Advantages of plastic:
1. Easy molding and good molding. 5. Excellent electrical insulation.
2. light weight. 6. The price is low.
3. Good corrosion resistance. 7. It can be produced in large quantities.
4. Good drug resistance.
Disadvantages of plastics:
1. Poor weather resistance and vulnerability to light irradiation.
2. poor heat resistance.
3. Low mechanical strength.
4. The wear resistance is very poor.
5. High water absorption.
(3) Purpose of plastic electroplating:
The purpose of plastic electroplating is to coat the plastic surface with metal, which not only increases the beauty, but also compensates for the shortcomings of plastic,
endows the metal with properties and gives full play to the characteristics of plastic and metal. Today, a large number of plastic electroplating products
have been applied to industries such as electronics, automobiles and household goods.
15.4 process of plastic electroplating
(1) cleaning: remove dirt and fingerprints left in the plastic molding process, which can be washed with alkali
and then neutralized with acid leaching and washed with water.
(2) solvent treatment: wetting the plastic surface to act with the conditioner in the next step
.
(3) conditioning: roughening the plastic surface into a concave hole with internal lock to make the coating tightly adhered
and difficult to peel off, also known as chemical roughening.
(4) sensitization: the reducing agent is adsorbed on the surface, commonly used (Stannous Chloride)
or other tin compounds, that is, Sn++ions are adsorbed on the plastic surface and have a reducing surface.
(5) nucleation: A catalytic substance such as gold is adsorbed on the surface which is sensitive (reducing),
after the reduction, it becomes a catalytic metal seed, and then the metal can be plated by electroless plating.
the reaction is as follows:
sn++PD+è sn4++PD
sn++2ag+è sn4++2ag
15.5 plastic electroplating solution
solvent treatment solution: including cleaning
cleaning without dilute acid or neutral cleaning and 1-2% interface activator.
solvent treatment: using acetone, diacetate methane and other active agents.
conditioning: chemical roughening and chemical etching.
example 1
anhydrous chromic acid CrO3 2 g/l
sulfuric acid H2SO4 specific gravity 1.84 6cc/l
bath temperature 6℃
time 15~3 minutes
example 2
anhydrous chromic acid CrO3 2 g/l
phosphoric acid h3po3 1 cc/l. L
bath temperature 69℃
time 1~2 minutes
sensitization:
stannous chloride SnCL2 2~4 g/l
salt acid HCl 1~2 cc/l
tuberculosis (nucleation) or activating.
example 1
palladium chloride PdCL2 .1~.3g/l
salt acid HCl 3~5 cc/l
example 2
silver nitrate AgNO3 .5~5 g/ L
ammonia water suitability
Example 3
Gold chloride AuCL3 .5~1 g/l
Salt acid HCl 1~4 cc/ L
15.6 patent documents of plastic electroplating
287472 294764 293885 299648 39539
31135 319784 3556955 346232 3563784
3579365 47 356241 3471376 347916 347132
3619245 3471313 3567532 348427 3597336
3555649 356577 3562163 359863 3647699
359268 3556956 367351 364 2584 3642585
3647512 3561995 355385 357681 3423226
31192 3532518 3633