PCB News - Teach multilayer circuit board factories to write 8D reports required by customers

Teach multilayer circuit board factories to write 8D reports required by customers

When the customer receives the circuit board, the next step is to mount the circuit board. Generally, we will use manual placement or machine placement. When the customer finds quality problems, we will contact the multi-layer circuit board supplier (Shenzhen multi-layer circuit board). For complaints from the board manufacturer, the supplier (multi-layer circuit board) needs to make a quality report and return it to find out the reason. Generally, the quality report of the multilayer circuit board manufacturer will use 8D. "If it is a human error, how to answer the customer’s 8D? What about the report? For example, the appearance defects of the PCB multilayer circuit board, the wrong labeling, the shortage of quantity, the missing processing steps, the wrong delivery and so on.

General customers don’t like us writing rectification measures such as ‘operating errors, personnel training, and quality awareness enhancement’, but how can they write them? It's impossible to prevent mistakes in everything, right?

In fact, first of all, I would like to say that not only is your customer dislikes 8D reports like this, I also don’t like people writing rectification measures and writing "operators have poor quality awareness, strengthen training", "punish the parties with 300 yuan", etc. . When I was the person in charge of quality in a company, whether it was my supplier or internal production engineering, apart from similar problems, if my SQE or process quality engineer gave me such an improvement report, I would definitely get my approval. .

Because the responsibility for quality problems is shifted to the operator, it is either irresponsible to deal with it, or it is not understanding quality management. Because in my work experience, most of the operators I have come into contact with are very simple workers. There are tricks and tricks, but they are rare. Therefore, all the problems in the above examples can be found in the management system and methods.

Let me talk about appearance defects first

Generally speaking, appearance defects require 100% visual inspection, and it is indeed easy to cause missed inspections. But it is still possible to find the reasons and formulate improvement measures from the following aspects.

1. Whether the appearance inspection standards are specific, clear, and agreed with customers. The appearance standard of some multi-layer PCB factories simply writes "no burrs, no bumps". However, during the on-site operation, the operators and production managers thought that "no bumps are impossible", so they grasped a vague standard according to their own understanding. The normative approach is to determine acceptable and unacceptable standards based on possible defects one by one according to the function of the product. Then describe it clearly in the form of pictures and texts. The standards should be clear, easy to understand, unambiguous, and realistic and feasible. Eliminate ambiguous "appearance standards refer to limited samples". If there is a limited sample, there must be a written description, which is the limited sample of which defect is the limited sample, whether it is a defective sample or a qualified sample, and what is the judgment condition of the defect and qualification must be clearly stated.

2. Is the job planning reasonable? For example, is the illuminance of the light source of the workstation requiring appearance inspection appropriate? Is the height of the appearance inspection workbench suitable for workpiece turning and operation observation? Has the observation sequence of employees' appearance inspection planned and solidified? That is to say, when inspecting the appearance of the parts, which faces and points should the eyes see, is the order of the turning of the workpiece and the walking path of the eyes fixed? Can the appearance inspection and production operations be completed within a limited time?

3. Whether the appearance standard has been clearly and clearly communicated to the employees. It is forbidden to say that the training is not in place in general, and only train the employee on this defect in terms of facts, and another problem of the same thing may happen again in another work station next time. If it is rectification in terms of employee training, we must look for reasons from the perspectives of training methods, training procedures, post-training assessment methods, mutual inspections of new employees at the beginning of the job, and the companionship of their masters, and find reasons for work methods and process systems, and make rectifications to prevent the next time. Similar things happen. For example, for appearance defect training, in addition to explaining appearance standards or work instructions to new employees, training should also be combined with a large number of defective samples, so that new employees can practice defects judgment. In the initial stage of the employee’s employment, the parts near the standard limit should be judged by the master or quality personnel. It is necessary to establish a key position management and post personnel training system to prevent new employees from being rushed in for temporary training.

Is there a quality warning card for the appearance defects that often appear to remind employees to pay special attention?

Finally, and most importantly, do you look for the cause at the source, and strive to reduce and eliminate appearance defects? For example, for bumps and bumps, will the product transportation rollers on the assembly line bump the parts? Will there be any bumps between the product and the product? Is the logistics turnover tooling reasonable? Is there a stack of artifacts? Is there any risk of collision in the process of staff operation and workpiece placement?

The second question, missing processing

In addition to setting up a continuous production line and setting up process error-proofing, improvements can also be considered from the following aspects:

Increase self-inspection and mutual inspection. Before each sequence is released, the operator checks whether the processing content of the sequence is completed by himself, and releases after the inspection or puts it into the rack and magazine. The next sequence checks whether the processing or assembly content of the upper sequence is completed before processing.

Fixed management, location storage. If it is a stand-alone operation, the parts to be processed and the processed parts in each stand-alone station must be placed separately and placed in a fixed position. Generally, the left-hand side is the part to be processed, and the right-hand side is the processed part. Mixing is strictly prohibited, and the processed parts to be processed are strictly prohibited from being placed in the same rack or box. In the work-in-process turnover area, the work-in-process of the whole material box should also be placed in different areas of the product in different process states, and clearly marked.

Hanging process accompanying card. For the production line of stand-alone operation, the accompanying card should be hung on the rack or the material cart, and the process status should be indicated on the accompanying card.

The third issue is the shortage of quantity

I also don’t agree with the increase of mutual inspections, because the efficiency is very low. In addition to using counters, improvements can also be considered from the following perspectives:

If it is a regular product, it should be placed neatly. A packaging box or a material box is fixed in several rows, several columns and several layers, so that the inspection quantity is converted into an appearance inspection of the arrangement shape, and the quantity confirmation becomes very intuitive.

If there are requirements in terms of protection against bumps and extrusions, then consider custom molding blister boxes or material boxes with partitions to place the products, one radish and one pit. The pit is not filled up, and the parts are missing, but the quantity is not enough.

Weighing method. However, when the number of parts is large, and the weight of each part fluctuates within a certain range, it may cause inaccurate weighing to determine the quantity. At this time, you can consider setting up a number of small packages in the large package, and the number of small packages should take into account that the sigma of the fluctuation range of the total weight is less than one-sixth of the weight of a part.

The fourth question is the wrong label

The wrong label is also a serious problem for many OEM customers. In some customers, if the label is misapplied twice, it may directly lead to controlled shipment. Mislabeling can be improved from the following perspectives.

Print on site, print as you use it, and print labels in advance is prohibited. Generally speaking, strict OEMs will require suppliers to install label printers at the packaging station of the production line. If the company has multiple production lines, an independent label printer should be installed at the off-line packaging station of each line. Avoid printing a bunch of labels in the office. Some companies have a variety of different products, and may also have different batches. They like to print a bunch of labels in the office, and then bring the bunch of labels to the side of the production line, and then look through the bunch of labels to affix them when packaging. Or after packaging, many boxes are stacked on top of each other and then labeled together. Some companies even leave it for a few days after packaging, and then label it before shipment. These incorrect practices are abnormal if there are no problems.

If the customer does not have a clear requirement for an independent printer, and the company cannot achieve an independent label printer for a while, it can also adopt the method of changing the type to ensure that the label is correct. I will write a separate article introduction when I have the opportunity to change the type of error-proofing method in the future. Simply put, in the case of multiple products being produced on the same line, when preparing to switch and process a certain type of product, the raw materials, finished products, semi-finished products, tooling, knives, tools, auxiliary equipment, various operating instructions, Various record sheets, packaging materials, including the procedures and process parameters called in the equipment, and of course labels, are all switched to be consistent with the model of the product to be produced. If it is inconsistent, make sure to withdraw or cover it from the production line and within the reach of the operator. Make it impossible to misuse and misuse, which is called change-type error prevention. When changing the model, the operator uses the "Change-over Error Prevention Checklist" to check and record that all the software and hardware switchovers have been implemented, and the team leaders check each other.

The fifth question, the wrong information

The most common mistake is that one or two products of different models are mixed in a large package of most correct products. It is generally caused by the following reasons. If these aspects are changed, the mixing problem is basically eliminated.

The most basic reason for such problems is that they have not done a good job in changing the type and preventing mistakes. There are different types of finished products and products in process at the production station and on the side of the production line.

Or in the packaging area, inspection area, different types of products exist at the same time, scattered or mixed. Therefore, fixed management and 5S are still the most basic requirements, not simply clean and tidy.

In addition to the above problems, there is another reason often used by suppliers, which is "the debugging parts are mixed in the qualified parts and submitted". This is also a statement that I and the SQEs of many OEMs hate. We often ask, how do you make sure that the piece is the debugging piece? Is there a traceability number on the part? Does the inspection record of the debugging part correspond to the traceability number? Even if the debugging parts are really mixed into the qualified products, the company needs to place and mark the non-conforming products, the fixed placement and marking of the debugging products, the inspection and confirmation before starting the machine, the first article confirmation, and other management methods. Reason analysis and improvement. Rather than simply boil down to thinking that the operation is wrong.
The Electronics Co., Ltd. is a manufacturer specializing in the mass production of PCB multilayer circuit boards.