Rugged solutions engineered for the world's harshest environments
PCB Design
Hardware Design Capability to Meet the Demands of Today's Electronics and Printed Circuit Board Requirements
Characteristics
- 14 or more conductive layers
- Power & ground planes to control stray noise
- Planes for Shielding from EMI & RFI
- Protection of sensitive circuits
- Control of crosstalk & parallel runs
- Management of RF signals
- Split-planes for added isolation between susceptible circuits
- Management & suppression of ground & power loops
- Clock speeds of 500 mHz or higher
- Striplines, Differential pairs, & controlled impedance connections
- Sets of matched lengths of runs
- Point-to-point signal delay control
Stackup Layers
Stackup layer planning is an important basis to the design of a sound PCB. This may involve plane layers, impedance controlled lines, special base materials, etc. Shown here is a simplified cross-section diagram for a typical 12 conductive layer, 62 mil thick PCB.
Characteristics
- Up to 35 components/parts per square inch per side
- 6000+ components/parts per board
- Up to 120 pins per square inch per side
- 19,000+ pins per board
- Up to 2800 nets per board
- 4 mil lines & 4 mil gaps
- Step-&-repeat, multi-channel, & reuse circuits
- Design for Manufacturability (DFM)
- Test points for debugging & performance analysis
- Reliability thru thermal management and heat dissipation
- Mezzanine or daughter board add-ons to facilitate vertical space
Density
CAD screenshot showing PCB with 6 conductive layers and BGA package. Some key nets and pads have been temporarily highlighted to visually aid the designer.
Characteristics
- High-density devices for miniaturization
- Ideal for tuff size constraints & enhanced functionality
- 1100+ pins or connections per ball grid array (BGA)
- Fine pitch BGAs (FBGA) or Micro-BGAs with 0.5mm ball-to-ball centers
- Use of versatile reprogrammable devices for fast revisions
- Field programmable devices for quick updates
- Use of space-saving dedicated devices
BGAs
A typical BGA package. This Xilinx FPGA device is less than 1.5 inch square, yet provides 1136 connections to the board (1mm pitch).
Characteristics
- Polyimide material has excellent high-voltage properties or dielectric breakdown
- Replacement of wiring harness eliminates wires and labor costs
- Flexible Printed Circuit (FPC) may be folded & positioned to solve high density packaging problems
- Lightweight
- Can withstand high-shock and vibration
- Optional elimination of connectors
- Excellent high-temperature breakdown properties
- Rugged properties for harsh environments
- Use with, or without stiffeners for mounting parts
- Plated-thru hole connections to multiple layers
- Multiple flex sections may be constructed with multiple rigid PCB sections as one integral design
Flex / Rigid-Flex Circuits
Rigid-flex circuit combo with coverlay and 2 solder-masked rigid sections
PCB Design Examples - Some Case Studies
A basic analysis of historical samples, as shown here, indicates practical design densities. Given some basic data about the physical attributes of a design, the viability of a proposed PCB may be predictable. Of interest will be the total number of physical / electrical pins and the usable board area on each side.Consideration should also be given to requirements such as high-voltages, step-&-repeat circuits, the proportion of digital vs. analog signals, impedance control, connection length/delay constraints, or other unusual design aspects.
Flex / Rigid-Flex Circuits
