Improving Signal Integrity
Service Detail from Summit Interconnect
Backdrilling
Cost Effective Means of Improving Signal Integrity
Backdrilling is a cost-effective method to improve signal integrity without adding costly additional sub-lamination structures. This process removes the unneeded portion of a via barrel that can cause signal reflections at high speed data rates, or on high frequency RF designs.
Benefits:
- Reduces deterministic jitter by orders of magnitude, resulting in lower Bit Error Rate.
- Reduces signal attenuation due to improved impedance matching.
- Reduces EMI/EMC radiation from the stub end and increasing channel bandwidth.
- Reduces excitation of resonance modes and via-to-via crosstalk.
- Reduces additional lamination structures.
- Minimizes design and layout impact with lower fabrication costs than sequential lamination.
- Improves microwave RF performance.
Design considerations:
- Define which side to start the backdrill.
- Define “Must Not Cut” (MNC) layer. The MNC layer is the layer that must remain connected that is closest to the backdrill depth.
- Keep back distance from MNC layer minimum is .005” with a tolerance of +/-.002”, standard depth is .010”. Please review the signal performance to determine which depth is required.
- Backdrill diameter is typically .008” over the original drill bit used to create the plated via.
- Increase the copper clearance for the backdrilled layers an additional .004”.
- The MNC layer must be at least .010” away from the outer layer from the backdrill side of the PCB. This provides the minimum keep back distance to the MNC layer and provides minimum insulation distance to the outer layer.
Technology Insights
Our teams have been manufacturing PCB's for more than 30 years. Here are some of the best practice guidelines and design resources to assist you in the design process.
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Summit Interconnect is one of the leading providers of complex, rigid, and flexible printed circuit boards in North America, offering solutions ranging from advanced prototyping to high mix, low-to-mid volume production. Summit serves customers across the aerospace, defense, and other highly demanding commercial sectors and has facilities in California, Illinois, and Toronto, Canada. Summit is a recognized industry leader in quick-turn manufacturing and has expertise with a wide range of materials like high-speed digital, RF/microwave, and mixed constructions.