PCB Manufacturing Cost Drivers

• Technology and density adders include the following
  • Blind vias (laser) – 10-15% per layer (second side is 5%)
  • Buried vias – 50-60% (plus any sub filling costs)
  • Blind vias (mechanical) – 50-60% (plus any sub filling costs)
  • Through hole fill (non-conductive) – ~20% per panel (15% Asia)
  • Subassembly fill (non-conductive) – ~15% per via structure
    • Note: Non-conductive fill maintains wrap plating design guidelines
  • Microvia copper fill – ~20% per layer (15% Asia)
  • Buried sheet capacitance – 0-5% per BC core
  • Buried sheet resistance – 75% per resistive layer
• HD
  • Adders for hole fill, laser microvias, and/or mechanical blind/buried are for the process itself, and are not dependent on the number of holes
    • Rule of thumb: Once you add one blind/buried/filled via, use them everywhere to take advantage of the density increase
    • Cost does not change (you pay for the process and not the number of vias/holes)
  • Use of HDI may be unavoidable in many cases
–   0.5mm BGA, 0.4mm BGA, via-in-pad, reduced PCB size, etc.  
  • The following examples use the index number concept on a 12 layer PCB to illustrate how different via configurations impact manufacturing complexity
–   Starting with a standard through hole design and adding blind/buried vias, microvias, and via-in-pad technologies to see how the index is                                       affected
• Stacku
  • The PCB stackup can have a large impact on the yield of a particular design, as well as its performance
  • There are some simple stackup rules which should be followed to ensure that the design is as robust as possible from a manufacturing point of view
• Stackup-
  • The most important step that can be taken to ensure that no bow & twist or residual stresses are present in the final product
  • The build should be symmetrical about the Z-axis, including copper, prepregs, and cores
  • Non-symmetrical builds can lead to heavy fallout and poor yields at assembly
• Stackup- Matching Copper
  • Designs should utilize the same copper weight on either side or cores
  • Mixed copper weights on cores will result in decreased yields, as special etching techniques need to be used (note that top and bottom copper on cores is etched at the same time)
• Stackup- Limiting Prepreg
  • When possible (except on higher copper weights), designs should use the least amount of prepreg between cores (not always possible on thicker designs)
  • Most economical approach, as each sheet adds cost to the PWB
  • For maximum cost benefit, always allow the fabricator to define the stackup

Cerra Systems is one of the leading PCB manufacturing solutions providers with PCB manufacturing plants located in North America, Asia with certifications for MIL, AS, TS, ISO, & NADCAP. Our products are Rigid, Flex, Rigid-flex, HDI, RF, and hybrid PCBs addressing up to 64 layers and 2 mil technology. Cerra Systems  Major  PCB Market is Aerospace, defense, Medical, computing, cellular & Industrial. PCB Manufacturer Company in India

For more information, visit- http://cerrasystems.com/

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