Calculating Mating and Un-mating Forces!
©Samtec, Inc. Phone: 1-800-SAMTEC-9
www.samtec.com 812-944-6733
Page: 1 Email: info@samtec.com
Rev: 0
Date: August 13, 2014
Cr
eated by: Kevin Meredith
Calculating Mating and Un-mating Forces for Samtec Connectors
The mating and un-mating force for Samtec connectors can vary dramatically
depending on the connector type and pitch. The mating force is a function of the
contact geometry, the contact spring rate, and the coefficient of friction. To better
understand these forces at the connector level we will examine what goes on at the
individual contact level. In most cases it will not be necessary for Samtec customers to
perform these calculations as Samtec tests the smallest, largest and middle pin count
connectors during the product qualification process.
For single and twin beam contact style connectors calculating the mating force is fairly
straight forward. You just multiply the peak force per circuit times the number of
circuits. This is an idealized approach as it does not take into account plastic binding
from misalignment but is useful for sizing injectors, extractors, or similar hardware in the
event test data is not available.
The mating force occurs in two stages, a spreading stage and a sliding stage (See
figure 1 and 2). The spreading stage is a stage of higher force and responsible for the
peak force (neglecting the bottoming out of the insulators). The insertion force is equal
to the Y component of force of both the friction and normal force. During this stage
there is friction plus the effects of spreading the contact open. The sliding stage is a
stage of lower force in which only the friction force must be overcome as the normal
force now acts in a perpendicular direction. There is no spreading effect in the un-
mating of connectors, which explains why it is generally more difficult to mate than un-
mate connectors.
Figure 1 (Spreading Stage) Figure 2 (Sliding Stage)
Calculating Mating and Un-mating Forces!
©Samtec, Inc. Phone: 1-800-SAMTEC-9
www.samtec.com 812-944-6733
Page: 2 Email: info@samtec.com
Rev: 0
Date: August 13, 2014
Created by: Kevin Meredith
Figure 3 is the mating and un-mating plot, cycled 20 times, of a typical low pin count
connector. It clearly displays the stages of mating at the connector level. This plot was
generated during actual product qualification. Figure 4 is the FEA prediction for the
mating cycle of a single circuit.
Figure 3 (FC5 25 position connector)
Figure 4 (SEAX contact and terminal)