|X-ray image of over-molded connector and cable. |
How often have we heard the refrain: "We don't need x-ray imaging; we don't place BGA components." This is a common misconception in electronics manufacturing circles, and there are a couple of reasons for this. But before we get into that, we need to back up a little and look at the x-ray imaging industry in general. X-Ray has been a valuable asset to manufacturing and industries like oil and gas generation for decades. But during the mid 1990s, the role of x-ray imaging in manufacturing was redefined by this new thing called BGA placement. Suddenly, x-ray became the answer for these new things called BGAs. X-ray imaging was all the rage in the electronics industry and x-ray inspection system manufacturers did not miss the opportunity get a piece of this market. Keep in mind that some forward-looking electronics manufacturers and OEMs had used x-ray for years as an R&D and process validation tool.
During that time there were some great companies that designed and built x-ray systems for a variety of industrial applications; each of these x-ray systems had been one-of-a-kind and solved a specific manufacturing problem. Because general industrial x-ray imaging in the early years was a one-of-a-kind solution, each x-ray system was designed to solve a problem. To be sure, this allowed x-ray system manufacturers to solve manufacturing issues, but also increased the overall cost of the imaging system, while generally lowering such a system's versatility.
|X-ray image of battery shows placement of internal components. |
Sure x-ray systems that were designed to inspect turbines could also be used to inspect other items and often were placed into service to do just that, but the process of inspection often required the engineer to become quite inventive to solve his process problem. On more than one occasion the process engineer would grab his first-run boards and make the journey to a local veterinarian's office for a few x-ray films of his product. During the early to mid 1990s x-ray system manufacturers happened upon this new thing called BGA placement. Sentiment in the industry was "What? We can build one platform and sell it repeatedly without any real changes," and so the BGA inspection industry was born. Unfortunately, the old misconception that if you're not placing BGAs, you don't need x-ray continues to this day.
Crude Early Instruments
Not too long ago affordable x-ray consisted of a crudely constructed lead-lined box, some variant of an image intensifier with a CCD camera and a very limited standalone image processing box. Advances in x-ray tube technology, x-ray image detectors and computers have actually reduced the cost of an x-ray system to the point that even smaller manufacturers can now afford what was once considered a luxury and only available to larger manufacturers. Today's affordable x-ray systems are full-featured x-ray systems that allow an engineer to program the system to inspect a large variety of sample parts with point and click ease. Operators no longer have to understand x-ray physics and basic technique factors because inspection routines are stored on the local computer or on a network drive. By adding an Internet connection, engineers have the tools available for quick consultation with managers and engineers worldwide; the x-ray system operating screen along with the imaging results is displayed on all of the attendee's desktops.
Do you have an issue with your product and want to know if x-ray imaging could solve your problem? Here is a quick overview of just a few of the often overlooked applications for using x-ray imaging.
Parts, Presence, Placement. Use this if you are building a complex assembly and want to insure that all of the parts are present and are functioning as designed. This type of x-ray imaging is also popular for battery inspection; batteries can be inspected for standoff spacing and potential shorts. When this method is combined with automated x-ray inspection, 100 percent inspection is easily achieved.
|X-ray image of spring-loaded probes. |
Typical users would be medical device manufacturers, electro-mechanical/switch manufacturers, manufacturers of subassemblies, and automotive component suppliers.
Resistance Welds. This application is used for inspecting plastic parts/tubing and smaller thin-walled metal parts/tubing as well as resistance welds of electrical connections. Aluminum Die Casting. This application applies to smaller die castings; items that can be effectively examined usually weigh less than 3 pounds (1.4 kilos). This is because of the small focal spot power limitation that most electronic x-ray inspection systems use. Shrinkage, inclusions and porosity can be imaged down to the 5 to 7µ range.
Plastic Molding. This application applies to plastic moldings up to 3 pounds. Cracks, voiding and inclusions can be detected in molded parts down to the 5 to 7µ range.
Solder Joint Quality. This application is used mainly in the PCB and surface mount industries; it is well known and requires very little explanation. Standard uses are BGA inspection, µBGA and flip chip inspection. PCB manufacturers would use x-ray to confirm the inner layer registration before drilling through holes.
IC and Component Inspection. This application is used primarily by IC manufacturers and component manufacturers. Standard uses would be wire sweep, die attach voiding, capacitor insulation and voiding in resistor packs.
Any x-ray system can be used for detection of counterfeit components; all you would need to do a counterfeit component inspection is to have a known good sample. Counterfeit components can be identified by the x-ray signature or the overall density of the sample component. End users of ICs and components would use x-ray to confirm the quality/authenticity of the incoming components.
Incoming Parts Inspection
As in counterfeit component inspection, incoming inspection can be performed on subassemblies and components such as printed circuit boards, drill offset can be quickly verified and documented by using x-ray imaging.
Over-molded and encapsulated medical devices present a difficult challenge when investigating process issues or returns from the field. This is due to the nature of their design. Visual inspection and electrical tests provide very little information as to why the assembly failed internally.
|X-Scope 1800 x-ray system from Scienscope. |
Destructive testing is a viable alternative to visual and electrical tests but often destroys the assembly and can easily obliterate or mask the actual component failure cause. If the intent is to repair the assembly and return it to the customer, the process of quoting the repair can become much more costly if only visual and electrical test modes are used in the evaluation and repair.
X-Ray Imaging has solved these problems for numerous medical device manufacturers and automotive component manufacturers by allowing the operator to quickly inspect and document an assembly and make an informed decision in the control of a process or repair of the assembly.
Repairs Made Easier
One medical device manufacturer was doing a visual inspection and electrical test before quoting the customer on the repair of a very expensive encapsulated assembly. By using the x-ray system for initial inspection, the company was able to reduce its labor costs in the evaluation phase and provide the customer with a faster and more accurate repair quote.
Another medical device manufacturer was visually inspecting over-molded components and using a time-consuming process of painstakingly removing the over molded materiel to reveal the suspect area. X-ray inspection saved tens of thousands of dollars in overtime costs per year.
Miscellaneous applications include biological research, geological research and agricultural research. Typical users for this application area would be research facilities that require detailed images without damaging the sample. Items that would be x-rayed are soil samples, bugs, fish, seeds for growth viability, grain for bug infestation and root systems of saplings.
X-Ray systems designed primarily for inspecting electronics do have limitations in the overall x-ray tube power and the lack of field of view due to the high magnifications required to inspect surface mount components, but those limitations are easy to overcome making a real-time micro focus x-ray system into a powerful inspection tool — one that can be used in all areas of the manufacturing environment from incoming inspection all the way through to after-sale customer support.
Contact: Scienscope, 5751 Schaefer Ave., Chino, CA 91710 800-216-1800 or 909-590-7273 fax: 909-494-5513 E-mail: firstname.lastname@example.org Web: http://www.scienscope.com