Instructions and Precautions

Equipment Used

Contact Tester: Test points: 1-128 (can be extend to 256 ); Test time: <0.5 seconds

Definitions

Transition Ring:

The transition ring is the visible ring on the top of the metal dome, where the dome radius transitions into the feet of the dome. The transition ring is the hinge point of the dome that forces the dome back to its original shape after the dome has been depressed or snapped over.

Bi-Stable:

The condition of a metal dome where, when actuated and then released, the metal dome does not return to its original condition. In this state, the dome exhibits two (2) stable conditions.

Any damage to the transition ring will affect the metal domes ability to return to its original form, thus reducing the domes actuation force, tactile ratio, or to the extreme, cause the dome to become bi-stable.

Damage can occur to the metal dome by any of the following means:

• Over-traveling the metal dome past its designed travel can cause damage to the transition ring. For most domes this means traveling the dome past the flat plane of the feet. Actuating the dome between the fingers with the center being unsupported is an example of over-travel.
• Denting the transition ring can be caused by actuating the metal dome with a sharp object such as a pen or fingernail. (Rubbing the finger across the dome with the fingernail, for example.)
• Depressing the metal dome with a rigid, flat surface which is equal to or greater than the transition ring diameter can cause damage to the transition ring. (Too large an actuator, for example.)
• Depressing the metal dome across the full width of the dome with some type of roller can cause damage to the transition ring.
• Actuating the metal dome when all of the feet are not evenly supported can cause damage to the transition ring.
• These are the most common causes of damage to the metal domes during assembly; yet do not include all sources caused by general rough handling.