Written by Super User on .Posted in Technical Paper
Air Gap Contactor
Prepared by Lam Tuck Hon
Presented at BiTS Workshop on March 6 – 9, 2011
Introduction
- The Signal Integrity performance of a Test Contactor is defined as the speed and quality of the signal transmitted and received via Probe Pins in the Test Contactor.
- These probe pins are further separated as Power, Ground and Signal pins.
- There are multiple variables that contribute to the electrical performance of the Test Contactors.
- Enhancing the multiple variables achieves an optimized Electrical Performance.
Basic Requirement
The (Signal Integrity) electrical performance of the Socket/Contactor will depend on:‐
Assign by Customer
- Pitch
- Number of GND Probe Pin
- Number of Signal Probe Pin
Advise By Socket/Pin Maker
- Diameter of Probe Pin
- Length of Probe Pin
- Material of the Socket
Normal Conventional Contactor
Consists of two plates (Top Plate & Bottom Plate) made of Engineered Plastic materials

Technical Challenge
The main challenge in optimizing the electrical performance/SI of a Test Contactor is to have good control of the Signal Path Impedance
The major parts that affect the impedance:‐
- Pitch to Pitch
- Diameter of Probe Pin
- Dielectric Constant of the Material
Pitch to Pitch
- Assigned By Customer
Diameter of the Probe Pin
- Machining limitation
- Limited choices for fine pitch pins
Material
- Looking for Low Dielectric Constant material
Air Gap Contactor
- A new feature known as an Internal Air Gap to further improve the control over impedance.
- By providing an air gap internally in the Test Contactor the Effective Dielectric Constant is further improved.
- This is because the Air Gap created provides the lowest Dielectric Constant possible and the best Dielectric Loss Tangent value achievable.
- By reducing the Dielectric Constant this helps in increasing the impedance of the Probe Pin as the impedance is inversely proportional to the Dielectric Constant.
- Dielectric Constant of Air = 1
- Dielectric Loss Tangent of Air = 0, Could not be achieved in any known materials.


- Due to some of the contactor materials being removed, it will make the contactor’s body structure become weak.
- Cosmoswork software will be used to analyze the Air Gap Contactor structure.

The technical reviews are as below:‐
- Solving Impedance mismatch issues especially when the impedance is lower than required impedance
- The Electrical Properties of Air provides the best electrical value ‐ could not be achieved in any materials
- Signal Pin
- Improve Insertion Loss
- Improve Return Loss

Summary
- Easily improve the Electrical Performance for current socket by adding the internal Air Gap, significantly save cost and time.
- To maximize the electrical performance of the AG Contactors, one must find out the correct height required to obtain the necessary impedance and thus maximizing the Signal Integrity of the Contactors.