Editing Printed circuit board milling (section)

{{Short description|Process of creating circuit boards}}
{{Undisclosed paid|date=June 2022}}
[[File:Milled PCB.JPG|thumb|A milled printed circuit board]]

'''Printed circuit board milling''' (also: '''isolation milling''') is the [[Milling (machining)|milling]] process used for removing areas of [[copper]] from a sheet of [[printed circuit board]] (PCB) material to recreate the pads, [[signal trace]]s and structures according to patterns from a digital circuit board plan known as a ''layout file''.<ref>{{Cite book|url=https://books.google.com/books?id=VY8iBAAAQBAJ|title=Printed Circuit Boards: Design, Fabrication, Assembly and Testing|last=Khandpur|first=R. S.|date=2005|publisher=Tata McGraw-Hill Education|isbn=9780070588141|language=en}}</ref> Similar to the more common and well known chemical PCB [[industrial etching|etch]] process, the PCB milling process is subtractive: material is removed to create the electrical isolation and [[ground plane]]s required. However, unlike the chemical etch process, PCB milling is typically a non-chemical process and as such it can be completed in a typical office or lab environment without exposure to hazardous chemicals. High quality circuit boards can be produced using either process.<ref>{{Cite journal|last1=Baschirotto|first1=A.|last2=Dallago|first2=E.|last3=Malcovati|first3=P.|last4=Marchesi|first4=M.|last5=Venchi|first5=G.|date=2007-02-01|title=A Fluxgate Magnetic Sensor: From PCB to Micro-Integrated Technology|journal=IEEE Transactions on Instrumentation and Measurement|volume=56|issue=1|pages=25–31|doi=10.1109/TIM.2006.887218|s2cid=27250870 |issn=0018-9456}}</ref> In the case of PCB milling, the quality of a circuit board is chiefly determined by the system's true, or weighted, milling accuracy and control as well as the condition (sharpness, temper) of the milling bits and their respective feed/rotational speeds. By contrast, in the chemical etch process, the quality of a circuit board depends on the accuracy and/or quality of the mask used to protect the copper from the chemicals and the state of the etching chemicals.<ref>{{Cite book|url=https://books.google.com/books?id=eeN_bsWEe_sC|title=Microelectronic Packaging|last1=Datta|first1=M.|last2=Osaka|first2=Tetsuya|last3=Schultze|first3=J. Walter|date=2004-12-20|publisher=CRC Press|isbn=9780203473689|pages=185|language=en}}</ref>