Plastic Encapsulated Microcircuits Research Articles

Qualification of plastic encapsulated microcircuits (PEM) for avionicsBased on ``Plastic Encapsulated Microcircuits (PEM) Qualification Testing'', by J. A. Scalise, which appeared in the Proceedings of the 46th Electronic Components and Technology Conference, Orlando, FL, U.S.A., 28–31 May 1996, pp. 392–397. © 1996 IEEE.

Microcircuit package qualification testing is used to establish the reliability of integrated circuit processes and devices as they relate to part packaging. This paper presents the results of package qualification tests conducted on plastic encapsulated microcircuits (PEMs) and plastic discrete devices (diodes, transistors) used in avionics applications. Highly accelerated stress test (HAST) and temperature cycle (TC) test results, including part failure mechanisms and associated failure rates, are provided. A variety of plastic package styles and integrated circuit functions have been tested. Examples of package styles tested include small outline (SO), plastic leaded chip carrier (PLCC), thin small outline package (TSOP), plastic quad flat package (PQFP) and plastic dual-in-line (PDIP). Manufacturers' devices have been evaluated and various plastic compounds have been compared to determine which provide optimum reliability. The testing showed that package qualification performance of PEMs is affected by type of compound, passivation (including die coat) and die size. HAST failures are caused by moisture penetration of the package while temperature cycle failures result from coefficient of thermal expansion (CTE) mismatch effects.

Why use PEMs in military equipment: users' response

Since the early 1980s, with significant improvement in plastic packaging of microcircuits, accelerated environmental testing has indicated continuous reliability improvements. These data have been generated by independent researchers, Universities, users and suppliers. The question which still remains concerns their use in high reliability applications for extended periods in harsh environments. Such applications would be in the military, automotive, and commercial airline markets. This report is the result of responses to a survey directed at military equipment developers. Its goal was to determine advantages and disadvantages in the use of commercial plastic encapsulated microcircuits (PEMs) versus the use of MIL approved microcircuits as received by the equipment manufacturer. Responses, however, impacted all three markets, not only military.

Plastic‐encapsulated Microcircuits (PEMs) : Long‐term Dormancy Studies

For many years, the concern over the use of plastic encapsulated microcircuits (PEMs) has been their capability to survive in harsh environments over a long term with continuous or intermittent operation. The issues centred around operational life limitation, due to failure mechanisms associated with internal corrosion, wires and wire bonds, and surface effects, It has now been conclusively demonstrated that best commercial practices will ensure that PEMs made using best commercial materials, processes, and quality techniques will permit devices to perform reliably in the most severe environments. Missile systems are low volume production items, which use relatively few microcircuits. They are required to operate for very short times after being unpowered (dormant) for very long times (10 to 20 years) and exposed to humidity, temperature cycle, and mechanical shock. This paper will address reliability concerns and provide data from studies which were performed to determine if PEMs could survive such long‐term unbiased applications. These studies include analysis of PEMs (some date coded 1968) from inventory or various storage locations and from applications where the electronic modules containing PEMs were stored for 10‐12 years in various environments. Regardless of the storage conditions, the significant factor is that these early vintage commercial grade PEMs, without screening or incoming inspection, survived assembly and extended storage.

Plastic-encapsulated microcircuit reliability and cost-effectiveness study : Douglas Emerson, Edward Hakim and Anand Govind. IEEE Transactions on Reliability, 45 (1), 19 (1996)

Plastic-encapsulated microcircuit reliability and cost-effectiveness study : Douglas Emerson, Edward Hakim and Anand Govind. IEEE Transactions on Reliability, 45 (1), 19 (1996)

Popcorning: a failure mechanism in plastic-encapsulated microcircuits : Anthony A. Gallo and Ramesh Munamarty. IEEE Transactions on Reliability, 44 (3), 362 (September 1995).

Popcorning: a failure mechanism in plastic-encapsulated microcircuits : Anthony A. Gallo and Ramesh Munamarty. IEEE Transactions on Reliability, 44 (3), 362 (September 1995).

Commercial-Components Initiative: Ground Benign Systems-plastic encapsulated microcircuits

The purpose of the Commercial Components Initiative-Ground Benign Systems was to determine if commercial off-the-shelf PEM (plastic-encapsulated microcircuits) are suitable for use in ground-benign, dynamically-fixed military electronic systems. If so, they could replace the more expensive components presently specified by DoD (US Dept. of Defense), resulting in appreciable life-cycle cost savings. At issue is whether the components produced for the commercial industry are reliable and durable enough to withstand the environments and life expectancies of military systems. Reliability was not formally proven. A more practical informal reliability test for this project, which DSD dubbed Run for Reliability, was to install the PCB in the system and let the operational hours accrue beyond the subsystem and Signal Processor lifetime allocations. The Run for Reliability shows promise that commercial hardware could be proven in a formal reliability demonstration test.

Reliability test on chip type of high capacitance multilayer ceramic capcitors : KENJI MURATA and TOSHIMA KAWAKAMI. Proceedings of the 24th Symposium on Reliability and Maintainability, Tokyo, Japan, 19 (6–8 July 1994)

Microelectronic devices, such as transistors, capacitors, and resistors, within an active chip, require some protection from the environment, as well as both electrical and mechanical connections to the surrounding components. Electronic packaging is the science of placing electronic devices and circuitry in protective enclosures and providing interconnections within and between different electronic devices. Electronic devices have been packaged in a variety of ways. One of the first methods was a kovar (high nickel alloy) preformed package. The device was bonded to the bottom, and the top was later secured. Ceramic packages, similar in construction to the Kovar casing, later appeared as a cheaper alternative. The first evidence of plastic encapsulation was seen in the early 1950s, using compression molding of phenolics. The phenolic material was compressed around electrical devices leaving the electrical connectors sticking out. The problem with this method was that the delicate connections were often severed due to the high pressure. By the early 1960s, plastic encapsulation emerged as an inexpensive, simple alternative to ceramics and metal encasing and during the 1970s virtually all high-volume integrated circuits (ICs) were encapsulated in plastic. As of 2015, plastic encapsulation is used in most devices in both consumer electronics as well as high reliability applications. A plastic-encapsulated microcircuit (PEM), often called a plastic package, consists of an integrated circuit chip physically attached to a leadframe, and/or signal traces on the substrate, forming an electrical connection to the I/O leads or interconnects, and encapsulated, forming a direct contact with the chip, leadframe, and interconnects. PEMs are made in either surface-mount or through-hole configurations.

Large format fabrication—a practical approach to low cot MCM-D : GEORGE WHITE, ERIC PERFECTO, DALE MCHERRON, THOMAS DEMERCURIO, THOMAS REDMOND and MAURICE NORCOTT. IEEE Transactions on Components, Packaging and Manufacturing Technology, Part B, 18(1), 37 (February 1995)

Plastic-encapsulated microcircuits (PEMs) are proposed for use in military systems to reduce cost and eliminate long-lead items such as packages and lids. Encapsulant materials must be evaluated for compatibility with devices and fine-wire bonds, and electrical stability on deposited elements and integrated-circuit devices. Reliability evaluations in screen tests and various temperature/humidity/bias environments are also essential prior to use in advanced packaging.Encapsulant reliability evaluation requires a test vehicle (MCM-C and MCM-L) to identify these key performance characteristics to assure environmental and mechanical protection because no complete multichip test vehicle, however, is available for use. An encapsulant test vehicle in previous work was modified by substituting a Sandia ATC04 chip and a silver-comb-pattern array with varying feature sizes, using only a single nichrome-resistor network, and adding a deposited comb pattern. The unpassivated resistor and a silver-comb pattern offer both a go/no-go and quantitative test for screening encapsulants and the Sandia chip facilitates stress measurements on the die as well as thermal dissipation evaluation with resistance heaters on the chip.An industry-standard encapsulant, Hysol® FP 4450, was modified to improve thermal conductivity. Exact filler selection and loading were optimized, balancing dispensability, wear, and flow characteristics. Control materials (Hysol® FP 4450) and improved, thermally conductive versions were exposed to short-term screen tests, long-term humidity, and elevated temperature storage testing. Thermal conductivity of Hysol® FP 4450 was improved by approximately 200% and both materials were comparable in temperature/humidity/bias and highly accelerated stress testing as well as thermal cycling and elevated temperature storage.

System level hardware module generation : MANI B. SRIVASTAVA, BRIAN C. RICHARDS and ROBERT W. BRODERSEN. IEEE Transactions on Very Large Scale Integration (VLSI), 3(1), 20 (March 1995)

Plastic-encapsulated microcircuits (PEMs) are proposed for use in military systems to reduce cost and eliminate long-lead items such as packages and lids. Encapsulant materials must be evaluated for compatibility with devices and fine-wire bonds, and electrical stability on deposited elements and integrated-circuit devices. Reliability evaluations in screen tests and various temperature/humidity/bias environments are also essential prior to use in advanced packaging.Encapsulant reliability evaluation requires a test vehicle (MCM-C and MCM-L) to identify these key performance characteristics to assure environmental and mechanical protection because no complete multichip test vehicle, however, is available for use. An encapsulant test vehicle in previous work was modified by substituting a Sandia ATC04 chip and a silver-comb-pattern array with varying feature sizes, using only a single nichrome-resistor network, and adding a deposited comb pattern. The unpassivated resistor and a silver-comb pattern offer both a go/no-go and quantitative test for screening encapsulants and the Sandia chip facilitates stress measurements on the die as well as thermal dissipation evaluation with resistance heaters on the chip.An industry-standard encapsulant, Hysol® FP 4450, was modified to improve thermal conductivity. Exact filler selection and loading were optimized, balancing dispensability, wear, and flow characteristics. Control materials (Hysol® FP 4450) and improved, thermally conductive versions were exposed to short-term screen tests, long-term humidity, and elevated temperature storage testing. Thermal conductivity of Hysol® FP 4450 was improved by approximately 200% and both materials were comparable in temperature/humidity/bias and highly accelerated stress testing as well as thermal cycling and elevated temperature storage.

Reliability comparisons for plastic-encapsulated microcircuits : BRETT BAKER and STEVE MARTIN. IEEE Transactions on Reliability, 44(1), 6 (March 1995)

Reliability comparisons for plastic-encapsulated microcircuits : BRETT BAKER and STEVE MARTIN. IEEE Transactions on Reliability, 44(1), 6 (March 1995)

Demonstrated reliability of plastic-encapsulated microcircuits for missile applications : SUN MAN TAM. IEEE Transactions on Reliability, 44(1), 8 (March 1995)

Demonstrated reliability of plastic-encapsulated microcircuits for missile applications : SUN MAN TAM. IEEE Transactions on Reliability, 44(1), 8 (March 1995)

The appropriateness of plastic encapsulated microcircuits in a specific wooden-round application

Improvements in design, materials, and processes of plastic encapsulated microcircuits (PEM) have increased their reliability dramatically, to the point where PEM can achieve the '20-year lifetime in unpowered storage' required by certain wooden-round applications. PEM are now the parts of choice from cost, market-availability, performance, and reliability viewpoints. Nevertheless, PEM require appropriate vendor selection, verification by highly accelerated stress test (HAST), and manufacturing precautions. The potential failure mechanisms of package damage, internal part corrosion, and intermetallic growth, due to high temperature and humidity exposure, have been largely eliminated by improvements in the plastic and in the assembly process, and by the addition of die passivation. Models and test methodologies for accelerating (and thereby identifying) these physical phenomena have been developed, proven by testing, and generally accepted within the industry. After thoroughly defining the application temperature/humidity environments, the models are used to define a test program to qualify candidate PEM. This program consists of a high temperature life test, a humidity/temperature HAST and a completely assembled board-level HAST. To insure that subsequent manufacturing processes at Textron DS (including higher assemblies) do not damage qualified PEM, the manufacturing flow has been modified to minimize human contact with components, to eliminate any potentially corrosive chemical interaction with PEM, and to minimize exposure to moisture.

Reliability assessment of fielded plastic and hermetically packaged microelectronics

This paper presents the results from multiple studies at Honeywell, of piece-part failure rates experienced in field use. These studies consider 7 line-replaceable-units (LRU), containing either hermetically sealed microcircuits (HSM) or plastic encapsulated microcircuits (PEM) or both. This paper compares the resulting field failure rates (/spl lambda/) of HSM and PEM: digital devices: /spl lambda//sub PEM//spl ap/0.5/spl lambda//sub HSM/; linear devices: /spl lambda//sub PEM//spl ap/3/spl lambda//sub HSM/; only a small fraction of the linear devices degraded in performance at 125/spl deg/C, though their performance at room temperature was within specification. The latter two points suggest that linear devices might require more attention relative to characterization over temperature and application considerations than do digital devices.

Plastic-encapsulated microcircuit reliability and cost-effectiveness study

This study evaluates the reliability and cost-effectiveness of using commercial plastic-encapsulated microcircuits (PEM) in a typical military system, with a view to increasing their acceptability in military applications. The cost comparison indicates an average 6-fold decrease in cost when commercial devices are used. Assurance testing did not reveal any special problems with commercial parts. Thus, if commercial PEM were proven to be sufficiently reliable for an intended military application, large cost savings would be gained by using them instead of hermetic packages. The 4.5 sigma enhanced inspection program and the process-control methods suggested here would enhance the manufacturing yield of the PLGR (precision lightweight global positioning system receiver) by encouraging improvements in the manufacturing process while simultaneously cutting the cost of a 100% rescreen to qualify the final product. Neither the requirements assurance tests (including the step-stress test-analyze-and-fix test), nor the reliability demonstration test, nor the operational test, showed more failures than are typical for any new development, and no problems unique to PEM were observed. Thus, the use of PEM did not lead to any special problems that caused PLGR-use specifications to be violated. Complete failure analysis of the isolated parts is in progress, and the results will help to understand the specific reliability issues involved with the use of PEM in military systems. These issues can then be addressed to improve the acceptability of such devices in future military applications.

Demonstrated reliability of plastic-encapsulated microcircuits for missile applications

For the past decade, overall reliability improvement and product availability have enabled plastic encapsulated microcircuits (PEM) to move from consumer electronics beyond the relatively large and reliability-conscious automotive market, into the military market. Based on the analysis of the worst-case PEM scenario for military applications, demonstrating the moisture reliability under long-term (20 years) dormant storage environments has become the last hurdle for PEM. Studies have demonstrated that PEM can meet the typical missile environments in long-term storage. To further validate PEM reliability in missile applications, Texas Instruments (TI) conducted three separate studies involving 6 years of PEM moisture-life monitoring and assessment, testing of the standard PEM electrical characteristics under the military temperature ranges (-55/spl deg/C to +125/spl deg/C), and assessing their robustness in moisture environments after the assembly processes. These TI studies support the use of PEM in missile (or similar) applications. Effective focus on part and supplier selection, supplier teaming, and process monitoring is necessary to maintain the PEM reliability over the required environments at the lowest cost. This paper assesses PEM reliability for a selected missile storage environment using the industry-standard moisture testing, such as biased HAST or 85/spl deg/C/85%RH (relative humidity), for demonstrating the PEM moisture survivability. The moisture reliability (MTTF) or average moisture lifetime of PEM is assessed to correlate PEM capability to anticipated field-performance environments. >

Reliability comparisons for plastic-encapsulated microcircuits

This paper briefly compares reliability test data obtained from plastic encapsulated microcircuits (PEM) purchased from various manufacturers. Tests include biased humidity, temperature cycling, autoclave, and life tests. The results indicate differences in reliability associated with PEM from the various manufacturers. These data highlight the need for a thorough understanding of supplier quality and reliability. >

Popcorning: a failure mechanism in plastic-encapsulated microcircuits

Popcorning is a failure mechanism in plastic-encapsulated microcircuits. It occurs when the inherently hygroscopic encapsulant is rapidly exposed to high temperatures during reflow solder assembly of the component to a printed circuit card. At these temperatures the moisture absorbed by the molding compound vaporizes and rapidly expands leading to the development of high stresses. When these stresses exceed both the interfacial adhesion strength and the fracture toughness of the molding compound, delamination and cracking result. Cracking is accompanied by a characteristic pop sound (and thus the name popcorning). Popcorning can: lead to a long-term reliability problem, since the cracks can be a path for ionic contaminants, causing corrosion-induced failures; and result in sheared or cratered ball bonds, causing electrical failures. >

Thermal resistance simulation of IC packages using a three-dimensional boundary element method : Toshiki Sotaet al. Proceedings of the 22nd Symposium on Reliability and Maintainability, Tokyo, Japan. Union of Japanese Scientists and Engineers, 5 (June 1992)

Plastic-encapsulated microcircuits (PEMs) are proposed for use in military systems to reduce cost and eliminate long-lead items such as packages and lids. Encapsulant materials must be evaluated for compatibility with devices and fine-wire bonds, and electrical stability on deposited elements and integrated-circuit devices. Reliability evaluations in screen tests and various temperature/humidity/bias environments are also essential prior to use in advanced packaging.Encapsulant reliability evaluation requires a test vehicle (MCM-C and MCM-L) to identify these key performance characteristics to assure environmental and mechanical protection because no complete multichip test vehicle, however, is available for use. An encapsulant test vehicle in previous work was modified by substituting a Sandia ATC04 chip and a silver-comb-pattern array with varying feature sizes, using only a single nichrome-resistor network, and adding a deposited comb pattern. The unpassivated resistor and a silver-comb pattern offer both a go/no-go and quantitative test for screening encapsulants and the Sandia chip facilitates stress measurements on the die as well as thermal dissipation evaluation with resistance heaters on the chip.An industry-standard encapsulant, Hysol® FP 4450, was modified to improve thermal conductivity. Exact filler selection and loading were optimized, balancing dispensability, wear, and flow characteristics. Control materials (Hysol® FP 4450) and improved, thermally conductive versions were exposed to short-term screen tests, long-term humidity, and elevated temperature storage testing. Thermal conductivity of Hysol® FP 4450 was improved by approximately 200% and both materials were comparable in temperature/humidity/bias and highly accelerated stress testing as well as thermal cycling and elevated temperature storage.

Plastic packaged microcircuits: quality, reliability, and cost issues

Plastic encapsulated microcircuits (PEMs) find their main application in commercial and telecommunication electronics. The advantages of PEMs in cost, size, weight, performance, and market lead-time, have attracted 97% of the market share of worldwide microcircuit sales. However, PEMs have always been resisted in US Government and military applications due to the perception that PEM reliability is low. This work surveys plastic packaging with respect to the issues of reliability, market lead-time, performance, cost, and weight as a means to guide part selection and system design. >

Reliability evaluation of plastic encapsulated parts

This work compares the failure rates of several families of plastic encapsulated microcircuits (PEMs) using both field and test data (test data are converted to device failure rates for field conditions using common acceleration equations) and Mil-Hdbk-217 calculations. Calculated failure rates are obtained from the Mil-Hdbk-217F for both plastic encapsulated and ceramic hermetic class-B microcircuits. Comparisons show that the results from Mil-Hdbk-217 are misleading and that the US military and Government part-selection methods should not be burdened by this -217 methodology. >