PCB News - Six problems and solutions affecting SMT production and delivery

At ipcb, we classify all problems occurred in the manufacturing process and review them on a weekly basis. After summarizing all the information, we realized that most of the problems were caused by missing or incorrect information in the documents provided by customers (BOM, Altium documents, pick & place documents, etc.).

We summarized the first six problems affecting manufacturing and delivery, and solutions for how to repair the data when it is provided to us. By providing clear instructions in your documents, we can greatly improve efficiency, ensure manufacturing simplicity, high quality standards and on-time delivery.

Problem 1: description does not match part number

The description (name) and (manufacturer) part number in the bill of materials do not match, which inevitably leads to the purchase of wrong parts. This may cause serious quality problems and may delay delivery. When notifying the customer of this difference, some will advise us to follow the instructions, others will advise us to follow the manufacturing part number.

Error: the manufacturing part number does not match the description in the BOM.

Solution:

Always carefully check the description and manufacturing part number of all components in the BOM to avoid any trouble to the customer. If there is any difference, please inform your ipcb account manager as soon as possible.

Correct: the manufacturing part number should match the description in the BOM.

Question 2: unclear "empty paste / assembly" instructions

During SMT loading, confusion is often caused by loading / not loading, which may cause that the loaded parts should not be on the PCB. When this happens, we need to stop production and negotiate with customers. Delays in customer communication usually lead to delays in production and delivery.

Solution:

On parts that you do not want to load, DNF is clearly highlighted in the BOM (not applicable).

Correct: DNF is clearly displayed in the bill of materials.

Problem 3: lack of polarity

The polarity is not clearly marked in the attached PDF file, silk screen or Altium file. This will lead to the wrong direction or polarity of SMT components, resulting in serious inefficiency.

Solution:

Clearly indicate the direction and polarity of components in PDF, silk screen or Altium documents to avoid delivery delay.

The image of component polarity is clear and prominent;

The image of component polarity is clear and prominent.

Problem 4: missing component value

When customers provide Altium or pick & place files, sometimes in some cases, these files lack component value information. In this case, we have to manually insert the correct value (from the BOM) into the pick and place file, which may lead to human error and quality problems.

Solution:

The fetch / drop file you provide should contain all component values that match the values and codes in the BOM.

Correct: component values in the selected and placed files should be clearly highlighted.

Problem 5: encapsulation error

If the package of a component is inconsistent with the package of PCB pad, we generally stop production and inform the customer of the difference.

The four most common responses we usually get from customers are:

a. Do not load parts ";

b. Can you install the part in this location? " We tend to avoid this option because it can lead to serious quality and function problems;

c. We will order the correct parts and send them to you. " This option means putting the machine in standby mode, which will lead to delayed delivery;

d. Continue the machine loading process indiscriminately; After receiving the correct parts, please install them manually. " Due to human error, this option is likely to have problems with quality and efficiency.

Solution:

Ensure that the pick and place file (component package) matches the BOM part and package.

Question 6: additional special instructions

Special instructions, such as:

a. Do not clean the circuit board because there are key components on the board;

b. Bake components before loading;

c. The Board shall have conformal coating;

There was no communication before assembly. This may cause quality problems and delay delivery.

Solution:

a. Before production, please clearly show these special instructions in the purchase order (PO) to the customer manager to avoid any quality problems or delays;

b. Please include any special instructions in your purchase order correctly: include any special instructions in your purchase order;

c. Ensure the smooth production process of high-quality board;

d. We recommend that you provide the following three documents to ensure the smooth production process: BOM document with correct description, manufacturer's part number and any necessary instruction documents;

e. Altium file with clear instructions on component orientation and polarity.