PCE in the manufacture of leadframes
When it comes to the cost-efficient and precise manufacture of leadframes, it is crucial to choose the right process and to be extremely careful when selecting a supplier in order to achieve optimal results. The micrometal Group has developed a next-generation photochemical etching (PCE) process that is ideal for producing leadframes and enables customers to manufacture innovatively designed leadframes with tight tolerances repeatedly and precisely – while also meeting the trend towards miniaturisation and weight reduction.
Jochen Kern, Head of Sales & Marketing at the micrometal Etching Group, explains: “Leadframes are used in the assembly process of semiconductor components and are essentially thin metal layers that connect the wiring of tiny electrical contacts on the semiconductor surface with large-scale circuits in electrical devices and printed circuit boards. When it comes to leadframe design, a one-size-fits-all solution does not always work for every application. There is often a need for customer-specific specifications and features, for designs that improve electrical and thermal properties, and for specific requirements regarding cycle times. micrometal has extensive experience in manufacturing leadframes using PCE for a wide range of customers. We etch simple as well as more complex leadframes from metals and alloys with very low thermal expansion at room temperature. These low-expansion alloys are used in modern applications where metals must be bonded to glass or ceramics, or where matching coefficients of thermal expansion are required to avoid problems in the joint area.”
Leadframes can be extremely complex and at the same time very delicate. In many cases, the geometric complexity as well as the requirements for maximum precision and tight tolerances mean that PCE is not only a suitable technology, but in fact the only technology with which certain leadframes can be manufactured.
When stamping leadframes, increasing complexity drives up costs – regardless of whether small, medium or large quantities are involved. Complex geometries require complex tooling, which in turn results in higher costs, an increased risk of tool failure and longer lead times.
PCE is independent of tooling complexity: neither costs nor lead time are affected by the component’s geometric complexity, as digital tooling is used. In addition, PCE enables tighter tolerances and finer structures than stamping – with minimal or no material deformation and virtually no burr formation or defects. Scrap rates are extremely low, and unlike stamping, every leadframe produced is perfectly flat – an essential requirement.
Kern adds: “There is no doubt that PCE is ideally suited to manufacturing leadframes. This process becomes even more compelling thanks to micrometal’s further developments. Not all PCE providers are the same. micrometal’s unique PCE process enables dimensional tolerances of up to +/-0.005 mm, minimum feature sizes of 25 micrometres, a minimum hole diameter of 80% of the material thickness, and repeatable tolerances in the single-digit micrometre range. By comparison, conventional chemical etching only achieves minimum feature sizes of around 100 micrometres, and the smallest hole diameter relative to material thickness is a factor of 1–2. It becomes clear how micrometal’s PCE process opens up numerous design possibilities in leadframe manufacturing that were previously impossible.”
When evaluating PCE for leadframe production, it is important to consider both the advantages of the process and the selection of the right partner – with their expertise and experience being decisive.
Kern concludes: “One example is the potentially higher susceptibility to defects due to the large number of process variables in PCE. Thanks to decades of experience, Europe’s leading PCE specialist micrometal has a robust and repeatable process for manufacturing leadframes that is difficult for other providers to match. This experience plays a key role in compensating for potential weaknesses in the PCE process. The company has invested heavily in process control to reduce variation, as well as in optical inspection systems to achieve zero-defect rates (0 ppm). Quality assurance is micrometal’s top priority: we work with 100% inspection, and defects are not tolerated. That is why we are proud to produce customised leadframes for some of the world’s leading manufacturers in semiconductor packaging.”
micrometal’s tight-tolerance manufacturing processes are suitable for numerous leadframe applications, but are particularly well suited to producing leadframes with high lead/pin counts and extremely fine pitch in large volumes.
