The 19-year-old loosehead prop lasted 72 minutes and looked strong throughout as the black, green and gold dominated possession and territory for long periods.
Exeter eventually won out, bagging five tries to Saints’ two, but Iyogun walked off to a loud ovation from his team-mates.
And Boyd, who was without all four senior loosehead props due to injury, said: “He’s a great kid.
“What he did is survive out there for 70 minutes and it was a remarkable effort because last week was his first men’s scrum.
Teimana Harrison and Fraser Dingwall scored for Saints, but they weren’t able to make their territorial dominance tell on so many occasions.
And it cost them dear as Exeter were ruthless, taking advantage of some porous defending to set up a home semi-final against Toulouse next weekend.
“We tried really hard but we had to work too hard to get our points and they didn’t work as hard to get theirs.
Boyd added: “Everybody took responsibility for us and it’s clear that Exeter are further along on their journey as a team than we are.
“We knew it would be difficult, we had to have an impact on the game, and we did.
And when asked to reflect on his team’s showing in the Champions Cup, Boyd said: “We had a couple of good games against Lyon to get us into this situation.
Northampton Saints, Exeter Chiefs, European Rugby Champions Cup
World news – GB – Boyd salutes Iyogun after young prop’s big showing at Sandy Park