I'm no expert, but it looks like Yinsen was the brainchild of that lackey at Marvel:

"Chu forced Tony and another captive, famed physicist Ho Yinsen, to create weapons for him. All the while the lethal bit of shrapnel was slowly working towards Tony's heart. Tony and Yinsen created an iron suit that would keep Tony alive and allow them to escape. During the escape Yinsen was killed, sacrificing himself to allow Tony time to change for the first time to Iron Man. Iron Man made short work of Chu and his men."

http://www.marvel.com/universe/Iron_man

The value of research! Thanks, Pam. Question answered - and interesting how closely the movie sticks to the franchise's set-up in the comic books.

Doing a little research of my own, here is a list of all the movies based on Marvel characters. And I believe that Iron Man is the first movie Marvel financed (partially or in its entirety) -- which not only maximizes their profit potential, but also their control over the content.

Despite enjoying the movie, I and my wife were quite taken aback by the lack of 'something more', to put it succinctly ;) Agreed that there was a great transformation, but in the end, the film ended up being nothing more than one hero versus a Bigger Monster Villain (who, strangely, has very little by way of a character arc to go by). Jeff Bridges, in an interview published a few months ago, remarked how strange it was shooting for IM since 'there was no script'!

http://www.slashfilm.com/2009/12/01/jeff-bridges-on-iron-man-they-had-no-script-man/

Jon and Robert, being great at improv, would make up scenes as they went along. All the had was a general outline of the film. And it shows in many places.
Unfortunately, in a film that starts off and even goes to Afghanistan, one sequence of him killing 6 random bad guys doesn't suffice. It had to say more about what he and his company had done to that country, about the world and war in general..but I guess Jon Favreau also had to keep in mind the ticket paying public's sensibilities about the conflict and America's role there. Because that would have made Stark's character as a real man in a modern world grow more real, as opposed to make him into this 'niceguy' who now has to fight someone who is just bigger than him, not smarter, not more insanely demented about the way the world is. It petered down towards the end for us, though I will, alongwith my wife, go and see the next one :) It was just good fun, but could have been so much more. And we live in a world now that needs to say more, even in entertainment.
'SINCE WARS BEGIN IN THE MINDS OF MEN...it is in the minds of men that the defences of peace must be constructed." From the preamble of UNESCO's Constitution'

I guess the Nolans and Alan Moore have made me a bit unrealistic in what can be expected of comic book movies.
But on another note - Scarlett Johannson as Black Widow?? Oh, come on! :p