-
- News
- Books
Featured Books
- smt007 Magazine
Latest Issues
Current IssueBox Build
One trend is to add box build and final assembly to your product offering. In this issue, we explore the opportunities and risks of adding system assembly to your service portfolio.
IPC APEX EXPO 2024 Pre-show
This month’s issue devotes its pages to a comprehensive preview of the IPC APEX EXPO 2024 event. Whether your role is technical or business, if you're new-to-the-industry or seasoned veteran, you'll find value throughout this program.
Boost Your Sales
Every part of your business can be evaluated as a process, including your sales funnel. Optimizing your selling process requires a coordinated effort between marketing and sales. In this issue, industry experts in marketing and sales offer their best advice on how to boost your sales efforts.
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - smt007 Magazine
A Breakthrough in 0201 Component Inspection
December 31, 1969 |Estimated reading time: 7 minutes
A new high-resolution digital color system provides solid automated optical inspection (AOI) as well as a stable solution to the populated printed circuit board (PCB) inspection challenge.
By Joseph L. Vilella
In November 1999, a California-based vision inspection system supplier* introduced to the manufacturing electronics industry the first large format high-resolution digital color system.** The project, begun in 1996, finally produced results that met and exceeded initial expectations. For innovations in the field of AOI, the technology has been granted all its critical process patent claims, and based on them the company has filed for worldwide patents. Today, the company's main customers and solid supporters include Qualcomm Inc. of San Diego, Calif. and Motorola Computer Group of Tempe, Ariz. Because of the pressing need to deal with 0402 and 0201 placement, prospective customer leads include other well-known manufacturing powerhouses and sophisticated mid-range manufacturing facilities that have been shooting 0402s for a while and see 0201 components moving into their space in the near future. Having said that, this new technology remains affordable to the industry because high-resolution digital color imaging provides a solid AOI solution. Furthermore, its advances allow the best and most stable solution to address the populated PCB inspection challenge.
Solving Problems DigitallyIn essence, this technology is to the manufacturing electronics industry what the high-definition digital television (HDTV) is to the consumer electronics industry. Both products are digital systems and both provide users with images that have millions of pixels of rich color. The digital images of an HDTV offer visual entertainment that truly amaze and give enjoyment. The powerful and information-rich digital images of the high-resolution digital system provide a computing platform with the necessary contrast and value data to perform accurate assessment of what is right or wrong on a board relative to a two-dimensional (2-D) field of view. It offers electronics manufacturers a digital way to solve a critical problem.
Today's 0201 Inspection Challenge As 0201 component placement integrates onto manufacturing floors, it is essential that the reliable capital equipment required to support such operations is available to manufacturing facilities. An earlier article on 0201 placement1 noted that various organizations have taken the necessary steps to provide a stable and consistent placement platform. This vision inspection system supplier, foreseeing the introduction of even smaller devices than 0402s in the new millennia, purposely developed the large format digital image with a substantial depth of field. This strategy allowed accurate inspection of a great variety of components, from the big or tall to the very small, such as 0201 chips. To do so, current systems use a 3.6 in2 image. New systems are being manufactured with the capability to provide either a 3.6 in2 image or 3.6 x 5.6" image.
The images shown in Figure 1 offer an insight into the large format imaging capabilities of the technology. To show a 1:1 representation of the average image size (half inch square) of a grayscale system, the image had to be magnified approximately 2.5X. This magnification level is such that the image produced would not fit in the space allotted for the graphics of the article or the width of the page. What is shown instead is a 1.5 in2 piece of the 3.6 in2 image. The resolution of the technology is such that an inspection image can be blown up 24 x 30" for a poster without losing image quality. Figure 1. What we see vs. what they see: a 2.5X magnification of a 3.6 x 5.6" image vs. a 1:1 ratio image of the competition.
A new large format camera with a 3.6 x 5.6" field of view will offer the same image quality with an increase in throughput due to the additional two inches of coverage in the X-axis. Today, a 3.6 in2 image adequately can support the production cycle times required by current customers. Within the year, planned enhancements to image acquisition capability will cut generation and inspection time to half of that required today. Once achieved, this speed increase will allow the image to zoom even closer to the target, increasing the effective pixel count per feature. This will provide orders of magnitude of accuracy in feature analysis over what has been benchmarked by current customers (both of which already are satisfied with inspection results).
(b) left image: (a) right image
Pixels Per 0201 Feature Because of its large format digital image, the technology provides millions of pixels from which features can be extracted on a given board. The company's 2,048 x 2,048 pixel sensor provides 4.2 million pixels fully usable within the 3.6 in2 image. Their 2,048 x 3,072 pixel sensor provides 6.3 million pixels fully usable within a 3.6 x 5.6" image. It is a fully parametric system. Nothing is memorized and compared by feature extraction. Every pixel is analyzed to perform feature characteristics determination based on an established set of rules. In the fully parametric inspection strategy, the more pixels a feature has, the better the inspection. In this case, with this massive pixel count, even a chip as small as an 0201 gets a fair share of the pixel count assigned to it. Figure 2. 0201 pixel count at near maximum magnification (a); magnified section of a 3.6 in2 image (b).
The images provided in Figure 2 illustrate this case. The left image (Figure 2a) is a near maximum magnification of the section circled in the right image (Figure 2b). In it you can appreciate the pixel count of the different features associated with the inspection of an 0201. Taking into consideration the fact that a two pixel count feature becomes questionable for the high-resolution digital system, following is a summary of the pixels available for analysis within the selected image:
- Pad Area 24 pixels per pad
- Pad Separation 6 pixels
- Pad Separation Area 30 pixels
- 0201 End Caps 20 pixels per end cap
- 0201 Mid-body Area 25 pixels
- 0201 Body Length 13 pixels
- 0201 Full Body Area 65 pixels.
As illustrated, there is more than adequate pixel count within the features of the 0201 chip shown in Figure 2 to perform an adequate and accurate AOI inspection.
Fundamental Inspection StrategyThe large format high-resolution digital color system is offered in two models an in-line system and a final assembly machine. The in-line system has a sophisticated conveyer system and is SMEMA compatible. It can inspect boards in a pre-reflow and post-reflow environment. At Qualcomm, it has proven to be useful in a pre-reflow environment supporting high-speed 0402 placement. The first pass yields of the boards under inspection immediately improved by five percentage points, and rework time was reduced significantly. Defective boards that typically would have taken five minutes to repair because of shields removal were being repaired in 45 seconds or less. This utilization gave Qualcomm a very fast payback in both of its systems. Even though the system was placed strategically in the pre-reflow portion of the line, it was fully qualified at Qualcomm through eight weeks of extensive evaluations in a post-reflow environment with outstanding results.
The final assembly version is unique in that the system is capable of performing final assembly inspection of SMT and through-hole components on boards that are in a ready-to-ship configuration because of the height of the camera and lighting assembly. In this particular application, items such as connector pins, connector alignment, label presence, hardware presence, jumper position, light emitting diode (LED) colors, barcode labels and other final assembly items are verified. Motorola has purchased a final assembly machine and benchmarked its SMT and through-hole capabilities. The system performed very well relative to the benchmark criteria. Additionally, enhancements that will be introduced within the next three months will provide even higher performance levels.
Other Digital Imaging Advantages One advantage of digital imaging is that it allows extensive testing of an algorithm by means of realistic modifications of the image to induce defective conditions. The emulator provides a solid simulation platform from which algorithms can be tested under actual and simulated performance conditions. It also provides the capability to perform remote support assistance by using the images and calibration data provided. This outstanding tool can emulate systems in the field and help provide necessary support in a timely manner.
Conclusion With the introduction of a large format high-resolution digital color system into the manufacturing process, companies that currently are shooting 0402 components and have to move to the 0201 component placement challenge can count on a system that will provide them with a very robust and stable AOI inspection capability.
*Vectron Inc., San Diego, Calif.**K2-AOI
REFERENCE1 Wischoffer, Scott, "0201 Assembly: From Roadblock to Routine Placement," February 2001, SMT Magazine, p. 56-60.
JOSEPH L. VILELLA, president and CEO, may be contacted at Vectron Inc., 10109 Carroll Canyon Rd., San Diego, CA 92131; (858) 621-2400; E-mail: joev@vectroninc.com