Auditing PCB (Printed Circuit Board) Assembly Lines - Fire And Safety Systems

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AndyN

Moved On
Hi Andy.

I would welcome any help in this area. e.g, how to set up an audit plan for process and system and anything else would be a great help..

Thank You
Paul.

Paul:

You have a number of options available to you, so that's both good - and confusing! You can do a system audit, a bit like a CB auditor would, from bare boards and components coming in the goods in door, through the kitting process, shop scheduling, board prep., pre/post assembly, soldering, testing, packing etc. This might not be a full system, because you'd end up with lots of 'branches' off to other parts of the business, like Purchasing when you do Goods in. This can make the audit extremely complex for a new person.

Alternatively, you can just do a process by process - each one being a smaller scope, quicker and less complex audit. For example, just audit Goods In, then another time, do kitting, then board prep, then each assembly cell. A bit like eating the proverbial elephant.

The main issue here is that both approaches will give you a result and you could 'claim' to have an audit program, but my fear is that you'll be missing the whole point - letting management know where the weaknesses lie that cause rejects etc.

You have to do some research up front to determine which parts of the various processes are exhibiting problems. Is one cell giving more rejects or test failure than others? Use this data (which should be readily available) to guide your audit enquiries to see if you can pinpoint the cause of the problems. This is 'value-added auditing'!

Of course, you'll have to factor your own qms documentation in planning each audit, so you get a familiarization with what is supposed to happen!
 

michellemmm

Quest For Quality
Hi I am new to this.

I need sopme guidance. The company I work for is approved to ISO 9001 2000. They manufacture fire and safety systems. This means the populate PCB's.

They have different manufacturing lines which populate differnt PCB's which get builti into one larger PCB which then get placed into a case at the finished assembly.

Can anyone give me any guidance on how to carry out audits. Do i have to audit each cell (20 cells) or is there another way. I have just joined the company and have been told by my manager to construct a schedule.
But I am totally lost on how to do this.

Do I have to audit each cell.

:thanx:

Joe,
Have you established critical process and product parameters?

What kind of process control (operator process control) do you have in each cell?

If you start with a simple flow chart and establish control points, you can easily use a turtle chart and balance the input and output and based on the criticality of the parameters and historical data, you can establish the frequency of the audits.

Good Luck!
 
J

joebrown

Hi Andy,

I carried out my first audit today on the surface mount manufacture.
I beleive I found a non conformace. The operators were using some solder paste so I checked the suppliers technicial data sheet and it stated when taking the product out of a fridge (which has to be stored at 4 degrees c) the product must stand between 4 - 6 hours to get back to room temp. if the product is used before that time scale then it may affect the performance of the product.

The operator informed me that when they take it out of the fridge they wait an hour and use it.

My question is:- there is no written procedure in our comapny stating when to use the material other then the suppliers data sheet. Can I raise this as a non conformance linking it to one of the clauses in ISO 9001 2000.


:thanx:
 

michellemmm

Quest For Quality
Hi Andy,

I carried out my first audit today on the surface mount manufacture.
I beleive I found a non conformace. The operators were using some solder paste so I checked the suppliers technicial data sheet and it stated when taking the product out of a fridge (which has to be stored at 4 degrees c) the product must stand between 4 - 6 hours to get back to room temp. if the product is used before that time scale then it may affect the performance of the product.

The operator informed me that when they take it out of the fridge they wait an hour and use it.

My question is:- there is no written procedure in our comapny stating when to use the material other then the suppliers data sheet. Can I raise this as a non conformance linking it to one of the clauses in ISO 9001 2000.


:thanx:

Did you observe any soldering (or safety) defect as the result of not following the solder paste manufacturing recommendation?

Does your internal procedure specify that you SHALL follow manufacturer's guidelines for solderpaste usage and consumption?

Do you have any historical data that ties solderjoint anomolies with current practice?

What the manufacturer of solder paste is recommending is not practical.
 
W

w_grunfeld

Hi Andy,


My question is:- there is no written procedure in our comapny stating when to use the material other then the suppliers data sheet. Can I raise this as a non conformance linking it to one of the clauses in ISO 9001 2000.
Joe,
I really don't know if I should jump in, as you addressed your question to Andy only. Anyway, take it as an unsolicited advice.
If there is no procedure controlling the whole SMT soldering process (and this is where the use instructions for the paste should be defined) this is definitely a violation of 7.5.1 and 7.5.2 . Soldering and especially SMT soldering is a complex process that needs to be controlled through a Process Specification or Work Instruction. If no such document exists, trust me , the wait time for the paste to attain room temperature is not the only uncontroled parameter, nor the most critical one. There are many other critical variables in the process and if there is no document the whole process is not properly controlled.
7.5.2 states :
"The organization shall validate any processes for production and service provision where the resulting output cannot be verified by subsequent monitoring or measurement. This includes any processes where deficiencies become
apparent only after the product is in use or the service has been delivered"
Soldering and in particular SMT soldering falls exactly in this category
Post soldering inspection can only detect the most obvious defective solder joints , if at all.
 

Jen Kirley

Quality and Auditing Expert
Leader
Admin
Well said w_grunfeld. :applause:

Solder paste controls are indeed very important. There needs to be a procedure or requirements called out somehow. It needs to be based on the solder manufacturer specs/guidelines (you have those) and the process and equipment considerations, if they are special.

In having missed this need for a procedure, I would take an interested look at what else the company perhaps hasn't thought of. I would draw a little picture of the process and label the steps. For each of those I would note the critical functions like flow ovens, materials (like the solder paste) and activities like handling. I would ask myself: "What would the requirements be for this step?" and look for evidence, like with the solder paste, that requirements exist. I would then look for evidence these align with our own defined processes, check for awareness and controls, and for a path to follow when something goes wrong.

Good catch about the solder paste! Well done. You are asking the right questions.
 

AndyN

Moved On
I think we're missing the point and debating what the ISO requirements say or whether the line should have procedures and process controls mentioing the pre-condition is, IMHO, of secondary importance. In preparing for the audit, the auditor should have already determined if there have been problems with the results of the process - rather than 'stumbling' over this issue and then having to find out what happened and the impact of that.

We've just emulated an external audit, instead of using the data to drive the audit to pin point this (potential) lack of a key (apparently) process control!

Well, found, indeed, but you've caused yourself more work and, are possibly going to loose managements' interest by quoting the standard at them about the lack of a procedure (or similar) for the solder paste.........
 
W

w_grunfeld

I think we're missing the point and debating what the ISO requirements say or whether the line should have procedures and process controls mentioing the pre-condition is, IMHO, of secondary importance. In preparing for the audit, the auditor should have already determined if there have been problems with the results of the process - rather than 'stumbling' over this issue and then having to find out what happened and the impact of that.

We've just emulated an external audit, instead of using the data to drive the audit to pin point this (potential) lack of a key (apparently) process control!

Well, found, indeed, but you've caused yourself more work and, are possibly going to loose managements' interest by quoting the standard at them about the lack of a procedure (or similar) for the solder paste.........
Andy,
I beg to differ. A complex manufacturing process such as an SMT line must be a Controlled Process, ISO or not ISO. Management understands that, trust me, to set up a line like that is a ~Mil $ project, any 1% variation in yield hurts the bottom line. Once a company has managed to set-up and fine tune an SMT line , its their vital interest to keep it in control, through among other things , a detailed and well documented process specification. There is worker turnaround, shift to shift variation, various raw material suppliers , machine drift and ageing....and other "insignificant" details that can screw up the yield.
A data driven audit is a good idea to a point....but it is reactive instead of being proactive. Following this logic, would you sugest to do nothing when a process drifts until you have hard evidence that it produces defectives?
I am sure you didn't mean that....
Add to it that substandard solder joints are hard to detect....would you wait until field returns compel you to do something about it?
I agree that she stumbled upon the paste issue accidentally.
What she should do, is to insist there is a decent process specification signed off by head of manufacturing, production engineering and so on and audit the process against their own procedure.
Whether to quote ISO or commonsense/business-sense to have such a control is up to her own organization's (read management) mentality.
 

AndyN

Moved On
Willy:

You're correct and I agree with most of what you've stated, as applies to the control of the SMT/soldering process - no dispute and I might have been incomplete with my assertions. However..........

Often people fall into the trap of using audits of the management system like QC of the product. This situation is analogous to a poorly designed product, where the QC inspection have discovered a (design) fault and have rejected it. Not good. The fact that a key process control parameter is missing from the documentation (design) of the management system shouldn't be an audit finding!

This where so many well intentioned auditors get very frustrated and quit. They find countless 'ISO violations' and they're fed piecemeal to management, who don't realized how this could have been missed, with the result that a wall builds between the 'people' and the 'auditors' - just like happened with the QC folks of old........
 
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