PCB´s Design - What about production technology of PCB? (part #4)
What about production technology of PCB, is it more valuable production either by etching or by milling? How to design and produce prototype?
DPS can be divided into single (with a conductive layer on top or bottom side), double sided (have conductive layer on tap and bottom side) and now the most commonly used multi-layer (have conductive layers also inside a PCB). For the multi-layer is very important layers layout. The PCB can be produced either by etching (i.e. Wet way) or milling (i.e. Dry way).
Professional PCB production procedure can be found on internet. On their web pages can be found teaching material about production of PCB by etching (wet method). First of all data need to be proceed, then film matrice is produced, then layer build-up, panel preparation, cutting, openings drilling, metalizing through holes, transfer of a conductive pattern from a film matrice on a production panel, galvanic embossing of a conductive layer, tin resist deposition, PCB etching, tin resist removal, solder mask, silkscreen, surface treatment, HAL, NiAu, mechanical finishing by milling, scoring, metalographic micro section. Final step is optical and electrical test.
A fast way to produce a functional PCB is a production by a dry way without a need for etching and creating a chemical waste. I tis suitable for prototypes and functional samples and production time is about 5-7 days. For this purpose various devices are used – enabling to process data (ODB++, Gerber, Excellon ...) from CAD design software via a software application and to create a file for drilling of holes and milling of isolation lines along the conductive tracks (surfaces). Gradually a copper material is being removed by means of special engraving tools and drills with diameters of 0.1 mm to 3.0 mm. For each tool can be automatically adjusts the depth of ingress and rotations according the needs. End shape of a tool is very important. It can be flat (End Mill) or conical (Cutter). Firstly we need to upload data from software and then define if the PCB is single or multi-layer. An important part is to identify the tools for production of PCB and placing them into the holder. Once it is ready we place a PCB on a workplace using a camera and start particular steps of milling (drilling, engraving, mill-cutting...). A control measurement of objects, track widths, holes diameters can be made on a finished board by a camera.
Design and manufacture of PCBs is certainly a broad topic. Other interesting information and a demonstration of the production of PCBs can also be found in the record of the webinar "What not to forget at the PCB design?" at www.soselectronic.com/webinar.