# Empty MPN and Manufacturer in BOM

**URL:** <https://librepcb.discourse.group/t/empty-mpn-and-manufacturer-in-bom/992>\
**Category:** Help\
**Created:** [January 28, 2026, 11:42pm UTC](https://librepcb.discourse.group/t/empty-mpn-and-manufacturer-in-bom/992 "2026-01-28T23:42:53Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![giancarlo64](https://yyz2.discourse-cdn.com/free1/user_avatar/librepcb.discourse.group/giancarlo64/32/296_2.png) [@giancarlo64](https://librepcb.discourse.group/u/giancarlo64)\
**Post date:** [January 28, 2026, 11:42pm UTC](https://librepcb.discourse.group/t/empty-mpn-and-manufacturer-in-bom/992/1 "2026-01-28T23:42:53Z")

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Hi,

I noticed that for some components the BOM does not show the MPN or Manufacturer, even though they are defined in the Device. I am still using LibrePCB v2 RC1.

- `device1.lp` → the information is not shown in the BOM

- `device2.lp` → the information is displayed correctly

I also noticed that device1.lp has two times the VALUE information.

The two files are attached for reference.

[device.zip](https://librepcb.discourse.group/uploads/short-url/3mKhFLiq4ff6wljcV45mSkefLOP.zip) (1.4 KB)

Gian Carlo

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<div class="post-metadata">

**Author:** ![ubruhin](https://avatars.discourse-cdn.com/v4/letter/u/c89c15/32.png) [@ubruhin](https://librepcb.discourse.group/u/ubruhin)\
**Post date:** [January 29, 2026, 3:33pm UTC](https://librepcb.discourse.group/t/empty-mpn-and-manufacturer-in-bom/992/2 "2026-01-29T15:33:36Z")

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Hi,

> [@giancarlo64](#):
>
> I noticed that for some components the BOM does not show the MPN or Manufacturer, even though they are defined in the Device.

The BOM is using the MPN which is defined in the schematic, not in the library where it initially originates from. Please have a look at the documentation which explains how this works:

> **[Component Assembly Data - Assembly Data | LibrePCB Documentation](https://librepcb.org/docs/user-manual/project-editor/assembly-data/#component-assembly-data)**
>
> This chapter explains how to specify assembly data like MPNs\[1\] in your project to get an accurate BOM\[2\] ready to order the correct parts. LibrePCB supports many different use-cases which will be explained below.

> [@giancarlo64](#):
>
> I also noticed that device1.lp has two times the VALUE information.

So you added it two times 🙂 It’s not harmful (the part attribute has priority over the device attribute), but honestly a `VALUE` attribute should not be added at all because `VALUE` is a built-in attribute. It would be better to add attributes `CAPACITANCE` and `VOLTAGE_RATING` and then set the value of the component (either in the schematic or in the library) to “{{CAPACITANCE}} {{VOLTAGE\_RATING}}”. Though I understand it is a bit cumbersome to do this for every component. We plan to add those attributes to our official capacitor components soon.