How to ensure pcba material quality using IQC incoming material inspection

Material inspection is the first quality control level of PCBA processing. It will affect the final quality of the product and the cost due to various defects.

PCBA manufacturers and customers must upgrade the IQC incoming inspection to a strategic position.

Strictly control the process to ensure the quality of the materials. In this article, PCBasic will introduce how to perform an IQC incoming inspection.

What is IQC’s Incoming Inspection?

The full name of IQC is Incoming Quality Control. The process refers to confirming and checking the quality of purchased PCB boards and board components.

It involves measuring, inspecting, and testing all of the main characteristics of the materials.

Then, correspond these characteristics with the specified application requirements.

To wrap this up, comparing and determining material compliance is crucial, which will help to judge whether the batch of products is defective.

If we find any defective material, the material distributor should report it to the system in time. Labeling the material as flawed for processing is necessary to avoid such costly mistakes.

What problems may occur with incoming materials for PCBA orders?

• 1. Wrong quantity – The incoming material does not match the BOM table or the amount of the material label. Incorrect BOM quantity might result in excess, less, or no material.
• 2. Wrong incoming material – The specifications of the incoming material are inconsistent. This means the relevant parameters of the material are inconsistent with the requirements of the order BOM table. Examples include the error value of resistance, capacitance, etc. In some cases, certain materials are expected. Instead, different materials are actually supplied.
• 3. Wrong label – The material is not defective, but no material designation exists. Sometimes the reason is a labeling error such as wrong P/N, more characters, fewer characters, etc.
• 4. Disordered packaging – multiple materials mixed in a single order. Often the labels or the packaging are found to be damaged. More reasons could be the packaging of one material gone loose, not properly placed, or the tape ended up in reversed order.
• 5. Wrong size – The PCB board or electronic component size is larger or smaller than the required tolerance. This includes the appropriate length, width, height, aperture, curvature, thickness, angle, spacing, etc.
• 6. Wrong surface treatment – PCB boards or electronic components end up damaged, scratched, peeled off, deformed, or dirty. There could be a difference in appearance and poor silk screen printing of materials.

defective materials marked with defective labels and placed in the designated defective storage location for processing.

How to do IQC incoming inspection to ensure material quality?

1. Documenting standard material ordering process

A standardized and standard process is the core of quality assurance. The process involves solving problems by precise execution.

The method involves sequences of specific tasks. Those tasks are a requirement in the standard operating manual of every manufacturer.

PCBasic has developed an entire standard process for incoming material inspection. We believe that firm adherence to standards is the key to ensuring material quality.

Ordered materials IQC tests:

• 1. Counting Quantity – The material counter uses the X-Ray machine to measure the material quantity. It prints the label and attaches it to the outer package.
• 2. Selecting an order – The material counter logs into the MES system, selects an order and publishes a transfer order.
• 3. Pick up materials – Confirm the order's material storage location in the "Storage Location" column. We navigate to the storage location to take out all the required materials.
• 4. Check the model – confirm whether the label model on the incoming packaging bag is consistent with the BOM. In case of a problem, record the issue with remarks. The process will also take a photo and upload it to the MES system for further investigation.
• 5. Check Quantity – Check whether the incoming material quantity is greater than or equal to the system demand quantity.
• 6. Measurement of resistance value – Conduct resistance-capacitance test for resistance, capacitance, and inductance. Print the label and paste it on the outer package when the test passes. If an "NG" product exists, it's necessary to paste a lousy title to distinguish it.

PCBA materials IQC tests:

• 1. Check the silk screen – In addition to the resistance-capacitance material for IC materials, confirm whether the label model of other materials is consistent with the actual silkscreen on pcb.
• 2. Check pads – Designed for materials above 1206 packages. Plug-in types, A\B types, structural parts, etc. The materials are placed with a tag number for confirmation.
• 3.  Cut off the remaining material – The incoming quantity of A\B materials is greater than the order demand quantity by 50PCS. In such a case, the excess material is cut off. The cutout materials shall be stored and recorded according to the storage location.
• 4. Abnormal feedback – Abnormalities include inconsistent pads, inappropriate materials, few incoming materials, etc. After verifying the actual situation of incoming materials, please take pictures and upload them to the MES system.
• 5. Material warehousing – SMD materials, DIP materials, and abnormal problem orders. All those ordered are placed in the corresponding placement area. 
• 6. Supervisor review: Focus on the processing of special orders and problematic orders. The supervisor will review and confirm that there are no problems in the order before entering production.

2. Prevention and improvement of material ordering process operation

The material can be judged as all materials only after the inspection is OK. This setting eliminates the loophole that the material point staff does not follow the process.

3. Standardization and improvement of the tool for spotting components

The COOD10 software is installed on the computers equipped with each pointer. The software ensures that all pointers have search conditions which improves the efficiency and accuracy of the pointer’s confirmation.

Conclusion