A versatile PCB plant
The market for printed circuit board systems is highly competitive. Nevertheless, with many years of experience and innovative ideas, which meet the requirements of the constantly developing technology, it is possible to be successful. This applies in particular to systems for electroplating printed circuit boards. An example of this is an electroplating plant developed and produced by Ludy Galvanosysteme GmbH, for the demanding requirements of a customer, which is described below. It was handed over to GreenSourceFabrication LLC in Charlestown USA in August 2018. This order was won because, among other things, new innovative solutions could be offered for the required versatility.
- Requirements of the glavanizing plant
- Project planning phase
- The copper cells
- The hoist as an innovative coordinate transport system
- Further details of the electroplaing plant
- plating electronic
- Sager + Mack
- The environmental compatibility
- For drying
- Further facilities and functions
A manufacturer of printed circuit boards is faced with many new requirements in terms of printed circuit board technology. He can only solve them optimally in close cooperation with the plant manufacturer and the supplier of the electrolyte, Atotech. This was once again demonstrated by the very ambitious project that was implemented. In a single plant, the following electroplating types and functions had to be possible for the deposition of copper and nickel / gold:
Panel & Pattern Plating, Blind Micro Via Plating, Button Plating and Resist Strip. The substrate ranges from flex circuits up to a thickness of 6.2 mm. The boreholes have an aspect ratio of up to 1:50. This treatment material is to be loaded and emptied automatically
In order to be able to optimally design such a versatile plant, extensive electroplating tests were suggested to the customer and accepted by him. A 1:1 scale test cell for acid copper was developed and built. This had variation possibilities, among other things, for the hydrodynamic conditions of the electrolyte, vertical and horizontal eductor inflow, goods movement, inert segment anodes, anode cathode spacing, orifices, vibrators, electrolyte temperature, electronic rectifiers for direct current as well as bipolar pulse current 1:3.
The electroplating tests were carried out by the customer in the USA together with his supplier, Atotech, of the electrolyte. The results then flowed into the final design and manufacture of the electroplating plant, namely into an immersion bath plant in two rows including three coordinate transport trolleys with integrated converters, which are optimally equipped for the required tasks.
Due to this upfront financial and time expenditure, the costs of which were borne by the customer, the chemical supplier and the plant manufacturer, all three companies involved were assured in advance of the actual performance of the entire project.
The heart of the electroplating plant supplied for printed circuit boards are the copper cells. They are designed for printed circuits boards with a maximum size of 21“ x 24“ and a minimum size of 18“ x 24“. At the end of each of the two installation rows of the system there are six copper cells. The special feature of the installation is that the copper baths of the two rows are united with each other. They practically consist of a wide container across the central aisle of the plant from one row to the other. This connection ensures that the electrolyte is in exactly the same state at the two storage positions of the flight bars. All measures for conditioning the electrolyte are only required once for both positions or storage locations. The above-mentioned versatility of the electroplating plant, in particular of the copper cells, required elaborate measures to implement certain hydrodynamic conditions. This was solved by means of so-called anode boxes. They are arranged in the electrolytic copper cell on both sides of the circuits boars to be treated. On the anode boxes the many eductors are particularly noticeable.
The three inert anodes are located in front of the anode boxes facing the PCB. Before each eductor they are cut out accordingly. The water-cooled electronic rectifiers can supply both direct current and bipolar pulse current. A printed circuit board is gripped by four clamps, each of which has four contacts per side. This esures a completely uniform supply of the galvanizing current to both sides of each circuit board. The copper electrolyte is supplemented with copper oxide.
This is dissolved in a special container with a stirring device and added to each copper bath including three further additives as required. Each copper bath is equipped with heating and cooling for thermal conditioning. Each copper cell also contains a versatile controlled agitation frame device.
Furthermore, there are vibrators not only on the copper cells for the flightbars but also in all other active baths.
It is also advantageous and innovative that the three hoists of the electroplating plant also extend over the two rows of the baths and thus also over the wide copper baths. The hoists contain not only the usual lifting device for each row of baths, but also a device for the cross transfer of the flightbars from one row to the other. Thus, the galvanizing plant also has three cross conveyors which can transfer goods at any position along the plant. This considerably increases the flexibility in the freely selectable creation of time/path diagrams, including the optimization of the throughput of the flightbars loaded in the storage locations. In addition, one system position in both bath rows is saved for the otherwise necessary stationary cross conveyor. The transmission of the signal data in both directions and the positioning of the transport units is carried out optically very innovatively via infrared laser beam and is completely installed without trailing cable.
The large 32 m long plant, arranged in two rows, is also equipped with the well-known equipment of electroplating plants, but each with high quality, which is traditionally of particular importance to Ludy Galvanosysteme GmbH. This includes for example the execution of the metal construction of the plant completely with V4A stainless steel as well as a cooperation with well-known subcontractors, such as the highly complex software control of the company IWAC, electronic bipolar rectifiers of plating electronic, eductor pumps of ASV Stübbe and circulation pumps and filter devices of Sager + Mack.
The rectifier technology also played a central role in this project, as the secifically required and demanding coating tasks and the versatility in the product and process spectrum can only be realized with the aid of reverse pulse plating (RPP).
Here the experience and high reliability of the equipment technology of plating electronic GmbH (pe) is trusted. Plating electronic GmbH is one of the world’s technology leaders in the field of pulse rectifier technology and pioneered this complex technology for electroplating plants around 30 years ago. Due to the individualised equipment technology in close coordination with the specific systems, the development and production of the equipment is still carried out very advantageously in Germany.
The compact units can be installed close to the bath due to water-cooled design. This and the special technology of plating electronic GmbH for the generation of pulse-shaped multi-channel output currents not only allows the perfect and complex pulse shapes to be generated, but also to be accurately transferred to the circuit boards to be electroplated.
Each anode segment is fed by an individual pulse rectifier. Here it is necessary to synchronize the pulse sequences for the front and rear side according to the type of printed circuit board for each flightbar. The synchronization is activated via the higher-level controller. The pulse sequences for the front and rear sides can be operated phase-shifted as required to achieve the best possible coating results.
As an international manufacturer of pumps, valves and measuring and control technology, ASV-Stübbe is a reliable partner for the realisation of export projects.
ASV-Stübbe can draw on many years of experience in metal and plastics processing, in particual for printed circuit board technology, as well as in the handling of demanding chemical substances when designing pumps and valves.
ASV-Stübbe meets the high quality requirements of Ludy Galvanosysteme GmbH with ist magnetically coupled pumps and valves.
For a perfect coating result in an electroplating plant one needs, among other things, an optimally matched filter technology with appropriately adapted filter pumps. Filter stations and magnetically coupled pumps from Sager + Mack are used for this purpose. They offer optimized flow conditions, which considerably improve the energy requirements for the applications. Another major advantage is the ergonomic handling of the filter stations, which has an extremely positive effect on work on the electroplating plant. Due to their sophisticated design, the pumps are less susceptible to wear and tear and thus provide long operating times. Depending on application, the standard materials used are PP, PVDF and stainless steel. All products used are highly resistant to the chemicals used. Sager + Mack distinguished itself as a powerful and reliable partner for this individually designed system.
Ludy Galvanosysteme GmbH has always attached great importance to achieving the greatest possible environmental compatibility in the planning and implementation of an electroplating plant. Proof of this is the complete housing of the electroplating plant, containers, lids and the continous drip tray under the baths.
Particularly worth mentioning is the almost complete absence of waste water in this plant. The waste water is treated in an elaborate separate plant and made available again as distilled water in a 20 m3 storage tank of the galvanizing plant as process water. A renowned specialist company supplied this waste water plant to Ludy Galvanosysteme GmbH, which continued to supply it to the customer as general contractor.
The drying of the printed circuit board also takes place in this electroplating plant with the proven Ludy drainage system (patent pending). The associated energy savings compared to conventional circulation air dryers are achieved by dehumidifying the air in the drainage tank.
The widely known equipment and functions round off the concept of a versatile electroplating plant.
This is also how this system was implemented:
Automatic loading and unloading of the flightbar by means of robots.
- Power transmission to the hoists without trailing cable.
- Storage locations to achieve optimum system occupancy.
- Maintenance runs on both sides of the baths.
- Automatic dosing devices.
- Electrolytic demetallization of the racks.
- Filter with 5 µm candels.
- Activated carbon filter.
- Resist stipper with associated band filter.
- Extraction with bath cover.
- Complete housing of the electroplating plant. Accesses with sliding doors secured by light barriers.
- Electronic control and visualization of the electroplating plant.
- Automatic optimization of the goods throughput.
- Logging of goods throughput and other events.
- Interface to a master computer.
This innovative project clearly revealed the many different and very demanding technological functions that a galvanizing plant for electroplating highly technological printed circuit boards has to fulfil. It is a challenge to realize such a complex plant. With extensive experience and resulting innovative ideas, coupled with the entrepreneurial spirit of everyone involved, the necessary solutions can always be found and implemented.