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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Upside Down Chips

Scott B

#5579

Upside Down Chips | 15 March, 2001

We are currently having a conflict of opinion with our QA department regarding the very few occurences we have of chip resistors being soldered upside down (i.e. the resistive element towards the board).

IPC-A-610C para 12.3.2 specifies that this condition on class 3 products should be regarded as a process indicator, however ANSI-J-001C para 6.4.2.2 specifies that this condition should be considered a defect on class 3 product.

QA are digging their heels in, insisting that ANSI-J-001 takes precedence and as such we should be reworking this condition or applying for concessions from our customers, where engineering feel that this is very much a cosmetic condition.

Does anybody know what the IPC take on this documentation conflict is?

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#5580

Upside Down Chips | 15 March, 2001

Good point. I'm having trouble with the words "electrical elements" in the J-STD. Is a marking an "element" ?? An upside down chip resistor is certainly not a defect in that it does not negatively impact product functionality or dependability. I suggest you contact IPC/EIA to get a ruling on this and get a clear definition of "electrical elements". I don't know anybody that repairs these defects. Doing so will not enhance product quality. It's a "visual" thing.

Pete

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JAX

#5582

Upside Down Chips | 15 March, 2001

Most of the companies I have worked with have their own quality standards for items such as this where the standards are unclear. In this situation I wouldn't worry about repair as long as at least one location for each part number has the value markings showing. This way you can visually see that all the parts are the correct value. ( Except for when you change a reel in the middle of a board.... That's a different issue, not my problem. )

That's just my opinion, I could be wrong!!!

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#5585

Upside Down Chips | 15 March, 2001

In a similar conversation ...

Alex Krstic, NovAtel Inc. said ...

Hello all. We recently received some boards with some of the chip resistors placed with their resistive elements towards the board. J-STD-001B and C view this as violation for both Class 2 and Class 3. However when you compare this with IPC-A-610C it is only a process indicator for Classes 2 and 3. The relevant sections are J-STD-001C 6.4.2.2 Devices with External Deposited Elements IPC-A-610C 12.3.2 Chip Components - Termination Variations - Deposited Electrical Elements - Mounting Upside Down. So, ... who is correct? Does it matter?

Jack Crawford, IPC Director of Assembly Standards and Technology said ...

Please be cautious on the IPC/EIA J-STD-001C interpretation. 6.4.2.2 does NOT identify this as a defect. It refers the user to review clause 1.4 with the implication that the supplier/use have to determine how to classify nonconformance to this requirement. The newly published IPC-HDBK-001 w/Amendment 1 provides some good words to help with the understanding (copied here), as well as an extensive cross-reference of changes between the B and C revisions.

"When the word shall appears in the document, it is stated that the associated requirement is binding. That means that the manufacturer needs to take action in order to comply with the requirements of the standard. In many cases, this is class specific, and the requirements of the text block explain the particular requirement for any given class of product.

"Where a text block includes a 'No Requirement,' this is a characteristic that has no associated requirement in the standard. The manufacturer will need to consider the hardware being assembled and determine if a requirement needs to be imposed or if 'no requirement' is adequate for the resultant hardware. Where a text block includes an 'Acceptable' condition, as is the case in some situations for Class 1 hardware, the requirement does not lead to a hardware condition that requires disposition. In many instances, a unique text block exists that includes the words 'Requirement See 1.4.' When this is given, it means that this requirement must be met for compliance to the standard.

"The manufacturer (assembler) is tasked with determining the course of action to take. As needed, the user (customer) may participate in the development of corrective actions. J-STD-001C does not address hardware conditions with the 'Requirement See 1.4' phrase but rather manufacturing system failures (such as process control, material compatibility, etc.). A review of the noncompliance and the appropriate corrective action plan with the customer may be required depending on the severity of the noncompliance or an internal correction may be enough."

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