What was the sequential increase in revenue in the consumer market in Q1 2021 
f driver assistance electronics and the electrification of more car models.
The consumer market returned to quarter-on-growth with an 8% sequential increase in line with expectations. IoT wearables continued to be an important driver for growth. Although, some supply chain constraints and expected product pipeline changes continue to be dynamic in this emerging product categories. Our overall product and customer pipeline for devices and advanced SiP solutions in the consumer market remain strong. We are confident that the end market for IoT devices will continue to be a growth area for Amkor.
Revenue in the computing end market set a new all-time quarterly record with sequential growth of 2% and a year-on-year growth of 30%. We experienced good performance in all computing applications and the strengthening of our project pipeline. We expect the computing market to drive further growth for outsourced assembly and test services and we anticipate growth in multiple applications ranging from personal computing to infrastructure and data centers. Over recent years, we have established a proven technology portfolio with required manufacturing scale. And Amkor continues to invest in capacity and technology for this market.
With a technology base ranging from larger body size flip chip, multi-chip modules [Indecipherable] and High Density Fan-Out we were able to offer customers a complete solution in this domain. With growing demand for high-performance package technology, we strengthened our engineering teams to develop specific solutions together with lead customers. These engagements allow us to introduce key enabling technologies, for example laser system bumping and high conductive thermal materials to resolve technical challenges.
The new technologies enable us to capitalize on opportunities not only in the computing domain, but also to extend these capabilities in other areas like automotive. Finally, our test business grew 15% year-over-year in Q1 as we increased the scope of our test services for 5G communication and system level testing and continue our focus on expanding test attach rate. Strong demand in the quarter resulted in good factory utilization and we saw utilization improvement especially in our Japan factories.
Our wafer-level and flip chip production lines were highly utilized and utilization rates in our lead frame and wire bond factories further improved with the recovery in the automotive and industrial markets. The high factory utilization contributed to a solid 20% gross margin for Q1. To prepare for future growth, our manufacturing organization is expanding clean room space in our facilities in Korea, China and the Philippines and we are further ramping our new T6 factory in Taiwan. We also have been watching closely the growing interest on activity in US semiconductor manufacturing and the new US forward looking investment policies. We are encouraged by efforts to fund the chips for America initiatives and are actively exploring to be part of the US semiconductor manufacturing supply chain.
Capex for the year is expected to be around $700 million, the capital intensity in the low teens. Major investments in 2021 are planned for wafer level and flip chip technology, SiP capacity, test capacity and the facility expansions I've mentioned previously. We also plan specific investments to support our industry for that O program, enabling an intelligent factory framework to improve quality, decision making speed and asset utilization.
Now, let me turn to our second quarter outlook. We are expecting another solid quarter, with revenue of $1.34 billion at the midpoint of guidance. This represents a year-on-year increase in Q2 of 14%. Short-term capacity constraints for wafers and substrates are expected to impact parts of the semiconductor supply chain, especially in the automotive market, limiting further growth in Q2. For the full-year 2021, we expect continued strength in all growth areas, particularly 5G communication and computing. We remain confident in our strong market position and the overall dema
f driver assistance electronics and the electrification of more car models.
The consumer market returned to quarter-on-growth with an 8% sequential increase in line with expectations. IoT wearables continued to be an important driver for growth. Although, some supply chain constraints and expected product pipeline changes continue to be dynamic in this emerging product categories. Our overall product and customer pipeline for devices and advanced SiP solutions in the consumer market remain strong. We are confident that the end market for IoT devices will continue to be a growth area for Amkor.
Revenue in the computing end market set a new all-time quarterly record with sequential growth of 2% and a year-on-year growth of 30%. We experienced good performance in all computing applications and the strengthening of our project pipeline. We expect the computing market to drive further growth for outsourced assembly and test services and we anticipate growth in multiple applications ranging from personal computing to infrastructure and data centers. Over recent years, we have established a proven technology portfolio with required manufacturing scale. And Amkor continues to invest in capacity and technology for this market.
With a technology base ranging from larger body size flip chip, multi-chip modules [Indecipherable] and High Density Fan-Out we were able to offer customers a complete solution in this domain. With growing demand for high-performance package technology, we strengthened our engineering teams to develop specific solutions together with lead customers. These engagements allow us to introduce key enabling technologies, for example laser system bumping and high conductive thermal materials to resolve technical challenges.
The new technologies enable us to capitalize on opportunities not only in the computing domain, but also to extend these capabilities in other areas like automotive. Finally, our test business grew 15% year-over-year in Q1 as we increased the scope of our test services for 5G communication and system level testing and continue our focus on expanding test attach rate. Strong demand in the quarter resulted in good factory utilization and we saw utilization improvement especially in our Japan factories.
 Our wafer-level and flip chip production lines were highly utilized and utilization rates in our lead frame and wire bond factories further improved with the recovery in the automotive and industrial markets. The high factory utilization contributed to a solid 20% gross margin for Q1. To prepare for future growth, our manufacturing organization is expanding clean room space in our facilities in Korea, China and the Philippines and we are further ramping our new T6 factory in Taiwan. We also have been watching closely the growing interest on activity in US semiconductor manufacturing and the new US forward looking investment policies. We are encouraged by efforts to fund the chips for America initiatives and are actively exploring to be part of the US semiconductor manufacturing supply chain.
Capex for the year is expected to be around $700 million, the capital intensity in the low teens. Major investments in 2021 are planned for wafer level and flip chip technology, SiP capacity, test capacity and the facility expansions I've mentioned previously. We also plan specific investments to support our industry for that O program, enabling an intelligent factory framework to improve quality, decision making speed and asset utilization.
Now, let me turn to our second quarter outlook. We are expecting another solid quarter, with revenue of $1.34 billion at the midpoint of guidance. This represents a year-on-year increase in Q2 of 14%. Short-term capacity constraints for wafers and substrates are expected to impact parts of the semiconductor supply chain, especially in the automotive market, limiting further growth in Q2. For the full-year 2021, we expect continued strength in all growth areas, particularly 5G communication and computing. We remain confident in our strong market position and the overall dema