Printed Circuit Board Production
of Prototypes in Germany

LeitOn manufactures printed circuits up to 24-layers multilayers with currently around 20 employees in Berlin, Germany. Our professional sales and CAM team is there to support you at any time. Our quality department preforms regular analysis, cross-sections and measurement reports. Most PCB prototypes are produced in a partner factory with around 60 employees in North Rhine-Westphalia. Below you can read about the most interesting machines and processes at LeitOn that allow us to produce your PCBs at the highest quality level.

Materials

We possess a very well-equipped special base-material stock that far exceeds standard FR4 materials and includes some exotic and hard to come-by materials. We do have almost every possible material thickness on stock, each with a variety of different copper cladding. Different types of Rogers high-frequency materials as well as Bergquist or Ventec IMS aluminum base materials are on stock. For multilayers we use Panasonic materials with a TG of 150°C. For TG170 materials we rely on the Taiwanese maker NanYa. Ultra-high TG250 materials like Ventec VT-901 or black FR4 are also available with slightly longer lead times.

Mechanical Processes

For mechanical CNC-drilling we use modern Schmoll-Cube drill machines.  Camera systems allow high-precision drilling. A digital Z-axis measurement system assures exact depth for blind-vias in multilayer PCBs. Both drilling spindles are working at up to 188.000 RPM and automatically adjust speed, plunge and retract according to the selected material. This allows a perfect drill quality. Automatic loading and unloading ensure a high output and cost-optimized overnight drilling. One machine does have a second spindle that allows high accuracy routing. While most other companies use older drill machines for routing, this 2013 built machine combines highest precision measurement systems to make routing as precise as a 0,10mm drill. 

Wet Porcesses

Though-hole-plating (THP) is done by an environmentally friendly polymer-based DMSE process. First all printed circuits are scrubbed to remove any burr from drilling and to roughen the surface for better resist adhesion. Then all boards are going through a "desmear" process that etches back epoxy inside the holes which may have "smeared" over the copper connections. In many companies this process is only used for multilayers but at LeitOn also double-sided PCBs run through this process to assure 100% connectivity of every via. After ultra-sonic cleansing and surface micro-etching the boards are through-hole-plated in the "black-hole-process", using environmentally friendly carbon particles.

Direct Imaging

A Ledia direct imaging system of the Swiss company PrintProcess exposes copper structures directly onto the resist without using films. This process preserves the environment and saves time - always critical in PCB express manufacturing. Furthermore, it allows imaging structures of down to 0,025mm (1mil) and automatically scales the image according to the drill pattern - eliminating drill-offsets almost entirely. A clever front-to-back alignment system for undrilled inner layers eliminates layer offsets almost entirely so that we can build HDI multilayers up to 24 layers.

Copper Plating

Copper plating is done fully automatically with a vertical plating line. Panel parameters like size, copper area and smallest structures are automatically converted into optimized plating currents and diving time for each tank. This ensures a homogenous copper distribution over the complete board. Several cleansing and processes ensure that chemical carry-over is minimized and all tanks remain clean and in perfect condition. The automation of the machine allows our staff to focus on analysis and process control rather than on the plating steps themselves. This assures a high level of reliability and quality in our plating line. 

Multilayer Lamination

Multilayer lamination is done with modern computer controlled Lauffer-lamination presses. Depending on the materials, custom-designed lamination cycles are saved and loaded easily. The vacuum chamber removes any air in the stack so that the adhesion of multilayers is optimized. A separate cooling press allows high through-put while saving energy at the same time. Currently, we manufacture multilayers up to 24 layers. Furthermore we can laminate a wide range of special materials and hybrid-stack-ups.The automatic recording of all press parameters allows easy quality control and dependability in the process.  

Cleaning & Solder Mask

Before solder mask application alls PCBs are chemically cleansed in a horizontal line. A chemical cleansing process prior to solder mask is superior to a mechanical process because already existing copper features are treated more carefully. Solder mask application is then done with a highly efficient curtain coater, which has far higher productivity and more stable quality than common silk screen printing methods. On a curtain coater all panels are driven through a curtain of laquer with very high speed so that the laquer is distributet evenly over the whole panel. Directly behind the curtain coater a evaporation line and horizontal pre-baking oven follow.

E-Test & Final Quality Control

All 2-layer and multilayer PCBs at LeitOn are 100% electrically tested before shipment. Several flying probe test machines from ATG with loaders and unloaders are in use. Soft-touch-needles can be used when bond-pads or very small fine-pitch pads are tested, so that a minimum amount of pressure is on the structures and leaves them intact. Using microscopes we control surface finishes and via-drill x-sections. Each tested panel receivs its own barcode-ID sticker after testing to make sure that all faults are deteced on the repair station.

Routing & Scoring

Final routing is done according to the requirements on a variety of machines. If required, above mentioned Schmoll-dual-head-machines with camera positioning systems are selected. This allows highest precision on most modern levels by exactly aligning the routing path to copper structures on the PCB. For scoring CNC-controlled Löhr & Hermann jump-v-cut machines are used. Jumping or "skipping" sections in scoring-path is useful for complex printed circuits. Aluminium-IMS circuit boards can be scored with diamond-toothed scoring blades, too.

Automatic Optical Inspection - AOI

Mass production quantities are inspected by an Automatic Optical Inspection (AOI). During AOI a camera is scanning the entire PCB panel and compares the pattern to the layout files. Trace-nicks or copper residuals are detected, even if an electric test cannot find them. This AOI process offers additional safety, especially for multilayer inner layers which are scanned prior to multilayer lamination. Especially for IPC-A-600 compliance regarding trace geometries, AOI offers big advantages. Due to its longer setup time, AOI is seldomly used for quick-turn prototypes.

Inkjet-Printing

White legend print is applied by an inkjet-printing process which is similar to conventional inkjet printing systems. Directly after printing, a UV-light is curing the ink on the PCB to avoid any smear. Inkjet-printing allows faster production cycles and higher flexibility. It is environmentally friendly, too, because films and screens are not required. Other colors like black (e.g. for white solder mask) are applied by traditional silk printing process. The advantage of silk printing is a clearer, raster-free print which is preferable for logos and other sophisticated printing objects.

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