Multilayer Registration ControlPrediction: Layer-to-Layer Alignment
One primary characteristic is layer to layer alignment. In addition to our MultiLine tooling systems, we have purchased and implemented the use of the PerfecTest system to fine tune our process and achieve highly accurate scale factor predictions for a variety of material types and core thickness. For most folks, this means investing in new tooling systems that have more pins to ensure greater layer-to-layer accuracy. Depending upon the current state of your tooling, this may not be necessary. The first step would be to check the condition of what you have already. Often, huge gains can be made just by checking the straightness of your pins, quality of your bushings, and flatness of your caul and lamination plates. The next step would focus on pre-engineering. Higher-technology PCBs often incorporate the use of thin cores and mixed copper weights that result in non-uniform stackups. With a non-uniform stackup you can no longer count on all of the cores shrinking or expanding at the same rate that you can correct for in drilling. We have found tools such as X-ray drills and PerfecTest to be invaluable at providing data to continuously tighten your process and scale factors.
Multilayer ImagingCritical Fine Line Resolutions
Saturn has purchased and installed four Olec AT-30 automatic alignment exposure units. These units use four cameras to align artwork top to bottom, and then use panel motion systems to automatically adjust the panel position to a best fit to the artwork. Furthermore, these units have hybrid-collimated light units that ensure exposure light attacks the panel at 90 degree angles to the artwork, which is critical for fine line resolutions.
Microvia DrillingMicrovia Formation Capabilities
Drilling small holes is one thing to master, but drilling small blind vias is a totally different chapter in the book. Most folks assume that both an expensive and time-consuming outsource is involved, or they will have to spend $500k on a laser drill. However, it is important not to overlook the advancements that have been made in mechanical drilling systems. The incorporation of linear motors and scales and refined contact drilling systems enable drill diameters down to 0.002”, with positional and Z-axis accuracy of 0.0005”. This is more than adequate for most designs at less than half the cost of a laser drill. Furthermore, unlike a laser drill, when the mechanical drill is not busy drilling blind microvias it can be commissioned to drill standard products to enhance its ROI. For more information be sure to check out this technical article we published: Microvia Fabrication.
Production PlatingStandard Production and Blind Microvias
Saturn has built a custom automatic PCB plating line that has been designed and constructed primarily in-house. The intent was to minimize plating variation, which is the main goal of production plating. To address issues with plating small and blind holes we use mechanical agitation to allow chemical to flow through holes and vibration to remove air from microvias and blind microvias.
Etching2 Mil Line & Spacing
Saturn has installed a new Hollmuller SES line. This line incorporates the latest in spray technology that minimizes chemical puddling. This is line capable to accurately and uniformly etch down to 2 mil lines and spaces. Most heavy copper projects will have you in inner layer etch at least 3 times as long as standard inner layers. It is critical that you address the strength of the dry film being used. Most standard dry film will manage up to three ounces, but things get sketchy beyond that. It is important that to run development panels to establish the true limits of your dry film; it makes no sense to save 50 cents on dry film just to end up scrapping out a $20 inner layer core.