🔧 How to Flash Unisoc / Spreadtrum (SPD) Firmware with the SPD Upgrade Tool
Not every budget phone uses MediaTek. Many Infinix, Tecno, iTel and ZTE models run on Unisoc (formerly Spreadtrum, "SPD") chips, and their firmware ships as a single .pac file flashed with the SPD Upgrade Tool (also called ResearchDownload or UpgradeDownload) instead of SP Flash Tool. This guide covers that flow end to end.
⚠ Important. Flashing erases your data and can brick the phone if you use the wrong .pac or disconnect mid-flash. Confirm your chipset is Unisoc/SPD, back up first, and charge above 50%.
What you need
- SPD Upgrade Tool (ResearchDownload / UpgradeDownload)
- Unisoc / SPD USB drivers
- A Windows PC
- USB cable
Steps
- Confirm the chipset is Unisoc/SPD. On the ROM Palace model page a "Unisoc" chipset badge means SPD. If it says MediaTek, use our SP Flash Tool guide instead — the tools are not interchangeable.
- Download the .pac firmware. Find your exact model on ROM Palace and download the stock firmware. SPD firmware is usually a single .pac file (sometimes inside a zip you extract first).
- Install the Unisoc / SPD USB drivers. Install the SPD / SCI USB drivers on your Windows PC so the tool can detect the phone in download mode. See our USB driver guide if Windows blocks them.
- Open the SPD Upgrade Tool and load the .pac. Launch ResearchDownload (or UpgradeDownload), click the gear/"Load Packet" button, and select your .pac file. The partition list loads automatically.
- Start the download. Click the "Start Downloading" (play) button. The tool now waits for a phone.
- Connect the powered-off phone. Power the phone off completely. Hold Volume Down (or Volume Up on some models) and plug in the USB cable. The tool detects it and begins flashing — a progress bar fills and turns green ("Passed") when done.
- Boot up. Unplug and power on. The first boot after flashing can take several minutes. Your Unisoc phone now runs clean stock firmware.
Tips & troubleshooting
- If the tool never detects the phone, reinstall the SPD drivers and hold the opposite volume key while connecting.
- A "verify" or "checksum" error almost always means the .pac does not match your exact model.
- If the phone lost its IMEI / signal after flashing, see our IMEI repair guide.
Ready to flash? Find your exact model on ROM Palace and download the matching stock firmware — free, direct, no waiting queues.