Apple service documents confirm presence of a membrane in the 2018 MacBook Pro keyboards
The keyboards of the MacBook Pros have been a point of contention lately owing to their increased propensity to cause issues while typing. Following the recent release of the 2018 MacBook Pros, Apple Authorized Service Providers have been supplied with service documentation that details the servicing aspects of the keyboards in the new MacBook Pros. The documentation confirms the presence of a 'membrane' underneath the keys to 'prevent debris from entering the butterfly mechanism'.
When the new MacBook Pros were announced, Apple did not mention any improvements to the keyboards apart from the fact that the third generation butterfly mechanism offers a quieter typing experience. It was only during iFixit's teardown of the notebook was a 'membrane' underneath the keys spotted. The service docs have now confirmed the presence of the silicone barrier. An excerpt from the document reads,
Keyboard and Keycaps
The keyboard has a membrane under the keycaps to prevent debris from entering the butterfly mechanism. The procedure for the space bar replacement has also changed from the previous model. Repair documentation and service videos will be available when keycap parts begin shipping.
Interestingly, another version of the document accessed by Apple Insider makes no claim about prevention of debris from entering the keys but is otherwise identical to the one that mentions it. We've previously heard of Apple patents referring to butterfly designs to prevent 'contamination ingress' and looks like Apple has implemented the same in this generation. The quieter nature of the keys during typing can also be attributed the presence of this silicone.