If you have a Windows computer that has a small hard drive that cannot accommodate an iTunes backup, you may be interested in how to back up your iPhone to an external drive with 3UTools, such as a USB drive or pendrive. In this tutorial we will use the 3UTools program, which is for Windows computers.
You can download the 3UTool program from the manufacturer's website https://www.3u.com
After installing and running the program, we need to connect the Apple phone or tablet to it, the data of which we want to protect in the form of a backup on an external drive. Then, after loading our device, select the Backup / Restore button.
Then press Backup.
In the Backup Path function, we need to indicate where to save the backups. To do this, click Change and select our external drive in the window, on which we want to save the backup. Press OK. After that, the path to the set disk should appear in the Backup Path section. However, before we press Back up Now, it is worth clicking on Managa Password and setting the backup encryption. This will allow you to keep the passwords for e-mail, websites, etc. while creating a copy. If you do not encrypt the copy, then after restoring it on a new phone, you will have to enter all passwords manually. To make a backup, press Back up Now.
After creating it, just recreate it and enter it on your new phone. A guide on how to do this can be found at the link below.
How to upload iPhone backup in 3UTools from external drive [Windows]