JP2007021506A - Electronic component box body and production method therefor, and laser beam spot welding method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide techniques in which in the case of using a material having light weight and sufficient strength such as magnesium material as an electronic component box body, the corrosion resistance as a problem is secured and also, various kinds of treating liquid such as chemical conversion liquid which is used for giving the corrosion resistance and acid, alkali, and washing water are not remained in the box body after welding, and further the welded mark on the outward appearance does not occure. <P>SOLUTION: After forming a corrosion resistant film by applying the surface treatment on both of a magnesium-made electronic component box main body and a magnesium-made member, this electronic component box body is obtained by performing a laser beam spot welding to both. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electronic device casing such as a mobile phone or a personal computer, a manufacturing method thereof, and a laser spot welding method in the manufacturing thereof.

  An electronic device casing, particularly a portable electronic device casing, is required to be lightweight and have sufficient strength. Here, a housing made of magnesium and its alloy is very promising because it satisfies the above properties and has added value such as a large amount of reserves and easy recycling.

  However, since magnesium and its alloys have a drawback of poor corrosion resistance, when the material is used as a casing, it is necessary to perform surface treatment (chemical conversion treatment or anodizing treatment) in order to ensure corrosion resistance. Here, in the case of stud welding and resistance welding (spot welding), which are typical welding methods of magnesium material, welding is performed before performing surface treatment because the basics of joining are that electricity flows. Is common. However, when performing surface treatment (for example, chemical conversion treatment) on the welded material, (1) the chemical conversion liquid does not enter the gap between the two plates in the vicinity of the welded portion or the amount of intrusion decreases. Anticorrosion treatment at the part is not performed at all or becomes insufficient. (2) Even when the chemical conversion liquid enters the gap, it is very difficult to completely remove the chemical conversion liquid present at the part. Invite the problem. In the case of (1), the product life is shortened. In the case of (2), the chemical conversion treatment solution remains in the product. In particular, all the conventional chemical conversion treatment solutions are hexavalent. When it contains a harmful component called chromium ion (JIS-H-8651, MIL-M-3171, etc.), it is not preferable for the health and environment of the user. In addition, acids and alkali components used for surface adjustment in the chemical conversion treatment process remain even after cleaning around the weld and between the plates, and there is a risk of deterioration of the weld due to changes over time. Has been. Also, after washing with water to wash various chemicals, it is subjected to a drying process, but it is difficult to completely remove the water that has entered the gap between the plates due to the shape of the welded part etc. There is. Thus, unstable elements such as deterioration of the welded portion based on the post-process exist unavoidably.

Furthermore, as described above, when stud welding (for example, boss welding to a thin-walled outer casing in a car navigation system or notebook PC) or resistance welding (for example, sheet metal overlay welding) is performed, the appearance is affected. In order to avoid this, it is necessary to perform welding in a short time in order to reduce the influence of heat. For example, in the stud welding, even in resistance welding (spot welding) in units of several thousandths of a second, machining is performed in a short time by using this type of welding power supply system as a capacitor system. However, in any case, when applied to a thin plate called an electronic device casing, there is a problem that a welding mark is generated on the outer surface and correction processing is required after welding. Here, according to these welding methods, there are many cases where the welding trace becomes concave or the surface itself undulates in a complicated manner, and skill is required to correct the welding trace and make it unnoticeable.
JP2001-198686 Japanese Patent Laid-Open No. 9-19778 JP-A-8-300173 JP-A-8-39277 JP-A-8-33996 JP 58-58988 A

  Therefore, the present invention secures the corrosion resistance which becomes a problem when adopting a lightweight and sufficient strength material such as a magnesium material as an electronic device casing, and also provides a chemical conversion treatment solution, an acid used for imparting the corrosion resistance. The purpose of the present invention is to provide a technique in which various treatment liquids such as alkali and cleaning water do not remain in the casing after welding, and further, welding marks are not generated on the appearance surface.

  First, the inventor can eliminate unstable elements such as deterioration of the welded portion in the post-process by shifting the timing of performing the surface treatment before welding. First, focusing on the fact that it can be prevented from remaining on the metal, the laser welding method is adopted instead of the conventional stud welding or resistance welding as a welding method for the magnesium electronic equipment casing, and the metal formed by surface treatment The anticorrosive film that has lost its gloss has been found to reduce the reflection of laser light, and the present inventions (1) to (8) have been completed.

  That is, the present invention (1) is an electronic device casing obtained by surface-treating both the magnesium electronic device casing body and the magnesium member to form an anticorrosion coating, and then laser spot welding the two. is there. Here, whether or not the electronic device casing is obtained by the method can be determined by checking the welded portion. The anticorrosion film only needs to be formed on at least the surface of the welded portion, and does not need to be formed on the entire magnesium electronic device casing body or the magnesium member.

  The present invention (2) is the electronic device casing of the invention (1), wherein the anticorrosive film is a film formed by a non-chromium chemical conversion treatment or a chrome chemical conversion treatment.

  The present invention (3) is the electronic device casing of the invention (1) or (2), wherein the lightness of the film is 65% or less.

  The present invention (4) is the electronic device casing according to any one of the inventions (1) to (3), which is a calcium manganese phosphate coating.

  According to the present invention (5), the magnesium member is a base for mounting an electronic component, a boss, a rib, a hook member, an internal structure, a claw-shaped object, a stay, a reinforcing member, an angle, a chassis, an L metal fitting, The electronic device casing according to any one of the inventions (1) to (4), which is a spacer.

  The present invention (6) is an electronic product in which an electronic component is incorporated in the electronic device casing of any one of the inventions (1) to (5).

  The present invention (7) is a method of manufacturing an electronic device casing, comprising a step of performing a surface treatment on both the magnesium electronic device casing main body and the magnesium member to form an anticorrosion coating, and then laser spot welding the two. It is.

  The present invention (8) is a laser spot welding method including a step of laser spot welding both of the magnesium electronic device casing body and the magnesium member after surface treatment to form an anticorrosion coating.

  According to the present invention, since the magnesium material is used as the electronic device casing material, the lightweight and sufficient strength is ensured and the surface treatment is performed, so that the corrosion resistance is also excellent. In addition to such known effects, according to the present invention, since surface treatment is performed before welding, there is an effect that unstable elements such as deterioration of the welded portion in the subsequent process can be excluded (specifically, For example, various treatment liquids such as surface treatment liquid and water do not remain in the case after welding). Furthermore, since the anticorrosion coating formed by the surface treatment efficiently absorbs the heat of the laser beam, the output of the laser beam can be reduced, and the influence of the heat on the external appearance of the housing is reduced. In addition to avoiding the occurrence of welding marks on the surface, there is also an effect that stable welding is possible because overmelting of the welded portion is eliminated. Furthermore, since laser spot welding is used, even if a welding mark is generated, the mark is often convex, and there is an effect that the mark can be corrected without much effort.

  The best mode of the present invention will be described below. It should be noted that the present invention is not limited to the following best mode, and is within the technical scope of the present invention, including equivalents, as long as it is the same problem and substantially the same solution.

  First, the electronic device casing according to the best mode is not particularly limited as long as it is a thin electronic device casing. For example, a mobile phone, a portable mobile device, a personal computer, a TV casing, a digital video camera, a PDA A case can be mentioned. Here, the electronic device casing is composed of a magnesium casing body and a magnesium member, and has a structure in which both are welded. Here, “magnesium” in the magnesium casing body and the magnesium member refers to magnesium or an alloy thereof. Furthermore, the “alloy” is usually an alloy of magnesium, aluminum, zinc, manganese, silicon, or the like, and its notation is defined by ASTM or the like. As an example of ASTM notation, in the notation “AZ31”, “A” is the first additive element, “Z” is the second additive element, “3” is the ratio of the first additive element, and “1” is the first additive element. This is the ratio of the two additive elements. That is, “AZ31” is an alloy containing about 3% aluminum and about 1% zinc. In practice, elements other than the main additive element are also included, and in this example, Mn, Si, Cu, Ni, Fe, and the like are included. In addition, the “magnesium member” is not particularly limited as long as it is a member to be joined to the electronic device casing body. For example, a member that plays a role of a pedestal of electronic parts, a structural member for reinforcement, and a nail when combined. Or a member having a hook shape, for example, a base for mounting an electronic component, a boss, a rib, a hook member, an internal structure, a nail shape, a stay, a reinforcing member, an angle, a chassis, an L metal fitting, or a spacer Can do. Moreover, the thickness of the housing body and the magnesium member is preferably 0.2 to 3 mm, and more preferably 0.4 to 2.0 mm.

  Next, the manufacturing method (laser spot welding method) of the electronic device housing according to the best mode will be described. First, before surface treatment (for example, chemical conversion treatment) of the magnesium housing body and the magnesium member, for example, (1) surface grinding (mechanical product processing, surface polishing for the purpose of adjusting the product appearance and dimensional accuracy) (2) Chemical pretreatment for the purpose of removing adhesion, corrosion protection, surface oxide film, corrosion products, embedded abrasives, seized lubricant, shots, foundry sand, etc. A pretreatment such as (degreasing treatment, pickling treatment) may be performed. In order to improve weldability, it is preferable to keep the surface state uniform, for example, by sandblasting the surface.

  Next, the magnesium casing body and the magnesium member, which are pretreated in some cases, are surface-treated. Here, the “surface treatment” is not particularly limited as long as it is a surface treatment on which an anticorrosive film having an improved heat absorption rate compared to magnesium metal is formed. For example, coating adhesion, corrosion resistance, and rust prevention Chemical conversion treatment and anodization treatment, which are known as methods for imparting the above, can be mentioned. A chemical conversion treatment is preferable, and specifically, a chromium chemical conversion treatment or a non-chromium chemical conversion treatment (zirconium-based, titanium-based, phosphoric acid-based, stannic acid-based, manganese-based treatment), for example, calcium phosphate manganese chemical conversion treatment (for example, a patent) No. 3307882), manganese phosphate treatment (for example, JP-A-7-126858), magnesium phosphate treatment (for example, JP-A-7-126858), zinc phosphate treatment (JP-A-9-31664). ), Calcium phosphate / aluminum treatment (JP-A-8-176842), zirconium-containing material treatment (JP-A-2005-23422, JP-A-2004-218073), and chemical conversion treatment using permanganate ions. A calcium manganese phosphate chemical conversion treatment is preferred, and a calcium manganese phosphate coating with an extremely high heat absorption capability is formed by this treatment.

Here, the film formed by the surface treatment preferably has a lightness (L) of 65% or less, more preferably 60% or less, and further preferably 55% or less. is there. The brightness was measured with a color difference meter (CR-241) manufactured by Konica Minolta Co., Ltd. (measurement diameter: 1.8 mm, light source: D ₆₅ ).

  And after the said surface treatment, for example, the said chemical conversion treatment, the chemical conversion liquid adhering to the said magnesium housing main body and the said magnesium member is wash | cleaned, and laser spot welding is performed after that. When performing the laser spot welding, the magnesium casing main body and the magnesium member are joined with sufficient strength by welding, and after the welding, there is a welding mark (an appearance defect such as sink marks) on the outer appearance surface of the casing. Conditions that do not occur are set (particularly considering the thickness of the magnesium casing body and the magnesium member). Prior to welding, it is preferable to dry the magnesium casing body and the magnesium member to sufficiently remove moisture remaining on these members during a cleaning process or the like.

  In addition, it is (1) magnifying and observing the laser welded part and (1) magnifying and observing the one subjected to chemical conversion treatment after laser spot welding (conventional product) and the one subjected to chemical conversion treatment (this best mode); 2) It can be determined by destroying the welded product and observing the overlapping surface. For example, with regard to (1), in the case of the conventional product, the film of the chemical conversion treatment can be visually observed even on the crater of the laser welded portion (for example, when a calcium manganese phosphate coating is formed, a thin iridescent pattern is observed. it can). On the other hand, in the case of the best form product, such a film cannot be observed, and a slightly dull surface is seen. Regarding (2), the surface of the conventional product that has overlapped is not processed (or an unprocessed portion is generated), and remains as a fabric. On the other hand, in the best form product, the overlapped surface is processed.

  Hereinafter, the present invention will be described more specifically with reference to examples. First, it describes in the Example of Unexamined-Japanese-Patent No. 2000-96255 with respect to the two magnesium test pieces (magnesium raw material AZ31: 20mmx8mmx0.5mm) which has the board thickness equivalent to an electronic device housing | casing and a base. Chemical conversion treatment {calcium phosphate manganese chemical conversion treatment (chemical conversion treatment agent: Million Chemical Co., Ltd. Grander MC-1000)} was performed according to the method (see FIG. 1). As a result, a 0.8 μm-thick film (L = 53.47) having low electrical resistance characteristics was formed. Thereafter, as shown in FIG. 2, the two test pieces subjected to chemical conversion were superposed, and the superposed portion was laser welded (YAG laser welder manufactured by Miyachi Technos Co., Ltd./transmitting wavelength: 1064 nm, maximum rated output: 300 W, maximum output energy 50 J / fiber diameter: 0.6 mm) was spot-welded (two locations). In addition, welding was performed using argon as an assist gas while spraying in the vicinity of welding. The welding conditions were a peak power of 1.9 kw and a pulse width of 8.0 ms. In addition, when the output energy at this time was confirmed, it was 8.1J. As a result, as shown in FIG. 3, it was possible to join each other without affecting the appearance. 3A is an appearance side of the welded product, and FIG. 3B is a laser welded side. Furthermore, when the state of the welded part surface was confirmed, it became a beautiful circular hollow shape, and the surface crack was not confirmed.

  For comparison, laser spot welding was also performed on two magnesium test pieces (magnesium material AZ31: 20 mm × 8 mm × 0.5 mm) that were not subjected to the chemical conversion treatment. Here, when the test was performed under the same conditions as those of the chemical conversion treatment product, the output was insufficient and joining was not possible. Therefore, as welding conditions, the conditions for appearance in the same degree of joining as in the above example were reset. As a result, the welding conditions giving the same appearance were a peak power of 2.5 kW and a pulse width of 8.0 ms. The output energy at this time was 10.4 J. As a result of welding according to these conditions, as shown in FIG. 4, welding marks were generated on the outer surface (circled portion in the figure). In addition, when the state of the welded part surface was confirmed, it became a circular hollow shape, and although some burns were seen around the welded part, no cracks on the surface were confirmed.

  Furthermore, the tensile shear strength was measured about the said composite body of the chemical conversion treatment product, and the said composite body of an untreated product. As a result, the conjugate of the chemical conversion product was 15 to 25 N / point, while the conjugate of the untreated product was 9 to 17 N / point.

FIG. 1 is a flowchart showing, in time series, various processes performed before welding according to the present embodiment. FIG. 2 is a conceptual diagram when performing laser spot welding according to the present embodiment. FIG. 3 is an electrophotographic view of the appearance side (a) and the laser welded part side (b) of the welded product according to the product of this example (chemical conversion treatment product). FIG. 4 is an electrophotographic view of the appearance side (a) and the laser welded portion (b) of the welded product according to the comparative example product (untreated product).

Claims (8)

  An electronic device casing obtained by subjecting both a magnesium electronic device casing main body and a magnesium member to surface treatment to form an anticorrosion coating and then laser spot welding them.   The electronic device housing according to claim 1, wherein the anticorrosion coating is a coating formed by a non-chromium chemical conversion treatment or a chrome chemical conversion treatment.   The electronic device housing according to claim 1, wherein the brightness of the coating is 65% or less.   The electronic device housing according to claim 1, wherein the coating is a calcium manganese phosphate coating.   The magnesium member is a pedestal, boss, rib, hook member, internal structure, claw-shaped object, stay, reinforcing member, angle, chassis, L bracket, or spacer for mounting an electronic component. Electronic device housing as described in any one of -4.   The electronic product which incorporated the electronic component in the electronic device housing | casing as described in any one of Claims 1-5.   A method for manufacturing an electronic device casing, comprising a step of subjecting both the magnesium electronic device casing body and the magnesium member to surface treatment to form an anticorrosion coating and then laser spot welding the two.   A laser spot welding method comprising a step of laser spot welding both of a magnesium electronic device housing body and a magnesium member after surface treatment to form an anticorrosion coating.