JP2002036149A - Printing method on metal plate by laser beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing method capable of setting the condition of irradiation of the laser beam in a relatively easy manner, and discriminating a printed surface without controlling the vertical of irradiation with excellent accuracy even in mass production. SOLUTION: This printing method comprises a step for forming a glossy plated layer on the surface of a metal plate 5, a step for forming unevenness on the surface of the glossy plated layer so that the concentration of reflection is <=0.7, and a step for forming the printed surface 6 by irradiating the laser beam on the surface of the plated surface with the unevenness formed thereon to melt the irradiated portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for printing on a metal plate with a laser beam.

[0002]

2. Description of the Related Art With the recent miniaturization of electronic equipment, it is required that electronic parts mounted inside the electronic equipment are thin, low, and mounted on a printed circuit board at a high density on the surface thereof. . For this reason, for electronic components such as crystal units, electronic components such as crystal units are housed in recessed ceramic packages in order to make them thin and low-surface mountable, and the openings of the ceramic packages are covered with metal lids. Surface-mounted electronic components that are covered with a body, joined by welding or the like, and hermetically sealed are mainly used.

Conventionally, surface-mount type electronic components are printed on the surface of a metal cover with a model name, a serial number, and the like, and visually checked by an operator, and a product identification during the process is performed by an automatic machine equipped with an image processing device. And used for product identification after shipment. As a conventional printing method, a method has been adopted in which ink is transferred onto a metal lid using a rubber stamp or the like, and the ink is cured in an oven.

[0004] In recent years, a method of printing by partially melting the surface of a metal lid by laser light has also been used. This printing method is a method of printing by utilizing the surface condition of a partially melted portion and the fact that the gloss is different from that of an unmelted portion.

[0005] This method does not require replacement of a rubber stamp and management of ink as compared with the above-described printing method using ink. Further, it is not necessary to cure the ink in an oven, and the process can be simplified. Further, since the print quality is not degraded due to print blur due to washing after being mounted on a printed circuit board, the printing method using laser light is becoming mainstream instead of the printing method using ink due to these advantages. ing.

On the other hand, since the metal lid of the surface mount type electronic component is welded to a metal ring brazed to the upper surface of the opening of the ceramic package, stress is generated by heat generated by welding, and the ceramic package itself is formed. In addition, there is a problem that cracks are generated at the joint between the ceramic package and the metal lid, and the airtightness is easily broken. In order to solve this problem, alloys such as 42 alloy and Kovar, which have a relatively close coefficient of thermal expansion to that of the ceramic package, are often used, and these are generally used for easier joining by welding. In order to prevent corrosion due to oxidation or the like, a plating process such as nickel plating, which has good weldability and is resistant to corrosion, is often performed in advance.

[0007]

A method of printing by partially melting the surface of a metal lid by laser light is used to make it easy to identify the printed model name, serial number, etc. after printing. In addition, a partially melted surface state and a surface state (glossiness) whose gloss is clearly different from that of the unmelted part are required.

However, in the prior art, the surface of the metal lid is plated with nickel or the like so that the surface state is flat and the surface is glossy. Even the part printed by partially melting the lid has a glossy surface due to melting, and there is a problem that it is difficult to distinguish between the molten part and the unmelted part by the laser beam due to the glossiness. .

In order to solve this problem, the irradiation conditions of the laser beam and the like are appropriately set, that is, the power of the laser beam, the irradiation width and the like are appropriately determined. Although it is required to control the irradiation conditions with high accuracy, there is a problem that the process is complicated and the yield in mass production is deteriorated.

The present invention has been devised in view of the above-mentioned problems, and makes it possible to set the irradiation conditions of laser light relatively easily, and even in mass production, without having to manage the irradiation conditions with high accuracy. Another object of the present invention is to provide a printing method using a laser beam that makes it easy to identify the printed model name, manufacturing number, and the like.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises a step of forming a glossy plating layer on the surface of a metal plate;
The present invention provides a method for printing on a metal plate by laser light, comprising: a step of forming irregularities described below; and a step of irradiating the surface of the plating layer with the irregularities with a laser beam and melting the irradiated portion to perform printing. I do.

According to the structure of the present invention, the glossy plating surface of the metal plate is formed with irregularities to reduce the gloss by setting the reflection density to 1.5 or less, and the surface of the uneven plating layer is irradiated with laser light. When the irradiated portion is melted, the unevenness of the printed portion is melted and flattened, and only the printed portion becomes glossy. In this way, if only the printed portion has gloss, the difference in gloss between the fused portion and the unmelted portion of the printed portion is sufficient, and the printed model name, serial number, etc. can be easily visually identified. It is.

Further, even if the laser beam irradiation conditions may change due to environmental changes or other circumstances, only the printed portion of the metal plate partially melted by the laser beam has gloss, so that the laser beam irradiation Even if the conditions are set relatively easily, a print surface that can be identified can be formed. In addition, even during mass production, it is not necessary to manage the irradiation conditions with high accuracy.

In order to form the glossy surface of the metal plate with irregularities, it is necessary to form irregularities that do not deteriorate the plating function. As a result, even when the metal plate is used as a metal lid that is hermetically sealed by welding to the opening of the ceramic package, the quality of the hermetic sealing does not deteriorate due to deterioration in weldability. Further, the role of preventing the metal lid from being corroded by oxidation or the like is also maintained.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a surface-mounted crystal oscillator having a metal lid, which is a metal plate used in the present invention,
FIG. 2 is a diagram showing an example of printing using the printing method of the present invention.

The crystal oscillator 1 comprises a concave ceramic package 2 and a metal lid 5 for sealing the opening of the ceramic package 2.

The ceramic package 2 is formed by appropriately stacking green sheets to form a concave package, and the inner surface of the ceramic package 2 is metallized at an appropriate position to form electrodes. A step is formed at one end of the inner peripheral portion of the ceramic package 2. One end of the crystal unit 10 is electrically and mechanically connected to the step with the conductive adhesive 3. Fixed. Note that the step formed inside the ceramic package 2 is not made of ceramic, but may be formed of metallized bumps.

A metal ring 4 is brazed to the entire periphery of the upper portion of the side wall of the ceramic package 2. The metal ring 4 is joined to the metal lid 5 by seam welding for hermetic sealing. As a material of the metal ring 4, 42 alloy, Kovar or the like is used.

Further, the metal lid 5 is made of 42 alloy, Kovar, or the like. The surface of the metal lid 5 is plated so as to have good weldability with the metal ring 4 and strong corrosion. This plating produces a glossy surface. The plating is performed by electroless nickel plating, but is not limited to this, and electrolytic nickel plating may be used.

Further, in the present invention, the glossiness is eliminated by forming the glossy surface of the plated metal lid 5 with irregularities. As a method for eliminating the gloss, it is necessary to heat-treat the glossy surface of the metal lid 5 below the melting point of the plating layer. This is because the metal used for plating is crystallized near the melting point of the plating by this method, and the crystal grows to make the surface state uneven. Therefore, when the heating temperature is equal to or higher than the melting point of the plating layer, the metal of the plating is melted, and the gloss is generated again, or the thickness of the plating changes, so that the original plating function is lost. Become. In addition,
The atmosphere for the heat treatment is preferably H ₂ , N ₂ or a mixed atmosphere thereof in order to prevent the surface of the metal lid 5 from being oxidized.

Here, when performing nickel plating, the temperature for the heat treatment is preferably from 600 to 800 ° C. If the heating temperature is lower than 600 ° C., the gloss will not be sufficiently reduced, and if it is higher than 800 ° C., unevenness in the gloss will occur or plating will melt.

As a method of forming irregularities on the glossy surface of the metal lid 5, besides the above, barrel treatment or blast treatment with an abrasive may be considered, but any method is required so that the original function of plating is not deteriorated. Need to be processed. In this case, it is necessary to form uneven valleys that do not penetrate in the thickness direction of the plating layer.

The gloss of the plating of the present invention is represented by the reflection density, and those having a reflection density of more than 1.5 are glossy.
When the reflection density is 1.5 or less, there is no gloss. The reflection density is measured based on the international standard: ISO3664.

The laser used in the present invention is a YAG laser, but is not limited thereto, and a carbon dioxide laser may be used. The power of the laser needs to be at least enough to instantaneously melt the uneven plating layer formed on the surface of the metal lid 5. Thereby,
This is because only the character portion melts and becomes flat, and only the character portion becomes glossy.

Next, a method of printing on a metal lid by the laser according to the present invention will be described. In addition, the method of making the surface of the metal lid 5 uneven by a heat treatment will be described. First, Kovar is used as the material of the metal lid 5. Kovar is pressed into a desired shape, and electroless nickel plating is performed. After that, put it in the conveyor furnace and
A high-temperature treatment of 00 ° C to 800 ° C is performed so that the surface has no gloss. Then, the metal lid 5 is seam-welded by the metal ring 4 formed on the ceramic package 2 and hermetically sealed. After that, the YAG laser light is applied to the plating layer in such a manner that the plating layer can be instantaneously melted, whereby the plating layer is partially melted to form a printing surface 6 having a model name and a serial number. The character portion printed by melting is glossy, and the unmelted portion is not glossy, so that the printed portion rises and can be easily identified.

[0026]

According to the structure of the present invention, in a method of printing a model name, a serial number and the like on a top surface of a metal plate by a laser, a step of forming a glossy plating layer on the surface of the metal plate; A step of forming irregularities with a reflection density of 1.5 or less on the surface of the glossy plating layer, and a step of irradiating the surface of the plating layer with the irregularities with a laser beam and melting the irradiated portion to perform printing. Since printing is performed, only the printing surface partially melted by the laser light on the plated surface of the metal plate becomes a glossy surface, so that characters in the printed portion can be sufficiently identified.

Therefore, by such a printing method, the irradiation conditions of the laser beam can be set relatively easily, and even in the case of mass production, the printed model name, serial number, etc. can be set without accurately managing the irradiation conditions. Can provide a printing method that can be easily identified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a surface-mounted crystal oscillator having a metal lid, which is a metal plate used in the present invention.

FIG. 2 is a diagram showing an example of printing using the printing method of the present invention.

[Explanation of symbols]

 1: Crystal oscillator 10: Crystal oscillator 2: Ceramic package 3: Conductive bonding agent 4: Metal ring 5: Metal cover 6: Printing surface

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Claims (1)

[Claims] A step of forming a glossy plating layer on the surface of a metal plate;
A method of printing on a metal plate by laser light, comprising: forming a concave / convex portion as described below; and irradiating the surface of the plating layer with the concave / convex portion with a laser beam and melting the irradiated portion to perform printing.