A fire interrupted Renesas Electronics’ N3 300mm production line at its Naka Factory in Hitachinaka, Ibaraki Prefecture, Japan, on March 19, 2021. The blaze was contained and caused no reported injuries or building damage, but damaged utilities and manufacturing equipment, stopping N3 temporarily. Renesas restarted production at less than 10% of its pre-fire capacity on April 17, restored capacity to 100% on June 24, and expected customer shipments to return to normal around the third week of July.
What happened at the Renesas fab?
The fire began at 2:47 a.m. Japan Standard Time on March 19, 2021, in plating equipment on the first floor of the N3 Building’s 300mm production line at Renesas’s Naka Factory. Renesas said the fire was extinguished at 8:12 a.m. that morning.
Renesas reported no employee casualties and no damage to the factory building. The fire damaged parts of the utility infrastructure, including pure-water supply and air-conditioning systems, as well as manufacturing equipment.
- About 600 square meters burned.
- The burned area represented about 5% of the 12,000-square-meter first-floor N3 clean room.
- Eleven manufacturing-equipment units burned, about 2% of N3 equipment.
The incident was therefore geographically limited within the factory, but its effect was significant because N3 supplied products used in a period of unusually strong semiconductor demand.
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When did the Renesas Naka factory fire happen?
The fire occurred on March 19, 2021, at 2:47 a.m. JST at the Naka Factory in Hitachinaka, Ibaraki Prefecture, Japan. Renesas issued a further cause-and-impact update on March 21 and a consolidated summary of its early updates on March 22.
What caused the Renesas factory fire?
Renesas’s March 21 update identified plating equipment as the point of origin. The company stated that the equipment casing and plating tank had relatively low heat resistance and that the equipment ignited following an overcurrent.
That description explains the immediate mechanism reported at the time, not a final underlying-cause finding. Renesas also said the cause of the overcurrent and the reason the equipment ignited were still under investigation. The available contemporaneous updates do not establish a later definitive root-cause conclusion.
Which production lines were affected?
| Factory area | Wafer size or function | Status after the fire |
|---|---|---|
| N3 Building | 300mm manufacturing | Production halted temporarily, then restarted in stages. |
| N2 line | 200mm manufacturing | Reported to continue operating and shipping. |
| WT Building | Wafer testing | Reported to continue operating and shipping. |
Renesas said roughly two-thirds of N3 products had an alternative production route either in-house or through foundries. Those routes could not immediately cover every product because semiconductor demand was already high, so substitution reduced but did not eliminate the disruption.
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Clean-room recovery
After cleaning and decontamination, N3 clean-room operations resumed on April 9. Renesas said partner companies and suppliers provided intensive assistance, with as many as about 1,600 people per day helping with the recovery effort.
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Production restart
Production restarted on April 17. Renesas reported that capacity was then just under 10% of the pre-fire level. The restart was therefore not an immediate return to normal output; equipment repair, qualification and process recovery continued after the first wafers were produced.
Full production-capacity recovery
Renesas announced on June 25 that N3 production capacity had returned to 100% of its pre-fire level as of the evening of June 24. This milestone refers to production capacity, not to all customer shipments already being back to normal.
How long did it take Renesas to recover production after the fire?
From the fire on March 19 to the initial production restart on April 17 took 29 days. The line reached 100% of its pre-fire production capacity on June 24, 97 days after the fire.
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Shipments were expected to recover later, around the third week of July. Work-in-process already in the factory had to complete its normal product lead times, so restored wafer output did not translate instantly into delivered chips.
Did the Renesas fire affect chip shipments?
Yes. N3 production stopped temporarily, creating a supply interruption for products that could not be moved immediately to alternative internal or foundry capacity. Renesas’s N2 line and WT wafer-testing building continued operating and shipping, and alternative routes covered some N3 products, but those measures did not instantly replace all N3 output.
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The company’s recovery milestones distinguish three different outcomes:
- Production restart: April 17, at just under 10% of pre-fire capacity.
- Full production capacity: June 24, restored to 100% of the pre-fire level.
- Shipment recovery: expected around the third week of July, after work-in-process completed product lead times.
What financial impact did Renesas estimate?
In March 2021, Renesas estimated that halting N3 could have an impact of about ¥17 billion per month. On March 30, it published conditional scenarios of about ¥17.5 billion if capacity recovery took 1.5 months, or about ¥24.0 billion if recovery took two months.
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Why the incident mattered despite the limited physical damage
The burned area and equipment represented a small share of the N3 clean room and equipment base, yet the affected line was a specialized 300mm operation embedded in a tight supply chain. A short interruption can therefore have effects that outlast the physical fire: capacity must be rebuilt, processes requalified, work-in-process must move through production, and customers must wait for shipments even after output has resumed.
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