The number two seeds won their first two matches in straight sets, before winning their Third Round encounter with Pierre-Hugues Herbert and Jordan Thompson by walkover following injury to Thompson.
They may have been well-rested for the last-eight match, but their preparations were disrupted by news breaking that Patten had been fined £9,200 on 29th June for allegedly abusing a Wimbledon staff member at an off-site training ground.
A tough test would be in order today against the fifth-seed pair who beat them at Eastbourne just last month. The opponents knew each other's games inside out, too, as Heliovaara was facing former partner Glasspool, while Patten has played alongside Cash.
Both duos began strongly on their own serve - in the first eight games, only seven points were won by the defending pair.
However, in game nine, poor work at the net from the Finn and Brit gave Cash and Glasspool the first break point of the match, which they took against the serving of Patten, before wrapping up the set 6-4 in the next game.
In the second set, the dominance on serve continued, particularly from the all-British pair, who conceded just their sixth point while serving across the whole match when tying things up at 4-4.
In game 10, Heliovaara and Patten put their opponents under real pressure for the first time - at 30-30, Cash mistakenly let an in-bounds Patten return pass him to give the favourites their first break and set point.
Cash and Glasspool defended two set points successfully, before an excellent return from Heliovaara secured a 6-4 win in the second set for the world number threes.
Cash needed some medical attention before the start of the third set, but was showing no sign of injury as the first 11 games went the way of the serving pair, putting Heliovaara and Patten 6-5 ahead.
A brillant start to the next game gave them three match points, but not only did Cash and Glasspool save all three with ease, they then secured the game to take the final set to a tiebreak.
Two losses of serve early on put the Helsinki and Essex natives under pressure, but they held their nerve with two breaks to level things at 7-7.
But a crucial loss as the match rolled past the two-hour mark gave the British pair two match points at 9-7.
Patten successfully defended the first off his own serve, but with Cash serving for the second, he and Glasspool got the point they needed to reach a first major Semi-final in either players' careers, taking the match 6-4, 4-6, 7-6.