What is the target operating margin for the EMS business in 2021 
 with my key customer, they really appreciate how Taiwan was managed throughout the pandemic, how the Taiwan semiconductor companies were managing the delivery in a very adverse supply chain environment, throughout the whole 2020.
And I believe that would carry us far. For the partner that we support, they're gaining market share. And I think this is another reason that I believe not only we will grow or capture a huge chunk of the semiconductor growing logic space, we will also force and enable more outsourcing for IDMs. That I believe that in the next few years, we will enjoy a higher growth rate as a result of all of these factors.
Charlie Chan -- Morgan Stanley -- Analyst
Thanks for the insight, for the insight, Dr. Tien. I think that's a very clear. I mean, I also have a follow up, Roland's question about your gross margin trend. Sorry, I am not sure if you did give the gross margin guidance for this year? Can you kind of breakdown by your ATM business and the EMS business, the gross margin trend in 2021? And also, I know you don't go comment about the pricing, right? But may I know for flip chip and testing, do you expect the price to go up this year?
Tien Wu -- Group Chief Operating Officer
Joseph, you will comment on the gross profit?
Joseph Tung -- Chief Financial Officer
As I mentioned earlier on, I think the -- for 2021, I think we will continue to see margin improvement at the gross level with the steady or improving opex ratio. I think also on the operating margin, we'll continue to see improvement. And that comes from a lot of the efforts that we put in, in terms of improving our efficiency, creating synergy with SPIL, and also the higher loading facility, of course, it helps, a friendlier pricing environment also help. I think all these put together give us a very high confidence that we will be improving our margin going forward for ATM.
As far as EMS's perspective, I think the more relevant margin is at the operating level. Because of the different product mix, it will have quite a bit of fluctuations on the gross level. So the more relevant or more meaningful benchmark is really on the operating level. For that, we are targeting a 4% operating margin for EMS business. That's slightly up from what we achieved in previous year, which was at 3.8%.
Tien Wu -- Group Chief Operating Officer
Okay, for the other line of business, flip chip, the fan-out and all of the others, we're also seeing a more friendly environment, but not as friendly as wirebond, they're friendly. Okay, I will not comment anymore.
Charlie Chan -- Morgan Stanley -- Analyst
That's OK. Okay, thanks, gentlemen. It's very helpful, thank you.
Operator
Next one to ask question, Sebastian Hou, CLSA.
Sebastian Hou -- CLSA -- Analyst
Thanks for taking my questions. So just follow on the pricing and the margin, that part. Just if I look at your Q4 2020 margin that has improved, I think there is a combination of the utilization rate improved, synergies, and then pricing. But looking now into your 1Q guidance, revenue and margin will be similar to last quarter. So, can we say that the pricing is not a factor anymore in this quarter to drive the margin for improvement?
Joseph Tung -- Chief Financial Officer
I think it's -- to have a similar margin for first quarter compared to last quarter, it's quite a bit of a challenge itself already, because we are facing further NTD appreciation, which will have a over 1% impact on the margin. We are going through Chinese New Year, and some of the factories are going through annual maintenance. So then we will have less working days. And also, throughout the -- there's a lot of homework that needs to be passed out. Overall, compensation expenses is going to be higher for the quarter. So all the things put together, I think we are doing a pretty good job in maintaining our margin at similar margin from fourth quarter.
Tien Wu -- Group Chief Operating Officer
I mean, just for clarification, the so-called seasonality is still here. In other words, some of the key customer run their high-volume device for consumer or
 with my key customer, they really appreciate how Taiwan was managed throughout the pandemic, how the Taiwan semiconductor companies were managing the delivery in a very adverse supply chain environment, throughout the whole 2020.
And I believe that would carry us far. For the partner that we support, they're gaining market share. And I think this is another reason that I believe not only we will grow or capture a huge chunk of the semiconductor growing logic space, we will also force and enable more outsourcing for IDMs. That I believe that in the next few years, we will enjoy a higher growth rate as a result of all of these factors.
Charlie Chan -- Morgan Stanley -- Analyst
Thanks for the insight, for the insight, Dr. Tien. I think that's a very clear. I mean, I also have a follow up, Roland's question about your gross margin trend. Sorry, I am not sure if you did give the gross margin guidance for this year? Can you kind of breakdown by your ATM business and the EMS business, the gross margin trend in 2021? And also, I know you don't go comment about the pricing, right? But may I know for flip chip and testing, do you expect the price to go up this year?
Tien Wu -- Group Chief Operating Officer
Joseph, you will comment on the gross profit?
Joseph Tung -- Chief Financial Officer
As I mentioned earlier on, I think the -- for 2021, I think we will continue to see margin improvement at the gross level with the steady or improving opex ratio. I think also on the operating margin, we'll continue to see improvement. And that comes from a lot of the efforts that we put in, in terms of improving our efficiency, creating synergy with SPIL, and also the higher loading facility, of course, it helps, a friendlier pricing environment also help. I think all these put together give us a very high confidence that we will be improving our margin going forward for ATM.
As far as EMS's perspective, I think the more relevant margin is at the operating level. Because of the different product mix, it will have quite a bit of fluctuations on the gross level. So the more relevant or more meaningful benchmark is really on the operating level. For that, we are targeting a 4% operating margin for EMS business. That's slightly up from what we achieved in previous year, which was at 3.8%.
Tien Wu -- Group Chief Operating Officer
 Okay, for the other line of business, flip chip, the fan-out and all of the others, we're also seeing a more friendly environment, but not as friendly as wirebond, they're friendly. Okay, I will not comment anymore.
Charlie Chan -- Morgan Stanley -- Analyst
That's OK. Okay, thanks, gentlemen. It's very helpful, thank you.
Operator
Next one to ask question, Sebastian Hou, CLSA.
Sebastian Hou -- CLSA -- Analyst
Thanks for taking my questions. So just follow on the pricing and the margin, that part. Just if I look at your Q4 2020 margin that has improved, I think there is a combination of the utilization rate improved, synergies, and then pricing. But looking now into your 1Q guidance, revenue and margin will be similar to last quarter. So, can we say that the pricing is not a factor anymore in this quarter to drive the margin for improvement?
Joseph Tung -- Chief Financial Officer
I think it's -- to have a similar margin for first quarter compared to last quarter, it's quite a bit of a challenge itself already, because we are facing further NTD appreciation, which will have a over 1% impact on the margin. We are going through Chinese New Year, and some of the factories are going through annual maintenance. So then we will have less working days. And also, throughout the -- there's a lot of homework that needs to be passed out. Overall, compensation expenses is going to be higher for the quarter. So all the things put together, I think we are doing a pretty good job in maintaining our margin at similar margin from fourth quarter.
Tien Wu -- Group Chief Operating Officer
I mean, just for clarification, the so-called seasonality is still here. In other words, some of the key customer run their high-volume device for consumer or