrometer

(96) In a case where the PFPE oil has a low concentration, the build-up of the coating to a surface reduced and thus the film thickness of the PFPE oil becomes small, and the detection is difficult with the analysis method described in section (1) (this is because a background intensity becomes high). Therefore, for such an analysis of a thin-film state, XPS that can analyze a top surface layer (e.g., a few to several nm) is effective. Similarly to EPMA, basically, the detected elements are C (carbon), F (fluorine) and O (oxygen). However, the bonding energy (horizontal axis) with respect to a photoelectric peak of each elemental (vertical axis) shifts depending on the bonding state (chemical shift). For example, when paying attention to the peak of C, it can be determined whether the compound exists in a state where it contains a CF or CH bond. Other than this, an AES (Auger Electron Spectrometer) is also effective for an analysis of the top surface layer.

(97) (3) Other Analytical Methods

(98) (i) GC/MS (Gas Chromatography/Mass Spectrometer)

(99) (ii) TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometer)

(100) (iii) RBS (Rutherford Backscattering Spectroscopy)

(101) (iv) LRS (Laser Raman Spectroscopy, Microscopic Laser Raman Spectroscopy)

(102) (v) NMR (Nuclear Magnetic Resonance Analyzer)

INDUSTRIAL APPLICABILITY

(103) Thus, according to the present invention, an electronic component showing an excellent corrosion resistance to the four-gas mixture flow with an inexpensive structure can be provided.

LIST OF REFERENCE SIGNS

(104) 10 connector (electronic component) 12 housing 14 contact (contact member) 141 contact portion 143 connecting portion 145 conductive substrate 147 undercoat plating layer 149 main plating layer 16 coating