There are many different ways to combine images into a document and convert it into a PDF file.
This document contains a step-by-step guide on how to combine images into a single PDF file using Microsoft Word 2016.
Combining individual pages or images into a PDF is a special case.
Other versions of Microsoft Word may require a different procedure. However, the same principles should apply.

Inserting a Page Break in Word

If you want to combine several images into one document, you can add a page break via the Insert - Page break menu items or via the Layout - Breaks - Page menu items.

Adding Images in Word

Using the Pictures button in the Insert tab, you can add images to your document.

You will be prompted to select the respective image. Please confirm your choice by clicking on the Insert button.

Modifying Images in Word

The following steps will allow you to adjust the chosen image to the page size and align it. This will be useful if you scanned a whole page and want to add it to your document in full page size.

Open the context menu for the image by right-clicking it and select the menu item Size and Position....

The Text Wrapping tab will let you choose the wrapping options for text that surrounds your image. For this guide, we assume that there will be no additional text surrounding the image. Please select In front of Text to enable all options for positioning.

On the Position tab, please select the Alignment button in the Horizontal section with the value Left and relative to Page. In the Vertical section, please select the Alignment button with the value Top and relative to Page.

Please note: If you selected the option In line with text on the Text Wrapping tab, you will not be able to select all options on the Position tab.

To adjust the image to the right size, please select the Absolute button in the Width section on the Size tab with a value of 21 cm. This is the correct width for a DIN A4 page.

Please confirm your modifications by clicking on the OK button.

PDF Export in Word

If you want to export your document as a PDF, please select the menu items File - Export. Then, select Create PDF/XPS Document.

Choose the save location and file name and confirm your choice with the Create PDF/XPS button.

PDF Printing in Word

Under Microsoft Windows 10, you also have the option of printing documents directly into a PDF file.

To do so, please use the menu options File - Print. In the dialog window that opens, please select the printer called Microsoft Print to PDF in the Printer section and confirm your choice by clicking Print. Then, choose the save location and confirm your choice with the Save button.