Take a look inside a PCB fabrication plant and learn how boards are professionally manufactured.
Royal Flex Circuits is a PCB manufacturing facility in Santa Fe Springs, California. The company is part of the Royal Circuits Group, owned by Royal Circuit Solutions, and focuses on flexible and rigid circuit boards, in particular fast-turn PCB manufacturing for enterprise-grade and individual board manufacturing.
AAC Technical Editor Mark Hughes was invited to tour a new installation in progress. Royal Flex Circuits had outgrown its previous slot and at the time of the tour was in the process of moving to a new one.
Part of the Royal Circuits team for the wet process spill containment area. In the photo from left to right: Scott Khono, Omar Madrigal, Larry Ybarra, Tracy Ho, Riki Gracia, Mihir Shah and Bob Meyer. All images are property of Mark Hughes.
So what equipment is in a PCB manufacturing plant? Here’s a look at the parts of the PCB manufacturing process.
DLG spindle only
The LENZ single speed DLG performs PCB micro drilling and routing. To maintain accuracy in wide temperature and humidity conditions, the machine is built on precisely ground granite blocks. An automatic spindle drills holes and sensors can detect broken holes.
Royal Circuits employee Danny Ho in front of the LENZ drill
UV Microvia Drill Laser
Microvias are laser drilled to achieve precise depths. The ESI UV laser microvia drill is shown below. Since the power output of lasers decreases over time, employees must carefully document and adjust the machine for each cycle and process.
ESI UV laser microvia Drill.
Computer vision and manual inspection
As you can imagine, creating a working PCB requires careful inspection and quality control during every stage of the manufacturing process. Manufacturers inspect with a variety of machines at all stages of the process.
Automated inspection machines use computer vision and conductive probes to ensure that there are no electrical or mechanical failures that could prevent a PCB from working. Humans inspect PCBs for faults that automated machines cannot detect.
Flying probe machine
A flying probe machine takes two conductive probes and touches various pads at different locations on each PCB. Electrical conductivity indicates that the pads are connected and that the network is electrically solid.
A flying probe machine tests continuity between networks by rapidly moving the probes around a PCB (image manipulated to blur patterns)
More machine vision and human inspection
Automatic machine vision cameras methodically search for PCB faults. Each potential error must be manually inspected by a trained technician who then accepts or rejects the potential failure. A Camtek inspection camera then looks for failures that could occur during the manufacturing process.
When a potential error is detected, a technician will determine its significance and then manually repair the PCB, if possible.
A technician manually inspects a PCB for errors.
Not all PCB testing is non-destructive. Each PCB has a small area of the board that is cut to determine the quality of the coating after a coating bath. Other parts of the PCB are encapsulated in epoxy and are viewed through a special microscope that inspects for quality and thickness.
Each table is tested to determine the quality of the plate. A part of each table is sacrificed for the test.
Board parts are epoxy coated for separate test forms
For very high speed circuits, a consistent impedance is essential. Something as insignificant as the varying amount of epoxy between layers of a PCB can change the impedance by several percentages, enough to cause signal integrity problems.
To confirm the actual impedance of a PCB, an impedance coupon is added to the edge of each PCB.
An example impedance coupon attached to some tables.
Impedance coupons are added to the perimeter of each board that has a controlled impedance specification. Technicians can measure the coupon impedance to determine the impedance of the board.
The full transition of the store from the old facility to the new facility is not entirely complete – the wet processing area is still under construction so I plan to visit again. But I certainly enjoyed watching the various stages of construction.
Thanks to the owners and workers of Royal Flex Circuits for their willingness to show me the store.