U.S. patent application number 12/504768 was filed with the patent office on 2010-02-04 for surface treatment method for housing.
This patent application is currently assigned to SHENZHEN FUTAIHONG PRECISION INDUSTRY CO., LTD.. Invention is credited to CHENG-SHIN CHEN, BIN LIU, JONG-YI SU, REN-NING WANG.
Application Number | 20100025256 12/504768 |
Document ID | / |
Family ID | 41327686 |
Filed Date | 2010-02-04 |
United States Patent
Application |
20100025256 |
Kind Code |
A1 |
SU; JONG-YI ; et
al. |
February 4, 2010 |
SURFACE TREATMENT METHOD FOR HOUSING
Abstract
A surface treatment method for housings comprising: providing a
metal housing and pre-treating it to be cleaned; electroplating the
housing to form a hexavalent chromium coating on the surface of the
housing; and electroplating the housing to form a trivalent
chromium coating on the hexavalent chromium coating.
Inventors: |
SU; JONG-YI; (Shindian,
TW) ; CHEN; CHENG-SHIN; (Shindian, TW) ; WANG;
REN-NING; (Shenzhen City, CN) ; LIU; BIN;
(Shenzhen City, CN) |
Correspondence
Address: |
PCE INDUSTRY, INC.;ATT. Steven Reiss
288 SOUTH MAYO AVENUE
CITY OF INDUSTRY
CA
91789
US
|
Assignee: |
SHENZHEN FUTAIHONG PRECISION
INDUSTRY CO., LTD.
ShenZhen City
CN
FIH (HONG KONG) LIMITED
Kowloon
HK
|
Family ID: |
41327686 |
Appl. No.: |
12/504768 |
Filed: |
July 17, 2009 |
Current U.S.
Class: |
205/205 |
Current CPC
Class: |
C25D 5/34 20130101; C25D
3/06 20130101; C25D 5/14 20130101; C25D 5/36 20130101; C25D 3/04
20130101 |
Class at
Publication: |
205/205 |
International
Class: |
C25D 5/34 20060101
C25D005/34; C25D 5/48 20060101 C25D005/48 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 30, 2008 |
CN |
200810303201.3 |
Claims
1. A surface treatment method for housings, comprising: providing a
metal housing and pre-treating it to be cleaned; electroplating the
housing to form a hexavalent chromium coating on a surface of the
housing; and electroplating the housing to form a trivalent
chromium coating on the hexavalent chromium coating.
2. The surface treatment method as claimed in claim 1, wherein the
metal housing is made of stainless steel or copper.
3. The surface treatment method as claimed in claim 1, wherein
electroplating the housing to form the hexavalent chromium coating
is carried out in a second electrolyte containing a chromium acid
component in a mass concentration of about 240-350 g/L and a
sulfuric acid component in a mass concentration of about 2-4
g/L.
4. The surface treatment method as claimed in claim 3, wherein the
second electrolyte further contains fluoride additive agent(s) in a
mass concentration of about 5-10 g/L.
5. The surface treatment method as claimed in claim 4, wherein the
electric current density through the second electrolyte is about
10-30 A/dm.sup.2, and the electroplating last for about 1-15
minutes.
6. The surface treatment method as claimed in claim 1, wherein
electroplating the housing to form the trivalent chromium coating
is carried out in a third electrolyte containing a chromium
sulphate component and a boric acid component, the mass
concentration of the trivalent chromium iron in the third
electrolyte is about 3-10 g/L.
7. The surface treatment method as claimed in claim 6, wherein the
electric current density through the third electrolyte is about
5-15 A/dm.sup.2, and the electroplating last for about 1-15
minutes.
8. The surface treatment method as claimed in claim 1, wherein the
housing is subjected to neutralization treatment after the
electroplating process in a neutralization solution including a
sulfuric acid component and an oxydol component.
9. The surface treatment method as claimed in claim 1, wherein
pre-treating the housing includes degreasing, electrochemical
cleaning and acid treating the housing.
10. The surface treatment method as claimed in claim 9, wherein
electrochemical cleaning the housing is carried out in a first
electrolyte containing a sodium hydroxide component, the
temperature of the first electrolyte is about 55-65.degree. C., the
electric current density through the first electrolyte is about 1-5
A/dm.sup.2, and the electrochemical cleaning last for about 4-10
minutes.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present disclosure relates to a surface treatment method
for housings, especially to an electroplating method for metal
housings.
[0003] 2. Description of Related Art
[0004] A typical surface treatment method now for portable
electronic devices' housings is electroplating. Commonly, the
housing is electroplated to form a trivalent chromium coating on
its surface to present high gloss appearance and enhance abrasion
resistance. To enhance the bonding between the trivalent chromium
coating and the housing, the housing is electroplated with a nickel
coating prior to the forming of the chromium coating. However, the
nickel coating and the whole process of electroplating with nickel
are not environmentally friendly because the nickel or nickel iron
contained in the electrolyte is toxic.
[0005] Therefore, there is room for improvement within the art.
BRIEF DESCRIPTION OF THE DRAWING
[0006] Many aspects of the surface treatment method for housing can
be better understood with reference to the following drawing. The
emphasis of the drawing is placed upon clearly illustrating the
principles of the surface treatment for housing.
[0007] The figure is a flow chart of an exemplary embodiment of a
surface treatment method for a housing.
DETAILED DESCRIPTION
[0008] Referring to the FIG, a surface treatment method for a
housing may include the steps S10 to S50.
[0009] In step S10, a metal housing is provided. The metal housing
may be made of, e.g., stainless steel or copper. The metal housing
may be a mobile phone, a digital camera, a personal digital
assistant, or a note book computer's housing. The metal housing may
also be a housing of a container.
[0010] In step S20, the metal housing is pretreated. The
pre-treating step may comprise one or more of the following:
degreasing, electrochemical cleaning, and acid treating the
housing.
[0011] The degreasing process may be carried out by dipping the
housing in a degreasing solution for about 5-15 minutes. The mass
concentration of the degreasing agent is about 150-200 grams per
liter (g/L). The temperature of the degreasing solution is about
55-65.degree. C.
[0012] After the degreasing process, the housing is removed from
the degreasing solution to be electrochemically cleaned.
Electrochemical cleaning the housing may be carried out in a first
electrolyte. The first electrolyte may contain a sodium hydroxide
component in a mass concentration of about 100-200 g/L and an
activating agent(s) component in a mass concentration of about
40-80 g/L. The activating agent(s) may be dodecyl sulfonic acid
sodium salt. The temperature of the first electrolyte is about
55-65.degree. C. The electric current density through the first
electrolyte is about 1-5 A/dm.sup.2. Electrochemically cleaning the
housing may last for about 4-10 minutes. The electrochemical
cleaning step can further remove lipids adhering to the housing and
smudges.
[0013] After the electrochemical cleaning process, the housing is
dipped in a sulfuric acid solution for about 1-5 minutes to remove
the residual basic liquid adhering to the housing's surface. The
concentration by volume of the sulfuric acid in the solution is
about 50-80 ml/L. The temperature of the sulfuric acid solution is
about 20-30.degree. C. After the acid treatment, the housing is
water washed; in this embodiment the housing is water washed three
times.
[0014] In step S30, the housing is electroplated to form a
hexavalent chromium coating on its surface. Electroplating the
housing to form the hexavalent chromium coating may be carried out
in a second electrolyte, with the metalized surface of the housing
being a cathode, and a stannum (Sn) plumbum (Pb) alloy anode being
provided and immersed in the second electrolyte. The second
electrolyte may contain a chromium acid (H.sub.2CrO.sub.4)
component in a mass concentration of about 240-350 g/L and a
sulfuric acid component in a mass concentration of about 2-4 g/L.
The second electrolyte may further contain additive agent(s), such
as fluoride. The additive agent(s) may improve the forming of the
hexavalent chromium coating on the surface of the housing. The mass
concentration of the additive agent(s) in the second electrolyte is
about 5-10 g/L. The electric current density through the second
electrolyte is about 10-30 A/dm.sup.2. Electroplating the housing
with the hexavalent chromium coating may last for about 1-15
minutes. The hexavalent chromium coating bonds well with the
housing because of having similar properties as copper or stainless
steel. After the electroplating, the housing is bathed in
water.
[0015] In step S40, the housing is electroplated to form a
trivalent chromium coating on the hexavalent chromium coating.
Electroplating the housing to form the trivalent chromium coating
may be carried out in a third electrolyte, with the metalized
surface of the housing being a cathode, and a iridium (Ir) tantalum
(Ta) alloy anode being provided and immersed in the third
electrolyte. The third electrolyte may contain a chromium sulphate
(Cr.sub.2(SO.sub.4).sub.3) component in a mass concentration of
about 240-300 g/L, and a boric acid component in a mass
concentration of about 70-90 g/L. The third electrolyte may further
contain additive agent(s) such as bromide and formate. The mass
concentration of the bromide in the third electrolyte is about
15-20 g/L, and the mass concentration of the formate is about 70-90
g/L. The mass concentration of the trivalent chromium iron in the
third electrolyte is about 3-10 g/L. The electric current density
through the third electrolyte is about 5-15 A/dm.sup.2.
Electroplating the housing with the trivalent chromium coating may
last for about 1-15 minutes. The trivalent chromium coating bond
well with the hexavalent chromium coating for the two coatings are
all contain the chromium element. The trivalent chromium coating
being formed on the hexavalent chromium coating prevents the
problem that the trivalent chromium coating is tend to split for
directly formed on the surface of the housing.
[0016] After electroplating, the housing is again bathed in
water.
[0017] In step S50, the housing is subjected to neutralization
treatment. The neutralization treatment is carried out by dipping
the housing in a neutralization solution for about 1-3 minutes to
remove any residual electrolyte adhering to the housing. The
neutralization solution includes a sulfuric acid component in a
concentration by volume of about 20-50 ml/L, and an oxydol
component in a concentration by volume of about 50-100 ml/L. The
temperature of the neutralization solution is about 20-30.degree.
C. After receiving neutralization treatment, the housing is bathed
once more in water.
[0018] The surface treatment method for housing described above
forms a hexavalent chromium coating on the surface of the housing
prior to forming the trivalent chromium coating, which prevents the
tendency of the trivalent chromium coating to split when directly
formed on the surface of the housing, and enhances the bonding
between the trivalent chromium and the housing. The two chromium
coatings can further enhance the rigidity of the housing and make
the housing present more glossy appearance, thus producing better
protected parts of the housing. Moreover, the two coatings do not
contain nickel and so are more environmentally friendly.
[0019] It is believed that the present embodiment and its
advantages will be understood from the foregoing description, and
it will be apparent that various changes may be made thereto
without departing from the spirit and scope of the disclosure or
sacrificing all of its advantages, the examples hereinbefore
described merely being preferred or exemplary embodiment of the
disclosure.
* * * * *