Multi-Layer FR4 PCB for Industrial Controls
This 12-layer, FR4 printed circuit board (PCB), shown below, was custom manufactured for the industrial controls industry. The first step was to pull the proper laminates for inner layer manufacturing. Tooling holes were drilled in the panels, and the order moved to the imaging department.
Our skilled technicians utilized various photolithographic methods to transfer the customer’s design to the inner-layer panels and performed a thorough in-process inspection. Next, the inner layers moved into the etching department, where all unwanted copper was chemically removed. Again, a thorough in-process inspection ensured that all specifications were met.
After receiving a oxide treatment, the inner layers travelled into lamination, where layup of the panels took place. The hydraulic press was set up to laminate the panels at the proper pressure, temperature, and duration to create a high-quality bond between all the layers. A cool down cycle took place before the panels moved into primary drilling.
After primary drilling, the panels were placed in our plasma etching unit where any residual drill smear was removed from the interior of the hole wall. This step helped to ensure the electrical integrity between the inner layers and the plated holes and vias. The panels then moved into our direct metalization line where a conductive polymer was chemically bonded to the interior hole wall to facilitate subsequent copper electroplating. After outer layer imaging, the panels were processed through the full build electrolytic copper line where a 1 mil minimum copper thickness was deposited on the hole walls and surface areas. A tin or tin-lead etch resist followed the copper process as the panels moved into the final etching process.
The circuit boards were then coated with a liquid photoimageable (LPI) soldermask, baked thoroughly, and then moved into hot air levelling where a thin coating of 63/37 solder was coated onto all the exposed copper surfaces and holes. The circuit boards were then returned to the soldermask area to receive a silkscreened legend which will later assist in component placement during assembly. The PCBs then travelled into final routing where CNC routers machined the circuit boards to their final size and shape.
The completed circuit boards then proceeded to final QA for inspection and electrical testing. Twenty-four multilayer FR4 printed circuit boards were manufactured for this client, vacuum packaged, and delivered to their facility in New York. The product met or exceeded both IPC-6012B and IPC-A-600 industry standards.
Multilayer FR4 PCB Highlights
| Product Description | This multi-layer PCB is used within an aerospace application | |
|---|---|---|
| Capabilities Applied/Processes | Pull proper materials for Inner layer manufacture
Multilayer Lamination CNC Primary Drilling Deburring Plasma Smear Removal |
Direct Metallization
Plating (copper, solder) Etching Hot Air Solder Leveling LPI Soldermask / Silk Screening Final Fabrication Packaging
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| Equipment Used | Alternative Oxide Line CNC Driller CNC Router Etcher |
Flying Probe Electrical Test Hot Air Solder Leveler Plasma Etch UV Exposure Unit, Developer Vacuum Lamination Press |
| Overall Part Dimensions | Layers: 12 Length: 6" Width: 11" |
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| Tightest Tolerances | +/- 0.003" Plated Holes +/- 10% on etched features ±0.005" Overall Routing Tolerances |
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| Material Used | Multifunctional FR-4 (IPC 4101 / 26)
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| Estimated Part Weight | 8 oz | |
| In process testing performed | Cross Section Analysis Full Electrical Testing Solderability Testing |
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| Industry for Use | Industrial Controls | |
| Standards Met | IPC-6012B - Qualification and Performance Specification for Rigid Printed Boards IPC-A-600 - Acceptability of Printed Boards UL94V-0 |