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TOPICCOVENTYA’S CHROME FREE ETCH TECHNOLOGY FOR PLATING ON PLASTICS

SILKEN BOND

COVENTYA’S CHROME FREE ETCH TECHNOLOGY FOR PLATING ON PLASTICS

SILKEN BONDCOVENTYA has developed a competitive, chrome free etch technology named SILKEN BOND for plating on plastic

applications. The unique technology exceeds current regulations for use of hexavalent chromium.

The SILKEN BOND process has performed well in several Beta Site Tests and we are in the process of installing the process at two large POP platers which means engineering of a new plating line without any chromic acid in the pre-treatment.

We have considerable experience with SILKEN BOND ETCH as one industrial site has been running it successfully for 18 months using the original solution without a new make-up.

There are two main issues commonly seen with the hexavalent Cr free etches presently being promoted. The main issue is undesireable, extraneous rack plating. COVENTYA developed an additive to overcome this and in several Beta Site

Tests the performance was confirmed. There is no plating of the racks whatsoever. This is a major accomplishment as the market reports that no other supplier has been able to overcome this.

The other issues are short solution life and very high permanganate concentration. The SILKEN BOND process has an integrated Oxidation Cell which greatly extends the life of the etch. Additionally, although SILKEN BOND is based on permanganate, the concentration is far below 1.0 g/l, typically an important benchmark for this type of technology.

The following is an important update on the status of the SILKEN BOND technology

Process sequence

Oxidation Cell

Rack plating

Bi-injected parts

Adhesion

Beta Site Tests

Competitors approach/position

Summary and Outlook

POINTSClick to select

SILKEN BOND THE TECHNOLOGY

SILKEN CLEANER 201/202

Double rinse

SILKEN BOND ETCH

SILKEN BOND NEUTRALIZER STEP 1 SILKEN NEUTRALIZER 404

SILKEN BOND NEUTRALIZER STEP 2

SILKEN BOND CONDITIONER

Hot rinse

Double rinse

Double rinse Double rinse

Double rinse

Process steps = 9 Process steps = 7

Rinsing steps = 13 Rinsing steps = 12

Total steps = 21 Total steps = 19

Pre Activator

SILKEN CATALYST 501

SILKEN ACCELERATOR 601

SILKEN METAL 701 / 709

Double Rinse

Double Rinse

Hot rinse

Triple rinse

Double rinse

Chrome sulphuric etch

SILKEN CLEANER 201/202 t = 2 - 4 min, T = 40°C

t = 9 - 15 min, T = 63 - 68°C

t = 1 - 3 min, T = 50°C

t = 3 - 4 min, T = 55°C

t = 3 - 4 min, T = 55°C

t = 1 - 2 min, T = 25°C

t = 3 - 4 min, T = 55°C

t = 1 - 3 min, T = 50°C

t = 2 - 4 min, T = 40°C

t = 9 - 15 min, T = 63 - 68°C

SILKEN BOND Process Conventional POPpre plate

Time & temperatureSILKEN BONDTechnologies

Time & temperatureConventional

pre plate

COVENTYA‘s SILKEN BOND Process uses an Oxidation Cell which provides process stability, enhanced performance

and extended solution life.

OXIDATION CELL

COVENTYA has developed the following processes for simple integration into existing plating lines...

PROCESS SEQUENCE

The use of such an Oxidation Cell offers many advantages for SILKEN BOND. • Whereas typical Chrome free systems oper-ate as high as 15 g/l permanganate, SILKEN BOND’s target level is < 1 g/L.

• Much longer solution life• Improved consistency of etch performance leading to reliable adhesion and appearance.

Tab.1

In an effort to improve the aesthetics and appeal to the consumer, European designers have increased the use of

plated bi-injected plastic parts for interior applications.

BI-INJECTED PARTS

Compared to Chrome containing etch cycles, the use of Chrome free etch technologies has made successful plating of bi-injected surfaces nearly impossible.

After exhaustive studies, COVENTYA modified critical operating parameters in the SILKEN BOND

Process, specifically in the SILKEN BOND ETCH and the SILKEN METAL Electroless Nickel. After these adjustments were made we saw no difficulty plating bi-injected parts with high selectivity on a lab scale. Evaluation at several industrial Beta Site locations is ongoing and will be reported shortly.

In the conventional pre plate process, hexavalent chrome from the etch poisons the PVC rack coating and therefore the Palladium adsorption is prevented. In a Chrome free etch technology approach, this poisoning is not possible so alternative methods to avoid the potential for rack

plating is required.

With the SILKEN BOND Process, COVENTYA has developed a technique to balance the system to avoid this tendency and eliminates its occurrence.

To date, the major obstacle in these new hexavalent Chrome free etches is the challenge to avoid rack plating.

RACK PLATING

Parts run through the COVENTYA SILKEN BOND Process have been subjected to multiple

automotive OEM thermal shock and peel tests.

ADHESION

ABS, 10 min Cr / H2SO4 etch

Parts are 2.5 cm wide and measurement was done in OEM labs.

ABS, 10 min SILKEN BOND

Results have been equal to or better than the OEM specified requirements. With the SILKEN BOND Process, even with a surface that has a smoother attack after etching, delivers adhesion values that are equal to a conventional pre plate process. Parts moulded with different ABS qualities and different moulding conditions have also passed various thermal shock and peel tests.The results in the graphs below show adhesion values of 14.6 – 17.2 N/cm for ABS and 7.2 – 8.0 N/

cm for PC/ABS. We have passed several thermal shock tests from different OEMs and industry segments.

The images below highlight this. On the left is an SEM image of an ABS part conventionally etched in a Chrome/Sulfuric and that on the right is the SILKEN BOND. Note the reduced amount of pores which indicate less overall attack.

ABS, 10 min Cr / H2SO4 etch ABS, 10 min Silken Bond

Parts are 2.5 cm wide and measurement was done in OEM labs.

6. BETA SITE TESTS

COVENTYA has performed Beta Site Tests at major POP Applicators across Europe. We collected critical data and following parameters have been confirmed:

1. Function of the Oxidation Cell 2. Avoidance of Rack Plating 3. Adhesion 4. Selectivity for bi-injected parts 5. Parameter for all necessary process steps 6. Long Life cycles of each process step 7. Positive yield comparison

One Industrial Beta Site Test is running production in a pilot line for more than 18 months with the original solutions used at make-up.

7. COMPETITORS SOLUTION

All major competitors of COVENTYA are working on a solution for a chrome free etch. All processes are based on acidic permanganate.

0

1

2

3

4

5

6

no rack plating long life process bi‐injected parts adhesion

Benchmark Chrome Free Etch Technology 

Coventya

Competitor 1

Competitor 2

Competitor 3

CrVI Etch, ABS 15 min 68°C

SILKEN Bond, ABS 15 min 68°C

CrVI Etch, PC/ABS,15 min 68°C

SILKEN Bond, PC/ABS,15 min 68°C

18 months with the original solutions used at make-up.

BETA SITE TESTS

COVENTYA has performed Beta Site Tests at major POP Applicators across Europe. We collected critical data and the following parameters have been confirmed :

One Industrial Beta Site Test is running production in a pilot line for more than 18 months with the original solutions used at make-up.

Function of the Oxidation CellAvoidance of Rack PlatingAdhesionSelectivity for bi-injected partsParameter for all necessary process stepsLong Life cycles of each process stepPositive yield comparison

All major competitors of COVENTYA are working on a solution for a Chrome free etch. All processes are based on

acid permanganate solutions.

COMPETITORS SOLUTION

Due to a number of successful Industrial Beta Site Tests, the SILKEN BOND Process is ready for the next step!

SUMMARY & OUTLOOK

The SILKEN BOND Process is state of the art and can be integrated with minimal effort into existing plating lines.

Adhesion values are similar to parts processed with conventional chrome sulphuric etch. The tendency to plate racks has been eliminated.

The process operates with the lowest amount of Permanganate (0.3 g/l) compared to other chrome free etch technologies.

The future in innovative POP Prep is here:

COVENTYA‘s SILKEN BOND Process

CONTACT: automotive@coventya.com Read more about Coventya: www.coventya.com