|The critical parts of an IC for counterfeit screening are the paddle, lead frame, wire bonds and the die itself. |
Counterfeit parts come in many colors. The electronics supply chain has been infiltrated with unfit, substandard, misrepresented, and parts intentionally counterfeited — predominately from China. What's worse, these components have made their way into electronic assemblies manufactured by EMS and OEM manufacturers. The number of incidents reported of counterfeit parts is increasing and poses a significant threat to product performance and safety in virtually all applications: medical, automotive, and defense-based electronic assemblies. Further, a new breed of counterfeiters is making parts authentication a complicated process, making it difficult to identify real vs. fake with a high level of certainty.
In reaction to this industry issue, stricter quality assessments and more complete inspection and documentation procedures have been adopted, especially by the distribution side of component purchase and re-selling.
Manufacturers together are adopting greater focus and more complete understanding of the component to ensure it is fit to enter the SMT assembly floor. Component supplier quality audits and as well as more thorough incoming assembly inspections at the SMT manufacturing sites have significantly risen over the past year.
|Upper and lower photos are markedly different, even though both are from the same reel, and identified by the package label as from the same lot with the same part number. Which one is the fake? Probably both. |
It's a common misconception that risks are minimal so long as components are purchased through authorized distributors. Even franchised distributors are at risk when surplus stock is returned for resale, potentially containing counterfeit parts.
Today there are numerous modes of screening components to identify unfit, misrepresented, fraudulent, or otherwise counterfeit components. These modes include visual inspection, surface inspection, marking permanency, radiographic or X-ray inspection, decapsulation including die marking verification, and electrical testing.
There is a concerted effort by OEMs, EMS and Independent Distributors, to ensure the quality of parts they receive from component suppliers with the assistance of several organization such as ERAI and IDEA. In addition, the G-19 Counterfeit Electronic Components Committee is chartered to address aspects of preventing, detecting, responding to and counteracting the threat of counterfeit electronic components.
Many OCMs (Original Component Manufacturers) have adopted this level of x-ray technology to also screen out defects passing to their customers while archiving images and data for traceability — specifically for their aerospace/defense and medical customers.
Using X-ray Inspection
Real Time X-ray is a proven and effective technique to non-destructively examine the internal structures of components. X-ray technology has been in use at Original Chip Manufactures, OEM and EMS companies for well over 30 years and has proven to be an excellent tool for understanding the internal structures of semiconductor components. Independent Distributors have also adopted the use of x-ray inspection equipment more widely over the past several years as they build up their own internal labs to validate components that they are sourcing.
What can x-ray tell us about a component? To address that question let's review the four major structures inside of a component or IC: the lead frame and how it attaches to the paddle; the paddle, including its size and shape; the die, including its size and shape; the wire Bonds around the die and out to the lead frame.
Using x-ray images of the interior of the part, the x-ray inspection can quickly assess whether they are consistent throughout the lot. When these parts were originally manufactured with the same part number, same lot number, same time, date, and place all four of these structures were identical in size, shape, and form.
Using x-ray imaging, these four structures are easily visible at the proper magnification and can identify how the paddle connects to the lead frame, the size and shape of the paddle, the size and shape of the die and most importantly the wire bond count and layout.
|FocalSpot Component Inspection Series inspects ICs in tape-and-reel using a servo-controlled indexer to accurately and repeatably index the parts by the standard 4mm tape pitch. |
A typical reel may be identified by the package label as from the same lot with the same part number. While the exterior markings reveal the same part number, lot number, date code and country of origin, the internal structures may be seen to not be identical at all — based on the lead frame design pattern and shape, the paddle size, die size, and wire bond layout. The only method for ever discovering this condition is when x-ray imaging is used to compare these two components. Using automated x-ray technology along with the use of a reference standard, this difference can be screened and positively identified. At the very least, the supplier of these parts is misrepresenting them as they could not be from the same lot number. Thus X-ray inspection can show if a part conforms to its representation by the supplier.
FocalSpot, Inc. has been manufacturing affordable x-ray inspection systems since 2004 but its roots date back to early 1990s with Nicolet Imaging Systems. FocalSpot has supplied x-ray equipment to EMS, OEM, and semiconductor companies as well as independent distributors, and introduced its first automated reel-to-reel system in 2007 for tape-and-reel applications. The company has since refined its system design and software to better address general IC package inspection in line with industry requirements of detection accuracy, low false fail, ease of programming, flexibility and speed.
FocalSpot's Component Inspection Series (CIS) allows for the inspection of ICs in Tape and Reel form by using a servo-controlled indexer which accurately and repeatably indexes the parts by the standard 4mm tape pitch. This subsystem is tooled onto a rigid table and without tools allows the user to quickly disassemble the indexer and replace it with a belt conveyor to run tube or trays, also by programmable servo control. To run a large bath of trays or single parts, the standard x-y table can be used. For advanced review, an oblique motorized fixture which holds single parts will allow the inspection of the IC on its side to allow for the measurement of die thickness.
Tool Changeover Time.
The system can be set up for use in four different modes of operation:
- JEDEC trays.
- Individual parts.
Automated motion can be achieved using an indexer for reels, or a belt conveyor for tubes, or an XY table for JEDEC IC Trays. This Tooling is designed to be loaded onto the XY table which provides the platform to mechanically locate and register the indexer or belt conveyor into position. A single universal cable disconnect provides power to either the indexer or the belt. In less than 30 seconds the indexer can be interchanged with the belt conveyor or vice versa. Both the indexer and belt also allow for quick width adjustment to accommodate tape widths up to 60mm as well as tubes or small trays. When neither the indexer nor conveyor tooling are in place, the system then operates as a standard XY to allow JEDEC tray inspection or single component inspection. In addition, optional tooling can be used to rotate individual components 90° using a rotation device to allow further inspection through the side of the package to check the die thickness and wire bond attach points.
Inspection capability can be measured by several attributes:
- Line Pair Gauge.
- Image Quality Indicators.
- Detection of Known Defects.
- False Call Rate.
Based on the package size and internal dimensions — 0.002, 0.001, or 0.0007-in. wire bonds (0.05, 0.025, or 0.0177mm) — to be inspected, magnification plays a key role in working toward 100 percent detection with the lowest false call rate. In order to maximize and achieve 100 percent detection (0 percent Escape) one must set the part to a minimum magnification to achieve at minimum 20lp/mm and the ability to visually see IQI indicators.
IQI's use are described in ASTM E-1171. We measure the general capability of the system by placing the IQI at the same position of the part.
Speed vs. Detection Capability
With 2 parts per view at 14X geometric magnification, the speed of the system can achieve 1,000 parts per hour. At this magnification we achieve 14lp/mm resolution and can visually see all the features on IQI . However, due to the small part size, at this magnification, in practice the attributes which are inspectable with high detection rate (>98 percent) and low false failure rate (<0.1 percent) will be the lead frame layout, paddle size and shape and die size and shape. What would be completely missed is the bond wire inspection at this field of view.
At 1 part per view at the system can the system can inspect over 2,800 parts per hour. At this magnification the image resolution is >20lp/mm and you can visually see all the features on the IQI.
|At 1 part per view, the system can inspect over 2,800 parts per hour. |
At 36x geometric magnification, all the internal features of the part are very clear including the 0.0007-in. (0.0177mm) diameter gold wire bonds. The resolution here is over 30 lp/mm and will allow for both high detection and low false calls during the component screening process. In practice, this means 100 percent detection of lead frame configuration, paddle, die size and shape with less than 0.1 percent false failure. Wire bond detection, meaning number of wires and integrity (broken wires) can achieve >95 percent detection with less than 2 to 5 percent false failure rates.
Throughput vs. Field of View.
The internal features of the part must be clearly visible and at minimum achieve 20lp/mm to inspect lead frame configuration, paddle/die size and shape, and wire bond quantity and integrity. Less than that number, and wire bonds will not be inspectable at a high detection and low false call rate. If the part is small and wirebonds are 0.0007 or greater then 40lp/mm will be required.
The FocalSpot system as currently configured can operate at 0.8 seconds per view. This includes motion indexing, detection and reporting. At 1 part per view, this means you can expect over 2800 parts per hour of capacity. Should there be no wire-bond inspection requirement, then one could expect to image 2-3 parts per view and increase the rate to 8400 parts per hour. A typical reel of 2500 parts could therefore be inspected in under 18 minutes without wire bond inspection.
Ease of Use
The system operation and use was designed for simplicity: turning on the x-ray, tooling changeovers, setup of the program and detection algorithms which can all be completed by an operator.
Detection Algorithm Setup
To keep the setup as simple as possible and allow any level of operator to set up an inspection program for component detection, FocalSpot used a template-matching strategy and simple slider bar to set the parts to be screened against the reference image. Operators simply draw 4 boxes around a component. The first box is the locator which will always register the part to be located in the center of the image. Parts in the tape or tube are not perfectly centered and rotate and shift during indexing. Location and Registration are crucial to ensure detection and low false call rates. Two boxes are then drawn around the paddle
Automated X-Ray inspection of components is a capable and efficient method of quickly screening tens of thousands of parts during a single shift. To complement x-ray inspection, camera-based systems can be integrated within the system and using optical character recognition, part numbers, lot numbers, date code and logos can be simultaneously inspected.
Contact: FocalSpot, Inc., 9915 Businesspark Ave., Ste. A, San Diego, CA 92131 858-536-5050 fax: 858-536-5054 E-mail: firstname.lastname@example.org Web: http://www.focalspot.com