Preproduction Engineering – Computer-aided Manufacturing

Once we have received your purchase order, Gerber files, or 1 to 1 artwork and drill files with fabrication drawing, our first step would be to perform CAM review.

Cam is a tool that provides quality compliance at every step of the manufacturing process. Our cam work stations enable us to perform design rule checks on Gerber data before creating panelized artwork and drill files that result in perfect registration. Our cam operators will review and edit all Gerber data to ensure compliance to DFM guidelines and quality control standards. Design Rule Check (DRC) allows us to to identify and resolve manufacturability issues before manufacturing.

Editing, tooling and panelization are all performed on our CAM engineering systems. In case of design/ board requirement conflict, our engineers will contact the customer to resolve the issue. Once all the layers are checked and files are  verified data is  than transferred to Laser Photoplotting for artwork generation.

Production Control

Key technologies used are computer workstations, numerically controlled drilling and routing machines, photographic and imaging systems, plating and etching machines, analysis equipment, lamination press and flying probe electrical testing machines.

Lamination (Multi layers)

  1. Maximum number of layers: 16
  2. Maximum Boards thickness: .125″
  3. We will engineer best balance stack up when not customer specified.
  4. Bow and Twist: Flatness is 1.5% worst subject to design and dielectric
  5. Panel thickness tolerances:
    015″ to .030″ – +/-.003″
    .031″ to .080″ – +/-.005″
    .081″ to .125″ -+/-.008″
    >.125″ – +/-10%


The most sophisticated boards are processed in our state of the art Excellon CNC drilling, routing and programming Department.  Drilling is the second largest expense of printed circuit board. number of drill hits, stack height and different hole sizes can affect your board pricing.  The number of boards that can be drilled in one setup is determined by drill diameter, registration tolerance and board thickness.
  1. Drill size is larger than finished plated hole size by .006″
  2. Minimum Drilled Hole Size:  .010″
  3. Max Hole Size: No Limit
  4. Minimum Slot Width: .025″
  5. Minimum Signal Pad:   .020″ > nominal hole size
  6. Minimum Annular ring if not specified:   .001″
  7. Minimum Plane Clearance : .020″ larger than nominal pad size or non plated thru-hole


  1. Minimum Conductor width:                   .006″
  2. Minimum Conductor spacing:               .007″
  3. Conductor to Board Edge:                       .020″
  4. Drill Hole Edge to Board Edge:              .050″
  5. SMT Pitch:                                                          .025″
  6. Layer to layer registration:                       .005″

Plating & Surface Refinishing

  1. Type: Acid copper
  2. Thickness: .001 Avg./.0008min
  3. Hole to surface ratio: 1.4 – 1.0
  4. Edge Connectors
    Nickel thickness: .0001″ to .0004″
    Gold thickness: .00003″ to .00005″
  5. ROHS HAL TIN Plating (96%)
  6. Soldermask Over Bare Copper(SMOBC) with Hot Air Leveled Pads and Holes
    Type: 63% tin – 37% lead
    Thickness: .0003″ to .0008″


This is a chemical process by which excess copper is removed from the bare boards. During the etching process the etchant due to impingement forces removes copper downwards and laterally. For outer layers due to additional copper plating the ratio of vertical vs lateral etch is 1:1 but for inner layers it is 2:1.
Hence copper clad weight is the most important factor in controlling trace widths. The trace width is controlled by the plotted artwork. The etching process does not reduce the base of the linewidth significantly but does affect the top of the linewidth and this in turn will affect electrical performance characteristics like impedance.
Finished Conductor Widths from the Original Artwork
  1. .5 oz Cu Internal layers – -.0005″ External layers -.001″
  2. 1 oz Cu Internal ( -.001″ ) External ( -.0015″)
  3. 2 oz Cu Internal (-.002″ ) External (-.003″)

SolderMask / Legend

This file is provided by the customer. Correct clearance sizes for pads is performed as part of the pre production tooling process. Liquid photo imageable solder mask is considered to be choice for most circuit boards due to their higher resolution, excellent electrical properties, and compatibility with surface mount technology.
  1. Solder Mask Pad Size : Screened mask .015″ over pad size LPI .005″ over pad size
  2. Thickness per IPC SM-840 (B)
  3. Legend Color: white preferred  yellow, black  orange available
  4. Legend Height: screened mask .060″ LPI .045″
  5. Legend Width: screened mask .010″ LPI .008″Thickness: .0003″ to .0008″

Electrical Testing

3 Main parameters for testing are:
  1. Voltage: Maximum test voltage: 115v to 230v . This is the amount of power applied to the circuits.
  2. Continuity resistance: 1 ohms minimum. This is the maximum resistance allowable to the circuit. Any higher resistance would indicate an open circuit.
  3. Isolation resistance: 100 ohms maximum. The minimum resistance allowable between electrical entities. A lower resistance would indicate a possible short circuit.
  4. CAD and Gerber to net list
  5. 100% netlist test on all boards including:
    Through hole
    Dual sided surface mount
    Fine Pitch
    Buried/Blind Vias
    Split plane
  6. Occasionally we will do Beep Test Coupons for testing inner layer registration
  7. All our testing is done on either ATG 1000 or Probot Flying Probe machines


The final manufacturing stage is to profile the PCBs and cut them out of the production panel. A computer-controlled milling machine or “router” will mills out any internal non plated small slots or cut-outs. It will than route out the board from the panel. V-scoring and or tab routing can also performed based on your array  layout.

Final Inspection

Final Inspection of all products ensures compliance with customer specifications, including finished hole sizes, dimensional measurements, through hole integrity and quality workmanship.

REquest a Quote

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“...For over twenty years, we've relied on Fineline Circuits Inc. to manufacture all of our circuit boards. While they compete favorably in both price and quality, it is their intangible services that set them apart from their competition...”
–Steve Sanislo
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