JPH05148681A - Solid phase plating method - Google Patents

Abstract

PURPOSE:To provide a solid phase plating method which is good in productivity by pressing a solid electrolyte which exhibits a high ion conductivity to plating metal ions to a body to be plated and energizing this body via the electrolyte. CONSTITUTION:Silver ion conductive glass which is amorphous and has a high electric conductivity is used for the solid electrolyte 3. A pure silver anode rod of 2mmphi having 99.99% purity is used as the source for supplying the conductive silver ions of an anode 4. The silver ions move in the solid electrolyte 3 when a degreased and pickled copper plate having 1mm thickness is used as the anode of the body 1 to be plated and a current is specified to 0.35A with 10V impressed voltage. Electricity is then discharged on the surface of the copper plate which is the body 1 to be plated of the cathode and metal silver is deposited. The film forming speed of the silver plating is 1.75m/sec.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel solid phase electroplating method capable of performing solid phase plating.

[0002]

2. Description of the Related Art Conventionally known plating methods include an aqueous solution electroplating method, a vapor phase plating method (vapor deposition, ion plating), a molten salt electroplating method, and an aqueous solution electroless plating method. Are known. However, although this conventional plating method is an old technique, it has the following problems when it is applied to the fine plating of electronic parts in recent years. There is a limit to processing.

(1) When a plating method using an aqueous solution is used for partial plating of electronic parts (lead frame, etc.), a soft rubber or the like is used to hold parts other than those requiring plating (referred to as a plating mask) and a mask. A method of spraying a plating solution on the opening and applying a DC voltage to perform plating is widely adopted.

In this method, it is impossible to perform plating with high positional accuracy due to bleeding of the plating solution. Further, there is a limit to the fine plating process due to the mechanical mask.

(2) The aqueous solution plating method requires a large amount of equipment investment for wastewater treatment facilities, and the pollution problem associated with this is a major social problem.

(3) Vapor plating methods such as the vapor deposition method, the ion plating method, and the sputtering method have few pollution problems, but because of plating in a vacuum, such as a vacuum pump, a high pressure resistant bell jar and an evaporation source heating facility. A large amount of capital investment is required. Further, these vapor phase plating methods have a drawback that the productivity is extremely poor due to a low film forming rate (growth rate of a plated film) and a long required time for vacuuming.

(4) The molten salt electroplating method uses a high temperature molten salt such as caustic soda, which causes problems such as deterioration of working environment and poor workability due to high temperature bath, and also for electronic parts. It cannot be applied to fine processing plating or partial plating.

[0008]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention is intended to solve the above-mentioned problems of the prior art, does not use a plating solution, does not require a large capital investment, and is a completely novel plating method. It is an object of the present invention to provide a solid phase plating method capable of industrially putting a method capable of plating with a solid phase which is

[0009]

In order to achieve the above object, the inventors of the present invention use a solid electrolyte as a plating medium, do not use a plating solution, etc., and require a large capital investment. A completely new plating method that allows solid-phase plating (hereinafter referred to as solid-phase plating method)
The present invention was accomplished by discovering the above and enabling industrial practical application.

That is, according to the first aspect of the present invention, a solid electrolyte composed of an ion-conductive inorganic compound or an ion-conductive polymer compound is brought into contact with an object to be plated, the object to be plated is used as a cathode, and The solid-phase plating method is characterized in that an anode made of the same material as the plating metal is connected to the solid electrolyte and a voltage is applied between the cathode and the anode.

The object to be plated is made of metal, plastic,
And ceramics are preferred.

The voltage is preferably a DC voltage, a pulse voltage or a rectangular wave voltage.

Further, the voltage is preferably an external power supply voltage.

The solid electrolyte is preferably brought into contact with the object to be plated by applying a load or pressure to the solid electrolyte.

The present invention will be described in more detail below.

The solid electrolyte used in the present invention may be any one as long as it shows high ionic conductivity as a solid with respect to the plating metal ion, and may be an inorganic compound or a polymer compound. That is, the solid electrolyte is
It may be an ion conductive solid crystal, an ion conductive glass (ceramics) or an ion conductive solidified paste.

Such a solid electrolyte has a function of selectively permeating ions, and the conductivity of the solid electrolyte is carried out by only one kind of ion.

Of these ions, any metal ion can be used as long as it can be used for plating. For example, Ag ⁺ (silver ion) and Cu ⁺ (cuprous ion) can be used.
And so on.

As the solid electrolyte showing high ionic conductivity with respect to Ag ⁺ (silver ion), Ag _1-x M _x I _1-y X _y
(0 ≦ x <1, 0 ≦ y <1), and for example, Ag ₃ SI, Ag ₁₉ I ₁₅ (P ₂ O ₇ ), Ag ₆ I ₄
(WO ₄ ), RbAg ₄ I ₅ , KAg ₄ I ₅ , (N
H ₄ ) Ag ₄ I ₅ , Q ₂ Ag ₁₃ I ₁₅ , QAg ₅ I ₆ (where Q is an onium ion), HgAg ₈ S
₂ I ₆ , Ag _1.8 H _0.46 Se _0.7 I _1.3 , RbAg ₄ C
Examples thereof include those having a structure similar to NI ₄ and α AgI, in which a part of I ⁻ or Ag ⁺ of AgI is substituted with an anion or a cation. Particularly RbAg ₄ I ₅ is conductivity ^{2.7 × 10 -1 Ω -1 cm -1} (25 ℃) and higher, _{also, Ag 6 I 4 (WO 4} ) is conductivity 4.7 × 10 ^-3 Ω ^{- 1}
Although it is not so high as cm ^-1 (25 ° C), it is preferable because it is advantageous in cost and excellent in stability.

Cu⁺High ion for (cuprous ion)
As the solid electrolyte showing conductivity, cuprous halide
Cation substitute, or anion and cation substitution
There is a body, for example, RbCu₃Cl_Four, CuI ・ C
H_TenSCH₃I, Rb_FourCu₁₆Cl₁₃I₇, 7CuBr
C₆H₁₂N_FourCH₃Br, 17CuI / 3C₆H₁₂N _Four
CH₃I, and RbCu_FourCl₃I₂Etc.
In addition, CuTeX (X = Cl, Br, I)
You can Especially RbCu_FourCl₃I₂Has a conductivity of 4.
7 x 10^-1Ω^-1cm^-1Since it is as high as (25 ° C), it is preferable.

Although the solid electrolyte used in the present invention has been described above in detail, in the present invention, the conductivity of the solid electrolyte generally has temperature dependence, and thus the conductivity and the plating efficiency are increased. Therefore, it goes without saying that the solid electrolyte may be heated.

In the present invention, electroplating is performed through the above-described solid electrolyte with the side to be plated as a cathode and the solid electrolyte side as an anode. Therefore, it is necessary to supply plating metal ions to the solid electrolyte. is there. As a method for supplying the plating metal ions to the solid electrolyte, any method may be used as long as it can supply the plating metal ions in an amount necessary for plating. For example, AgI powder or the like can be used, but preferably, The anode connected to the solid electrolyte is preferably made of a material containing a plating metal.
The anode may be composed only of the plated metal, or the plated metal may be put in a container and the container may be used as the anode.

The object to be plated used in the present invention may be anything as long as it can be plated, but for example, metal, plastic and ceramics are preferred.

In the present invention, the object to be plated and the solid electrolyte are brought into contact with each other during electroplating. However, in order to make the contact state dense, a load is applied to one or both of the object to be plated and the solid electrolyte. It is preferable to apply pressure by a spring or the like between them or both.

The contact pressure applied when the solid electrolyte is brought into contact with the object to be plated is 300 g in order to completely bring it into close contact.
/ Cm ^{2 to} 1000 g / cm ² is preferable.

The applied voltage used in the present invention may be any voltage capable of plating, but is an external power supply voltage, and is preferably DC voltage, pulse voltage or rectangular wave voltage.

In the solid phase plating method of the present invention, a cathode is connected to the object to be plated, an anode is connected to the solid electrolyte, and the voltage is applied between the cathode and the anode, The plated metal is plated on the object to be plated while supplying the plated metal to the solid electrolyte via the solid electrolyte contacted with the object to be plated.

In the solid phase plating method of the present invention, in order to make the crystal grains of the plating finer and increase the plating current efficiency,
Ultrasonic waves may be applied to either or both of the solid electrolyte and the object to be plated.

Here, as a method of applying ultrasonic waves,
A method in which an ultrasonic vibrator is applied to the solid electrolyte or the object to be plated for irradiation is preferable.

The reason why the crystal grains of the plating become fine due to the load of ultrasonic waves and the plating current increases is that the ultrasonic energy destroys the thin oxide film on the plating surface of the object to be plated. This is because the nature is enhanced.

The apparatus configuration for carrying out the solid phase plating method of the present invention will be described below in more detail with reference to the preferred embodiments shown in the accompanying drawings.

FIG. 1 shows an embodiment of an apparatus for carrying out the solid phase plating method of the present invention (hereinafter referred to as a solid phase plating apparatus).

As shown in FIG. 1, the solid electrolyte 3 protected by the protective cylinder 2 is brought into contact with the object to be plated 1. An anode 4 is embedded in the solid electrolyte 3 to connect a cathode − of an external power source (not shown) to the object to be plated 1 and an anode + of the external power source.
And the anode 4 are connected.

Here, the protective cylinder 2 may be of any shape or of any material as long as it can protect the solid electrolyte 3 and does not hinder plating, but an insulating material such as, for example, A rigid polyethylene cylinder, a Teflon cylinder, a nylon cylinder and the like are preferable.

The shape of the solid electrolyte 3 may be any shape, but the shape of the contact portion is preferably the same as the shape of the plated portion of the object to be plated 1 or slightly larger and substantially the same.

As described above, the anode 4 is preferably used as a supplementary source of the plating metal ions, preferably the plating metal or the one containing the plating metal, and the shape thereof is not particularly limited, but the rod-shaped one is preferable.

Further, as shown in FIG. 2, in order to keep the temperature of the solid electrolyte 3 at a high temperature, a heating device may be provided in the protective cylinder 2 of the plating device shown in FIG. In FIG. 2, the solid electrolyte 3 is heated by arranging the heating cylinder 5 on the outside of the protective cylinder 2 and allowing the high temperature fluid to flow from the inlet 6 provided below the heating cylinder 5 to heat the solid electrolyte 3. The high temperature fluid can be discharged from the outlet 7 provided above the heating cylinder 5. Of course, the heating device used in the present invention is not limited to the example shown in FIG.

In the solid-phase plating apparatus shown in FIGS. 1 and 2, when ultrasonic waves are applied to either or both of the object to be plated 1 and the solid electrolyte 3, the object to be plated 1 or the solid electrolyte 3 is subjected to ultrasonic waves. It is better to load from the upper side of 3.

The apparatus for carrying out the solid phase plating method of the present invention has been described above, but the present invention is not limited to this, and is within the scope not departing from the gist of the present invention.
Of course, various improvements and design changes are possible.

[0040]

EXAMPLES The present invention will be described in detail below based on examples.

Example 1 The solid phase plating method of the present invention was carried out using the solid phase plating apparatus shown in FIG.

Here, as the solid electrolyte 3, an amorphous and highly conductive silver ion conductive glass (Ag ₆ I ₄ (WO ₄ )) was used. The cylinder 2 which is a protective body of the solid electrolyte was a hard polyethylene cylinder. As the anode 4, a 2 mmφ pure silver anode rod having a purity of 99.99%, which is a supply source of conductive silver ions, was used.

Next, the plating procedure will be described.
A 1.0 mm thick copper plate used as the object to be plated 1 (10
(0 × 100 mm) was degreased and washed to dry the surface. Next, the solid electrolyte 3 is added to about 500 g / cm ²
A single-phase full-wave DC current was applied by bringing them into contact with each other. The cross-sectional area of the rod-shaped silver ion conductive glass that is the solid electrolyte 3 is 5 mmφ = about 20 mm ² , and the tip is 0.06 μm.
Polished to an average roughness of m.

FIG. 3 shows the current-voltage curve of partial plating in this Example 1 (at room temperature of 25 ° C.). When a voltage was applied, there was first a polarization voltage (area A) of about 0.5 V, ie, this was an activation overvoltage corresponding to activation energy. When the polarization voltage (area A) was exceeded, the current moved to the rising area B and plating was started. When a current starts flowing, silver ions are injected from a pure silver anode rod which is the anode 4, and the silver ions move through Ag ₆ I ₄ (WO ₄ ) which is the solid electrolyte 3 to form the cathode plated object 1. Discharged on the surface of the copper plate and extruded as metallic silver. The current value when an applied voltage of 10 V is 0.35 A = 1.75 A / cm ² = 1
It was 75 A / dm ² (per cross-sectional area of solid electrolyte 3). The film formation rate of silver plating is 0.01 μm / sec according to Faraday's law when the current density is 1 A / dm ² , and therefore the film formation rate in Example 1 is 0.01 × 175 =
The value was 1.75 μm / sec. The film formation rate was 50 to 100 times that of conventional electroplating, and 2 to 5 times that of the latest high-speed jet aqueous solution plating method.

Example 2 The solid phase plating method of the present invention was carried out in the same manner as in Example 1 using the solid phase plating apparatus shown in FIG. In the second embodiment, in order to maintain the temperature of the solid electrolyte 3 at a high temperature, the heating cylinder 5 is added to the solid-state plating apparatus of the first embodiment.
Was placed outside the cylindrical body 3, hot water of 100 ° C. was injected from the boiling water inlet 6 and discharged from the boiling water outlet 7. This allowed the internal average temperature of the solid electrolyte 3 to be maintained at 100 ° C. The maximum current of the applied voltage of 10 V is shown in FIG.
As shown in 0.42A = 2.1A / cm ² = 210A
/ Dm ² . The film forming rate at this current density was 0.01 × 210 = 2.1 μm / sec, which was 2.4 to 6 times that of the high-speed jet plating method. The required plating thickness of silver plating of IC lead frame etc. is about 2-4 μm,
With the method of the present invention, it was possible to achieve this thickness in about 1 second when the applied voltage was 10V.

As described above, the conductivity of Ag ₆ I ₄ (WO ₄ ) solid electrolyte is about 4.7 × 10 ^-2 Ω ^-1 cm ^-1 (25
C)), which is 0.47 A (at 25 ° C.) at a voltage of 10 V when it is considered as a normal electric conductor, but a current of about 0.42 A in Example 2 and about 0.35 A in Example 1. Was achieved. The actual current becomes smaller than the current calculated from the conductivity because the voltage component due to the contact resistance between the object to be plated 1 and the solid electrolyte 3 and the dissolution of the silver electrode 4 into the solid electrolyte 3 and the object to be plated 1 This is because the activation overvoltage component of silver ion protrusion is included.

(Example 3) RbAg ₄ as a solid electrolyte
The solid phase plating method of the present invention was carried out in the same manner as in Examples 1 and 2 using I ₅ . In this case, the conductivity is Ag ₆
It was about 5.7 times that of I ₄ (WO ₄ ), and a high plating current was obtained at a low voltage. In Example 3, the maximum current density with an applied voltage of 10 V is 1.9 A without heating and 950 A / d from the current value of 3.85 A when heated to 100 ° C., respectively.
m ² , 1925 A / dm ² . In this case, the film formation rate was 0.01 × 950 = 9.5 μm / sec without heating, and 0.01 × 1925 = 19.25 μm / sec with heating. Therefore, the time required for the required plating thickness of 4 μm is 4 ÷ 9.5 = 0.42 seconds without heating, and 4 ÷ 19.25 = 0.20 seconds when heated to 100 ° C. I was able to finish.

If the voltage is increased to 10 V or more and the current value is increased, higher speed plating can be performed, but the plating time is too short to control the plating thickness, which is not practically suitable.

(Example 4) An ion conductive polymer material was used as the solid electrolyte and the same procedure as in Examples 1 and 2 was repeated.
The solid phase plating method of the present invention was carried out. This ionic conductive polymer material is PEO (polyethylene oxide) with AgI
Made to react.

The conductivity of this ion-conductive polymer material is
Generally smaller than that of inorganic solid electrolytes, PEO
-In case of AgI reaction product, 10 ^-1 Ω ^-1 cm at about 100 ° C.
It is ^-1 , but it is suitable for solid-phase plating in the case of a material to be plated with uneven surface because it is soft with a polymeric material and has good surface familiarity with the material to be plated 1 It was Embedding an anode pure silver rod in PEO-AgI
A hole smaller than the diameter of the anode pure silver rod was provided in PEO-AgI by grinding, and the anode 4 of the pure silver rod was attached. This was the same method as in the case of the inorganic solid electrolyte. This PEO-Ag
FIG. 5 shows a current-voltage curve when I was used as the solid electrolyte and the solid-phase plating method was carried out in the same manner as in Example 2.

The maximum current when the voltage is 10 V is about 0.75 ×
It is 10 ⁻² A, which corresponds to a current density of 3.75 A / dm ² . The film formation rate in this case is 0.01 × 3.75 =
The plating time required to obtain a silver plating thickness of 2 μm at 0.0375 μm / sec was 2 ÷ 0.0375 = 53 seconds.

(Embodiment 5) The solid phase plating method of the present invention was carried out in the same manner as in Embodiment 1, using pulse voltage and rectangular wave voltage as applied voltage. The waveforms used are shown in FIGS. 6 and 7. The waveforms of FIGS. 6 and 7 are used for the purpose of increasing the electric current density of electroplating of an aqueous solution, improving the adhesiveness, and miniaturizing the plated crystal. However, the ratio of the positive / negative time of the voltage The pulse waveform or the rectangular waveform is variously selected depending on the required plating film quality. Therefore, FIGS. 6 and 7 were selected as typical waveforms of the present invention. In the case of the pulse waveform shown in FIG. 6, the plating current is 0.40 when the applied voltage is 10V.
A, in the case of the rectangular wave voltage shown in FIG. 7, it improved to 0.44A. Further, with the pulse waveform and the rectangular wave, plating with fine crystal grains and good adhesion was obtained.

(Embodiment 6) A ceramic substrate having a thickness of 0.5 t was used as the object to be plated 1 and electroless copper plating was applied to the entire surface thereof at 1.0 μm. A solid phase plating method was carried out. The silver plating could be similarly performed under the same conditions as in Example 1.

(Embodiment 7) In carrying out the solid phase plating method in Embodiment 1, an output of 75 is applied to the object to be plated 1.
An ultrasonic wave of W and a frequency of 200 Hz was loaded. As an ultrasonic loading method, an ultrasonic vibrator was applied from below the object to be plated 1 for irradiation.

The effect of ultrasonic waves was such that the crystal grains of the plating became fine and the plating current increased to 0.44 A when the applied voltage was 10 V.

Since the thin oxide film on the surface of the object to be plated 1 is destroyed by the ultrasonic energy, the adhesion of the plated film is enhanced.

(Embodiment 8) In carrying out the solid phase plating method in Embodiment 1, RbCu ₄ C was added to the solid electrolyte 3.
l ₃ I ₂ was used. 99.99 for the anode due to copper plating
% Pure copper rod was used. The conductivity of RbCu ₄ Cl ₃ I ₂ was 4.7 × 10 ⁻¹ Ω ⁻¹ cm ⁻¹ , and when the applied voltage was 10 V, a current density of 4.0 A = 2000 A / dm ² was obtained. The deposition rate of copper is 0.00 when the current density is 1 A / dm ² .
74 μm / sec, and therefore 1 at 2000 A / dm ^2.
A film formation rate of 4.8 μm / sec was obtained. The particles of the plating film were very fine and the adhesion was good.

As described above, the performance of the solid-phase plating film obtained by the solid-phase plating method carried out in Examples 1 to 8 was tested. The conditions and results are shown in Table 1. Here, in order to investigate the bending adhesion, the plating thickness is 10 μm, which is higher than the required value.
set to m.

The bending adhesion test was carried out by bending 90 ° to 0.5R with the plated surface inside and then bending back to 10
It was observed with a microscope (× 10). As a result, it was judged by peeling due to fine cracks reaching the bare ground.

Next, a comparison was made between the conventional method and the method of the present invention in electroplating with respect to the plating position accuracy, the minimum possible plating area, the plating speed and the plating grain size. The results are shown in Table 2.

[0061]

[Table 1]

[0062]

[Table 2]

As is clear from Tables 1 and 2, the solid-phase plating method of the present invention enables high-accuracy plating with a fine grain size to be performed at high speed.

Further, high-quality plating can be obtained by setting the waveform of the plating voltage to a pulse voltage or a rectangular wave voltage or applying an ultrasonic wave. Further, by heating, higher speed plating can be performed.

[0065]

As described above in detail, the present invention has the following effects.

(1) According to the present invention, it is possible to solve the pollution problem that is always associated with plating. That is,
No chemicals are used when plating, so no pollution problems occur.

(2) According to the present invention, since the positional accuracy is higher than that of the conventional plating method, partial plating can be performed easily and finely with high accuracy without using a plating mask.

(3) According to the present invention, ultrahigh-speed plating can be performed as compared with the conventional plating method. About 42 times (Ma)
x) speed is obtained.

(4) The plating performance can be improved. The solid phase plating has very fine adhesion because the grain boundaries of the plating are fine.

(5) According to the present invention, the economical efficiency of plating can be improved. Since no plating chemical is used,
The plating cost can be reduced.

The plating cost per IC lead room is currently 1.20 yen / p, but it is 0.1 yen / p due to the reduction of the processing cost by reducing the plating chemical and improving the plating speed.
Can be reduced to

(6) According to the present invention, the cost of plating equipment is low. Equipment cost is low because expensive long plating tank is not required. For example:

Conventional plating equipment (IC lead room, 1
(10 million / month) = 70,000,000 yen.

The plating equipment of the present invention (IC lead room,
10 million pieces / month) = 30,000,000 yen.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of an apparatus for carrying out the solid phase plating method of the present invention.

FIG. 2 is a schematic view of another embodiment of the apparatus for carrying out the solid phase plating method of the present invention.

FIG. 3 is a graph of a DC voltage used in the solid phase plating method of the present invention with respect to a power supply voltage.

FIG. 4 is a graph of a DC voltage used in the solid phase plating method of the present invention with respect to a power supply voltage.

FIG. 5 is a graph of a DC voltage used in the solid phase plating method of the present invention with respect to a power supply voltage.

FIG. 6 shows waveforms of pulse voltage and rectangular wave voltage used in the solid phase plating method of the present invention.

FIG. 7 shows waveforms of a pulse voltage and a rectangular wave voltage used in the solid phase plating method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Object to be plated 2 Protective cylinder 3 Solid electrolyte 4 Anode 5 Heating cylinder 6 High temperature fluid inlet 7 High temperature fluid outlet

Claims (5)

[Claims] 1. A solid electrolyte comprising an ion-conductive inorganic compound or an ion-conductive polymer compound is brought into contact with an object to be plated, the object to be plated is used as a cathode, and the solid electrolyte is made of the same material as the plating metal. And a voltage is applied between the cathode and the anode. 2. The object to be plated is metal, plastic,
The solid phase plating method according to claim 1, wherein the solid phase plating method is ceramics. 3. The solid phase plating method according to claim 1, wherein the voltage is a DC voltage, a pulse voltage or a rectangular wave voltage. 4. The solid phase plating method according to claim 1, wherein the voltage is an external power supply voltage. 5. The contact of the solid electrolyte with the object to be plated,
The solid phase plating method according to any one of claims 1 to 4, which is performed by applying a load or a pressure to the solid electrolyte.