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PCB Fab Quality Control

Incoming Material Control


SysPCB ensures that incoming material quality is always top concern; it is the base of all the following process. We never compromise with substandard quality materials.

When purchasing materials for our boards, our IQC team carefully checks everything being sent to us. Meanwhile, we are careful to adhere to all the specifications you required, on top of those set by the regulating bodies we subscribe to.

We always honor the quality of our material and integrity of our services and products. We will not settle for less than excellence, and we are ready for your most rigorous requirements.

Below are the material suppliers we normally use. These are well-known raw material brand in PCB industry, who guarantees the steady product quality of SysPCB. We constantly pay attention to our long-term relationship establishment between raw material suppliers and SysPCB to assure the stability and Reliability of the top quality material supply. The friendly relationship leads to the mutual support and growing-up since our PCB business started.

In Process Control


At SYS technology, quality, customer satisfaction and continuous improvement are the primary focus; every employee is aware and proud of his or her individual contributions to the overall effort to continually improve the levels of quality and customer satisfaction. Quality is considered in every stage in PCB fabrication from development through distribution.

At each stage of production, we conduct inspections of all PCBs. All the boards are quality-controlled as following rules.
1. Standard production PCB capability & quality is by IPC 6012 Class.2
2. UL 94V-0 Flammability rating
3. Outgoing Inspection: G-II A.Q.L 0.65%
4. A.O.I inspection for inner layers and outer layers
5. 100% electrical test
6. ISO9001:2015 & ISO14000
 
 

1. Design Rules Check (DRC)

 
The DRC is a quite important step and in-depth review of your production data in PCB manufacturing, which is carried out by our experienced CAM engineers with GENESIS software before production of your printed circuit board. A comprehensive Design Rule Check helps to identify many errors in advance, thus avoiding problems and complaints. We also do the PCB manufacturing rule check to make sure the PCB design is workable. If we find any errors we will get in contact with the customer.
 
 

2. Electrical Testing

 
The electrical testing (E-Test) for circuit boards is performed after manufacture. We use flying probe test for small volume and prototype PCB orders, but use E-Test fixtures to test production batch PCB orders. The tester will check for short circuits, open circuits and make sure the nets of the PCB we manufactured is the same as the nets in your design. PCB boards that are identified as defective are eliminated; defective PCB boards in panels are specially marked.
 
 

3. Automated Optical Inspection (AOI)

 
We use AOI to check the inner layers of multilayer PCB. This inspection is much more reliable and repeatable than manual visual inspection and it will guarantees the high reliability of multilayer circuit boards. AOI visually scans the surface of the PCB. The circuit board is lit by several light sources and observed by a scanner or by a number of high definition cameras. This enables the monitoring of all areas of the printed circuit board. AOI for a bare PCB board inspection will detect the features include:
  • Line width violations
  • Spacing violations
  • Excess copper
  • Missing pads
  • Cut traces or pads
  • Hole breakage
 
 

4. X-Ray

 
Testing the layer offset with X-ray technology is very important in the manufacture of multilayer PCB. X-ray images are the best (and only) way to identify and correct layer displacements in the pressing process.
Drill holes in multilayer PCB are also optimized using X-ray images. Any minor deviations in the geometry of the circuit board image compared to the geometry of the drill hole coordinates will be identified. By changing a correction factor within a clearly defined tolerance range, it can be ensured that the optimum drill reference point will be determined for each axis, with an optimal interpolation for all layers. These corrections take place in the µm range!

 
 

5. ISO9001:2015 and UL certified

 
We're ISO 9001:2015 certified PCB manufacturer. Our quality control system records the customer requirements and creates a system for communicating with customers about product information, inquiries, contracts, orders, feedback and complaints. Moreover, our quality control system is regularly audited and evaluated for conformance and effectiveness.

Outgoing Quality Control

 
We refuse to compromise on our outgoing quality just like we make no compromises on our incoming material quality. Our product is your raw material; we believe a win-win relationship will last much longer. Our E-test dept. will make sure all the PCBs passed are out of open or short issues; Our professional FQC and OQA team will make sure the cosmetic of PCB is 100% perfect. Our labs will make sure other aspects of PCB. We know that our products are created with the best possible processes, and that everything we do conforms to the ISO bodies to which we subscribed.

SysPCB believes in making your products happen by providing you with quality service and the best possible product. We are proud to stand by our products, we are also proud to boast about our high ratio of repeat and loyal customers. When your customers stay with you, it is because you always choose perfect supplier for your products.

We invite you to rely on our service. We value the faith and trust of our customers above everything, and do everything possible to ensure that your expectations are met or exceeded. We have a proven track record of quality that we intend to maintain.

Content of PCB incoming testing

 

 
One company once did a statistics to classify the causes of PCBA product quality problems and found that there are four major causes: design, incoming materials, manufacturing process (production), and storage and transportation, respectively accounting for 25%, 50%, 20%, 5%. Issue of incoming materials accounted for 50%, so it came to the conclusion that incoming materials inspection is quite important. Similarly, in order to ensure the PCB base board quality used in the production of SMT production lines, these incoming materials must be tested before they are put into production to determine whether they meet the production standards. Incoming material inspection is generally carried out by visual inspection in actual production.

The content of PCB incoming inspection includes PCB size and appearance inspection, PCB warpage and twist inspection, PCB solderability test, PCB solder mask integrality test, PCB internal defect inspection.


 

PCB size and appearance inspection

 
PCB size inspection mainly includes: diameter inspection of processing holes, spacing and tolerance inspection, and PCB profile size inspection.

The appearance inspection mainly includes: inspecting the alignment of the solder mask and the pad; whether the solder mask has abnormal conditions such as impurities, peeling, wrinkles, etc; whether the fiducial marks conforms to the standard; whether the circuit conductor width (line width) and spacing meet the requirements; whether the multilayer board has delaminate issue, etc. In practical applications, special equipment for PCB appearance testing is often used for inspection.
Typical equipment is mainly composed of computers, automatic workbenches, and image processing systems. This system can inspect the inner and outer layers of multilayer boards, single-sided/double-sided boards, and base photoimaging films; it can detect problems such as scratches, pinholes, conductor widths, conductor spacing, rough edges, and large-area defects etc.


 

PCB warpage inspection


Unreasonable design and improper processing in the processing process may cause PCB warpage. The test method is stipulated in the IPC-TM-650 standard.

The test principle is:

Expose the PCB under testing to a representative thermal environment of the assembly process, and conduct a thermal stress test on it. Typical thermal stress testing methods solder dipping test and float test. In this test method, the PCB is immersed in molten solder for a certain period of time, and then taken out for warpage testing. The method of manual measuring PCB warpage is to put the 3 corners of the PCB close to the desktop, and then measure the distance from the fourth corner to the desktop. This method can only be used for rough estimation, and more effective methods include the application of ripple imaging technology.


 

PCB solderability test


The solderability test of PCB focuses on the test of pads and plated through holes. The IPC-S-804 standard specifies the solderability test method of PCB, which includes edge dipping test, spin dipping test, wave dipping test and solder bead test, etc. The edge dipping test is used to test the solderability of surface conductors; the spin dipping test and wave dipping test are used for the solderability test of surface conductors and plated through holes; the solder bead test is only used for the solderability test of plated through holes.

 

PCB solder mask integrality test


PCBs used in SMT, dry film solder mask and optical imaging solder mask are generally used. These two kinds of solder mask have high resolution and immobility. The dry film solder mask is laminated on the PCB under the effect of pressure and heat. It requires a clean PCB surface and an effective lamination process.

This kind of solder mask has poor viscosity on the surface of tin-lead alloy. Under the impact of thermal stress generated by reflow soldering, the phenomenon of peeling and breaking from the PCB surface often occurs. This kind of solder mask is also relatively fragile, and microcracks may occur under the influence of heat and mechanical force during HASL process.

In addition, physical and chemical damage may also occur under the effect of cleaning agents. In order to discovery these potential defects of the dry film solder mask, strict thermal stress tests are supposed to be performed on the PCB during incoming material inspection. This inspection mostly uses the solder float test, the time is about 10-15s, and the solder temperature is about 260-288℃. When the solder mask peeling phenomenon is not observed during the test, the PCB test piece can be immersed in water after the test, and the capillary effect of the water between the solder mask and the PCB surface can be used to observe the solder mask peeling phenomenon. The PCB test sample can also be immersed in the SMA cleaning solvent after the test to observe whether it has physical and chemical action with the solvent.


 

PCB internal defect inspection


The internal defects of PCBs are generally inspected by microsection technology. PCBs are inspected for microsection after solder floating thermal stress test. The main inspection items are the thickness of copper and tin-lead alloy coatings, the alignment of the internal conductors of the multilayer board, laminate voids and copper cracks, etc.

In summary, incoming material inspection occupies an overwhelming position in the PCB assembly company's product quality control, so the quality control of incoming materials must be raised to a strategic position to deal with.
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