Surface Mount Technology (SMT) flowlines are by design highly automated and each of the process steps needs to be performing at an optimum level to ensure production of printed circuit board assemblies meet the desired Key Performance Indicator (KPI) from a first time quality pass rate.

Here are just four different phases that will go towards achieving a defect free SMT production line:

1. Preventative Maintenance
2. Optimized setup
3. In Process inspection
4. Data analysis and continuous improvement

1. Preventative Maintenance

Implementation of a preventative maintenance program on all the SMT machines will not only improve efficiency and up-time but will also save money for the factory due to lost production time due to reduced number of breakdowns and unscheduled maintenance requirements.

By properly planning and preparing the preventive maintenance you can minimize any interference with regular operations, for example by performing the respective activities offline or in periods during which the line stands still anyway.

The overall net effect of scheduled preventative maintenance is not just improved quality but also increased up-time for the production line which results in a greater efficiency and increased quantity of PCBs being manufactured.

Unfortunately, a VERY low proportion of Chinese factories have a preventative maintenance plan in place. This is something our consultants work on pretty often.

2. Optimized Setup

Each process step or machine within the flowline should be set up following an optimized documented process so that each of the elements is set correctly every time. There are so many different parameters that need to be set in order for the entire flowline to run as smooth and stead heart beat which is impossible to achieve without an optimized setup procedure.

One of the main faults with PCBAs stems from solder issues so something as simple as setting up the alignment of the solder paste screen is of critical importance when you are looking to eliminate faults or poor quality.

Another area of concern are the pick and place nozzles, any slight defect in this part of the system and components will start to be dropped, placed incorrectly or not picked up at all.

Reliability and repeatability of machine each set up is a critical step in working towards a defect free production line. But again, just like preventative maintenance, documenting the setup process is not something that Chinese engineers do naturally.

3. In Process Inspection

In-process inspection on the SMT flowline is paramount in identifying any errors before the next step of the process, for example, checking the solder paste is in the correct position and that all places that should have solder actually have solder. If the system picks up any errors, they can be corrected before the next step in the process thus preventing poor quality boards going through the complete assembly line.

A wide variety of inspection equipment has been invented in order to fulfil the task of inspecting Printed Circuit Boards. From the simple magnifying glass to x-ray monitoring systems, there are many options available and the key point to inspection of PCBs is to ensure that the most reliable inspection system is used at the right stage within the manufacturing process.

We touched on the functional tests in an earlier article.

4. Data Analysis and Continuous Improvement

You cannot improve something if you do not know what needs improving and you cannot tell what needs improving unless you measure it. So the first thing to do is to understand the entire system and measure key elements, in other words, set up your Key Performance Indicators (KPI) and gather data for analysis.

A successful KPI program collects the correct information, processes it in a meaningful and timely manner, and communicates it to the people best suited to effect change and control over the process. This communication method must be done in a way that enforces this feeling of responsibility and empowerment to effect improvement.

A successful improvement program must:

1. Collect the right information
2. Process the information in a timely and meaningful manner
3. Communicate this information in an easy to understand manner
4. Engage the production people as self-actualizing high performance team

There are many other pieces to this jigsaw, but these simple steps will get you on the right track to achieving the optimal defect free SMT flowline.