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Direct plating system: the only alternative to electroless copper

System-S is a revolutionary amphoteric three-metal alloy direct plating system. Its unique immersion copper technology gives the best conductivity of all direct plating processes. It’s the only alternative to electroless copper.

Superior conductivity gives outstanding copper penetration

High resistance remains a major problem with today’s direct plating processes, a rather unexpected state of affairs since conductivity must be regarded as one of the first priorities of a plating-through-hole process.

Through-hole conductivity generates the throwing power in the electrolytic plating baths; insufficient power thus leads to thin copper deposition in the holes. Due to its innovative three-metal alloy, System-S is the only direct plating process that can deliver conductivity on a par with electroless copper. Competitive processes actually reach resistance levels measured as high as hundreds or even mega ohms. To successfully produce today’s HARB, obtaining low resistance with a thin coating of the conductive layer is essential. With System-S plating, the uniform highly-conductive coating is measured in ångströms.

Plating process comprises three basic steps:

1. Conditioner neutralizes the negative charge to give a positive charge to the hole-wall
2. Negative-charged colloidal activator is attracted by and absorbed on the hole-wall
3. Colloidal activator is transformed in a highly-conductive coating


Direct plating system

  • Superior conductivity, through- hole resistance ≤ 1 ohm
  • Perfect adhesion; produces PTFE without special pre-treatment
  • Selective (no barriers and pure copper-to-copper bonding)
  • Easy to control with wide operating window
  • The only direct plating system with perfect results in both vertical and horizontal applications
  • Environmentally-friendly (no chelators, low water consumption)

Three-metal activator increases conductivity

The most important feature of System-S is that instead of using a typical Pd-Sn suspension, the activator employs a three-metal combination. By introducing amphoteric metal from the III or IV group (e.g. Al, Ti, Ga, In, etc.), the through-hole conductivity increases significantly.

A further key benefit of a third metal relates to its application as a chloride salt. The strong acidity of products such AlCl3 or TiCl4 eliminates the use of free HCl acid, both in the preparation of the activator and its operating solution. Eliminating free HCl acid is very important for reducing activator acidity, thus making it more suitable for horizontal application and reducing so-called black seeding between tracks.


In the rinses following the activator step, the colloid breaks down and hydrolyses to form stannous and stannic hydroxide as well as a metalloid compound of the third metal. In the following step, the amphoteric metal accomplishes the function of the reaction. The action of the third metal increases the concentration of metallic tin on the hole-wall and inhibits the formation of metastannic acid in the gaps between the metal sites. The metalloid compounds significantly increase conductivity between the metal sites.

After the Intensifier step, an acidic rinse eliminates all hydroxides, leaving a 60 to 80 ångström thin pure-metal alloy layer of palladium, tin and the third metal on the hole-wall.

System-S with flash plated 6 μm J-Plate Cu 400. The ångström thick System-S 3-metal amphoteric alloy gives outstanding copper penetration and adhesion.

Throwing power blind via

No 1 2 3 4 5 6
Width 140 130 120 110 100 90
Depth 60 60 60 60 60 60
T/P 108% 108% 107% 108% 111% 110%

Stable throwing power >100% independent of aspect ratio due to superior conductivity.


Process Acid Cleaner Acid Dip Acid Copper
Chemical AC DS-900 10% H2SO4 J-Plate Cu920 BVF

1.8 ASD

Time 3 min 1 min 30 sec 80 min

Before thermal shock

Shock x 1: 288°C 10 sec dip

Shock x 3

Viafill Test in VCP line

Process Acid Cleaner Acid Dip Acid Copper
Chemical AC DS-900 10% H2SO4

J-Plate Cu920 BVF

1.8 ASD

Time 1 min 20 sec 1 min 50 min

System-S Width 120 µm

Electroless Copper Depth 60 µm