CO-BRA Bond® HL Process
High
copper loading, low copper removal
Back to InnerlayersCO-BRA Bond ®
HLBath operation and maintenanceEtch rates: Graph
1Product Description
The CO-BRA BOND® HL Process is a modified peroxide/sulfuric acid process designed to prepare copper surfaces prior to multilayer lamination of printed wiring boards. The CO-BRA BOND® HL solution promotes the formation of a brown copper-organic coating, which enhances the surface for resin bonding.The CO-BRA BOND® HL Process is designed for lower copper removal and permits higher copper loading in solution without affecting performance. Reduced copper removal and higher loading reduces waste treatment costs by up to 60%. Reduced copper removal results in lower copper profile which benefits signal propagation and reduces loss at high frequencies.
This structure improves bond strength over conventional oxide coatings, especially on high Tg, high performance materials. The CO-BRA BOND® HL process is a much shorter process than a standard oxide process and operates at a lower temperature
Solution makup
CO-BRA BOND® HL Predip:| CO-BRA BOND® HL Modifier | 3.0% by volume |
| CO-BRA BOND® Oxidizer - 50 | 2.0% by volume |
| OR | |
| CO-BRA BOND® Oxidizer - 35 | 2.9% by volume |
| Deionized Water | Balance |
CO-BRA BOND® HL:
| Concentrated Sulfuric Acid | 4.5% by Volume |
| CO-BRA BOND® HL Modifier | 11% by volume |
| CO-BRA BOND® HL Promoter | 20% by Volume |
| CO-BRA BOND® Oxidizer - 50 | 2.75% by volume |
| OR | |
| CO-BRA BOND® Oxidizer - 35 | 3.9% by volume |
| Deionized Water | Balance |
Operating condiitions
| Nominal | Range | |
| HL Predip | ||
| CO-BRA BOND® Oxidizer - 50 (% v/v) | 2.0 | 1.5 - 2.5 |
| OR | ||
| CO-BRA BOND® Oxidizer - 35% (%v/v) | 2.9 | 2.1 - 3.6 |
| CO-BRA BOND® HL Modifier (% v/v) | 3.0 | 2.0 - 4.0 |
| Sulfuric Acid (g/L) | 1.35 g/L | 0.9 - 1.8 |
| Temperature | 27°C (80°F) |
21 - 32°C (70 - 90°F) |
| Dwell Time (sec.) vertical | 30 | 20 - 40 |
| Dwell Time (sec.) horizontal | 30 | 20 - 40 |
| Filtration: | 3 - 5 turnovers per hour during operation using a 1 - 5 micron polypropylene wound filter. |
| Agitation: | Filtration pump and mechanical movement. |
| CO-BRA BOND® HL | ||
| CO-BRA BOND® Oxidizer - 50 (% v/v) | 2.75 | 1.5 - 4.5 |
| OR | ||
| CO-BRA BOND® Oxidizer - 35% (%v/v) | 3.9 | 2.1 - 6.4 |
| CO-BRA BOND® HL Modifier (% v/v) | 11.0 | 10.0 - 24.0 |
| CO-BRA BOND® HL Promoter (% v/v) | 20.0 | 16.0 - 24.0 |
| Sulfuric Acid (% v/v) | 4.5 | 3.5 - 5.5 |
| Copper Metal (g/L) | 35 - 40 | 2 - 40 |
| Temperature | 35°C (95°F) |
32 - 38°C (90 - 100°F) |
| Dwell Time (sec.) vertical | 30 | 20 - 40 |
| Dwell Time (sec.) horizontal | 30 | 20 - 40 |
| Total Etch Amount | 1.0 µ (40 µin) |
0.64 - 1.5 µ (25 - 60 µin) |
| Filtration: | 3 - 5 turnovers per hour during operation using a 1 - 5 micron polypropylene wound filter. |
| Agitation: | Non-compressed air. Single row of 1/16 inch holes every 1.5 inches apart in a 1 inch pipe (pointing down). Each leg should be spaced a maximum of 6 inches apart, perpendicular to innerlayers. Use a separate feed pipe for every two sparger legs. |
Recommended process cycle
| 1. | CO-BRA BOND® HL Cleaner |
| 2. | Deionized water rinse |
| 3. | CO-BRA BOND® HL Pre-Dip |
| 4. | CO-BRA BOND® HL |
| 5. | Water Rinse |
| 6. | Dry |
Bath operation and maintenance
The CO-BRA BOND® HL Process is controlled similar to other peroxide/sulfuric etchants. CO-BRA BOND® Oxidizer (peroxide), sulfuric acid and copper are monitored and controlled via simple titration.CO-BRA BOND® Oxidizer, CO-BRA BOND® HL Modifier, CO-BRA BOND® HL Promoter and sulfuric acid are consumed in proportion to the amount of copper removed. For etching 1 surface square foot of laminate (50% copper surface area) during the feed and bleed condition, the amount consumed will be:
| CO-BRA BOND® Oxidizer - 50 | 0.85 mL |
| OR | |
| CO-BRA BOND® Oxidizer - 35 | 1.2 mL |
| CO-BRA BOND® HL Modifier | 1.3 mL |
| CO-BRA BOND® HL Promoter | 1.75 mL |
| Sulfuric Acid | 1.1 mL |
As work is processed the copper concentration will continue to increase. The copper level should be kept at or below 40 g/L to provide consistent etch rate.
The amount of copper etched should be monitored on a regular basis using cleaned copper clad laminate.
The amount etched can be calculated as follows:
Amount etched (µin) = weight loss (g)/(0.0212 x surface area (sq. ft.))
Amount etched (µ) = amount etched (µin)/39.4
The etch rate is affected by the CO-BRA BOND® Oxidizer concentration as shown in Graph 1.
Equipment
Tanks, tank linings, pumps, and other handling equipment should be suitable for use with 8% v/v sulfuric acid and 2 - 4% v/v hydrogen peroxide.Most 300 Series Stainless Steel equipment may be used to handle the CO-BRA BOND® HL solution, provided the bath contains a minimum 3.85 g/l of metallic copper (15 g/l CuSO4 5H2O). Passivation of newly welded stainless steel equipment with nitric acid is recommended.
The mixing procedure outlined in this bulletin is recommended to minimize attack on stainless steel.
Tanks
Reinforced fiberglass (oxidation resistant resin), polyethylene, polypropylene, stainless steel (300 Series), etc.
Pumps (Circulation and Transfer)
Stainless Steel (300 Series), PVC (unplasticized), etc. The supplier should approve magnetic-driven plastic pumps.
Pumps (Metering)
Stainless Steel (300 Series), polyethylene, polypropylene; diaphragms and check valves should be constructed from Teflon®, Hypalon®, Viton®, or equivalent.
Heating
Coils (heating and cooling) - 316 "Type L" Stainless Steel or Teflon®.
Immersion (electric) 300 Series Stainless Steel or quartz.
Piping
PVC, reinforced fiberglass with oxidation-resistant resin (FRP), Stainless Steel (300 Series), polyethylene, etc.
Valves (Plug, Gate, Diaphragm, Ball, etc.)
Stainless Steel (300 Series), PVC, etc.
WASTE TREATMENT for the CO-BRA BOND® HL Solution
| 1. | For every gallon of spent CO-BRA BOND® HL solution, add 3 gallons of water to the mixing tank. |
| 2. | Add the spent CO-BRA BOND® HL solution to the mixing tank with the agitation system operating. |
| 3. | Using 25% sodium hydroxide, increase the pH of the solution in the mixing tank to within a range of 2.0 - 2.5. |
| 4. | Add Sodium Bisulfite to the solution in the mixing tank in increments of 1 g/l, until the solution indicates no oxidizer on the KI - Starch test paper. |
| 5. | Using 25% sodium hydroxide, increase the pH of the solution in the mixing tank to within a range of 8.5 - 9.0. |
| 6. | Let the solution settle. |
| 7. | Decant the solution through a filter system. The solution should go to the waste treatment system for discharge in compliance with municipal regulations. |
| 8. | The precipitate is a hazardous material and should be properly disposed in accordance with municipal regulations. |
NOTE: Dispose of solutions and precipitate in accordance with all applicable federal, state and local regulations.
Consult the appropriate Material Safety Data Sheets for safety, health and environmental information.
Graph 1: Typical etch rates
Back
to Bath operation and maintenance