ABSTRACT
Where Else? Other information related to interconnecting circuit sections can be found in Chapter 2, "Surface Mount Technology"; Chapter 4, "Direct Chip Attach"; and Chapter 5, "Circuit Boards."
Interconnect devices must meet certain performance requirements in most or all of the following categories:
• Signal integrity • Powerless • Electrical characteristics: contact resistance, inductance and capacitance; voltage and power rat-
ings; shielding; filtering • Mechanical characteristics: contact count; contact spacing; contact forces; polarization/keying;
wiping characteristics; shock and vibration; size; soldering technique; CTE with respect to substrate • Environmental issues: soldering technique; cleaning materials; thermal; corrosion protection
Signal integrity is defined by loss of quality of the input signal. Ideally, the signal at the output of an interconnect should be equal in all characteristics with the signal at the input of the interconnect. In reality, signal degradation occurs. The user must define what level of degradation is acceptable or> alternatively, must define minimum acceptable signal levels at the output. Tests that indicate signal integrity include
• Voltage standing wave ratio (VSWR) • Frequency response • Rise-time of signal edges • Current flow
Both THT and SMT technology connectors are available for most uses. It is possible to use THT connectors and sockets in SMT designs and processes by using the pin-in-paste process described in Chapter 2. The limiting factor on using THT sockets is that, for some connectors, the plastic housing is not designed to withstand reflow heating temperatures.
