Consolidating Electronics Plating Lines

At ITT Industries, Cannon, cycle time is essential to the efficiency of the electronics plating department. This was top in the minds of Steve Chou, lead manufacturing engineer for plating, Amir Saket, manufacturing engineering manager and other engineers when they reviewed the plating systems and strategies at the company. In particular, they wanted to improve cycle times and ensure environmental compliance while improving customer satisfaction.

The pr'ous metal plating lines within the department were the first reviewed. This section of the plating department had three lines. Two lines were manual and one was a 25-year-old automated line. "None of these lines was being fully utilized," stated Dr. Chou.

The strategy was to consolidate the three lines into one automated line with maximum flexibility and a minimum discharge of waste. A cross-functional team consisting of Cannon employees was formed to work out the performance requirements and then design sp'fications of the plating system. The team focused on the waste segregation and minimization. However, Cannon's needs did not fit "off-the-shelf" equipment, so it had to work closely with the vendors to design a system that was uniquely adapted to Cannon and its customers' needs. "There was a lot of give and take," noted Dr. Chou. "It was a real learning experience for all of us. We had to find vendors who were willing to work with us to really meet our needs."

As stated, Cannon could not work with off-the-shelf equipment because of the variety and number of parts it plates (900 different electrical contact parts inside various connector bodies). "We supply parts to a number of industries, from communications to aerospace," Dr. Chou commented. "Our customers are worldwide, ranging from IBM to Boeing." Cannon worked with HBS Equipment to develop an enclosed automated system that could plate parts using barrel, vibratory basket, rack or wire fixturing.

Only 5% of the parts are racked or wire fixtured, however. The rest of the parts are barrel plated in a rotational or vibratory barrel. Heavier, thicker parts are plated in the rotational barrels, while more delicate parts are run in the Vibroset vibratory plating barrels from ECI Technology.

"We use the vibrating barrels for our delicate parts that cannot withstand the tumbling action of the barrels," noted Dr. Chou. "It also helps us successfully plate into the blind holes we have on many of these tiny parts."

A constant current is applied to the parts in the vibratory barrel, equalizing the deposition rate over the entire part. There are numerous cathode button contact in the bottom of the basket and numerous parts in the basket, all in contact with each other. The amplitude and frequency are carefully chosen to move the parts around the basket but avoid vigorous jumping action that could even momentarily break the electrical contact.

This constant contact also allows for even current distribution over the parts, thus eliminating the dogboning effect that may occur with other types of plating (see sidebar). The vibratory action blurs the distinction between the edges and flat portions of the parts.

Anodes are placed outside of the vibratory barrel, baffled by the walls of the basket. The vibratory action also helps blur the distinction between high and low current density regions and improve throwing power. Parts move around the barrel at a predetermined rpm. Parts can slide over each other, but there is little impingement, which could cause scratching or defects.

Each fly bar on the line can hold up to three vibratory barrels, three rotational barrels or three racks. Sixteen different jobs can run on the line at one time because of the random loading software program built into the system. Presently, the Cannon system has approximately 35 plating r'pes programmed into the system, which has the capacity to handle hundreds more. Parts are loaded manually, and that is the last time they are touched by human hands. After loading, the system automatically runs them through the program designated by the plating operator.

"We went with an enclosed system and new chemical scrubbers to significantly improve the working environment for employees," commented Dr. Chou. The work place is very clean because the chemical fumes from the cyanide plating processes are contained in the enclosure and treated with scrubbers. All maintenance is done behind the enclosed plating line. Filtration systems, pumps, piping, metering systems, etc. are contained behind the line so they do not interfere with the actual plating process. Also, the plating line does not have to be "opened up" for chemical additions, filter changes or other maintenance procedures. "With the old line we had to pull drums to the process tanks to make chemical additions. With our new line, we pump acid solutions to tanks from the back of the tank."

The new pr'ous metal plating line at Cannon has improved cycle time, product quality, saved money, improved worker safety and environmental conditions and expanded plating capabilities, and the entire consolidation effort was accomplished without any interruption to customer service.

Because of the success with the pr'ous metals line, Cannon is now working on consolidation of its other plating lines. This is an even taller order, since there are five lines in this section of the plating department. "We have successfully consolidated one section, and that has given us the confidence to tackle the next section. We are able to do this without interruption in customer service. Our customers actually benefit from the consolidation and improved plating processes as much as we do," maintained Dr. Chou.

What is the Dogbone Effect?

Dogbone refers to an electrochemical phenomena that results in higher current densities on the edges of a substrate than on the flat portion. Current flow is described as passing through canals or tubes. The number of canals per unit area is dependent on geometry. Because of the dogbone effect, it is difficult to plate to conform to the shape of the substrate.

Current Density

Macro current density: Determined by the setting on the gage on the rectifier. The macro current density is set to a sp'fic value of amps per sq ft after calculating the surface area of the load.
Effective current display: The current on different regions of the part may be quite different. For example, the current on the edges is typically higher than the current on flat portions of the part.
Diffuse/ability of the electrolyte: As metal is plated on the part, the solution next to the part is depleted of the metal. The solution next to the part must be replenished with fresh solution. An electrolyte with a high diffusability is good for rapid replenishment. High metal content, high ionic strength and good wettability enhance high diffusability.
Anode/cathode area ratio: The ratio of the anode to the cathode area should exceed 2. This avoids high current densities on the anode that may damage the anode.
Agitation: Efficient agitation encourages rapid replenishment of the solution adjacent to the part.
Solution exchange rate: The solution exchange rate for a given plating tank depends on the configuration of the part, the diffusability of the electrolyte and the efficiency of agitation.

ITT Industries, Cannon at a Glance
ITT Industries is a $4.5 billion global corporation that designs and manufactures electronic components, military defense equipment, fluid handling/controls and automotive products. Cannon, the connectors and switches division of ITT Industries, makes up about 17 to 20% of the company's total market. This division has 18 plants in North America, Europe and Asia, with products sold worldwide.

Key products of the division include interconnects, cable assemblies, RF connectors, switches, keypads, I/O card kits, smart card systems, LAN components and high speed/high-bandwidth network systems and services.

Cannon products are used for payload launch systems, manned space stations and the Mars Rover. In fact, NASA has sp'fied Cannon for all its shuttle missions.

Beginning with the first propeller-driven passenger flights and advancing to the supersonic Concorde, Cannon has long set the standard in commercial aviation. Rack and panel assemblies invented by Cannon are still used for mission-critical aircraft radar controls, communications equipment and instrumentation.

Cannon's slogan is "Engineered for Life." However, it is really more than that, as Glenn Leibowitz, advertising manager explained, "It is simply the way we approach each and every one of our customer's projects."