peiker’s Management Goal: Zero Defects
by Gerd Koschnick, Senior Process Technician
peiker is a leading provider of components in the area of communications technology – both for cars and for professional radio (PMR). Founded as an acoustics company in 1946, its product portfolio extends to all components of in-car infotainment and entertainment. peiker’s connectivity modules are suitable for use in vehicles and enable a fast and reliable data transmission on the road; under the heading of “connected car”, it thus opens the car door to the internet, navigation, other manufacturer-specific assisted services, and emergency call (eCall). Among peiker’s regular clients are renowned international auto manufacturers, industrial firms, government agencies, and mobile phone manufacturers. More information is available at www.peiker.com.
Automotive electronics is one of the more demanding segments of the electronics manufacturing industry. Product quality and reliability, therefore, become paramount for peiker along with customer demands for traceability. Gerd Koschnick, Manager of the SMT and Process Department at peiker, has set a goal of achieving zero-defect production. Automotive clients typically require a quality level of maximum 50 ppm, while peiker is currently running at 15-20 ppm.
A further challenge for Mr. Koschnick is that he manufactures a large number of different printed circuit boards (PCBs) on a weekly and monthly basis. In 2012, peiker manufactured in excess of 340 unique PCBs. Another challenge is to achieve the required quality both in their factory at its HQ in Germany as well as at its second factory located in Mexico.
Car manufacturers require a high level of traceability, including process traceability. Should a product fail in use at a later stage, it is important to identify the root cause in order to eliminate the possibility of this defect occurring in the future. A second purpose of traceability is to limit the scope of such a potential recall. When tracing the root case and identifying which production run was affected, the recall can be limited to only the products from that production run. Fortunately, to date, peiker has not needed to recall any products; however, the system is in place should it be necessary. Mr. Koschnick’s focus is to avoid producing any defects or latent defects in the first place. His philosophy is to make sure that every single process in his production department is safe — not only as individual and separate processes but also the order in which they occur. peiker has implemented routines and locking mechanisms that prevent processes occurring out of order. It is not, for example, possible for a technician to divert the normal process flow by performing automated optical inspection (AOI) prior to soldering.
While world-class quality and traceability are non-negotiable requirements, peiker needs to achieve these with low-cost production. The cost pressure in the electronics industry in general is relentless and continuous. Mr. Koschnick, however, does not see any inherent conflict in these two separate goals. As a matter of fact, high production quality may lead to lower cost by eliminating or reducing scrap, rework and waste. Waste is a term not limited to avoiding scrap and wasted material. Waste is a large category spanning all kinds of inefficiencies such as unnecessary production downtime, excessive electricity use, low productivity and much more.
A real life example on how peiker executes its production philosophy can be seen in its soldering process. Several years ago, peiker’s automotive customers required daily or weekly profiles of their PCBs in order to verify that their products were being processed in spec. In other words, the profiles were required to document that the components were not being stressed beyond the tolerances set by their manufacturers, and that the solder joints were strong by following the time versus temperature profile limits set by the solder paste manufacturer. Mr. Koschnick saw several weaknesses by such a routine. First, it essentially meant running his thermal process blind nearly all the time, with the exception of that single PCB that was profiled on a periodic basis. Second, it was inefficient by requiring significant amounts of manual labor and causing production downtime. Third, it introduced opportunities for error and it did not lend itself to provide process control and process improvements.
Manual profiling is inherently subject to inaccuracies and it is inconsistent. Because it relies on spot checking, no information exists in between profile runs. The biggest problem, however, relates to the deterioration of the measuring vehicles over time. Automotive manufacturers want to know the profile on their specific PCBs and typically will not accept profile data on a fixture that is not representative of their particular product. This then requires attaching thermocouples (TCs) to a representative PCB and running manual profiles for that PCB. Repeated runs with the same PCB will cause it to break down and change its thermal properties. Already after less than 10 runs, the PCB is physically lighter and it no longer provides representative profile data. This forces the electronics assembler to replace the profiling PCB with a new PCB and reattach all the TCs. It is very difficult to attach TCs in the exact same manner and tends instead to cause measuring variances. This is especially true when using conductive epoxy or high-temperature solder for TC attachment. Just a small variation in the position and volume of epoxy/solder will affect the readings. Using aluminum tape for TC attachment reduces this problem because the tape is nearly inert and thus does not affect the temperature reading much at all.
The solution peiker chose to overcome all these issues was to implement the KIC RPI, an automatic profiling system that measures each PCB’s thermal profile in real-time. The system also verifies on the fly whether each PCB profile falls within the customer’s process tolerances. During a visit to SMT Nuremberg in 2013, Mr. Koschnick listed a number of benefits that his implementation of automatic and continuous profiling had achieved. At the top of his list was the fact that now he could “sleep well at night.” By that he explained that he no longer runs his thermal process blind. Each PCB is profiled and verified. Should the process be out of spec, or out of control, an alarm will sound immediately. They also can automatically shut down the oven feed conveyor to allow the responsible engineer to correct the process before production continues. Quality is secured by making sure that each PCB is processed correctly in the reflow oven. Built-in real-time SPC charts are available to control the process and to act as an early warning system that enables the engineers to adjust the oven before any defects may occur.
The automatic profiling system utilizes 30 sensors permanently installed in each reflow oven. A board sensor detects the position of the PCB in the oven at all times and a speed encoder measures the conveyor speed. The automatic profiling system requires an initial programming routine before automatically measuring each PCB profile. The programming is performed using a manual profiler with TCs attached to the relevant components on the PCB (preferably using aluminum tape for attachment). This one-time manual profile run collects two sets of simultaneous data: The time-temperature data from the manual profile and hundreds of thousands of datapoints generated by the 30 sensors in the oven along the path of the PCB. The dynamic data from the 30 sensors measure the environment to which the PCB is exposed. Knowing this environment and the thermal properties of the PCB is all that is required. Since the relationship between the two sets of data stays constant (set by the laws of thermodynamics), a correlation can be calculated easily. The end result is that when production starts, the 30 sensors can very accurately measure each PCBs profile on the fly with no further manual intervention. The accuracy of such a system is extremely high, (usually better than manual profiling), and it can easily be verified with a simple accuracy and repeatability study.
peiker is implementing bar codes on many of its products for traceability purposes. Some of the products are assembled attached to a fixture that holds several PCBs. In this case, the fixture or panel frame has a unique barcode as opposed to barcodes on the individual PCBs. The bar code system still works because the number of PCBs is always known per panel frame. Should a product fail in the field at a future date, the KIC RPI system will use the bar code data to retrieve the process information specific to that PCB. The thermal profile and how it fits with its process window is available for any specific PCB at any time. The system stores all the process data electronically for future retrieval should this be necessary.
One of the other benefits of such a system is that it provides better process information that can be used to identify any shortcomings of the thermal process. There also is a built-in process optimization software that essentially does an exhaustive simulation of all possible oven setups (zone temperature and conveyor speed combinations). The software will guide the technician to the best setup in order to operate in the “sweet spot” of the process for each PCB type.
This oven setup optimization software is also used to find a single oven recipe that can process numerous, different PCB types in spec. A handful of different oven recipes now can solder the vast majority of peiker’s 340 different PCB types in-spec. This has cut down tremendously on oven changeover time. Such upfront process optimizations are one of the reasons for peiker’s exceptional yield results. It should be mentioned that, as an OEM, peiker has the added benefit over a contract manufacturer by controlling the design of its own products. There is an intimate communication between peiker’s Production and Design departments, allowing them to change and optimize the PCB design for better manufacturability when needed. This leads to far fewer defect issues on the production line, but nevertheless the process control systems are already in place should they be needed.
Future considerations
peiker is constantly developing new and more advanced products that will make soldering even more challenging in the future. One concern is that some of the new applications will lead to slower conveyor speeds. Should this happen, the oven setup software will be used to search for recipes with faster conveyor speeds that can still process the PCBs in spec. The constant price pressure is expected to remain in the future. Last year, peiker successfully produced 6 million PCB sides (a double-sided PCB counts as two sides) in Germany. Over the next couple of years, the company will ramp up the production volume significantly. Because Germany is not a low-cost country, the low-cost/high-quality production will require more automation and near perfect process control. Although Mr. Koschnick may be sleeping well at night, he will continue to stay very alert at work.