Connector pressing offers substantial advantages that soldering cannot match. In addition to the basic points such as high process speed, reliability, quality and simple handling, it is also possible to implement special technical solutions, such as interface connectors and wire-wrap connections. Dies, machines and the connector systems themselves have meanwhile been optimally adapted to the processing technology.

Press-in machines that offer a robust and simple construction, force/stroke monitoring and easy operation are used particularly in large backplane companies, where speed and quality control are especially important, but also by small contract manufacturers who have to process a large number of different applications and whose customers demand quality-assured processing.

Since the advent of press-in technology, Harting has been studying reliable processing of the accompanying connectors. It was quickly seen that the measurement and evaluation of the press-in force was the key to reproducible, high-quality connections. This is why the family of CPM machines (Component Press-in Machine) was created for the production of backplanes and daughter cards back in the 1990's, and why Harting continues to improve and expand this family. The latest development step is the type "CPM prestige" machine. The press-in machines were developed in close cooperation with customers right from the outset, which has ensured that the machines provide the technical features necessary for a reliable process while also offering the simplest operation, safe die handling and efficiency. In detail, the following features deserve mention.

100 kN Press-in Force for all Applications

The machine features a servo-electric drive that can generate forces from 1 to 100,000 N depending on the selected gear ratio. This allows all relevant connector systems to be reliably pressed in, with the press-in forces measured with a resolution of some 5 N. Using an electric drive system makes it possible for the downstream evaluation logic also to carry out a reliable and very precise cutoff (< 3 ms), which would not be possible with pneumatic or hydraulic systems. In order to handle the high forces safely, high-precision guides are used that prevent the die from tilting. This allows even connectors outside the center of the force to be reliably processed without having to be repositioned - the PCB is simply displaced linearly.

Open Press Frame for an Optimal View

The company has chosen a C-shaped base frame in order to ensure a better view and simple handling also when processing very large PCBs (up to 1000 mm x 500 mm). Because high forces also always lead to unwanted deformations (respiration) of the relatively light C-frame, it is necessary to compensate for these changes during the process. By using FEM calculations and a special return spring element, it was possible to find a frame shape that actively counters the so-called respiration and consequently ensures that the upper and lower die are always parallel to one another. The active compensation ensures that there are no problems when pressing connectors with a large number of contacts or also when pressing a number of connectors at the same time.

Die System Guarantees Convenient Handling

The necessary dies were developed in a manner oriented to the system and, particularly, the handling, drawing on the company's many years of in-depth experience in manufacturing connector systems. Consequently, a high level of process reliability and simple die operation are guaranteed. The dies are held by a simple trunnion or optionally by a quick-change holder. In order to allow processing of both daughter and backplane circuit boards, a guide frame was developed that can be adjusted simply and precisely, and that can process PCBs sized up to 500 mm x 1000 mm. For some time, connector systems that can be processed with simple, flat counter dies have been used. Inserts that guarantee a high level of process reliability and availability were developed for the corresponding male connectors.

The Path to Quality

The machine's controller is crucial for the press-in system's simple operation and convenient handling. It allows automatic cutoff of the press-in procedure, regardless of outside conditions such as PCB thickness tolerances, tolerances of the end holes diameter and the connectors used (systems and suppliers). The universal cutoff algorithm (Autosense) uses the precise data for stroke and force in real-time in order to generate and interpret curves. This allows precise calculation of the cutoff point that is determined for the press-in process depending on the die system used. The selected drive concept's rapid response time minimises the press-on force. The press-in data acquired are naturally available for further statistical processing, which allows swift and uncomplicated quality analyses. The essential advantage of Autosense, however, is that users do not have to make any measurements of the influencing variables or settings based on them, which practically avoids faulty operation. The idea for simple operation by using Autosense was carried over to the operating interface, a monitor with a touch panel. All runs are initiated by simply touching the monitor, and the user receives all necessary data. The PCB to be processed is shown schematically. The position of the connector to be processed, its image and the die to be used are displayed so that the operator can place the PCB on to the machine correctly. The programming is just as simple. Drag &Drop is used to take the connectors from the provided database, move them on to the PCB and position them. Subsequently, a teach-in dialog is used to move to the appropriate height and store this information. The data can be maintained directly on the machine, or by an external computer using a remote process."All of the computer-supported processing takes place on a dual-core embedded computer system that runs under Windows XP. Because the system has no moving parts, such as a hard disk or the like, it is largely maintenance-free. Simply replacing a CF memory card allows the system to be restored after any malfunction, and the system can be switched on and off at any time without a loss of data. The machine controller was implemented in its own mini control system, separate from the process data processing. This eliminates possible time problems and ensures that the machine's operation is intrinsically safe.