I am a single father in the tech field. I have had the exact same issue. I can usually find times to go to critical travel events - go when my kid is out of school and can stay with a friend, have her go see her mother (I have custody but her mom's still in the state and is good for short visits), etc. - but last year my company had a week-long engineering kickoff overseas at another company location during a school week and I couldn't go. Well, I could have - I could have imposed really hard on the other parents-of-friends I already impose on, or had her fend for herself for a week (she's old enough that it's legal here) - but in my judgement it was best not to.

To mitigate the effects, I was proactive in trying to make it up:

1. Let them know way ahead of time of my restriction - in fact I put my two cents in on the scheduling of the kickoff when I heard it was in the offing. (I brought it up during the hiring process and waited for the "Oh yes family's most important" answer before taking the job. It doesn't mean you can then do whatever, but if a company doesn't at least say that then you're on a short path.)
2. Showed lots of regret that I couldn't go. Asked if the meetings there could be WebExed or whatnot so I could participate remotely (they weren't).
3. Immediately traveled to that other location as soon as I could (when the kid was off for Spring Break) to meet the people there and build relationships.

But does it still have some residual effect against your career? Yes, of course it does. It's part of the tradeoffs you make in life. I've passed up lucrative gigs in Silicon Valley because I want my daughter to be able to visit her mom and have a stable life (friends, school, etc.).

So you have to be smart about it. Pass when you have to but go when you can. To be honest, "my partner has to care for a kid for a week on her own" is not a compelling reason not to go in my opinion (I and about a million other people have cared for a kid solo for many years straight), but peoples' values and abilities vary.

Just participate as much as you reasonably can, make it up where you can, and be smart about the tradeoffs you make.

I am a single father in the tech field. I have had the exact same issue. I can usually find times to go to critical travel events - especially ones where I can pick the timing. I go when my kid is out of school and can stay with a friend, have her go see her mother (I have custody but her mom's still in the state and is good for short visits), etc. - but last year my company had a week-long engineering kickoff overseas at another company location during a school week and I couldn't go. Well, I could have - I could have imposed really hard on the other parents-of-her-friends I already impose on, or had her fend for herself for a week (she's old enough that it's legal here) - but in my judgement it was best not to.

To mitigate the effects, I was proactive in trying to make it up:

1. Let them know way ahead of time of my restriction - in fact I put my two cents in on the scheduling of the kickoff when I heard it was in the offing. (I brought it up during the hiring process and waited for the "Oh yes family's most important" answer before taking the job. It doesn't mean you can then do whatever, but if a company doesn't at least say that then you're on a short path.)
2. Showed lots of regret that I couldn't go. Asked if the meetings there could be WebExed or whatnot so I could participate remotely (they weren't).
3. Immediately traveled to that other location as soon as I could (when the kid was off for Spring Break) to meet the people there and build relationships.

But does it still have some residual effect against your career? Yes, of course it does. It's part of the tradeoffs you make in life. I've passed up lucrative gigs in Silicon Valley because I want my daughter to be able to visit her mom and have a stable life (friends, school, etc.).

So you have to be smart about it. Pass when you have to but go when you can. To be honest, "my partner has to care for a kid for a week on her own" is not a compelling reason not to go in my opinion (I and about a million other people have cared for a kid solo for many years straight), but peoples' values and abilities vary.

Just participate as much as you reasonably can, make it up where you can, and be smart about the tradeoffs you make.