Cluso First Article Inspection meets all of Itron’s expectations

In the printed circuit board assembly space, a new breed of first article inspection system is saving substantial time and money, so claims production engineering specialist Cluso and, its Americas Distributor, Brock Electronics. We put this to the test by asking a valued and long standing user, Itron, for their views on the whole First Article Inspection (FAI) space, as it applies to PCB Assembly.

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Itron provides advanced resource and business process management and data collection software and hardware for utilities companies worldwide. 

Itron’s production facility in Waseca, Minneapolis, produces high volumes of a limited variety of printed circuit boards. Typically, the circuits are single-sided, approximately 40mm x 90mm, containing between 100 and 150 components, though there are some smaller batches of physically larger products, with higher part counts. Components may range anywhere from 0402 chips and 0.5mm pitch QFNs, to 25mm tall electrolytic capacitors.

First Article Inspection at the Itron facility was traditionally carried out by qualified inspectors who would simply visually inspect the first populated board, and then compare this first-off to an assembly template. Techniques such as this have been used since the advent of PCB assembly but there were a number of potentially serious challenges with this practice. For example, quality personnel were conscious of a 20 minute window before an "inspection delay" brought the line to a grinding halt! Batches of new products (NPI), or higher part count assemblies, placed still greater emphasis on the First Article Inspection process, resulting in significantly more demanding, yet lengthier, inspection routines. Inspectors were occasionally missing defects, such as polarity marks on electrolytic caps, as the inspection routines became longer, more challenging and more pressured. Some old inspection favorites, including missing or extra parts, occasionally cropped up too. The added work and attention required to guarantee quality to Itron's high standards was becoming more expensive and ever more demanding. Maintaining accuracy of inspection records was also difficult and time-consuming, adding still more workload to the already heavy burden on the engineering & support resources.

Having researched the market for a more advanced and reliable solution, Itron decided to purchase a Cluso Vision System, having seen it demonstrated at a local SMTA event. Following a demonstration, Cluso was happy to accommodate Itron’s specific requirements for a large format scanner and clearance for tall parts, and the first system was delivered in 2006. While the Cluso Vision System certainly delivered first article inspection value for Itron over time, the engineering team subsequently reviewed how AOI might improve the whole inspection process, also comparing AOI solutions to the later version of the Cluso system and its newer software platform that had evolved still further over the years. The early system was subsequently upgraded to the current Cluso model, with Itron having sufficient expertise to set it up with no more than cursory remote assistance from Cluso’s Americas distributor, Brock Electronics. The new system is now in daily use at Itron, and continues to ease the FAI burden in this high technology facility.

The primary use of the Cluso system is for first-off inspection of prototypes, new product innovations and major revisions. From the outset, the system was found to be easy and intuitive to use. Unlike AOI systems, the Cluso does not require any program generation, only data import. Itron now incorporates the generation of the necessary files, for input to the Cluso system, into its standard placement program creation procedures. One of the key advantages of Cluso in the FAI space is its capability to run inspection routines, without any requirements for programming, with the corresponding time savings that are so critical for first article inspection and improved SMT line utilization. This FAI system is designed to improve the capabilities & effectiveness of the visual inspection process & not to replace the human element in that critical phase.

The updated system, installed in 2009, incorporates the new and improved software, which has made Cluso, not only more capable, but also more user friendly than the original. This has proven to be of particular value for prototype builds, for when multiple models are built on the same multi-up panel, and for those assemblies with part counts that are more challenging for visual inspection. Interestingly, Itron also uses automated optical inspection on its line, complementing the Cluso first article inspection, by comparing production items with the approved golden board. This is very much in line with the Cluso philosophy, where FAI is seen as a complimentary rather than a competitive or replacement process to AOI.

To Mark Rasmussen, Principal Engineer, at Itron Manufacturing, the key benefits are clear: reduction in the time taken for first article inspection and accurate inspection of prototypes. 

On a day-to-day basis, while Rasmussen finds the speedy set-up time (that gives him a really short FAI time from start to finish at around 15 minutes) to be of paramount importance, it's the dramatic improvement in the quality of visual inspection results that really makes for a really good winning combination. The reliable and detailed reports, along with the capability to store images for later review, and the ability to use either drawings or known good boards as the golden sample for comparison, are all of great benefit. Additional supporting advances introduced on the more recent Cluso system also bring some positive elements to the equation for Itron, such as the ability to handle pdf files and to manipulate scanned images for improved detection.

Rasmussen comments: “I believe that the Cluso system does a great job of documenting the placement machine output, is easy to program and use and is very applicable to a variety of production situations such as NPI, low-volume, high-value circuit inspection, first article inspection and archival documentation of the product. It has certainly met all of our expectations.”

Our thanks to Mark for his insight & comments.

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Cluso claims that First Article Inspection saves time and money while providing a far higher level of confidence that production defects, due to placement errors, are virtually eliminated. It would appear that some users might agree!

Six of the top ten CEMS globally are Cluso customers.

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For more information visit Cluso web site www.cluso.com.au 

Or contact Paul F. Walsh email Paul@BrockElectronics.com 

Innovative Behaviour

I was reading an article on Evertiq (www.evertiq.com) a while ago and it was commenting that there was an incredible lack of innovation in the USA and that was the reason that the US electronics industry in particular was not doing well in recent times. After years of selling Automated First Article Inspection Systems (FAI) I tend to agree that the article was fairly accurate in its assessment. The more I speak to people the less I think they are aware of what goes on in their own factories.

In particular a lot of companies believe that FAI is something that is simply done but does not hold a high importance to the outcome of their SMT operation. I guess I hold a vested interest in this opinion but I also have run a CEM in Australia for the past 25 years so I have knowledge pertaining to this subject from a users aspect as well. We originally designed the Automated FAI for our own use in our facility. We recognised that there were 2 distinct problems due to FAI that we needed to tackle. One was a QA issue in that we had at random times loaded incorrect parts on PCB's. The 2nd issue was the time it took to perform the manual FAI and the disruption to the production flow being the SMT loaders were idle during this process.

The QA issue was attempted to be tackled by increasing inspection of the manual process of conversion of data by having someone checking the data. This had limited effect and reduced the problems but they still occurred at random times due to human error. The other QA issue was attempted to be resolved by again, more inspection. A 2nd person double checked the feeder setup. This seemed to work but after time the problem was that the personnel in the SMT area were double checking their friends work and could not be 100% effective. We thought of barcoding but came to the conclusion that this would only push the problem upstream to the people placing the barcodes on the reels, they can still make the same mistake as anyone. Everyone knows that you cannot inspect quality into a product, they must be designed in.

The 2nd issue of time was a substantial one which seemed more difficult. Every time the lines were changed over there was several hours during which the manual FAI was done that the lines were idle. Because we had 4 SMT lines being changed a minimum of 2-3 times a week it seemed as if half of our lines were down waiting for FAI permanently. Like all CEM's we are under ever increasing pressure to keep costs down and machines laying idle did not fit this mode. 

We designed our first Automated FAI machine to fulfil this purpose for our own use and then later on started to sell the system worldwide. In my discussions with other CEM's around the world the most accepting and innovative companies seem to be from Eastern Europe and China in particular. This fact actually bucks the so-called perception that in China they simply copy things and do not innovate their processes. Companies in China have a real handle on the problem and are actively seeking solutions to those problems. In the USA there is a distinct attitude that if they did not think of it then it is not useful or it is not what they want. A lot of companies do not believe there is a problem, it is either being hidden, or not highlighted by staff. There are even some who think it is not even necessary to check the the first PCB assembled  and it is a waste of time!

One leading CEM evaluated our system a long time ago and  wrote a glowing report that the system would save $70KUSD per week in the one factory premises only, which put the ROI on the system at 2.1 days, and then promptly sent the demo unit back to us. It took an unbelievable 3 months before they purchased it and the reason was that there was no other system of its kind at that time to compare it to and their rules were that there must be minimum 2-3 quotes to purchase. During those 3 months we sold 5 units to their other facilities(same company) in Hungary, Israel and China before they authorised the purchase for themselves. Based on the report they distributed internally their overseas counterparts felt they could not wait for the red tape to resolve and authorised and purchased the systems locally.

Innovative behaviour is what made the United States unique and strong, if innovation is lost then I cannot imagine what may happen to the manufacturing base, or for that matter, the country. As the USA comes out of the GFC it is time to re-evaluate innovative behaviour in every aspect of their business. Maybe it is time to reinvent themselves as their historical counterparts did, this will be the only way to survive. Complaining that the work is disappearing to China or wherever will not bring it back, innovation is the key. Customers recognise value added in their suppliers, they just have to be shown that it exists.

The problem in a lot of cases is that the innovation is just not there. 

Greg Ross

Cluso Vision Systems

Management - Introducing Automated First Article Inspection Series

Management have a difficult time in determining which equipment to invest in and which ones to stay away from. Each department usually comes with a seemingly sob story about why you should authorise some money to make his job easier and supposedly save the company enough money to make it worth it. Management have to weigh up the endless options from staff suggesting equipment and processes with technical reasons that sometimes are self motivated to the employees own agenda. These can sometimes be as simple as building an inspection dynasty for themselves and as devious as hiding some inability to perform a job and the equipment will hide this.

An Automated First Article Inspection System is a very easy system to justify financially except it is a difficult one to suggest because the department that will use it, and is providing the technical reason for the purchase, has to come clean that basically they cannot do their job properly without it. This will expose the fact that there is NO traceable system in place that 100% covers this function. They will have to admit that they do not perform a 100% FAI and/or are not exposing the time it takes to do it. They are afraid the obvious question will arise... "What the hell do I pay you for if this is the first I hear of this hole in our SMT Inspection area".

Somehow this impasse has to be broken if the FAI process can be fixed. The seemingly simple process of FAI is that prior to switching the machines to full speed building product in SMT after a changeover is that someone 100% checks the first PCB coming off the line to ensure it is built to the customers specification. When the SMT builds it wrong the management step to in ask the question, what went wrong. Usually there are a variety of excuses like, Someone did not check the feeders properly and management decide that a 2nd person should check and consider the problem solved and everyone pats themselves on the back, job well done. The other is to train the operators on inspecting the feeder setup, or simply fire someone, or both.

The problem will not go away, the fact is that in any manual process there will be human error. In the FAI process there are 2 places for error, in the conversion of the customer CAD/BOM data to Pick and Place file and placing the feeders in the right places. When checking these places at FAI the operator is left to check this without any help and the result of his inspection will load 100's of thousands of parts onto PCB's, potentially wrong. And he is being pressured to perform this task in a ever reducing length of time. In some factories I have looked at they are given 10 minutes to perform FAI for a PCB that contains 700 parts. This means the person performing this FAI must locate the part on the PCB and check if it is the right part in under 3/4 of a second average per part. That is the simple math. Since this is not possible they must NOT be inspecting the PCB 100%. Which parts are not being checked, does it matter, any part missed at FAI means that every PCB assembled will be wrong. Does this not worry you, it would scare the hell out of me.

At Cluso we have our own CEM facility here because we started as a CEM and designed the Cluso system for ourselves many years ago. We know the problems and we have solved them with the Cluso system. In the 7 years we have been using the Cluso system we have not loaded a single part in the wrong location... 

Can you say that??

The ROI on the system has been calculated in weeks not months. One of the largest CEM's calculated that the system would save them $70KUSD per week at the one facility when measured against 100% manual FAI methods. Needless to say we have sold many around the world to this company. Maybe you can wait until the next time you have to explain to your customer that you loaded 5000 PCB's with the wrong component and it was in a location that the test did not pick up...

Good Luck.

Greg Ross

Cluso Vision Systems

Surface Mount Department - Introducing Automated First Article Inspection Series

In the SMT department they are really at the coalface of the issue in that they are under crushing pressure to keep the machines running at maximum speed with no downtime. Production Management are increasingly pressuring them to provide more output and coming down heavier when things go wrong. The SMT department is left with being responsible for the quality of its own output like all workcells in manufacturing but the tools to ensure this are not keeping up with the technology of P&P machines. These machines are getting faster and more expensive than ever and downtime is not acceptable in financial terms. Anything that can be done to get them up and running faster is being experimented with. The problem is until automated FAI came around there was nothing to help except throwing manpower at the FAI or reducing the level of FAI. These methods are either costly, risky or both.

One of the key processes in SMT that has downtime is at changeover time when a new product or batch is put onto the SMT lines. The time it takes to get the Pick and Place machines back up to speed is being monitored and criticised the most. The main problem here is that SMT has not been provided with any automated processes to allow them to reduce these times, in some cases it is only the loud voice of management driving them to reduce these times, OR ELSE. Left with the ominous choice of, either reduce the times or someone else will, then the only option is to cut corners and do not tell anyone thereby running the risk of the wrath of management.

Using an Automated First Article Inspection System these changeover times CAN be reduced without cutting corners, using these systems properly actually increases inspection coverage, simplifies the process and adds a level of traceability unheard until now. As well the times are brought down to a manageable level. For manufacturers dealing with the assembly of highly traceable products like medical or military products these system can easily provide them with the results required to satisfy the scrutiny of any ISO13485 system requirements.

With an automated FAI on board in SMT the personnel can actually concentrate the business of producing PCB's and not performing FAI's under extreme time pressure wondering when the wrath of management is going to crush their future employment due to the length of time the FAI has taken or worse still because a mistake was made during their normal reduced manual inspection and 10,000 PCB's are loaded with an incorrect part and the customer is screaming for heads to roll.

Greg Ross

Cluso Vision Systems

Quality Control - Introducing Automated First Article Inspection Series

The Quality Control department is left to perform the duties spelled out by the QA people in their procedures and practices. When the QA department says they must perform a 100% First Article Inspection on all product coming out of SMT they are supposedly bound to do so however at times left with no time to do it. The pressure from production to get the lines moving again is incredible, as long as the lines are not producing, the company is not making money and their massive investment in high speed assembly equipment is laying idle. There is negotiating over the length of time it takes to perform FAI and guess who loses, management think that 1 hour is excessive for FAI and most believe it should only take 10-20 minutes tops.

The simple math is that a PCB that 500 parts on it and manually inspected can be broken down like this:

- 15  seconds to locate each part on the PCB by reference designator using the customers BOM

- 5 seconds to inspect part

- 500 parts X 20 seconds (above) = 10000 secs = 2.77 hrs.

This means that at a minimum using a manual FAI method this inspection will take almost 3 hours not including time to document and file results for traceability. A lot of management are not aware fo this and actually believe that it is a quicker process but these are the simple facts. I machines are run during this process an incredible risk ensues. The manual method checks for 2 things, that the PCB actually contains the parts that the customer requested by checking against the customer BOM and that the Pick and Place file has been converted from the BOM and CAD data properly at the same time.

Using the Cluso Automated FAI the time for the inspection exampled above is reduced to approx. 20 minutes. This is because the Automated FAI uses the P&P file and the customers BOM which has all of the coordinates and part descriptions in them so there is no time required to locate the parts and the full details of what the parts are is on the screen streamlining the whole process. The operator simply starts at the beginning of the dataset and steps through the parts passing or failing as they go. When they get to the end of the parts there is 100% confidence that all parts have been inspected. Also once complete the inspection can produce a report that details the parts inspected as well as failures encountered. The system can also store this inspection as a golden sample for subsequent inspections of the same assembly and the system can even archive the entire process including the scanned image, report and the dataset for full traceability. This wraps up this FAI process into a manageable, simple and fully traceable process that is 100% repeatable and foolproof.

As far as the QA aspects we are discussing using Automated FAI fulfils all requirements of the Quality control plans which are that the inspection is 100% and the traceability of the process is 100%. As well it performs this with a massive time reduction saving money at the same time. The ROI on this type of equipment is measure in months or even weeks in some cases after which it is money in the bank. The QC department finally have a way to perform the 100% inspections demanded from them in the time allocated by the their supreme commanders. 

What more could you ask for.

Greg Ross

Cluso Vision Systems

Quality Assurance - Introducing Automated First Article Inspection Series

I have intentionally kept Quality Assurance separate from Quality Control as they are generically different departments that look at production from a different viewpoint.

Quality Assurance institutes the procedures and practices in a global sense for the company ensuring that all aspects of Quality are covered procedurally as well as all aspects of traceability are covered. The will also ensure that ISO standards are adhered to. The Quality Control people ensure that the procedures, practices and inspections are performed using the correct papers and documenting this fact for traceability reasons.

The aspects of Automated First Article Inspection that affect Quality Assurance are discussed in this blog section of this series. For all processes within manufacturing the QA department must ensure that there are records detailing that the process, inspection or procedure has been performed as well as traceable documents exist relating to this fact. 

At First Article Inspection there normally would be a FAI sheet filled in by the operator signifying that the inspection has been performed. This document would then need to be filed appropriately complying with the traceability aspect of the quality plan for that product. With an Automated FAI such as Cluso this is documented automatically using the reporting and archiving functions contained in the system. The system would automatically document the operator, Batch numbers of inspection, Quantity of part inspected and list all failures noted in the FAI performed. This PDF report would be simply filed in a secure server location by batch number providing full traceability the inspection was performed to satisfaction.

In Engineering there is a little known hole in the QA process. The SMT Engineering department receive BOM's and CAD data from the customer and convert them into Pick and Place files. The CAD data contains the Reference Designators and X/Y coordinates and the Bill of Material details the parts. The SMT Engineering must manually merge the two datasets together to output the P&P file. This is a manual process that risk which is hidden and normally only found out if a 100% FAI is performed which verifies the assembled PCB sample against the customers BOM. With an automated FAI this process can be desk checked with the differences reported automatically. 

The ultimate effect on QA that an Automated FAI has is extremely positive and a very simple, effective solution for these manual processes. The automated solution streamlines, documents, and turns this incredibly important issue into a simple traceable process solving many problems in one easily implemented solution

Greg Ross

Cluso Vision Systems

Engineering - Introducing Automated First Article Inspection Series

 Engineering is the first area affected by the New Product Introduction of customers PCB's. The customer hands over to them the Bill of Material and PCB CAD files for the product being introduced. The Engineering department must perform a few tasks being entering the customers BOM into the CEM's ERP/MRP system. They then must create a Pick and Place(P&P) file used to populate the PCB in the SMT Area. They also may have to create a AOI Inspection file used by the AOI Equipment. The P&P file and AOI file is created essentially by either manually of semi-automatically combining the customers BOM which tells us what the parts are and the PCB CAD file which tells us where the parts go on the PCB. This process is at best semi-manual and at worst a completely manual process.

This manual process has no way except manually to double check whether or not a mistake has been made. If a mistake is made here then the FAI check against the P&P file will only tell you the PCB file is assembled as per the P&P file, potentially incorrectly. With the AOI program if a mistake is made then all the AOI machine is going to do is verify that all PCB's are assembled wrong but the same.

Using the Cluso First Article inspection System the engineer can desk check to P&P file against the BOM automatically. This will ensure that program contains all the components the customer designed to be placed on the PCB. Both the top and bottom side P&P files can be loaded into system and compared to BOM at the same time. This checked program can then stored stored as a Cluso file for use later at the FAI process. 

W using the Cluso system in Engineering these loopholes in the process are closed and ensure that the output of this Engineering process is 100% perfect.

Greg Ross

Cluso Vision Systems

greg@cluso.com.au

Introduction - Introducing Automated First Article Inspection Series

For anyone who is not aware of who I am by now it is probably best to get an introduction down that will show my interest in First Article Inspection. My name is Greg Ross and my company is the developer of the Cluso Vision Systems Automated First Article Inspection System. The Cluso System is arguably  the first commercial system of it's kind that focuses strictly on FAI systems. Cluso was first developed by a CEM in Sydney, Australia in 2003 and still is manufactured and developed there. Cluso Vision Systems is not an Engineering company disconnected from the manufacturing attempting to second guess features that may or may not be required. Cluso is designed by CEM's for CEM's with no excess technological gadgetry which disguise the operation or usability of the system. It is purely developed to be the very best way to perform a First Article Inspection in the most effective manner.

I was pondering who is affected by introducing an Automated First Article Inspection and have decided it is too large of a topic to cover in a single entry. My definition of a complete FAI is ensuring that the SMT P&P machines are producing what the customer intended them to produce at the right revision level. Sounds simple but because of manual methods of inspecting for this are inherently flawed problems emerge randomly and additional steps are added and because problems turn up with them as well and more steps are added, cascading the complexity into an unmanageable octopus, all manual. A total rethink of the entire process that brings it back to the simple root what is the basic need, was required. This is exactly what the Cluso system was designed to do. It allows companies introducing Automated FAI to streamline a lot of areas which become redundant and enhancing the process as a whole. So I have decided to run a series of Blogs which will cover the individual areas affected by the introduction of an Automated FAI. These will include:

Engineering

Quality Assurance

Quality Control

Surface Mount

Management

Any others that may crop up.

Because I am familiar with Contract Manufacturing this series of topics will be centered around the common methods used by CEM's. I will dissect each area and the problems associated with New Product Introduction and FAI in the manual methods. Then I will go on to explain how an Automated FAI system like Cluso will enhance and make the output more reliable. This series will span over several weeks as I get time to write the sections.

Greg Ross

Cluso Vision Systems

greg@cluso.com.au

Las Vegas IPC/Expo roundup

I just got back from the Las Vegas IPC/APEX show in April. Was an interesting time with all participants looking forward to a better year than last year. Things are on a positive in the USA with CEM's leading the way. I am surprised with all the distractions of Vegas that anyone attended the show. Saw a lot of blurry eyes there pretending they had a good nights sleep.

Anyways, with regards to first article inspection peoples opinions seem to be divided into 2 distinct camps. These are the SMT, QA and Engineering departments and the Management.

The SMT and Engineering department personnel know what the problem is except until recently there has never been an automated system available to help with this situation. The problem is that to date these employees along with the QA personnel have been left to their own demise having to use manual QC methods to inspect FAI PCB's. The problem is there is incredible pressure from Management to keep costs down so this leaves them with little option but to stop performing 100% inspections on FAI PCB's. They delude themselves into believing that if they double check the feeders then the problem is reduced. This just bandaids the situation. 

Management believe that the QA is under control and they pat themselves on the back because because they saved money in inspection with what they believe is no detrimental effects. Every couple of weeks something goes wrong which is attributed to FAI but someone is blamed and they institute another inspection supposedly to take care of the problem. as they perceive it, and life goes on.

Now that there is a automated solution is available the dilemma begins. The engineering is sold because they have a way of desk checking SMT programs. The SMT operators are sold because they have a tool that allows them a way to ensure they are producing the right product. QA is sold as they have a traceable solution that meets ISO standards requirements. The management should be sold because this solution would save money but nobody can justify this equipment because to do so would mean that someone would have to admit that there is a problem that was not solved. They would be under risk that the management would ask the obvious question...

"What the hell have I been paying you to do until now if is so bad we have to buy equipment?".

Management pays people to solve these problems and have been told that there is no problem because their valued employees have done their jobs and taken care of it. The reality is that cost reduction campaigns have reduced the time allowed to perform these FAI inspections properly and the result is that mistakes are going to happen resulting in PCB's assembled incorrectly. Firing people will not make it go away. Someone will have to bite the bullet and tell management the truth.

Now which one of you has the guts to do it?

Greg Ross
Cluso Vision Systems
greg@cluso.com.au

First Article Inspection Strategies

In these days of high mix low volume there is increasing pressure on the SMT departments of manufacturing companies to reduce changeover times and increase machinery utilization.  An enormous effort has been taken within the SMT, Production Engineering and QA departments to ensure the setup of pick and place machines are accurate, and still issues of incorrect parts loaded onto PCB’s exist.  Each time this seemingly random event occurs there is enormous speculation as to how it happened and generally an additional control is concocted to supposedly correct this from “ever happening again”.  All this has done is added more wasted time in the changeover of each job on the SMT line. 

What needs to happen is an entire re-think of the process of SMT line changeover and to use technology to assist and streamline this process.  First Article Inspection Machines are available to ensure that incorrect set-ups are a thing of the past as well as speeding up the entire process so that the downtime on your expensive SMT lines is kept to a minimum.  This study has been done in order to compare the standard manual processes used in normal CEM environments to the automated First Article Inspection(FAI) System assisted methods and the results are presented here.

In order to fully understand the process improvement aspects of the First Article Inspection System assisted methods a comparison of both processes is detailed below that highlight the drawbacks as well as the areas that are improved. 

Manual First Article Inspection Method

The manual method described here is the most common method used in SMT areas within a CEM environment and is the one that was used by the company related to the study discussed later in this paper.  

The PCB/First Article is built by the SMT machines and sent to the QA department for the purposes of checking the product assembled against the Bills of Materials (BOM) to ensure that the program contained in the SMT Loaders is correct as well as the parts are placed into the feeders in the correct locations.  The steps involved in this process are described below:

The feeders with the parts installed on them are loaded into the SMT Loader into designated slots pre-established by either a manual method or CAD Conversion program specifically designed for this purpose.  Normally there is a double check from QC or another operator to ensure that the correct parts are contained in the right feeders.

Normally the program that runs the Pick and Place machine is split into two parts, the feeder file and the program listing.  The feeder file is the one that contains the locations of the feeders and the parts contained in them. The Program listing contains the X/Y/Z locations on the PCB.  This data is normally automatically generated using the CAD Data supplied from the customer or engineering departments.  This CAD Data shows the positions (X/Y) and the Reference Designators. 

Once this is done the first PCB is then screen printed and populated using the SMT Loader. Normally prior to reflowing the PCB is initially inspected by the operators.  This minor inspection is limited to IC’s and polarised parts generally for correct values and direction.

After reflow the First Article is then turned over to the QA department within the SMT area for full inspection.  To perform this function QA is required to search the PCB using the BOM, Loading Diagram (This is because most SMT PCB’s do not have reference designators marked on the PCB) for each of the reference designators looking under a magnifying lamp or microscope to visually inspect the parts to ensure the accurate setup of the SMT Loader.  The QA inspector must manually cross off the parts one by one until all parts are found and inspected.  The SMT loader program is also crossed off to ensure that no additional parts are loaded that are not contained on the BOM.

This stage of the First Article Inspection Process is an absolute nightmare to ensure all possibilities of errors are checked out.  The documentation that requires cross checking includes the Customers BOM, the BOM from the MRP system, loading diagrams, Feeder lists and Pick and Place files.  This is in addition to searching under a microscope for the correct part locations.  All paperwork must be checked against each other as well as the PCB in order to ensure that the Pick and Place machines are set up properly.  This is an extremely tedious routine which can produce errors at so many levels.

The SMT loaders are possibly not run during this process as it could potentially be loading incorrect parts. Normally the SMT loaders start running once the major parts (IC’s, capacitors, and any polarised parts) are checked.  This is to minimise the length of downtime associated with the SMT Loaders. The rest of the parts are then inspected. When military or medical products are manufactured the SMT loaders must wait until all inspections are performed as these types of customers do not allow rework to PCB’s and if incorrect parts were loaded then it would be far too costly to allow this to happen. The economic reality is that the machines cannot be stopped for this long and risks are taken every day and sometimes the gamble does not pay off and rework occurs.

Sometimes inspection aids are used in conjunction with these processes such as scanners (Mylar sheets with locations and polarities marked) which are overlayed on top of the PCB which indicate particular areas of interest and the feature (Location and Rotation data) to be inspected.  These scanners can take significant time to construct and are generally made as aids to subsequent runs of the same PCB’s. They are very time consuming to construct and are limited in their ability to located incorrect part quickly and reliably. 

Automated First Article Inspection Method

The methodology used with an Automated First Article Inspection System is very similar to the conventional method described above however it is inherently faster and more accurate. 

Using the Automated method the same process for setting up the Pick and Place machine takes place and the First Article is reflowed and turned over to QA for inspection.  The system of inspection is markedly different in an automated system.

The First Article PCB is scanned into the system and the CAD data from the SMT machine that loaded the PCB is combined with the digital image of the PCB.  The digital image is magnified to ensure that the markings on even the smallest parts are legible.  The engineering BOM used to generate the Pick and Place loading program is loaded as well.  This will cross check the Pick and Place file against the customers BOM to ensure that no extra, missing or changed parts exist.  

For the first PCB ever inspected of this type all of the data on the BOM is stepped through with the image on the screen showing a greatly expanded view of the part being inspected.  The operator does not need to worry about checking off parts in the system as the data contained in the BOM came from the SMT loader so it is 100% accurate.  The location of the individual parts on the PCB is automatic as well because the X/Y coordinate data comes directly from the pick and place files.  This enables the operator to concentrate on the visual inspection of the parts on the PCB.  The combination of all data and image into a unified computer based environment makes the job of First Article Inspection very efficient and 100% effective.  

Once the first PCB of this type is inspected it is saved as a sample for future reference.  Any subsequent batches of PCB’s of this version will automatically be compared to the sample stored.  This process will ensure that no parts have been added or deleted, moved or rotated.  This guarantees that once a PCB has been manufactured once, all subsequent runs will be the identical providing unparalleled consistency in manufacturing. 

Case Study

The case study introduced here was performed on a CEM in Sydney, Australia that introduced an automated First Article Inspection System several years ago.  This contractor is a medium sized manufacturer that has 5 SMT lines including two MyData standalone systems, two Yamaha lines and a Juki line loading approx 5 million parts per month.  They do not own any AOI systems and perform only functional testing (not ICT) on product manufactured.   This variety of equipment is to accommodate all types of short runs of complex PCB’s.  As is common in the United States most CEM’s in Australia are geared up for this as most large quantity manufacturing runs are being sent to China.  This has required the SMT department to focus heavily on reducing downtime due to changeovers between runs of PCB’s. This CEM performs a full changeover of every SMT line at least 2 times a week.     

Prior to the installation of the automated system a review of all problems encountered that was attributable to the SMT assembly process took place.

Random parts missing/incorrectly loaded (skewed, tombstoned, etc) – This is when parts are randomly missing or incorrectly loaded on PCB’s with no consistency.  These were attributable to the Pick and Place machines and handling of the PCB’s prior to reflow.  These types of defects would only be corrected with an AOI.

Soldering defects – These include solder shorts, cold joints, etc which are mainly attributable to the screen printing process.

Incorrect parts – These are parts that have been loaded incorrectly due to incorrect set up of Pick and Place or due to swapping an incorrect reel during the batch.  These are the main area of concern which an automated first article inspection system will alleviate.   

The first two categories can be controlled with an AOI system in place however it was deemed that AOI is not suitable or cost effective at the level of manufacturing that this CEM is involved with.  Five AOI systems would have to be implemented at very high expense involving hundreds of thousands of dollars.  In addition to this, the programming time required to keep up with short run, high complexity assemblies would be prohibitive rendering the AOI option not feasible.

The final category is the one of most interest as there are a large percentage of defects pertaining to these types of problems and that there is an economical solution to these.  The implementation of an Automated First Article Inspection System also reduced the changeover time associated with the SMT lines.

The problem of the incorrect reels of parts inadvertently loaded onto PCB’s appears on the surface to be a fairly random event however this cannot be further from the truth.  If a company produces 5 million parts a month on PCB’s (medium contract manufacturer levels) the first article inspection process would be checking approximately 10,000 parts per month.  This is because only the first PCB’s are checked in this process. If human error leads to be 1 problem in 1,000, which would be considered extremely good, there would exist 10 potential problems each month.  Using the manual method, given that the probability of inspecting 100% of parts is low and likely to be only 70%, then this would reduce this to 3 problems per month.  If each of those 3 problems were associated with reels of 5000 parts, which is common to reel sizes, then 15,000 parts are possible to be incorrect every month.  As entire reels are unlikely to be used up on any given run is low prior to someone finding out that the parts are incorrect then the figures are likely overstated by potentially 80%.  Even at these levels there would exist 3,000 parts incorrect each month on average.

The reason that Automated First Article Inspection Systems are not utilised is that there is a belief that these errors can be traced backed to things like not checking the reels in machines.  So the common mistake is to have another person verify the set up which appears to work and everyone feels the problem is solved.  Being a manual system this is a bandaid solution and the problem resurfaces. The fact is that with every manual system there is a level of human error and when we deal with vast quantities of potentials for error eventually one occurs.  It is like attempting to inspect quality into a product, it does not work, it is critical that it is built in to it.

Besides the stated QA reasons for implementing Automated Systems, there is a monetary one in that the manual process is a very lengthy process. As shown in the figure below four PCB’s were sampled with respect to the time it takes to inspect them 100%.  The PCB’s used for this chart contain a variety of SMT parts on them between 300 and 600 components on each.

The first column indicates the time it took to inspect manually.  The next two columns is the length of time it takes to inspect the same PCB’s using an automated system.  Because of the way the automated systems work it is much faster to inspect subsequent runs of the same PCB as the system compares the PCB being built now with a stored sample manufactured before.  There are incredible savings in time achieved especially if you consider that the Pick and Place machines are not producing during this time. 

If these times shown are extrapolated out to take into account all of the First Article Inspections performed in our test case the results are outstanding.  If you take the average of the 4 PCB’s discussed being 3 hrs per changeover the saving would be $960/week @ $40/hr.

Manual First Article Inspection Time average	3 hrs
Automated Inspection Time average	0.6hrs
Labour rate per hour	$40/hr
Changeovers per week (5 lines, 2 per week)	10
Time spent on manual inspection	30 hrs
Time spent on automated inspection	6 hrs
Time saved per week	24 hrs
Dollars saved	$960 per week

 

This does not take into account the savings made in Pick and Place downtime which would be substantially more than the figures stated above.  Lost Opportunity Cost is the cost per hour that the SMT Pick and Place line earns per hour if it were producing product instead of waiting for First Article Inspections to complete.  If the lost opportunity cost is accounted into the equation then it would bring the total dollars saved into thousands each week.

This particular CEM deals mostly with high end medical and military equipment and the QA requirements are such that the SMT lines cannot begin loading product prior to completion of the first article as rework is not an option with these types of customers.  Also the CEM was reaching capacity for the SMT output they were at the crossroads of either to reduce changeover times or purchase additional equipment. The implementation of the First Article Inspection System provided the CEM with an additional 24 hrs per week of SMT throughput allowing them to put off buying expensive new SMT equipment. 

An additional use for the automated FAI system is that a sample of each line is taken once every 2 hours and put through the FAI process to ensure that no incorrect reels have been replaced in the SMT loader.  This can happen when restocking feeders in the middle of production.

Conclusion

In these days where there is ever increasing pressure to produce short runs of high complexity PCB’s faster changeover times are high on the agenda to save time in manufacturing.  Every hour of downtime is costing big money. 

Utilising an Automated First Article Inspection System the SMT section has the ability to confidently assure consistent output.  It has been stated that all functional areas within an electronics manufacturing environment must have the ability to verify their own output quality.  This is impossible to achieve using manual inspection methods.  Automated methods will enable the SMT department to verify its own output at minimal expense.

Greg Ross

Cluso Vision Systems

greg@cluso.com.au