KR20040057861A - Surface treatment method of the products for wireless communication systems - Google Patents

Abstract

PURPOSE: A surface treatment method of products for wireless communication is provided to seek economic efficiency by preventing silver from coating on an unnecessary part of wireless communication products and minimize loss of signal and maximize protection of the products by improving close adherence between products and coating layer. CONSTITUTION: In a surface treatment method of housing and cover of band-pass filter for wireless communication, the surface treatment method comprises a step of treating chromate on the housing and cover; a step of masking a part corresponding to the inner surface of the housing and cover when assembling the housing and cover; a step of painting the masked housing and cover so that the masked part of the housing and cover is not painted; a step of removing the masking; a step of coating silver on the part corresponding to the inner surface of the housing and cover when assembling the housing and cover; and a step of heat treating the housing and cover, wherein the housing and cover are manufactured of aluminum, magnesium, iron, copper or an alloy thereof, wherein the masking material is a material capable of enduring a temperature of 200 deg.C or more, wherein the painting step is performed by using an electrical method for injecting the powder paint onto a covered body by passing powder paint through nozzle of powder painting gun, wherein a paint used in the painting step is an acid resistant or alkali resistant paint, wherein the surface treatment method further comprises a step of coating a prime layer on the housing and cover before performing the silver coating step on the housing and cover, and wherein the heat treatment step is performed in a sealed space at a temperature of 120 to 190 deg.C for 20 to 50 minutes.

Description

SURFACE TREATMENT METHOD OF THE PRODUCTS FOR WIRELESS COMMUNICATION SYSTEMS

The present invention relates to a surface treatment method for outdoor and indoor products used in the field of wireless communication. More specifically, the present invention relates to a method of plating and painting the housing and cover of a band pass filter for wireless communication.

A band pass filter passes only signals in a frequency range of a predetermined band, and removes signals in other frequency ranges, and transmits and receives signals in both directions, and plays a role in determining the communication quality in a wireless communication field. The first consideration in products in the field of wireless communications, such as band pass filters, is to increase the efficiency (eg, radio frequency skin depth effect) of components that process signals. In the above, the surface effect is a phenomenon in which the current flows only near the surface of the conductor as the frequency increases when the current flows through the conductor. If this property is used well, it is not necessary to use gold or silver, which has good conductivity, as its component. By coating (plating) the outside of the component, the high frequency conductivity can be increased, and alternating current loss can be prevented. However, even when a signal flows along and is processed along the surface of a plated component in a bandpass filter, some loss of the signal due to various environmental conditions is unavoidable, and efforts to minimize such losses are required. .

To minimize signal loss in wireless communication products such as band pass filters, a silver plating method has been used. At this time, a method of additionally coating the outside of the product for the purpose of protecting the product from the external environment has been conventionally used. Conventional plating and painting methods, the first housing 100 and the cover 101 of the band pass filter produced by the silver plating process to form a silver plating layer 102 (see Fig. 1a), the housing on which the silver plating layer 102 is formed After assembling the 100 and the cover 101, the outer surface of the obtained bandpass filter is applied to form a coating layer 103 (see Fig. 1B). The plating method using silver is generally used because it is an economical method in which the electrical conductivity of silver is good and the loss is relatively low compared to other metals in consideration of the skin effect. Typical silver plating treatment is by deposition. The deposition method is a method of depositing a part in a plating solution to electrolytically react (electroplat) the plating solution and the part, or electroless chemical reaction (electroless plating) to plate the part. The shaped surface is entirely silver plated.

However, according to this conventional method, as shown in FIG. 1B, the outer surface of the product has a shape of a double layer in which the coating layer 103 is formed on the silver plating layer 102, and the silver plating layer 102 is formed. Problems due to very low adhesion between the paint layers 103 are likely to occur. For example, when a product is exposed to ambient conditions such as humidity, temperature, ultraviolet light, the coating layer is easily broken and separated, which accelerates the corrosion and oxidation of the product, which in turn can affect the flow of signals inside the product. And therefore cannot satisfy the desire to minimize signal loss.

Korean Patent Laid-Open Publication No. 1999-29716 discloses a method for laminating a coating film containing an ultraviolet absorber on a coating layer as a way to solve this problem. That is, in the above invention, in the product in which the coating layer is formed on the plating layer according to a conventional method, in order to prevent the ultraviolet rays transmitted through the coating layer from deteriorating the paint at the interface with the plating layer, causing peeling of the coating layer, The coating film containing a ultraviolet absorber is laminated on a coating layer. However, the present invention does not consider the influence of other environmental conditions, that is, humidity, temperature, etc., and has a limitation that it does not deviate from the existing method of forming an unnecessary silver plating layer on the front of the product. In fact, the silver plating layer may be formed only on the inner surface of the assembled product in which the circuit elements are located for minimizing signal loss and for efficient signal processing and passing, so silver plating on the front of the product unnecessarily increases manufacturing costs. It is not economically desirable.

Therefore, although silver plating and painting are essential for minimizing signal loss, the effect is remarkably inferior because the efficiency of surface treatment and the persistence of product protection are low.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of preventing silver plating on unnecessary parts of a product for wireless communication, improving economics, minimizing signal loss by increasing adhesion between the product and the coating layer, and maximizing product protection. .

1A and 1B are cross-sectional views after a silver plating treatment of a housing and a cover according to a conventional method, and a cross-sectional view after a painting treatment, respectively.

2A to 2F are cross-sectional views showing a process of silvering and painting a housing and a cover of a band pass filter according to the surface treatment method according to the present invention.

3 is a schematic diagram of a band pass filter with surface treatment in accordance with one embodiment of the present invention;

<Explanation of symbols of main parts in drawings>

100, 200: housing 101, 201: cover

102, 202, 302: silver plating layer 103, 203, 303: coating layer

210: chromate layer 220: masking

330: internal components of the bandpass filter

In the present invention, as a result of repeated studies to achieve the technical problem as described above, when the band pass filter is assembled, a silver plated layer, a chromate layer and a coating layer are formed on the inner surface, thereby passing the signal of the band pass filter And a method for treating a surface of a product for wireless communication that increases treatment efficiency and enhances a product's protective effect.

A method of surface treating a housing and a cover of an article for wireless communication, the method comprising: chromating the housing and cover; Masking a portion corresponding to an inner surface when the housing and the cover are assembled; Painting the masked housing and cover; Removing the masking; Performing silver plating on a portion corresponding to an inner surface when assembling the housing and the cover; And it provides a method of surface treatment of the housing and cover of the band pass filter comprising the step of heat-treating the housing and cover. The housing and cover are preferably made of at least one metal selected from the group consisting of aluminum, magnesium, iron and copper, or an alloy of two or more thereof. As the coating method in the above, an electrical method of spraying the powder coating material through the nozzle of the powder coating gun and spraying on the grounded coating body can be used. After the injection, it is preferable to sinter at about 200 to 250 ° C. for about 25 to 40 minutes, and therefore the masking material is preferably a material that can withstand 200 ° C. or more. The masking material can be selected from heat resistant paper, aluminum foil and adhesive tape for high temperature. It is preferable that the paint used at the time of coating is acid- and alkali-resistant paint, and it can select from ester, an epoxy, and a urethane type compound. In addition, it is preferable to further include the step of the base plating treatment before the silver plating treatment step of the housing and cover, the base plating treatment is preferably an electroless nickel plating treatment and / or an electro copper plating treatment. The heat treatment of the housing and the cover on which the silver plated layer is formed is preferably performed for about 20 to 50 minutes at a temperature of about 120 to 190 ° C in a closed space.

Hereinafter, with reference to the drawings, the surface treatment method of the band pass filter according to an embodiment of the present invention will be described in more detail.

First, the housing 200 and the cover 201 of the band pass filter are deposited in a chromate solution to form a chromate layer 210 on the front surface as shown in FIG. 2A. The chromate layer 210 improves the electrodeposition force between the product and the coating layer formed thereafter, and serves to prevent corrosion of the product due to external environmental conditions.

The assembly corresponding to the inner surface of the product during the assembly in the chromated housing and cover is masked 220 (see Fig. 2b). The masking material 220 is preferably a material that can withstand the heat treatment temperature (about 200 ℃ or more) in the post-painting sintering step, for example, for heat-resistant paper, aluminum foil or high temperature It is preferable to use an adhesive tape. When using heat-resistant paper or aluminum foil for masking, the paper or aluminum foil may be cut to an appropriate size, and then fixed to an area to be masked with adhesive or adhesive tape. When using a high temperature adhesive tape as a masking material, what is necessary is just to produce and use it to the magnitude | size as much as the site | part to mask.

Subsequently, the coating layer 203 is formed on the masked housing and the cover as shown in FIG. 2C. In the coating process, a conventional coating method such as liquid coating may be used, or an electrical method of spraying the powder coating material through the nozzle of the powder coating gun and spraying the grounded coating may be used. The powder coating is preferably a paint having alkali and acid resistance that can withstand chemical reactions in subsequent processes (plating pretreatment, under plating and silver plating), and particularly, in the group consisting of ester, epoxy and urethane series. At least one species selected may be used. After the spraying, in order to prevent peeling of the coating layer, it is preferable to sinter the housing and the cover at a high temperature of about 200 ° C. or more to dissolve and cure the coating applied on the housing and the cover. When coating is completed by powder coating and subsequent sintering process, a strong electrodeposition force and a beautiful coating layer are formed on the chromate layer.

The masking 220 is removed from the painted housing and cover. At this time, while the masking 220 is removed, the coating layer 203 formed on the masking is also removed, and the chromate layer 210 is exposed. The exposed chromate layer 210 may be removed along with other impurities through a plating pretreatment process. Generally, a housing and a cover of a wireless communication product including a band pass filter are made of at least one metal selected from the group consisting of aluminum, magnesium, iron, and copper, or two or more alloys thereof, and are cut or cast. Since it is manufactured by the method as described above, the plating pretreatment for this is appropriately selected from conventional methods according to the surface material. That is, when the surface is made of aluminum, a plating pretreatment step consisting of degreasing, alkali treatment, desmut treatment, and alkali zinc treatment steps is performed. In the case of a general steel alloy material, alkali degreasing, pickling, electrolytic degreasing and activation steps are performed. A plating pretreatment step is performed.

2D shows a cross-sectional view of the housing and cover after peeling off the chromate layer 210. As mentioned above, when the coating material has alkali resistance and acid resistance, the coating layer 203 is hardly affected by the plating pretreatment process.

After the plating pre-treatment, before the silver plating process, the base plating treatment can be additionally performed. The underlying plating treatment improves the corrosion resistance, hardness and flexibility of the product, and enables plating with good adhesion. As the base plating treatment, in order to obtain a uniform and smooth surface layer, electroless nickel plating can be used. When the electrical conductivity of the electroless nickel plated layer is not suitable for a high frequency region other than the frequency band, it is possible to further conduct electro copper plating on the electroless nickel plated layer or to perform only electro copper plating. The silver plating treatment is carried out using an alkali type deposition electroplating method after silver-strike plating in order to improve the adhesion with the electroless nickel plating layer or the copper plating layer. The specific silver plating method used in the present invention is based on the method disclosed in Korean Patent No. 321802. When the silver plating process is completed for the housing and cover of the band pass filter surface-treated according to the present invention, as shown in FIG. Is formed, and the part where the outer coating layer 203 is formed is not silver plated. At this time, the silver plating layer is preferably formed to a thickness of about 3 to 10㎛, in order to satisfy both good electrical conductivity and economical efficiency.

As mentioned above, since the solution used for the plating pretreatment process, the base plating treatment and the silver plating treatment contains strong acid and strong alkali components, the use of acid and alkali resistant paints is required as the coating material. However, since the use of the paint alone does not completely prevent discoloration, degreasing or erosion of the coating layer under the influence of strong acid and strong alkali, the housing and cover of the silver plated bandpass filter are finally heat treated. When the housing and the cover are heat-treated at a high temperature of 120 ° C. or higher in an enclosed space, the coating layer, which has been discolored, degreased or eroded, is swelled through silver plating to be reduced to a beautiful coating layer.

FIG. 2F shows a cross-sectional view when the housing and cover of the band pass filter manufactured according to the surface treatment method of the present invention are assembled. FIG.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited by the embodiments, and the simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes are within the scope of the present invention. It can be seen as included.

Example

The housing and cover of the band pass filter cast by aluminum processing were sufficiently washed with water, immersed in dilute nitric acid solution for about 10 seconds, and washed with water for about 10-15 seconds in the "UL-110" mixed chromate solution. The chromated housing and cover were left in air for about 20 seconds and then washed thoroughly.

Next, when the housing and the cover were assembled, the heat-resistant paper was placed on a chromate layer corresponding to the inner surface and masked by adhering the surroundings of the paper with a high-temperature tape.

A polyester powder coating material (ML101K, manufactured by Interpon) was sprayed through the nozzle of the powder coating gun to the masked housing and cover. After the injection, the housing and the cover were sintered at about 200 to 250 ° C. for about 25 to 40 minutes to form a coating layer having a thickness of about 60 μm.

The masking paper was removed by removing the high temperature tape bonded above. The housing and cover with the chromate layer exposed by the removal of masking were immersed in sodium hydroxide solution for about 1 to 2 minutes and then washed with nitric acid to remove the chromate layer with impurities.

The housing and cover having the aluminum part exfoliated and the chromate layer extruded and the part having the coating layer formed thereon were electroplated by dipping in an alkali type cyanide copper plating solution at 60 ° C. for about 25 to 35 minutes, and at 1 to about 15 to 30 ° C. Silver-strike within minutes. Preferably, the silver strike treatment is carried out at a temperature condition of about 25 ° C. The housing and the cover on which the silver-strike plated layer was formed were immersed in an alkali type silver cyanide plating solution for about 50 to 60 minutes under a temperature condition of about 20 to 30 ° C., thereby forming a 10 μm thick silver plated layer.

The housing and the cover on which the silver plating layer was formed were heat-treated at a temperature of 120 to 190 ° C. for about 20 to 50 minutes in a closed space. After mounting the components inside the housing obtained through the above method, the housing and the cover were assembled to complete the band pass filter for wireless communication. 3 shows a schematic diagram of a band pass filter having a surface treatment according to the embodiment of the present invention.

Experimental Example

In order to test the adhesion between the coating layer formed by the present invention and the product surface, an experiment was made with reference to the "ISO 2409 cross-cut test". The ISO 2409 cross-cut test consists of cutting the article on which the paint layer is formed under sufficient pressure, and then attaching and detaching an adhesive tape such as MPP 128 to the paint layer. In order to perform the test, when the thickness of the formed coating layer is 60 µm or more, the product is cut into a square shape having a width of 2 mm, and when the thickness of the coating layer is less than 60 µm, a square having a length of 1 mm is formed. The product was cut into the shape of.

According to the conventional method, a cover having a 60 μm coating layer formed on a silver plated layer and a cover having a 60 μm coating layer formed on the surface of a chromate treated product according to the present invention are cut to a size of 2 mm horizontally. A total of 121 fragments were subjected to the adhesion test of the above manner. As a result, when the coating layer was formed on the silver plated layer, the coating was separated from at least half of the cut product, and when the coating layer was formed on the chromated surface, the coating was separated from only two pieces. From the above result, it was confirmed that it is preferable to form a coating layer according to the surface treatment method of this invention for the improvement of adhesiveness.

In addition, in order to test the effect of preventing cracking and corrosion of the product by the coating layer, from the results of the salt water resistance test through the salt spray such as "ASTM B117", "KS D 9502", the present invention than the product by the conventional method It was observed that the corrosion resistance of the product obtained by performing the surface treatment according to the remarkably excellent.

When the housing and cover of the band pass filter coated and plated according to the present invention are assembled, the silver plating layer is formed only on the inner surface of the product, so that the product can be manufactured economically without any influence on signal transmission. In addition, the adhesion between the bandpass filter and the coating layer is significantly improved, thereby minimizing signal loss and product damage. In addition, the present invention is widely used not only for bandpass filters, but also for indoor and outdoor products, such as filters / duplexers, power dividers / synthesizers, and other enclosures, which are plated, painted, or painted and plated in a metal housing among wireless communication products. Applicable

Claims (11)

In the surface treatment method of the housing and cover of the band pass filter for wireless communication, Chromating the housing and cover; Masking a portion corresponding to an inner surface when the housing and the cover are assembled; Painting a masked housing and cover, wherein the masked portion is not painted; Removing the masking; Performing silver plating on a portion corresponding to an inner surface when assembling the housing and the cover; And Heat treating the housing and cover; Surface treatment method of the housing and cover of the band pass filter for wireless communication comprising a. The method of claim 1, The housing and cover is made of at least one metal selected from the group consisting of aluminum, magnesium, iron and copper, or an alloy of two or more thereof. Surface treatment method. The method of claim 1, The masking material is characterized in that the material that can withstand 200 ℃ or more Surface treatment method. The method of claim 3, wherein The masking material may be selected from heat resistant paper, aluminum foil and adhesive tape for high temperature. Surface treatment method. The method of claim 1, The coating method is characterized by using an electrical method of spraying the powder paint to the grounded coating material through the nozzle of the powder coating gun Surface treatment method. The method of claim 5, After the injection, it is characterized in that the sintered at 200 to 250 ℃ for 25 to 40 minutes Surface treatment method. The method according to claim 1 or 5, The paint used in the coating is characterized in that the acid and alkali resistant paints Surface treatment method. The method of claim 7, wherein The acid and alkali resistant paints are selected from ester, epoxy and urethane based compounds Surface treatment method. The method of claim 1, And additionally performing a plating process before the silver plating process of the housing and cover. Surface treatment method. The method of claim 9, The not plating treatment Electroless nickel plating treatment and / or electro copper plating treatment Surface treatment method. The method of claim 1, The heat treatment is performed for 20 to 50 minutes at a temperature of 120 to 190 ℃ in a closed space Surface treatment method.