wiki:DFM

This page is dedicated to analyzing how to keep costs low by Designing For Manufacturing (DFM). To see the steps involved in PCB manufacturing click here.

Definitions

  • Annular Rings
    • The donut ("annulus") created when your drill pierces a copper layer. It is defined as the radius of this donut. For example, a .030" pad with an .020" hole would have a .005" annular ring
  • Finished Hole Size (Plated Through Holes)
    • Size of through hole AFTER plating
    • Plated all the way through the board
    • Plated Through Holes are normally drilled 4-6 mils over nominal finished hole size. Copper and solder plating generally reduces hole diameter by ~3-5 mils
  • Unfinished Hole Size (Non-Plated Through Holes)
    • Size of through hole directly after drilling, BEFORE plating
  • Aspect Ratio
    • Board thickness divided by smallest drilled hole (via's).
    • HIGHER aspect ratios (bigger board thickness, smaller hole) increases probability for voids in holes.
  • Further Understanding of terminology with pictures
    • Sunstone Circuits has a great page here that has fantastic pictures illustrating what is what in terms of lingo.

Specs to Minimize Fabrication and Assembly Costs

Note: This list is very conservative, and if followed you should be able to send your design to any manufacturer, assembly house, etc. and get their lowest price possible.

PCB Shape

  • PCB’s must have 2 parallel sides (preferably the 2 longest sides) for process through most automated assembly equipment.
  • Breakaway rails and/or panelization can be used to accommodate a wide variety of odd board shapes.

Board Layer Count & Construction

  • Even number of layers.
  • Odd number of layers lead to warpage problems.
  • Layer stackup should be symmetrical with regard to dielectrics, copper weights, and layer design. Asymmetrical designs are a primary cause of warped boards.

Copper Weights / Trace Widths / Trace Spacings

  • Trace line/spacing
    • 7/7 mils minimum
    • This is for most common copper weights, like .5oz, 1oz,2oz. For higher weights you will need larger width/spacing.
  • Copper Weights
    • less CU weight is cheapest. Such as .5oz for inner layers and 1oz for outer layers *Go as light as possible and still have good current handeling.

Drill

http://www.atechcircuit.com/pcb-capability/rigid-pcb

  • Hole Size* * Annular Rings
    • For cheapest price across all companies, go >=15mils if you can. This includes vias.
  • Annular Rings
    • 7mil minimum
  • Aspect Ratio
    • No higher than 6:1
  • Hole Tolerances
    • Plated Through Holes
      • 6 mil window is ideal (+/- 3 mils)
      • If PTHs over 100 mils are located at the edges of the board, they should have large outer layer pads to prevent too fast plating.
        • Pads 200 mils larger than the hole
    • Non-Plated Through Holes
      • 4 mil window

Select PCB Fabricator Requirements and Minimums

OSH Park (Only Fab, no Assembly)

  • Design Rules
    • 2 Layer Board Minimums:
      • Trace Width and Spacing
        • 6 mils
      • Traces to Edge of Board
        • 15 mils
      • Drill size
        • 13 mils
      • Anular Ring
        • 7 mils
    • 4 Layer Board Minimums:
      • Trace Width and Spacing
        • 5 mils
      • Traces to Edge of Board
        • 15 mils
      • Drill size
        • 10 mils
      • Anular Ring
        • 4 mils
    • 1.6mm thick (0.063")
    • 1oz copper on outer layers, 0.5oz on inner layers
    • Can have internal cutouts (draw on board outline layer)
    • NO plated slots
  • Prices and Turnaround times
    • For prototyping (price includes 3 boards)
      • 2 Layer boards: $5/square inch. Ship in under 12 calendar days from order
        • NOTE: You can get turn time to 5 business days for extra cost of $89 per design. Super Swift Service
      • 4 Layer boards: $10/square inch. They go to the Fab once a week and have a 2 week turn time once in fab.
    • Larger orders:
      • Minimum of 150 square inches (no upper limit)
      • You can have different designs, but each design must be ordered in multiples of 10 (and in total add up to 150 square inches)
      • 2 Layers
        • $1/square inch
        • Ship in ~3 weeks from order
      • 4 Layers
        • $2/square inch
        • Ship in ~1 month

Advanced Circuits / 4PCB (Fab and Assembly)

  • Phone Number, sales department in East Cost: 1-800-979-4722 EX. 1339 (Ashley)
  • Design Rules
    • All board minimums
      • Trace Width and Spacing
        • A premium is charged for trace width/spacing less than 7 mils
        • 0.5oz CU (inner layers): 4 mils
        • 1oz CU (outer layers): 4 mils
        • 1oz CU (inner layers): 5 mils
        • 2oz CU (inner & outer): 6 mils
        • 3oz CU (inner & outer): 10 mils
        • 4oz CU (inner & outer): 12 mils
      • Copper to Edge of Board
        • Outer Layers: 10mils
        • Inner Layers: 15mils (20 mils preferred)
        • For Scoring, Outer Layers=15mils Inner Layers=20mils
      • Drill size
        • 13 mils
      • Pad Size/Anular? Ring
        • Vias:
          • Pad Size=10mils over finished hole size, so annular ring=5mils
        • Component Holes:
          • Pad Size=14mils over finished hole size, so annular ring=7mils
      • Inner Layer Clearances
        • 10mils
      • Hole Tolarances
        • 4mils (if we don't specify, default hole tolerance is 5mils)
      • Board Thickness (tolerance may vary 10% (min. +/-5mils))
        • 2 Layer: 20mils
        • 4 Layer: 20mils
        • 6 Layer: 31mils
        • 8 Layer: 47mils
        • 10 Layer: 62mils
      • Rout (board outline and internal cutouts)
        • +/-10mil tolerances
      • Slot Width
        • 31mils
      • Silkscreen (Legend)
        • 5mils line width
    • Offer 0.5,1,2,3,4 oz copper on inner layers, and 1,2,3,4 oz copper on outer layers
    • NO custom oz CU (like 1.5 or 2.5oz)
    • Links:
    • Standard Specs:
      • Non-plated slots & cutouts
      • Green soldermask, white legend, FR4
      • 1oz CU inner layers, up to 2oz CU on outer layers.
      • Overall thickness: 31,62,93, or 125 mils
      • Trace/Space? at 5/5mils *Gold finders, lead-free solder
      • Rout Tolerance +/-10mils, Hole Tolerance +/-5mils
      • Minimum Hole Size=10mils
      • Fiducials and/or Tooling Holes
  • Assembly Considerations
  • Prices and Turnaround times, fab and assembly
    • DFM Check, which will give insight onto clearances that the manufactuer uses
    • For prototyping:
      • 2-Layer PCBs
        • $33 offer
          • $33/board, minimum of 4 boards Note: with Student Program, no minimum PCB quantity. type word 'Student' in COMMENTS section when placing each board. Must have University shipping addresss
          • Turn around time=5 days
          • Plated or non-plated holes
          • NO slots, internal routing (cutouts), scoring, tab rout, or drilled hole board seperations.
          • Minimum 6mils line/space, Minimum 15mil hole size
          • FR-4, 62mils, 1oz CU
          • Max size=60in square
          • Max 35 holes/sq. inch
        • BareBones?
          • FR-4, 62mils, 1oz CU
          • Plated or non-plated holes
          • 6mil line/spacing minimum
          • Tin finish over 1oz CU
          • NO internal routing (cutouts), scoring, tab rout, or drilled hole board seperations, mask, legend
          • Rectangle only
          • Minimum size: 1.25" x 1.25" Maximum Size: 12" x 16"
          • Gerber 274X prefered (274D also good)
          • English Units for drill (Excellon)
          • Minimum Hole size: 15mils
          • Max size=60in square
      • 4-Layer PCBs
        • $66/board, minimum of 4 boards Note: with Student Program, no minimum PCB quantity. type word 'Student' in COMMENTS section when placing each board. Must have University shipping addresss
        • Turn around time=5 days
        • NO slots, internal routing (cutouts), scoring, tab rout, or drilled hole board seperations.
        • Minimum 6mils line/space, Minimum 15mil hole size
        • FR-4, 62mils, 1oz CU
        • Max size=30in square
        • Max 35 holes/sq. inch
    • Larger orders:
      • Standard Specs are same as above listed.
      • Custom Specs will cost more.
    • Fabrication Quotes: *Quote matrix here.
      • Need to know smallest hole size, # pads on top/bottom, thickness, etc
      • Max quote of 100 boards, larger you need to call
      *FreeDFM quote.
      • Need gerber files and quote will be emailed to you in minutes.
      • Also shows potential issues with manufacturing
    • Talk to a person
  • Assembly Quotes:

Sunstone Circuits (Screamiung Circuits for Assembly)

  • Design Rules
    • Depend on service, see below for details
  • Prices and Turnaround times
    • Detailed list for all options can be found here.
    • PCBExpress Quickturn and ValueProto? PCB Prototype Services
      • Quantity: 1-100, practically only for small runs 1-15
      • Lead times:
        • PCBExpress Quickturn:
          • Next Day (2-layer) , 2-Day (2,4-layers), 3-Day (2,4,6-layers)
          • Pricing in table form, no input required
        • Value ProtoPCB:
          • 5-Days (2-layer)
          • Pricing, need demensional input and quantity
          • MUCH cheaper than Quickturn on most orders
      • # of Layers: *1(treated as 2 layer)-6
      • Copper Weights:
        • Inner: 1oz
        • Outer: 1oz
      • Trace/Space? minimums:
        • Inner: 6/6mils
        • Outer: 6/6mils
      • Clearance for TH drill
        • Inner: 25mils larger than finished hole size
      • Pads for TH drill
        • Inner: 18mils larger than finished hole size
      • Board Thickness Availible
        • 62mils ONLY
      • Soldermask color
        • Green
      • Soldermask minimum web (smallest strip possible, such as between two pads NOT INCLUDING soldermask relief)
        • 5mils
      • Silkscreen info
      • Drill info
      • Board Size:
        • Max: 12" x 14"
        • Min: .25" x .25"
      • Slots, Cutouts, Routing, etc: For percise details go to here, and scroll down to Route (Tab) and V-scoring.
      • Tin-lead finish only
      • FR-4
  • PCBpro Full Feature
    • Quantity: 1-15,000
    • Lead times:
      • 2 days to 5 weeks
    • # of Layers:
      • 1-14 layers
    • Copper Weights:
      • Inner: .5, 1, 2oz CU
      • Outer: 1, 1.5, 2.5oz CU
    • Trace/Space? minimums:
      • Inner: .5oz CU (5/5mils), 1oz CU (6/6mils), 2oz CU (8/8mils)
      • Outer: 1oz CU (5/5mils), 1.5oz CU (10/10mils), 2.5oz CU (13/13mils)
    • Clearance for TH drill
      • Inner: 20mils larger than finished hole size
    • Pads for TH drill
      • Inner: 18mils larger than finished hole size
    • Board Thickness Availible
      • 31, 47, 62, 93, 125 mils (and custom thickness)
    • Soldermask color
      • green/blue/black/red/white
    • Soldermask minimum web (smallest strip possible, such as between two pads NOT INCLUDING soldermask relief)
      • 4mils
    • Silkscreen info
    • Drill info
      • 10mils = smallest drill
      • Details
      • Note: holes 18mils or less may be plugged
    • Board Size:
      • Max: 14" x 18"
      • Min: .25" x .25"
    • Slots, Cutouts, Routing all YES
    • FR-4 Tg, High Tg, High Td, Low CTE
  • Fabrication Quotes:
    • DFMplus quote.
      • Need gerber files and quote will be emailed to you in 2 hours.
      • Also shows potential issues with manufacturing
    • Easy online quote, no gerber files or specific # of pads required. Quotes are here
    • Talk to a person
  • Assembly Quotes:
    • What they need (look here for specifics on the below):
      • BOM
      • Gerber Files (RS-274X - same as PCB fabrication)
      • Centroid (Pick and Place, CPL, and other names).
        • They can generate this from Gerber for an extra charge
      • ASCII-Formateed CAD data
        • ONLY for Short-Run Production Orders
      • Assembly Drawings, instructions or photos
        • NOT REQUIRED, but "Do help to ensure all special PCB assembly instructions are carried out properly. If requresting any non-standard processes or have ambiguous placements, provide helpful documentation.

Gold Phoenix PCB (Fab and Assembly)

*Design Rules

  • Layers
    • 1-12 Layers of FR-4
  • Minimum Board Thickness *
  • Prices and Turnaround times *For Quick Online Quote:

wiki:3Dprinting

Last modified 7 years ago Last modified on May 29, 2015, 10:29:14 AM

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