InPulse 2 - The New Dimension for Horizontal Plating Technology

Ever increasing demands for HDI or IC Substrate production processes call for innovative, future-oriented solutions. The new InPulse 2 copper plating system extends the limits of horizontal plating technology to a new dimension. With its full range of major technical improvements, such as minimum anode/cathode distance, wide area contact system, segmented anodes and matching electrolytes, InPulse 2 is in large scale production today and is well prepared for tomorrows challenges. The latest developments in handling allow processing of the thinnest base materials also with minimum copper foil thickness.

InPulse 2 - Main features and benefits for the circuit board producer:

• Best throw in blind microvias
• Controlled copper thickness - at hole edges and in the hole
• Highest current densities applicable
• Compatibility with ultra-thin base copper (thin RCCs or bare dielectrics)
• Production proven with ultra thin foils (can be applied for thin core flex sheet and reel-to-reel)
• Highest process reliability
• Reduced maintenance
• Capable for BMV and through hole filling
• No Anode Sludge
• Very easy copper replenishment
• No down time for anode maintenance
• Constant anode conditions
• Use of pure copper, eliminating contamination risks

Throwing power
Uniform copper thickness on the surface and in the hole is a pre-requisite for reliable circuit board manufacturing. With InPulse 2 technology this can be achieved not only on the surface, but also in through holes and Blind Micro Vias - at current densities of up to 12 A/dm². Supported by the exclusive Uniplate pulse switch system, throwing power performance is achieved in production machines worldwide.

Fine line capability
Fine line technology with < 75 µm lines and spaces requires ultra thin base copper. Contacting these ultra thin base copper foils at high current density is a challenge. With InPulse 2 technology the new clamp design in combination with optimized solution flow can manage this challenge. The contact area of the new clamp is 220%, compared to the former design. On an 18-inch panel this results in an applicable current density of up to 12 A/dm².

Uniform surface thickness
The panel plating uniformity with the Uniplate is a production proven technology. Due to the new clamp design, combined with the close proximity segmented anodes the uniformity extends even further into the contact area.

Blind micro via capability
For high yield Blind Micro Via production reliable wetting of the holes is mandatory. Advanced flooding devices (AFDs) with a unique volume pressure characteristic are incorporated into the equipment. Together with special InPulse electrolytes, reliable wetting and fast plating initiation is guaranteed.

Close proximity segmented anodes
The InPulse 2 technology incorporates close proximity anodes. With this development the need for shielding has been eliminated. The anodes are segmented to enable best surface distribution also with thin copper conducting layer. Such layers have an inherent resistance over a panel which can lead to uneven copper deposition. The InPulse 2 with segmented anodes enables targeted copper plating ensuring ± 10 % surface distribution with 1 µm copper conducting layer.

Surface topography
The copper surface plated with the InPulse process is uniformly slightly matt with distinct roughness characteristics. It is production proven with a large variety of resists that this resulting surface morphology is most suitable for reliable resist lamination. Atomic force microscopy (AFM) has been used to investigate the morphology of the InPulse Cu. Using standard pulse parameters the surface roughness ranges between 0.24 - 0.28 µm across the panel, this is ideal for resist adhesion without extensive surface preparation.

Via Filling / Through Hole Filling
The InPulse 2 system is production proven for BMV filling. Additional to this through via filling can now be achieved. This combined capability is very dependant on the Atotech inert anode / redox system which ensures long electrolyte lifetime in full production.

Inert anodes for low maintenance and high productivity
The use of inert anodes for copper plating has been developed and established by Atotech for many years.
With today's fine line requirements any anode sludge coming into contact with the board surface could dramatically reduce yields. The specially coated Titanium anodes do not develop anode sludge and exhibit a long life time without need for "refilling". Nevertheless copper needs to be replenished. An auxiliary redox system is incorporated into the InPulse process, which dissolves copper in an external chamber. This closed loop system allows copper replenishment during production.

No Oxygen Development
With Atotechs patented technology no oxygen develops during copper plating.
The production advantages are:

• Low consumption of organic additives
• Low organic bath loading
• Extended electrolyte life cycle
• Extended anode lifetime
• No surface defects caused by oxygen bubbles
• No oxygen bubbles in blind micro vias