Molded interconnect devices (MID) based on laser direct structuring LPKF‐LDS® technology are widely used in the realm of electronics. Nowaday, design and development of new materials with improved properties for 3D‐MID are in focus. In this work, novel materials based on alumina ceramic with copper oxide additives are developed for this technology. The effect of the sintering temperature and the doping amount of copper oxide on the metallization quality is investigated. Furthermore, the influence of laser process parameters (e.g., laser power, velocity’, and frequency) on process output namely groove dimensions, groove profile, characteristics of structured area, and quality of the final 3D‐MID products are discussed. The novel ceramic materials show high flexibility to realize very fine structures. Moreover, the laser‐structured and metallized area shows a free edge lap with good quality. After metallization high accuracy with copper line/pitch of 16 μm/20 μm is achieved.
Nanostructure formation on bulk metals (copper, gold, and silver) by picosecond (FWHM = 10 ps) Nd:YAG laser irradiation was studied aiming at the production of low-reflectivity surfaces. The experiments were performed at two distinct wavelengths (λ = 355 and 1064 nm) using 20 kHz repetition frequency. The fluence was varied in the 1-11 J/cm 2 range, while the samples were shot by an average pulse number from 0 to 50 depending on the scanning speed of the applied galvanometric scanner. The reflectivity of the treated surfaces was recorded with a visible near-infrared microspectrometer in the 450-800 nm range. Morphological investigations of the irradiated metal surfaces were performed with scanning electron microscope, which showed that mainly two types of nanostructures can be responsible for the reflectivity decrease depending on the type of the illuminated metal. Finite element modeling was performed to simulate the laser absorption-induced heating of the illuminated samples, which helps in the understanding of the structure formation process. It was found that two main processes take place in the production of micro-and nanostructures on the surface; the ejection and falling back of molten metal droplets, and the back scattering and aggregation of nanoparticles.
Laser direct structuring (LDS) is very important step in the MID process and it is a complex process due to different parameters, which influence on this process and its final product. Therefore, it is very important to use a reliable model to predict, analyze and control the performance of the (LDS) process and the quality of the final product. In this work we develop mathematical models by using Artificial Neural Network (ANN) and Response Surface Methodology (RSM) to study this process. The proposed models are used to study the effect of the LDS parameters on the groove dimensions (width and depth), lap dimensions (groove lap width and height) and finally the heat effective zone (interaction width), which are important to determine the line width/space in the MID products and the metallization profile after the metallization step. We also study the relationship between the LDS parameters and the surface roughness which is very important factor for the adhesion strength of MID structures. Moreover these models capable of finding a set of optimum LDS parameters that provide the required micro-channel dimensions with the best or the suitable surface roughness. A set of experimental tests are carried out to validate the developed ANN and the RSM models. It has been found that the predicted values for the proposal ANN and RSM models were closer to the experimental values, and the overall average absolute percentage errors were 4.02 % and 6.52%, respectively. Finally, it has been found that, the developed ANN model could be used to predict the response of the LDS process more accurately than RSM model.
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