JP7565807B2 - Resin member for plating and its manufacturing method - Google Patents

Description

The present invention relates to a resin member for plating treatment and a method for manufacturing the same.

In recent years, the number of applications in which resin members are plated with metal has increased, and the requirements for adhesion between the plating and the resin member have become stricter. For example, in mobile devices such as smartphones, electrodes are formed directly on the resin member by plating to reduce weight (Patent Document 1), and plated resin members are used as electromagnetic shields (Patent Document 2).

JP 2020-184090 A JP 2020-195105 A JP 2019-131839 A

Because these mobile devices are handled in a variety of ways, the plating can peel off from the resin components, which can be a direct cause of malfunction of the mobile devices. Prior to plating, the surface of the resin component to be plated was roughened with a laser and then treated with a chemical, but this alone was not sufficient (Patent Document 3).

The present invention aims to provide a resin member for plating with good adhesion and a method for manufacturing the same.

The object of the present invention has been achieved by the following:

1. A resin member for aluminum plating, the resin member having a surface to be plated with a plurality of grooves having a depth of 1 to 15 μm, the interval b between the plurality of grooves being 10 to 500 μm, the grooves having burrs around openings having a height a of 5 to 30 μm, the height a of the burrs and the interval b between the plurality of grooves satisfy the following formula (1):
Formula (1) b≦35a-24
The resin member is formed from any resin selected from the group consisting of polybutylene terephthalate, polyphenylene sulfide, and liquid crystal polymer.
2. The resin member according to 1 above , wherein the width c of the opening of the groove is 50 to 200 μm.
3. A method for manufacturing a plated resin member by plating a resin member with aluminum , the method comprising the steps of: forming, on a surface to be plated of the resin member, a plurality of grooves each having a depth of 1 to 15 μm, the plurality of grooves having a spacing b of 10 to 500 μm, the grooves having burrs with a height a of 5 to 30 μm around openings, the height a of the burrs satisfying the following formula (1) with the spacing b of the plurality of grooves, by irradiating the surface with laser light ;
Formula (1) b≦35a-24
The method for producing a plated resin member, wherein the resin member is made of any resin selected from the group consisting of polybutylene terephthalate, polyphenylene sulfide, and liquid crystal polymer.

The present invention provides a resin member for plating with good adhesion and a manufacturing method thereof.

FIG. 2 is a cross-sectional schematic diagram showing multiple grooves of the present invention. 1 is a graph showing experimental results obtained by calculating formula (1) of the present invention.

The following describes an embodiment of the present invention in detail.

<Resin material>
The resin member of the present invention is a resin member for plating treatment, characterized in that the resin member has a plurality of grooves with a depth of 1 to 15 μm on a surface to be plated, the grooves have burrs with a height a of 5 μm or more around openings, and the height a of the burrs and the interval b between the plurality of grooves satisfy the following formula (1):
Formula (1) b≦35a-24

<Resin>
The resin forming the resin member of the present invention is not particularly limited as long as it can be plated. For example, thermoplastic resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), aliphatic polyamide, aromatic polyamide, polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyether ether ketone (PEEK), polyimide, polyacetal (POM), ABS resin, and cyclic polyolefin (COC) can be used.

These resins may contain inorganic fillers such as glass fillers and mineral fillers. These resins may be used alone or in combination of two or more types.

<Groove>
The surface of the resin member of the present invention to be plated has a plurality of grooves having a depth of 1 to 15 μm.

The surface of the resin member of the present invention to be plated has multiple grooves with a depth of 1 to 15 μm formed thereon. In FIG. 1, a indicates the height of the burrs formed around the opening of the groove from the flat part of the resin member. b indicates the spacing between the multiple grooves, c indicates the width of the groove, and d indicates the pitch between the multiple grooves.

The periphery of the groove opening refers to a range of about 30 μm from the groove opening toward the flat portion. The height a of the burr refers to the highest point within a range of about 30 μm from the groove opening toward the flat portion. The burr does not have to be formed all around the periphery of the groove opening, but good plating adhesion can be obtained by forming the burr on at least 60% or more of the periphery of the opening, more preferably 70% or more, and particularly preferably 80% or more.

The height a of the burr is 5 μm or more, preferably 5 to 30 μm, and more preferably 5 to 20 μm. The grooves are formed at intervals b, and the number of grooves is determined appropriately depending on the area to be plated. The intervals b do not have to be the same on all surfaces to be plated. If the height a of the burr exceeds 30 μm, in addition to poor appearance, the electromagnetic shielding properties may be reduced due to poor adhesion of the plating on the side of the burr.

The grooves may be arranged in a line like contour lines with both ends connected, or may be formed in stripes that do not intersect, or in a grid pattern where the grooves intersect, or in polka dots. If the grooves are formed in a grid pattern, they may be diamond shaped.

The length of the groove is not particularly limited, and if the groove is short, the shape of the opening may be rectangular, round, or elliptical. To obtain an anchor effect, it is preferable that the groove is long.

In the present invention, the spacing b between adjacent grooves is preferably 0.5 to 4 times the groove width c, i.e., if the groove width c is 100 μm, then 50 μm to 400 μm, and more preferably 1 to 2 times the groove width, i.e., if the groove width is 100 μm, then 100 μm to 200 μm.

The distance b between adjacent grooves is preferably 600 μm or less, more preferably 500 μm or less, and particularly preferably 300 μm or less.
In the present invention, the burr height a and the groove interval b have the relationship expressed by formula (1).
Formula (1) b≦35a-24
Equation (1) is a relational expression between the burr height a and the groove interval b obtained from the experimental data shown in FIG.

<Method of forming grooves>
The grooves in the resin member of the present invention are preferably formed by irradiating the surface of the resin member before the grooves are formed with a laser beam to partially remove the resin. The conditions such as the type, wavelength, output, and irradiation time of the laser beam can be appropriately selected according to the resin composition constituting the target resin member, and it is preferable to adjust the burrs to 5 μm or more from the flat portion and the groove depth to 1 to 15 μm.

In order to ensure image quality and adhesion strength, the area of the grooves to be formed is preferably 20% or more of the plating area, more preferably 30% or more, even more preferably 40% or more, and especially preferably 50% or more. Because the formation of burrs improves adhesion, the upper limit is preferably 90% or less, more preferably 80% or less, and especially preferably 70% or less.

In particular, when grooves are formed over the entire surface of a plated resin part by irradiating it with laser light, the inorganic fibers become exposed by the laser treatment, and if plating is performed, they may peel off from the exposed inorganic fiber part. Also, in order to shorten the laser treatment time, treatment of the entire surface of the plated part should be avoided.

If the presence of a carbonized layer of resin can be confirmed by Raman spectroscopic analysis of the groove, it can be determined that the groove was formed by irradiation with laser light.

It is also preferable to add colorants (light absorbers) such as dyes and pigments to the resin workpiece of the present invention in order to efficiently absorb laser light, and transparent near-infrared absorbers that do not affect the hue of the resin, and it is more preferable to add inorganic colorants (e.g., carbon black) rather than organic colorants.

The present invention will be described in detail below with reference to examples. The evaluations were carried out in an atmosphere of 23°C and 50% RH unless otherwise specified.

<Formation of test specimen>
<Formation of resin member for forming groove>
Using the following resin manufactured by Polyplastics Co., Ltd., a test specimen of a flat resin member having dimensions of 100 mm x 100 mm x 3 mm was formed by injection molding.
1. LCP resin LAPEROS (product name) LCP E130i (glass fiber 30%)
2. PPS resin DURAFIDE (product name) PPS 1140A6 (glass fiber 40%)
3. PBT resin: Duranex (product name) PBT 733LD (glass fiber 30%)
[Molding conditions]
・LCP resin Cylinder temperature CT 350℃ Mold temperature 100℃ Injection speed 1m/min
PPS resin Cylinder temperature CT 320℃ Mold temperature 140℃ Injection speed 1m/min
PBT resin, cylinder temperature CT 260℃, mold temperature 80℃, injection speed 1m/min

<<Formation of burrs on resin parts: Laser processing>>
Any 20 mm x 20 mm portion of the surface to be plated of the injection-molded test specimen was irradiated with laser light at a wavelength of 1064 nm using a Keyence laser marker: MD-X1520, to form lattice-shaped grooves with a width of 80 μm, a length of 20 mm, a depth of 10 μm, and pitches of 200, 300, and 500 μm.

<Measurement of burr height a and spacing b>
The measurements were made using a laser microscope.
<Test specimen preparation: plating process>
The resin member having the groove formed therein was plated by vacuum deposition (aluminum plating) to form a plated test piece. The plating thickness was 80 nm.

<Adhesion test: Cross-cut peel test (cross-cut method)>
In accordance with JIS K-5600-5-6, a cutter knife was used to make six cuts at 1 mm intervals in the vertical and horizontal directions on the plated surface of the plated specimen, forming a total of 25 1 mm squares, and commercially available cellophane tape was attached to the squares and rubbed well with fingers from above to adhere to the painted surface. One end of the cellophane tape was then pinched with fingers and peeled off in one go, and the peeling state of the plated surface was observed. The test was conducted in an atmosphere of 23°C and 50% RH. Of the JIS K-5600-5-6 classification of 0 to 5 points, a score of 2 or less was considered to be a pass. The results are shown in Table 1.

Figure 2 shows the results of Table 1 in a graph. The graph shows the relationship between a (horizontal axis, unit μm) and b (vertical axis, unit μm), with ● indicating pass and × indicating fail. The straight line in Figure 2 is the mathematical equation with the equal sign of formula (1). As can be seen from these results, adhesion is good within the range that satisfies the relationship of formula (1).

Equation (1) is a regression equation derived from five critical points from experimental data, and the correlation coefficient is greater than 85%.

a Burr height b Groove spacing c Groove opening width d Groove pitch

Claims (3)

A resin member for aluminum plating treatment, the resin member having a surface to be plated with a plurality of grooves each having a depth of 1 to 15 μm, a distance b between the plurality of grooves being 10 to 500 μm, the grooves having burrs around openings each having a height a of 5 to 30 μm, the height a of the burrs and the distance b between the plurality of grooves satisfy the following formula (1):
Formula (1) b≦35a-24
The resin member is formed from any resin selected from the group consisting of polybutylene terephthalate, polyphenylene sulfide, and liquid crystal polymer. 2. The resin member according to claim 1 , wherein the width c of the opening of the groove is 50 to 200 μm. A method for producing a plated resin member by plating a resin member with aluminum , the method comprising the steps of: forming, on a surface to be plated of the resin member, a plurality of grooves each having a depth of 1 to 15 μm, the plurality of grooves having a spacing b of 10 to 500 μm, the grooves having burrs with a height a of 5 to 30 μm around openings, the height a of the burrs satisfying the relationship between the spacing b of the plurality of grooves and the following formula (1) by irradiating the surface with laser light :
Formula (1) b≦35a-24
The method for producing a plated resin member, wherein the resin member is made of any resin selected from the group consisting of polybutylene terephthalate, polyphenylene sulfide, and liquid crystal polymer.

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