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Top 6 issues that impact manufacturing and delivery

At Precision we catalogue every issue that occurs during the manufacturing process and review them on a weekly basis. After collating all the information together, we realised that most of the issues are caused because of missing or incorrect information in the files supplied by our customers (BOM, Altium files, Pick & Place files, etc).

We have put together the top 6 issues that impact manufacturing & delivery, and solutions on how you can fix your data when you supply them to us. By providing clear instructions in your files, we can greatly improve efficiencies, ensure ease of manufacturing, high quality standards and on-time delivery.

ISSUE 1: Description does not match part number

The description (name) and (manufacturer) part number of components do not match in the BOM, which inevitably results in purchasing the wrong part. This can lead to severe quality issues and potential delayed deliveries. When customers are notified of this discrepancy, some will advise us to follow the description and some will advise us to follow the manufacturing part number.

Incorrect: Manufacturing Part Number does not match Description in BOM


Always double check the description and manufacturing part number of all components in the BOM to avoid any complications. If there is a discrepancy, notify your Precision account manager as soon as possible.

Correct: Manufacturing Part Number should match the Description in BOM

ISSUE 2: Unclear DO NOT LOAD/FIT instructions

There is often confusion during the SMT loading process regarding load/do not load, which can result in loading parts that should not be on the PCB. When this occurs, we need to stop production and consult with customers. A communication delay from customers can often lead to production and delivery delays.


Clearly highlight DNF (DO NOT FIT) in the BOM for parts that you do not want Precision to load.

Correct: Highlight DNF in your BOM clearly

ISSUE 3: Missing Polarities

Polarities are not clearly marked on the supplied PDF file, Silk screen or Altium file. This results in SMT loading components in the wrong direction or polarities causing severe inefficiencies.


Clearly indicate the direction and polarity of components either on the PDF file, Silk screen or Altium file to avoid any delivery delays.

ISSUE 4: Missing component values

When customers provide Altium or Pick & Place files, sometimes there are cases where these files have missing component value information. In these cases, we must manually insert the correct values into the Pick & Place file (from the BOM) which could result in human error leading to quality issues.


Your supplied Pick & Place file should contain ALL component values that should match the values and the designators in the BOM.

Correct: Component values should be clearly highlighted in the Pick & Place file (right image)

ISSUE 5: Wrong footprint

If a component (from the BOM) does not fit in the PCB footprint, we will need to halt production and advise customers of the discrepancy. The 4 most common responses we get from customers are:

  1. ‘Do not load part’
  2. ‘Can you fit the component part onto the location?’ We tend to avoid this option as it can cause severe quality and functionality issues
  3. ‘We will order the correct part and send it to you’. This option means putting the machine on hold, which will lead to a delayed delivery
  4. ‘Continue the machine loading process without part; Hand load the correct part once you receive it.’ This option is more likely to have quality and inefficiency issues due to human error.
Image 1&2: Large component on a small PCB footprint. Image 3: Small component on a large PCB footprint


Make sure the Pick & Place file (component packages) matches with BOM parts and packages.

ISSUE 6: Additional special instructions

Special instructions such as:

  1. Do not wash boards because it has critical components
  2. Bake components before loading
  3. Boards should have conformal coating

are often not communicated before commencing the assembly process. This can lead to quality issues and delayed delivery.


Clearly highlight these special instructions in the Purchase Order (PO) to your account manager before manufacturing to avoid any quality issues or delay.

Correct: Include any special instructions in your Purchase Order

Correct: Include any special instructions in your Purchase Order

Ensuring smooth production flow for high quality boards

We recommend you to provide the following 3 files to ensure a smooth production flow process:

  • BOM file, with correct description, manufacturer part number and any instructions necessary (eg: DO NOT FIT)
  • Pick & Place file, with correct values
  • Altium file, with clear instructions on direction and polarity of components

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