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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Placement accuracy

CJ

#5149

Placement accuracy | 6 February, 2001

I am looking for some assistance with placement accuracy studies for chipshooters(Fuji CP4-Cp642) and platform machines (GSM all configurations, Siemens HS50/S25). I would like some information on companies and recommendations on process of evaluating CPk for each nozzle/rotation and dialing in the placement to the results. Any information is appreciated. My goal is to use this to validate and maintain the units!!!

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#5156

Placement accuracy | 6 February, 2001

Most prominent placement machine suppliers understand well the capability index of their machines and can ship each machine with specific information on the capability of that machine in a very nice bound volume. You should contact the companies of interest and request the information you desire.

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Kyle

#5159

Placement accuracy | 6 February, 2001

The Universal GSM is a very accurate and repeatable machine. I have had one for the last 5 years and it is still repeatable to +/- .0015". I use a Robotic Vision Systems glass plate kit to check the repeatability. it has glass slugs and glass board. Accuspec also makes this type of verification kit.

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CJ

#5166

Placement accuracy | 7 February, 2001

I did a quick some quick searches for Accuspec and saw some links to a PCB manufacturer. Is this the same company, or do you know the #??

I am not really in the equipment evaluation mode. I am looking for a system that will assist in maintaining capability throughout all of the platforms I listed originally. I want to use this a periodic (annual) measurement. I am beginning to look at Topline (they provide a PCB to do CPk studies). However, I am unclear on how accurate the results will be. I appreciate the feedback.

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CAL

#5167

Placement accuracy | 7 February, 2001

Precision parts and precision boards are nice for the initial evaluation but are costly for routine monthly accuracy tests. I know for a fact all the Siemens machines leaving Germany are evaluated with precision parts and board and placements are evaluated with a coordinate measurement system. I am sure UIC does the same. But in the field the service engineers (Siemens) use an aluminum PCB with laser etched pads to track accuracy. They use double sided tape and standard reel components to do the field evaluation. This aluminum PCB and cad data can be purchased from Siemens for a few grand. The other option is to create your own Board. The PCB should be approximately 12�x14� in overall size. I would test Chip components in a brick wall pattern (i.e. a row of components with the minimal spacing allowed. the next row should be parallel to the first but offset by half a component. Think of is as a brick house the bricks are not stacked in rows and columns but rows are off set by one brick). This should be done for 0402 through 1206. The theory of this is to use the straight edge of the component to aid in the visual for skew. I would put down a double row of SOT23�s in a pattern to form a circle. Add some QFP�s, BGA�s, �BGA�s, Tant Caps (all colors), Soic�s, tsop�s and that should be enough to help verify the accuracy.

Best regards, Cal

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JAX

#5169

Placement accuracy | 7 February, 2001

I' ll have to agree with Dave on this one. Just get the information from the Suppliers. The Glass plate, Aluminum board, Glass slugs, etc... are all used to determine if a calibration is needed or if it was succesful.( they can also give you offset inputs to complete certain machine calibrations. ) If the Calibrations are good, the machines should be able to comply with the Specifications given by the suppliers.

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Kyle

#5174

Placement accuracy | 7 February, 2001

What are you placing on this equipment? If you are placing flip chips, you need to have a glass plate test system to verify your machine is accurate and repeatable. If you purchase new equipment and plan to place flip chips or ultra fine pitch, it makes good sense to verify your new equipment. Pick & place equipment manufactures can supply you with all the data you want. How do you know their equipment really does what is says it will? You don't! I have found some of the new equipment, that I have considered purchasing, not meet the published placement cpk specs. In fact one manufacture claimed a certain cpk and when I brought my glass plate and slugs to check the machine, he was amazed that even such a device existed. How the hell did he make such cpk claims? He used an etched PCB and dummy components. This is fine for most applications but not for ultra fine pitch. If you do not verify the manufactures cpk claims, take their word as truth, and believe that every machine produced is the same, don't place ultra fine pitch. I use my glass plate after every software upgrade, every major machine fix, and at least quarterly. I can't even tell you how many times software upgrades have thrown the cpks out of spec. I will get you the #s for the glass plate verification kits. They are the way to go.

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#5178

Placement accuracy | 7 February, 2001

Accuspec, Technology Information Corp., Silver Spring, MD 408-270-8900

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