1、T ua ua m EIA ENGINEERING BULLETIN Guidelines for Using Plastic Encapsulated Microcircuits and Semiconductors in Military, Aerospace and Other Rugged Applications SSB-1-C (Revision of SSB-1-B) ELECTRONIC INDUSTRIES ALLIANCE GOVERNMENT ELECTRONICS AND INFORMATION TECHNOLOGY ASSOCIATION A SECTOR OF Co
2、pyright Government Electronics distribution is wilunited. Copyright Government Electronics smaller package configurations allow higher circuit board packing density, therefore, reducing propagation delays Unit prices are lower than ceramic parts because of high volume, high yield, and high quality a
3、utomated manufacturing; cost benefits decrease with higher integration levels and pin counts due to the high price of die Devices are more readily available than hermetic devices due to market demand Unit price Availability The uncontrolled use of plastic encapsulated microcircuits and semiconductor
4、s can introduce a number of technical risks in military and aerospace equipment applications that are not associated with hermetic packaged devices. These potential risks include: Moisture ingress induced by humidity Electrolytic / galvanic corrosion, delamination and crack propagation induced by co
5、mbined effects of temperature cycling, humidity and bias conditions Outgassing of volatile substances induced by vacuum Device manufacturers characterize electrical performance over limited temperature ranges (e.9. Industrial Temperature Range: -40C to +85”C) “Popcorn” package cracks or in delaminat
6、ion induced by thermal effects during soldering Cumulative effects of mechanical and thermal stresses from assembly manufacturing, testing and service conditions on device long term reliability ii Copyright Government Electronics for power dissipation, calculate ATe; power dissipation can make pure
7、temperature cycling accelerated testing significantly inaccurate. All accelerated test cycles shall have temperature ramps c20C/min., and dwell times at temperature extremes shall be 15 minutes measured on the test boards. This will give -24 cycles/day. The failure/damage mechanism for solder change
8、s at lower temperatures; for assemblies seeing significant cold environment operations, additional “COLD” cycling from perhaps -4OOto OC with dwell times long enough for temperature equilibration and for a number of cycles equal to the “COLD” operational cycles in actual use is recommended. The fail
9、ure/damage mechanism for solder is different for large cyclic temperature swings transversing the stress-to-strain -20 to +2OoC transition region; for assemblies seeing such cycles in operation, additional appropriate “LARGE AT” testing with cycles similar in nature and number to actual use is recom
10、mended. 8 Copyright Government Electronics 20 years) Temperature Cycles Relative Humidity I up to 95% condensing I up to 95% condensing I I 7,305 (1 cycle per day; 20 years) IEquipment Life (Device Failure Rate) I 20 years I 300 FIT I 4.2.1 Service life Define the anticipated service life of the sys
11、tem and establish the acceptable Mean Time To Failure (MlTF) for the device. Allocate an acceptable failure rate (A) to the device and define the acceptable confidence level (a). 4.2.2 Temperature (Operating and Storage) Define the minimum and maximum temperature extremes the device will experience
12、in storage, shipment and in non-operating conditions. Define the maximum operating junction temperature of the device under consideration. It may be necessary to factor in the effects of heat sinking, cooling, loss of coolant, and other factors, as applicable. Failure rates should be estimated for e
13、ach application of the device to account for different operating junction temperatures. 4.2.3 Temperature Cycle Estimate temperature range(s) and the total number of temperature cycles that the device will experience. This should also be expressed as a function of time to convert device-cycles to de
14、vice-hours in order to estimate the sum-of-the-failure-rates for the device (see SSB-1 .O04 for further discussion). 4.2.4 Relative Humidity Determine the relative humidity that the part will experience in its application (storage and operation). 4.2.5 Operating Duty Cycle For some applications it m
15、aybe appropriate to take into account the operating duty cycle for the purpose of establishing realistic service life conditions. 9 Copyright Government Electronics this may be enough additional data to support the desired FIT. You may also inquire if they have any qualification data. If the supplie
16、r is a typical automotive supplier, the standard qualifications for most step stress tests are 3 lots of 77. This would be an additional 231,000 device hours per qualification. In the event that no additional device hours can be obtained from the supplier a decision must be made to either look elsew
17、here for a suitable supplier, or to perform additional tests. In the event of choosing the later a reverse model calculation is provided in SSBI .O04 to determine what sample size tress conditions or by other means and reevaluate Device Qualifies Do additional test, or tests to obtain needed device
18、hours for evaluation Figure 4 - Evaluation 15 Copyright Government Electronics & Information Technology Association Reproduced by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright Government Electronics & Information Technology A
19、ssociation Reproduced by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-EIA Document Improvement Proposal Document No. If in the review or use of this document, a potential change is made evident for safety, health or technical reasons,
20、 please fill in the appropriate information below and mail or FAX to: Document Title: Electronic Industries Alliance Engineering Department - Publications Office 2500 Wilson Blvd. Arlington, VA 2220 1 FAX: (703) 907-7501 Submitters Name: Telephone No.: FAXNo.: e-mail: Address: Urgency of Change: Imm
21、ediate: 0 At next revision: 0 Problem Area: a. Clause Number and/or Drawing: b. Recommended Changes: c. ReasodRationale for Recommendation: Additional Remarks: Signature: Date: FOR EIA USE ONLY Responsible Committee: Chairman: Date comments forwarded to Committee Chairman: Copyright Government Elect
22、ronics & Information Technology Association Reproduced by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright Government Electronics & Information Technology Association Reproduced by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-
