JPS60255947A - Novel nickel/indium alloy for manufacture of electric contact portion of electric device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel solderable nickel and indium alloy useful in the manufacture of electrical devices.

More particularly, the invention relates to the use of nickel/indium alloys of this type in the manufacture of some devices in which this alloy wholly or partially replaces gold in the construction of the electrical contact areas. Yet another aspect of the invention relates to electrical devices manufactured by the method of the invention. Other aspects of the invention will be apparent from the following description and claims.

The electronics industry requires conductors and contacts for transmitting signals to and from components and component arrangements. K to guarantee high reliability when used in electronics connectors for many years.
required a gold coating. For example, in the manufacture of printed wiring boards, the edge contact areas of the distribution board that provide electrical contact between the wiring board and other electrical components of the system are typically coated with a layer of gold or a gold-based alloy.

Gold or gold alloys are known for their contact resistance, corrosion resistance, conductivity,
% for these applications because of their wear resistance and soldering potential, and because they are inert to oxidation.
It is useful for

In recent years, there has been considerable interest in reducing the amount of gold used in the fabrication of electrical contact areas in electrical devices while maintaining the same performance characteristics. This interest was supported by rising gold prices and higher overall costs compared to others. Several alternatives to gold have been proposed. For example, the following, among others, have been proposed as electrodeposited layers to replace gold in electrical connectors: palladium, palladium/nickel alloys, ruthenium, tin and tin alloys. Each of these alternatives has a number of drawbacks, which limit their suitability as direct substitutes for gold.

Although recently developed palladium coatings exhibit interesting features for certain applications, the use of palladium or palladium coatings remains hesitant due to problems associated with its use. One potential problem is the high stress and microcracking caused by hydrogen gas evolution, the highly active catalytic nature of the palladium electrodeposited surface when the palladium is mated with itself, and the formation of a non-conductive tribological polymer film. formation, inconsistent wear properties, and lower corrosion resistance than gold. Furthermore, palladium is difficult to electrodeposit in a highly ductile state. Recent advances have attempted to eliminate some of the above drawbacks. However, palladium-based contacts still prove unacceptable for widespread use and, when used, are usually combined with a thin layer of gold.

Some disadvantages with the use of ruthenium are that the deposited layer from any type of electrolyte is highly stressed, and unless an anode diaphragm is used, the electrolyte itself contains toxic volatile ruthenium tetroxide at the anode. generate. Ruthenium complex salts for taming, suitable for producing metals, are also extremely expensive.

The main disadvantages of tin and tin/lead alloys are that they are extremely poor in wear resistance, are not oxidation resistant, and require relatively high voltages to destroy the insulating oxide film that forms on their surfaces. It is necessary to. Furthermore, tin itself has the disadvantage of being prone to forming metallic "whiskers".

In accordance with the present invention, a new and improved nickel/indium alloy containing an "effective amount of indium" is provided,
This alloy is useful as a total or partial gold replacement in the manufacture of electrical contact areas in electrical devices.

Yet another aspect of the present invention is that the electrical contact region comprises a nickel/indium alloy containing an effective amount of indium, or a nickel/indium alloy and a noble metal such as gold, or a gold-based alloy. The present invention relates to electrical devices coated with laminated coatings, as well as methods of manufacturing such devices. As used herein, an "electrical contact area" is an area that provides electrical continuity for an electrical device and forms a mating surface. □ Figures 1 to 10 correspond to the sequential process steps in the manufacture of printed wiring boards with tacked through-holes in which gold is wholly or partially replaced by a nickel/indium combination containing an effective amount of indium. Figure 2 is a series of fragmentary cross-sectional views.

The nickel/indium alloy used in the present invention is “effective amount”
Contains indium. The 1" effective amount of indium used herein is sufficient to enable the alloy to be soldered and/or to trap excellent contact resistance, giving corrosion resistance, and at the same time is sufficient to give good electrical conductivity. In general, all or some of these alloy properties can be achieved when the alloy contains from about 0.1% to about 95% indium by weight of the alloy. In a preferred embodiment of the invention, The amount of indium in the alloy is from about 1% to about 25% by weight of indium, based on the total weight of the alloy, and in particularly preferred embodiments from about 2% to about 20% by weight, based on the total weight of the alloy. Among embodiments of the present invention, alloys containing from about 3 to about 15% by weight indium, based on the total weight of the alloy, are preferred for use in electrical contact areas of electrical devices, with the amount of indium being about 10% by weight of the alloy. 4°
Also preferred are alloys of the present invention 1c/I that are from about 14% by weight.

In the most preferred embodiment, the amount of indium in the alloy will vary depending on whether the electrical contact is a female contact or a female contact area. For example, if the contacts are male contacts,
That is, if the contact area is a contact on the outside surface, the amount of indium in the alloy is preferably from about 3 to about 7% by weight; For example, the amount of indium in the alloy is about 6% to about 14% by weight.

The nickel/indium alloy used in the practical IMK of the present invention can be prepared by electrodepositing it from a plating bath onto a preferably conductive metal (eg copper) using conventional electrodeposition techniques. Useful electrodeposition methods include both barrel and rack plating methods. “Electroplating Engineering, New York” (Kenneth Graham, ed., Van Nostrand Reinhold, Inc., New York, NY, 1971) These general electrodeposition methods detailed are well known in the field of electroplating technology. , and will not be described in detail here.

In a preferred embodiment of the present invention, the alloy of Novel Nickel/Indium Alloys and Prints thereof, co-filed in the United States by the present applicant, is electroplated. The new bath used in the present invention consists of:

(G) at least about 0.5 M nickel cations and at least about 0.001 M indium cations; (b) chloride ions at about 2.6 M; (c) maintaining the pH of the bath at about 5 or less; (d) an effective amount of one or more chelating agents; and (g) water.

In a preferred embodiment of the invention, the concentration of nickel cations and indium cations in the bath is from about 0.5 to about 2.5M, and from about 0.001 to about IM, respectively. In a highly preferred embodiment of the invention, the concentration of nickel cations and indium cations in the bath is from about 0.5 to about 2.0M, and from about 0.009 to about 0.1M, respectively. The most preferred of these particularly preferred embodiments are those in which the concentration of nickel and indium cations in the bath is from about 1 to about 2M, and from about o, o is to about 0.06M, respectively.

The bath used in the present invention contains one or more chelating agents capable of chelating indium cations. The type of chelating agent used in the practice of this invention can vary widely. For example, useful chelating agents include those that chelate ferric iron (Fe3+). Specific examples of chelating agents in this food include Ramunas J, Matekaitis and Arthur E, Martel, "Inorganic Chemistry", 1980, 19.16.
46-1651; Wesley R, Harris and Arthur E, Martel, "Inorganic Chemistry",
15.713 (1976); and K.A., E., Martel and R.M., Smith. , bicine, catechol,
Iminodiacetic acid, nitrilotriacetic acid, ((hydroxyethyl)imino)diacetic acid, cyclohexanediaminetetraacetic acid, diethylenetriaminentaacetic acid, salicylic acid, chromotropic acid, hydroxamic acid, N.

N'-bis(0-hydroxybenzyl)ethylenediamine-N, N'-diacetic acid, ethylene-1,2-bis(
0-hydroxy) phenylglycine, N-hydroxybenzyliminodiacetic acid, N-hydroxyethylethylenediamine-N, N', N'-) ricin, N, N
'-Ethylenediaminediacetic acid, N,N-ethylenediaminediacetic acid, N,N-bis(2-aminoethyl)glycine, N,N'-diglycylethylenediamine-N",N"
-tetraacetic acid, N-hydroxyethyliminodiacetic acid, N
-(2-Hydroxy-5-sulfobenzyl)ethylenediamine-N,N''bis(methylenephosphoric)acid,)riedelenetetraminehexaacetic acid,tetraethylene(ethylaminehebutaic acid ff, ethylenediamine-N,N'-diaceteincou) N, N'-bis(methylenephospon) el!, glycine-N, N'-bis(methylenephosphonic) acid, ethylenediamine-N, N'-bis(
methylenephosphonic) acid, 1-hydroxy""i">-1
+ 1-diphosphonic acid, 2-(hydroxybenzyl)iminobis-(methylenephosphonic) acid, ethylenediamine-N,N,N',N'-tetrakis(methylenephosphonic) acid, and N-(phosphonomethyl)iminodiacetic acid.

Other useful chelating agents for use in the practice of this invention include carboxylic acids with one or more carboxy functional groups ("carboxylic acids"), one or more carboxy functional groups, and IWA. or carboxylic acids with two or more hydroxy functional groups (“hydroxycarboxylic acids”), and carboxylic acids with one or more amino functional groups and one or more carboxy functional groups (“aminocarbo/ acids), as well as their salts. Specific examples of this type of material are as follows. Citric acid, malonic acid, tartaric acid, adipic acid, phthalic acid, oxalic acid, glutaric acid, isophthalic acid, maleic acid, fumaric acid, succinic acid, glycolic acid, dariogysylic acid, glutamic acid, glyceric acid, malic acid, lactic acid, hydroxybutyric acid , mandelic acid, valine, arginine, aspartic acid, pyruvate, glutamine, leucine, lysine, threonine, inleucine, valine and asparagine. Chelating agents can be used alone or combinations of chelating agents can be used. For example, using varying amounts of a relatively strong chelating agent such as ethylenediaminetetraacetic acid in combination with varying amounts of a relatively weak chelating agent such as malonic acid, citric acid, malic acid and tartaric acid or more. However, the amount of "electroactive indium", ie the amount of indium used in electroplating, can be controlled.

Preferred chelating agents for use in the practice of this invention are relatively weak chelating agents such as carboxylic acids such as malonic acid and tartaric acid; hydroxycarboxylic acids such as citric acid and malic acid, and their salts. Hydroxycarboxylic acids and their salts are particularly preferred for use, with citric acid, malic acid and their salts being most preferred.

The use of chelating agents is a nickel/
It is important for the electrodeposition of indium alloys and for controlling the amount of indium in the alloy and the distribution of the amount of indium as a function of effective current density. Without wishing to be bound by any theory, it is believed that by properly selecting the chelating agent or combination of chelating agents of 2 m or more, the type used in plating can be obtained at a relatively constant value over a relatively wide operating time. It is believed that the amount of indium can be controlled by effective pressure. The use of this type of chelating agent therefore provides a means of controlling the percentage of indium in the plating.

An "effective amount" of one or more chelating agents is included in the bath. As used herein, an "effective amount" of chelating agent is an amount effective to control the amount of electroactive indium to any degree. The amount of chelating agent can vary widely depending on a number of factors. where K is the chelating agent used, the amount of electroactive indium desired,
This includes the desired indium concentration, current density, pH, etc. during plating. Generally the amount of chelating agent will be at least about 0.001M. In preferred embodiments of the invention, the amount of chelating agent is from about 0.001 to about 2.6M, and in preferred embodiments from about o,oos to about 1%.
．． It is 6M. The most preferred of these particularly preferred embodiments provide that the amount of chelating agent in the bath is about 0.0
5 to about 0.25M.

The nickel and indium cations used in the plating baths used in this invention can be derived from any source. In a preferred embodiment of the invention, the nickel and indium cations are nickel and/or indium chlorides, nickel or indium carbonates, water-soluble nickel and/or indium salts of sulfamic acids, and hydroxycarboxylic acids, Derived from aminocarboxylic acids (those without mercapto functionality), as well as nickel and/or indium salts of silicic acid, which also function as chelating agents. Specific examples of useful bathable nickel and indium salts include citric acid, acetoacetic acid, glyoxylic acid, pyruvic acid, glycolic acid, malonic acid, hydroxamic acid,
iminodiacetic acid, salicylic acid, glyceric acid, succinic acid,
Nickel and indium salts of malic acid, tartaric acid, hydroxybutyric acid, arginine, aspartic acid, asparagine, glutamic acid, glycerin, glutamine, leucine, lysine, threonine, inleucine, valine, etc. In a preferred embodiment of the invention, the concentration of chloride ions in the bath is from 0 to about 2.6M. Chloride ions can be obtained from any metal salt that is not electrodeposited under the operating conditions of the bath, or from nickel and/or indium salts. Examples of useful metal salts of this type are sodium chloride and potassium chloride, non-metallic salts such as ammonium chloride,
Such as nickel chloride or indium chloride. Chloride ions are preferably derived from indium chloride and/or nickel,4 with nickel chloride being a particularly preferred source of chloride ions. In a preferred embodiment of the invention, the concentration of chloride ions in the bath is about 0.001. ~
The concentration of chloride ion in the bath is between about 0.005 and about 1.6M;
It is. Most preferably, in these particularly preferred embodiments, the concentration of chloride ions in the bath is about 0.0
5 to about 25M.

The plating baths of the present invention are typically less than about 5, preferably about 1.
p of 4 to about 5.0, most preferably about 2.8 to about 8.6
Has H. The pH of the plating bath can be maintained at the desired pH through the use of buffer substances.

The type of buffer substance used can vary widely depending on the desired pH. For example, the pH may be maintained within the preferred pH range by the use of substances such as boric acid or basic substances such as ammonium hydroxide, charcoal nickel, sodium hydroxide, triethylamine, triethanolamine, pyridine, charcoal, etc. It can be adjusted by adding sodium, etc. When the carboxylic acid casing or its salt is the chelating agent, the pH can also be adjusted by the use of sulfone E or hydroxycarboxylic acid.The particular pH used in particularly preferred embodiments of the invention is It will depend on the particular buffer substance. For example, when a hydroxycarboxylic acid such as citric acid is present with the selected buffer and chelating agent, the pH is about 1.4.
to about 4.7, preferably about 1.8 to about 8.8. Hydroxycarbon II!
In particularly preferred embodiments of the invention using as buffering substances and chelating agents, the pH is between about 2.0 and about 2.0.
In the most preferred embodiment of the present invention, in which hydroxycarboxylic acids are used as buffering substances and chelating agents, the pH may range from about 2.1 to about 2.7. On the other hand, experiments have shown that best results are obtained when boric acid is the buffer of choice provided the pH is maintained in the range of about 1.5 to about 3.5. In preferred embodiments of the invention, where boric acid is the buffer of choice, the pH is between about 2.0 and about 8.0, and in particularly preferred embodiments, the pH is between about 2.5 and about 8.0. It may be about 8.0. In the most preferred embodiment of the invention, in which boric acid is the buffer of choice, the pB is between about 2.8 and about 8.0.
You can come.

In a preferred embodiment of the present invention, the nickel/indium alloy 4i is incorporated into the nickel/indium alloy described in pending U.S. patent application Ser. +1
(filed April 80, 1984). Preferred baths of the present invention employ a combination of chelating agents and buffers selected from the group consisting of dicarboxylic acids, hydroxycarboxylic acids, and their salts.

Generally preferred baths for this cage consist of:

(81) at least about 0.9 M of nickel cations; (6) of at least about 0.001 A/indium cations; (6) chloride ions at about 2.6 M; (C) from dicarboxylic acids, hydroxycarboxylic acids and their salts; A combination of buffering substances and chelating agents selected from the group of about 25 to about 1.6 M;

Particularly effective plating baths used in the practice of this invention consist of:

(c) about 0.9 to about 2M nickel ions; (b)
About 0.4 to about 2.5M chloride ion; (C) about 0
．． 004 to about 0.05Af; (d) a combination of buffering agents and chelating agents selected from the group consisting of dicarboxylic acids, hydroxycarboxylic acids and salts thereof (alone or in combination with other chelating agents); ) about 0.2 to about IM; and (6) water.

The bath in the present invention may contain, together with the plating bath, other optional components commonly used in plating baths. For example, the plating bath of the present invention may contain one or more compounds for reducing surface pitting, such as alkyl sulfonates.
Good too. Other optional substances that may be included in the baths of the present invention include dextrose-type stabilizers for the indium, as well as other alloy modifiers, such as internal stress and appearance of the electrodeposited alloy. Saccharin, funarin, etc. may be contained in the bath, which may affect the properties.

During the electrodeposition process, the plating bath is normally maintained at a temperature of about 10 to about 80°C. In preferred embodiments of the invention, the electrodeposition temperature is from about 20°C to about 65°C, and in particularly preferred embodiments of the invention, the electrodeposition temperature is from about 85°C to about 65°C. Among the particularly preferred embodiments of the present invention, the most preferred is an embodiment in which the electrodeposition temperature is from about 85 to about 55°C. In the electrodeposition process, the current density is determined by either the panel plating method or the barrel plating method. It can vary widely depending on the use. However, in most embodiments of the invention using panel plating methods, the current density is typically maintained in the range of about 1 to about 200 mA/am. In preferred embodiments of the invention using panel plating methods, The current density is about 5 to about 100 tnA/an'',
In particularly preferred embodiments, about 10 to about 60 mA
/an''.The most preferred of these particularly preferred embodiments using panel plating methods are '1Ef
I density is about 20 to about 40? X A /an''. When using the barrel plating method, the typical current density given is the electric current density used for panel plating.
The machining depth is also approximately 2-10 times smaller.

In the most preferred embodiment of the invention using barrel plating, the current density used depends on whether the contacts to be electrodeposited are on the internal surface (i.e., female contacts) or on the external surface (i.e., male contacts). It will vary depending on the temperature.

In these most preferred embodiments, the current density used to plate the male contact areas is from about 8.2 to about 5.9 mA; Approximately 6.45 to approximately 9.7 mA/
The electrodeposition step is allowed to last for a period sufficient to electrodeposit the desired amount of nickel/indium alloy. As will be apparent to those skilled in the art, electrodeposition times will vary widely depending on a number of factors. These include, but are not limited to, the desired electrodeposited layer thickness, flow density, bath temperature, and factors known to those skilled in the plating process. Typical plating times range from several minutes to several hours.

Broadly speaking, the new nickel/indium alloys are intended to replace, in whole or in part, gold-based alloys in electrical devices where gold is currently used as an electrical contact light source. This alloy is particularly useful in this application because of its excellent contact resistance and corrosion resistance. For example, the novel alloys of the present invention can be used in the manufacture of electrical connection devices, such as electrical contact areas such as connector pins. These electrical devices are well known in the art and will not be discussed in detail here. Furthermore, this nickel/indium alloy can be used as a partial or complete replacement for fireflies in these devices in the manufacture of the electrical contact areas of switches and in the construction of the electrical circuits of devices of this type.

The nickel/indium alloy described above is particularly useful in the method of the present invention for the construction of electrical contact areas such as printed wiring boards, switches, electrical connectors, chip carriers, and the like. For example, the nickelide/indium alloy described above can be used in the production of electrical contact regions of printed wiring boards manufactured by equisubtractive, equiadditive or semi-equal additive processes. The general techniques for making printed wiring boards by the equisubtractive, equiadditive, and quasi-equaladditive methods are very well known in the art and will not be discussed in detail here. Examples of equal subtraction, equal addition, and quasi-equal addition are U.S. Pat. No. 8.6'I 8.680;
No. 88; No. 8,980.968; No. 8.625. ?
No. 58; No. 8,956,041; No. 8.854,97
No. 8; is, a 94.250; No. 8.628,99
No. 9; No. 8.8 '74,897; No. 8.960.5
No. 78; No. 8,685. '758; No. 8.615. ?
No. 86; No. 8.865,628 and No. 4.217
, No. 182 Specification.

The following specific examples are provided to describe the invention in more detail.

Example 1 General Processing Standardized commercially available nickel sulfamate (Ni l
5OsNTo), ) solution 12.55M nickel sulfamate) was partially diluted with deionized or distilled water so that the remaining components of the bath were #! I made it easy to understand.

Nickel chloride was added along with diammonium citrate. The pH was then adjusted to slightly above the desired working bath pE by addition of a mixture of sulfamic acid, nickel carbonate and aqueous dispersion of ammonium or hydrochloric acid. Then indium sulfamate (I s l S 0sN
Ht)s) was added as the hydrated salt followed by a trace of wetting agent (sodium lauryl sulfate). Next, take a bath! Addition of i* or deionized water 1
The volume has been reduced to 1, and it is now ready for use. A plating bath was prepared by the above treatment.

Its physical parameters are shown below.

Table I (G) Sulfamine-dispersed nickel ・・・・・・・・・
1.8 M(b) Ammonium citrate...
...0.25M(a) Nickel chloride ...
...0.075M(d) Sulfamine-dispersed indium...0.018M(-) Sodium lauryl sulfate...0.0004Ar plating bath for electrical connections conducted preliminary experiments to evaluate the utility of the nickel/indium alloy as a total or partial replacement for gold in electrical contact areas, for example, for connector pins, printed wiring boards, and other electrical devices. . The above plating bath and the following
Using the processing conditions and general barrel plating method,
The electrical contacts of the female and male parts were plated with the alloy of the present invention.

夛I (α) Temperature... 50℃ (b) Current density---8,2~11mA/cm" (6)
pH... ・ ・ ・ ・ ~ 2.8 The electrical connection board and the weights X of nickel and indium in the alloy are shown in Figure I below.

2 m Batch corrosion Contact type Composition 951B .

Plating thickness of nickel/indium alloy for each batch 2)
- Measurements were made using a common fluorophore histological method per sample loft. As a result, for batches 1 and 2, the Celsius plating thickness was 0.00020 to 0.00040.
It was shown that the plating thickness for Batch 9, Batch 8 and Batch 4 was 0.00020 to 0.00060 μm.

The six pairs of contact resistances (CE'') fitted together are NIL-
Tested according to the method of C-890V2r.

(a) Batch 1 and Batch 2 Cb) Batch 8 and Batch 4 (e) Batch 4 and Batch 1 (d) Batch 2 and Batch 8 The contact resistance (CR'') of the control mated male and female pair is also
Standard center contact plating - beryllium/copper contacts Q) Gold plated
)@etc.R-E-(minimum thickness 0.00127cm) using Federal, S+rD-100-15 and Federal 5TD-1
Tested according to method 00-117. A comparison of the results showed that the contact resistance of the contacts plated with the nickel/indium alloy was acceptable.
They were divided into two test groups and evaluated as follows.

A) Test group 1 is NIL-8TD-202.

Evaluated in a 48 hour salt spray test using the Method 101 method. The results of this salt spray test are shown in Table 1 below.

Test group 1 Test pair Male Female after initial CR salt spray
Number of [yycΩ) CRI 艷) Batch 2 - Batch l
4 1.24 1.89 Batch 4-Batch 8 4 1.
71 1.94 Batch 2-Batch 3 4 yE” 2.
08 Batch 4-Batch 1 4 NB” 2.65 tatami Not recorded.

B) Test Group 2 (4 replicate specimens each) was evaluated in the durability test described below. The male and female contact pairs were mechanically fitted and removed. Contact resistance C
E'') 8 initially and 500 mating cycles;
Measurements were taken after 1000 and 2000 times. The results of this test are shown in Table V below.

C) Test group 8 each MIL-8TD-20
2. Method 107, test conditions C, >↓ and MIL-8TD-
It was evaluated in a thermal shock test and a moisture proof test using Method 106. The results of these tests are shown below.

D) Test Group 4 was evaluated for ductility, soldering suitability and adhesion as described below.

Ductility Test Male and female connector parts are hand crimped and then visually inspected for nicks in the nickel/indium plating.

For soldering, use non-corrosive flux [Kester Flux (
Kmstor FLsz ) 41544 ) 5-10
2 seconds and then immersed in solder consisting of 60 tons of 40X lead tin for 80 seconds. The test piece is then spun out and gently shaken to remove excess solder.

The specimen is then inspected to determine the amount of solder coating that adheres uniformly to the nickel/indium plating without forming lumps.

Adhesion Test (α) Bake Test - Bake the specimen at a temperature of 148.9°C for 1 hour. After cooling, the specimens are inspected under a microscope for blistering, peeling and V-king at 10x magnification.

(6) Insertion test - make at least 6 mated pairs. The specimens are visually inspected using a microscope at 10x magnification for peeling or flaking that exposes the underlying plating or matrix. If peeling or flaking is observed, increase magnification to 80x to confirm findings.

(cl Scratch Test (Cut Test) □ Make a cut on the test specimen with a knife, razor or needle, extending from the nickel/indium alloy to the base metal, from the neat end of the female contact to the back end. Using air pressure, Clean and remove loose particles from the contacts and visually inspect for flaking or peeling protruding from the cut using a microscope at 10x magnification. Only dislodged material should be observed. .

(d) Bending test - breaking the end of the contact or 90
Bend it until it forms an angle of °. Then using a microscope 10
Visually observe the contacts at 2x magnification for flaking, peeling, or separation of the plating from the base material or underlying plating.

The results of each of the above tests are shown below. The process is shown in ■.

Table ■ ■、Ductility 8 8 0 2. Aptitude for soldering 8 8 0 b. Insertion test 7 7 0 C6 scratch test 4 4 0 d1 bending test 8 3 0 Table ■ L Ductility 8 8 0 2. Aptitude for soldering 8 8 0 b. Insertion test 7 7 0 G. Scratch test 4 4 0 d0 bending test 8 8 0 Example 2, Plating bath 8 was prepared using the method of Example 1.

Its physical parameters are shown in the table below.

Table ■ d/J <b) Nickel chloride hexahydrate...15g/1
(C) Diammonium citrate...60971
1(d) Indiram sulfamate pentahydrate・・・・・・・・・51//1 Using the plating bath shown in Table ■ and the general barrel plating method, make general female and male electrical contacts. Plated with nickel/indium alloy. The operating parameters for male contact plating are shown in Table X below.

Plating time: 170 minutes (C) Current density: 4-6 mAIam” (d) pH
2-6 (adjusted with NH40B) Adjust the operating parameters regarding the female contact plating as shown below)! IVc is shown.

Table X <a) Temperature 45°C (6) Plating time 80 minutes (c) Current density 9. 'j mA /cIL' (d)
pH 2-6 (nM in NHaOH) The weight percent of indium and nickel in the alloy in the contact area is shown in the table below. Female 14.8-5.8 95.7 -9472 Male 2B
, 2 96.8 8 Female 34.8-5.895.7-9471, manufactured and sold by Allied Corporation under the part 8°21"919 designation Female Center Connector Bin for N = Series Connectors .

2. 821922 by Allied Corporation
Salt Center Connector Bin 08 for "N" Series Connectors manufactured and sold under the product designation 822852 by Allied Corporation
-Female center connector pin for N” series connectors manufactured and sold under product designation 7.

These batches were divided into several test groups and pairs of female and male connectors were evaluated in salt spray tests, thermal shock tests and moisture resistance tests using the methods described in Example 1Vc.

The results of the salt spray test are shown in Table Xm below.

TABLE XII F8-HIF182 0.957 1-106 Batch 8-Batch 2 82 0.979 1.571 Batch 8-Batch 21 90 0.988 1.616 The results of the thermal shock test are shown in Table XIV below.

Batch 8-Batch 1 B1 0.924 1.572 Hatch 8-i<7f2 82 1.07? 1.988
The results of the moisture resistance test are shown in Cloth X■ below.

Batch 8-Batch 1 B1 0.964 1.659 Batch 81 Bench 2 B1 1.584 1.988 Example 8゜Referring to the drawings, Figures 1 to 10 start with the substrate for processing and end with the final product. 1 shows the sequence of process steps according to a preferred embodiment of the invention for employment in printed wiring board manufacturing. The final product is a double-sided printed wiring board with copper circuitry, plated through-holes, and optional gold edge contact areas where the inventive nickel/indium alloy is a total or partial gold replacement.

The starting substrate is shown in FIG. This is similar to the commercially available laminate 10. Plate 10 is comprised of a substrate 12 of non-conductive material, such as glass fiber reinforced epoxy or thermoplastic material. The substrate 12 has a very thin copper cladding or film 14 laminated to each opposite side thereof. Copper film 14 workmanship 16 is approximately 0.0085
It has a thickness of 6 cm, while the substrate has a thickness of about 0.157 mm.

Holes or openings 18 are formed through the laminate 10 at predetermined locations where plated through holes are required.
form. Hole 18 is shown in FIG. 2 and can be formed, for example, by drilling with a tape-controlled drill press. The plate 10 can also be supported during the drilling operation by aluminum or paper phenolic inlet and outlet materials.

After drilling, the laminate 108 is cleaned.

It is desirable to first sensitize the entire laminate, the exposed surface of the substrate 12 in the drilled holes 18. This can be done by immersing the plate 108 in a suitable catalyst, such as tin palladium chloride.

A thin film or layer 19 of copper is then plated onto the plate 10 by conventional electroless plating techniques. This can be done, for example, by electroless copper plating on a film approximately 0.000254 cm thick.

Layer 19 also covers the surface of hole 18, as shown in FIG.

However, preferably a dry film photoresist is applied, followed by exposure and development. After that, first clean the board IO.

This can be done with a sander or a brush with fiber bristles and pumice. The plate 10 can then be rinsed with deionized or distilled water and dried with filtered compressed air.

Dry coat photoresist layers 20 and 22 are applied to each opposite side of board 10. An example of a suitable photoresist material is DuPont Liston I DsPont R15ton218R1
registered trademark). Photoresist coatings can be applied by passing the resist and plate through a laminator.

This is 104.5 to 12 depending on the laminator board used.
Bamboo can be made at a temperature of 4℃. The thickness of the photoresist layer 20 and 22 is determined by the desired thickness of the plated circuit.

Typically, the photoresist layer 20 and 22 may be slightly thicker than the desired thickness of the plated circuit, approximately 0.000762 cR. For example, to obtain a plated circuit with a thickness of about 0.00881 crrL, photoresist layers 20 and 2z
should have a thickness of approximately 0.00457°.

Photoresist layer 20 thus applied or laminated
Both parts 22 are then photographically exposed with appropriate masks removed. Next, photoresist layer 2oj? Develop the process 22. This will remove the non-polymerized areas 24 that are susceptible to development Wj. Areas 24 on photoresist layers zO and 22 correspond to the surface of the circuit areas and holes 18 to be plated.

The photoresist layer 20 and 22 then have overlapping regions 26. It is resistant to etching agents and treats all other areas of photoresist layers 20 and 22 as shown in FIG. Photoresist WI20 and 22%
The light source can be exposed for about 1 minute in a vacuum of 77.97 kPa or greater. After exposure, the pressure is released and the photoresist layer 20 and 22 are allowed to stand at room temperature for at least 80 minutes. Photoresist layers 20 and 22 can then be developed in a suitable automatic processor.

FIG. 5 shows the plate IO after the developer-sensitive non-polymerized areas 24 have been removed. This can be done, for example, by dipping the plate in a suitable developer solution exposing the holes or apertures 18 and the desired circuit image on both sides. For example, a phosphate process can be used to obtain a minimum steel plating 30 (FIG. 7) of 0.00254 cm on the opposite side of hole 18, resulting in a copper circuit 82 of about 0.00381 cm. The circuit plating 82 is the seventh
Encased within the wall confines of polymerized photoresist 26 as shown.

After the copper electroplating process, when the plate 10 is removed from the electroplating pattern plating bath, it is placed in a drag aud bath.
washed with water in a gout bath, rinsed with water, and subjected to an anti-stain treatment, for example, in IMASA C14-56 (ili! 5 mark) for about 1 to 2 minutes at about 20 to 25 °C,
Rinse with water and dry. Exposed copper layers 80 and 8
2 is then washed in a micro-etching acid cleaning bath for about 20 to 2
Wash for about 2 minutes at 5°C and soak the plate 10-'p in water for about 1 minute.
Rinse in deionized water for approximately 25 minutes. The exposed copper layer 80 is then etched 82 with a suitable phosphorescent etch resist, such as a tin/lead solder or alloy, with a weight of about 3 to about 90% indium, preferably gold, based on the total weight of the alloy. Electroplating with a nickel/indium mixture containing about 1 to 8 weights*X of indium based on the total weight of the material.

The manufacture and use of the latter is described in our pending U.S. patent application entitled ``Novel Nickel/Indium Alloy Process and Method of Using the Same in the Manufacturing of Printed Wiring Boards.''
No. 605.852 + filed April 80, 1984).

Upon removal from the electroplating bath, the plate 10 is rinsed in a dragaud bath for about 10 seconds, then in a boiling water bath for about 1 minute;
Rinse in water and dry. Plate 10 is then coated with an alkaline solvent strip IJ coating agent [e.g., Robertson's I
Robertsons IEP-118) for about 10 minutes at about 60-70°C, and a second bath of alkaline solvent stripping agent for about 5 minutes at about 60-70°C. An alkaline solvent stripping brush machine is connected to remove the photoresist 26 as shown in FIG. The plate 10 is then treated in a conventional manner with an ammoniacal etching agent [such as Mac-Dgrmi etching agent 9].
d) Erasing a nickel/indium etch resist using 9151:1 at about 45 DEG C. to remove copper from areas of the plate 10 that are not coated. Care is taken to keep the etching agent within its normal operating limits and avoid over-etching. L9 for excessive etching, nickel/nickel that acts as an etch resist during etching.
Copper layer 80 and B2 to such an extent that slivers of indium alloy may break and enter the printed wiring.
The edges are undercut. After etching, the board is rinsed in 10% water, dried, and masked to plate only the edge contact areas.

Nickel/indium alloys have electrical properties similar to those of gold. Therefore, the edge electrical contact 38 is simply the copper layer 80jl of the edge electrical contact 88. and 32 to the required thickness with a nickel/indium alloy, thereby replacing gold entirely.
8 is formed.

Alternatively, the edge electrical contacts 88 may be made by plating the copper layers 80 and 82 in the edge contact areas with a nickel/indium alloy to increase the thickness of the layer 80 in the edge electrical contact areas 8z and then plating with gold. It can also be obtained by

Copper layers 80 and 82 in edge contact area 8B are coated with nickel/
To prepare for electroplating with indium alloys or gold, layer 80 and layer 82 are coated with light chalk (lig).
ht chalk) clean or hot alkali clean, 1
A 25 second rinse and treatment in 096HCL reactivates the nickel in the nickel/indium alloy deposited on the layers 80 and 32. Activated board 10
Rinse in water for 1 minute and in deionized water for 25 seconds.

If the layer 80 in the edge contact area is electroplated first with a nickel/indium alloy and then with gold, the above operations are performed before plating with the nickel/indium alloy and before plating with gold. be exposed.

The electrical contact area 83 is typically about 1 to 10% based on the total weight of the alloy.
Electroplating with a nickel/indium alloy containing about 25 parts by weight of indium, preferably about 2 to about 20 parts by weight of indium based on the total weight of the alloy. In a particularly preferred embodiment of the invention, the electroplated indium on the electrical contact area 88 contains from about 8 to about 15 parts by weight of indium per total weight of the alloy; It contains from about 4 to about 14 parts by weight of indium based on the total weight of the indium. The nickel/indium alloy can be electroplated onto the electrical contact areas using conventional plating techniques. The plating bath and operating parameters used are shown in fThXVHc below.

夛Sodium uryl sulfate...0.0004M (a) Temperature...
・・50℃ω current density 1・・・・15～60f
nA/α2<h) pH... ~2.8 tatami
The current density will depend on the shape of the parts being plated.

Is the plating layer 801 in the edge contact area? ↓ and 82iC are cured for a period sufficient to deposit a nickel/indium alloy of the desired thickness. In preferred embodiments using a nickel/indium alloy as a total replacement, the thickness of the alloy is at least about 1 micron, and in particularly preferred embodiments where total replacement is desired, at least about 2.5 microns. It is. In preferred embodiments of the invention in which the nickel/indium alloys of the invention are partial replacements for violet, the thickness of the deposited alloy is at least about 0.5 microns and the partial replacement of gold is desired.
In a preferred embodiment, it is at least about 1.8 microns.

To gold plate the nickel/indium alloy seeded copper layer 30 in the edge contact area, the plate IO is loaded into a plating bath and a current density of about 10 A/ctn" +
10ASF) At a machining temperature of about 85°C, deposit the required thickness of gold (e.g., about 0.25 to about 2.5 microns,
Electroplate for a sufficient time (usually about 5 minutes) to deposit a thickness of about 1 to 1.8 microns (preferably from about 1 to about 1.8 microns).

By employing the method of the present invention, the printed circuit is masked and tin/lead removed from the edge contact areas,
Removing the masking, applying a new mask, and reintroducing the tin/lead alloy (all of these steps are required by conventional methods when manufacturing printed circuits with flat gold-plated edge contacts) is completely avoided, resulting in both time and energy savings. Also, since the gold is replaced entirely by a nickel/indium alloy or plated directly onto this alloy, it is possible to obtain a good bond between the gold and the adjacent tin/lead alloy experienced in known methods. The difficulties involved can be avoided. Furthermore, nickel/
Indium alloys have a bright glossy, dull appearance when electroplated onto the conductive material of layers 80 and 82, and ordinary soldering does not soften at temperature and flow.
The finished printed circuit with the components soldered thereon is more aesthetically pleasing in appearance and less prone to shorting than printed circuits conventionally manufactured using tin/lead alloys. Furthermore, precious metals can be saved since no or less gold may be used in the edge contact areas of printed circuits with edge contacts.

The final bullet wiring board with plated through holes is the first
Shown in Figure 0. This can be used in the same way as a printed wiring board manufactured by a conventional method; for example, by flow soldering, an L solder mask can be applied to this to fix the structure.

[Brief explanation of drawings]

Figures 1-10 show that a nickel/indium alloy containing an effective amount of indium is used to replace gold throughout the sequential process steps in the manufacture of printed wiring boards with plated through-holes. Figure 3 is a series of corresponding fragmentary cross-sectional views; lO: Laminate: 12: Substrate 14. 16: Copper film 18: Hole; 19 Dicopper film 20. 22: Photoresist layer 24: Polymerization region (photoresist layer) 26: Polymerization region (photoresist layer) 28: 80.82 : Copper plating; 88: Edge electrical contact patent applicant Allied Corporation (5 others) FIG, 6 FIG, 7 FIG, 8

Claims (1)

[Scope of Claims] (1) The improvement is essentially from about 0.1 to the total weight of the alloy.
An improved electrical device of the type having an electrical contact area comprising an electrical contact area electroplated with a nickel/indium alloy consisting of 95% by weight indium and nickel. (2) The weight percent of indium is approximately 2 to 2% based on the total weight of the alloy.
A device according to claim 1, which is 20% by weight indium. (3) The weight percent of indium is approximately 4% based on the total weight of the alloy.
Claim 2, which is ~14% by weight indium.
Devices listed in section. (4) the alloy is electrodeposited from an aqueous bath having a pH of about 5 or less, the bath containing (a) at least about 0.5 M nickel cations and at least about 0.001 M indium cations; (6) about up to 2.6 u of chloride ions; (c) a sufficient amount of buffering material to maintain a constant pH of the bath below about 5; (f) an effective amount of one or more chelating agents; and (g (5) The device of claim 4, wherein the chelating agent is selected from the group consisting of hydroxycarboxylic acids and salts thereof. (6) The chelating agent is citric acid, apple 1!!, or a salt thereof, and the amount of the chelating agent in the bath is about 0.2~
6. The device of claim 5, wherein the device is 1.3M. (7) The device of claim 6, wherein the chelating agent is selected from the group consisting of carboxylic acids and salts thereof. (8) The device according to claim 7, wherein the chelating agent is Maa7 powder or tartaric acid. (9) Further comprising a material selected from the group consisting of gold and gold-based alloys electroplated on all or a portion of the plated nickel/indium alloy on one electrical contact area. The device of claim 1. The device of claim 1, wherein the nickel/indium alloy plated on the electrical contact area has a thickness of at least about 1.0 micron.