Cennamo Electronics, LLC
-Reliability Program Planning and Execution
-Electrical and Mechanical Design
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- Reliability Prediction
- Electrical De-rating
- Failure Mode and Effects Analysis (FMEA)
- Testability Aanalysis
- Maintainability Analysis
- Failure Reporting, Analysis, and Corrective Action System (FRACAS)
- Highly Accelerated Life Test (HALT)
- Highly Accelerated Stress Screening (HASS)
- Safety Analysis
- Internal and Vendor Quality
- Failure Analysis/Root Cause Analysis (RCA)
- Electrical and Mechanical Design
The reliability prediction provides an estimation of the product's expected reliability. During design this is used to identify and evaluate design improvement opportunities. Ongoing design changes are evaluated for impact to current expectations during the decision process. The results are also used for forecasting logistic needs of the system and provide an expectation to the customer.
The reliability prediction process should be performed as a continuous task to analyze the design at various stages and provide a current estimation of the expected reliability for evaluation against the product's needs. Reliability predictions can be performed on the final design only, but that significantly reduces the possible impact on design which is a true benefit of continuous and early evaluation. The cost of design changes increases as the program progresses and are extremely costly toward the end of the design process.
The reliability predictions performed by Cennamo Electronics are based on excepted reliability prediction methodologies and are backed by years of experience performing predictions and comparing results to field experience. This experience allows Cennamo Electronics to use excepted approaches when applying the methodologies as well as interpret and explain the relation of the results to true expectations. Recommendations for design improvements are based on both prediction results and experience with component types, board placement, vibration effects, thermal effects, and electrical stress (when an electrical analysis is requested).
There is more about continuous design evaluation on the Reliability Program Plan (RPP) page accessible here. There is also more about Reliability Prediction on the RPP page accessible here.
Reliability predictions can be accomplished without the inputs from any other listed service, but the prediction is enhanced with the Electrical De-rating service used as an input. Some of the other services listed require reliability prediction results as a prerequisite while others are enhanced when the results are incorporated.
Electrical de-rating utilizes a full electrical stress analysis on the design circuitry and compares the applied stress values to rated values of the components. Cennamo Electronics has developed an internal de-rating standard which provides suggestions for maximum component stresses. This standard, or another standard identified during the quoting process, will be used to provide recommendations for design enhancement to increase the expected life of the product.
Electrical de-rating can be accomplished without the inputs from any other listed service, but this service is most often combined with the Reliability Prediction at a minimum. It significantly enhances the reliability prediction which will ripple through other services enhanced by the reliability prediction as well.
The FMEA identifies failure modes, their internal effects, resulting end effects, and assesses the severity of each to help identify critical areas to mitigate. During design this is used to identify and evaluate design improvement opportunities. The results provide an assessment of the severities expected and are used to assess the risk of the design. When a Criticality Analysis (CA) is performed, using the reliability prediction results, the probability of occurrence for each failure mode/end effect combination will also be used to assess risk of the design. This is often referred to as a Failure Mode, Effects, and Criticality Analysis (FMECA) and adds the ability to assess the probability of the end effects occurring.
FMEA/FMECA should be a continuous task like the reliability prediction process, but can also be performed on the final design only. The continuous task is much more beneficial to programs for the same reasons as stated in the Reliability Prediction section.
There is more about FMEA on the RPP page accessible here.
FMEA can be accomplished without the inputs from any other listed service, but this service is most often combined with the Reliability Prediction to provide a CA making the report a FMECA. The FMECA is required to perform a Testability Analysis as the criticality is used to assess Fault Detection (FD) and Fault Isolation (FI) percentages. The FMECA is also required to perform a Safety Analysis based on current industry guidance.
The Testability Analysis provides the Fault Detection (FD) and Fault Isolation (FI) percentages of the product as well as the method of detection, related Built-In-Test (BIT) information, and assessment of isolation probability for the failure mode/end effect combinations identified in the FMEA/FMECA. These failure modes are analyzed for the product's ability to detect and report the failure. The assessment of detectability and isolation to the Line Replaceable Unit (LRU) are made utilizing the associated failure rate of the analyzed circuitry (some circuitry is excluded such as redundant circuitry and connectors).
The Testability Analysis requires a FMEA with a CA. Electrical De-rating is recommended to enhance the reliability prediction values used in the FMECA.
The Maintainability Analysis provides an estimation of the product's expected inherent maintenance times. During design this is used to identify and evaluate design improvement opportunities to reduce the amount of time required to repair the product upon failure and reduce the unique tool and skill requirements. Ongoing design changes are evaluated for impact to current expectations during the decision process. The results are also used for forecasting logistic needs of the system and provide an expectation to the customer for support tools and training.
The Maintainability Analysis requires the Reliability Prediction.
FRACAS is a systematic approach to reviewing failures with cross-functional personnel and assigning resources to resolving issues. FRACAS starts during the design phase with Root Cause Analysis (RCA) performed on test failures such as Highly Accelerated Life Test (HALT), Qualification testing, flight testing, and continues to track failures experienced after fielding the product. During earlier stages of design and fielding all failures should get complete RCA to quickly catch inherent issues before many units have been produced and fielded. More units fielded with a defect increases the cost of correction and, more importantly, increases the amount failing in a customer's hands which decreases satisfaction with the product and the company negatively effecting future sales. As the design matures the focus will shift to trends.
FRACAS consist of a cross-functional Failure Review Board (FRB) which meets on a regular basis to review failures and assign resources. This cross-functional team should consist of leaders and decision makers from Engineering, Quality, Production, and Service at a minimum. The organizer of the FRB should review all failure data since the last meeting and prepare summaries and recommendations to the FRB so the review can result in actionable items. The FRB will assign resources to any item they feel warrants attention from the review and will receive status updates at future meetings during the review of action items.
FRACAS can be accomplished without the inputs from any other listed service.
HALT is a destructive test initially performed on the prototype design (potentially later design iterations as well). The objective is to find the weakest points in the design as early as possible in the design cycle. This is accomplished by applying increasing stress levels during the test to push the design to its destruction limits. Pushing the design to these extreme stress conditions is required to simulate the life of the product in a short time. Often simple fixes are found that make the product more robust and increase the expected life.
There is more about HALT on the RPP page accessible here.
HALT can be accomplished without the inputs from any other listed service. HALT is required to perform Highly Accelerated Stress Screening (HASS) as the discovered product environment limits are used to generate the HASS profile.
HASS is a screening process meant for each product to go through prior to delivery to the end customer. The purpose of HASS is to catch any process and manufacturing variation induced latent failures in the assembled product. While HASS may catch some design issues in the early design life that were not caught during HALT or other testing, it's focus is on a solid design with latent processing and manufacturing defects such as cold solder, contamination, intermittent connections, etc.
HASS is a more intense version of Environmental Stress Screening (ESS). HASS stresses will go beyond design specifications to accelerate the discovery process where ESS stress limits are within specifications. This allows HASS to significantly reduce the time required to perform on an individual product and decreases the build cycle time significantly as a result. HASS uses the HALT experience to "discover" true product limits instead of specifications. These limits are proven out not to significantly reduce the product life prior to HASS implementation.
Removing latent defects from the product will increase the fielded or perceived reliability of the product and reduce Quality rejections. Although the majority will be processing variations and not true design issues, the end customer will not distinguish the difference as both are failures and decrease satisfaction with the product and company performance.
There is more about HASS on the RPP page accessible here.
HASS requires HALT to generate the profile.
Cennamo Electronics has Safety Analysis experience in both military and airborne standards. Military analyses consist of a Hazard Analysis which analyzes FMEA failure modes and also looks at other potential user interface hazards during both operation and assembly. Hazards are tracked and mitigated and then included in the Safety Assessment Report (SAR) along with a summary of findings, identification of hazardous materials used in assembly, and a list of hazards with current status and risk evaluation.
Airborne standards start with a Functional Hazard Assessment (FHA) which details the product functions and assesses their criticality levels when not available or incorrect. This list is maintained and updated as design changes dictate. The Preliminary System Safety Report (PSSA) uses the identified hazards and evaluates them using Fault Tree (FT) Analysis. At this stage most FTs do not get probability numbers and are used to evaluate any mitigation that is in-place or needed in the design. Critical hazards may require some level of probability input to evaluate needs and a case by case basis. These trees should be kept current and the basis for making design decisions concerning these potential hazards. The final stage is the System Safety Assessment (SSA) which consists of the same FTs, but all FTs above minor should now be evaluated for their probability and compared to system requirements set forth by the Federal Aviation Administration (FAA).
The Safety Analysis requires a FMEA with a CA. Electrical De-rating is recommended to enhance the reliability prediction values used in the FMECA.
Internal and vendor quality issues can result in failures that dominate the perceived life of a product even if the core design is sound. Process and manufacturing variations can lead to latent defects manifesting during assembly, test, or in the hands of your customer. These issues can lead to excessive rework and scrap costs, component shortages, extended build time, missed customer deliveries, customer quality concerns, warranty costs, perceived fielded reliability performance, and even lost business. To avoid these costly issues good process controls must be put in place with a system to address new issues as they arise.
Cennamo Electronics has experience with evaluating both internal processes and vendor processes for potential causes of variation and poor quality product. The evaluation can be aimed at addressing current issues experienced through Root Cause Analysis (RCA) and correcting those individually or a complete review of the process to catch potential future issues as well.
A complete review of a process employs Process Failure Modes and Effects Analysis (PFMEA) techniques which follow the same fundamental guidelines as the FMEA described above, but applied to a process. This starts with developing a representative process map. This may be a newly developed map or a review and potential update to an existing process map. The next step is to evaluate each step of the process for potential failure modes and the causes of those failure modes. These instances are ranked according to importance and the top items are addressed with control plans based on identified mitigation activities. This can continue until all items are addressed or the items left are to an acceptable level.
In addition to the evaluation and PFMEA mentioned, establishing a good corrective action system is essential to on-going success.
Internal and Vendor Quality can be accomplished without the inputs from any other listed service.
Failure analysis is required to ensure issues are addressed or corrected in a manner to significantly reduce or eliminate future occurrences. The true nature of a failure goes beyond the replacement of a subsystem or component. While some random failures do occur, typically a failure can be attributed to a single or small subset of contributing causes which can be addressed in a manner to prevent future occurrences. Root Cause Analysis (RCA) is designed to determine the true root(s) for correction and avoid treating the symptom. In fact, a failure such as a blown capacitor can be due to several issues that will remain in the circuit even after replacing the capacitor or the symptom. Even if replacing that capacitor works for the remainder of the CCA life, the root may have been due to initial processing variation that future assemblies will experience.
RCA is an essential component during design to prevent failures from ever being experienced in the field. Once production has started, early experienced failures need RCA to limit the number of units shipped with defects that may increase the field failure rate. As time goes on the threshold for the analysis need may change as more products are fielded without issue and confidence is high that the failure rates are acceptable. Early in the product life this luxury does not exist.
Failure Analysis/RCA can be accomplished without the inputs from any other listed service.
Cennamo Electronics possesses the tools and capabilities for electrical circuit card and mechanical design. Design begins with the definition of input and output requirements and continues with other constraints such as size and cost. These requirements and constraints are evaluated and a design approach is proposed. The design will be tested at the sub function and top levels for compliance to the requirements. The completed design can be delivered or demonstrated in many ways depending on the requirements of the customer.
Cennamo Electronics uses EAGLE CAD software for schematics and circuit card layout. After breadboard prototypes are successful and the initial design and the layout has been completed, Cennamo Electronics has relationships with bare board fabricators and circuit card assemblers to build reliable circuit cards with surface mount technologies for reduced size. These circuit card assemblies can be purchased, fully assembled and tested, at various quantities. Price is dependent on the quantity purchased in a single run (cheaper with higher quantities) and details of the design.
Cennamo Electronics uses TurboCAD Platinum Pro for 3D mechanical design. After initial design of mechanical structures, they are prototyped on a Lulzbot TAZ 5 3D printer for fit and function. Cennamo Electronics has relationships with mechanical fabricators for both low rate and high rate production of mechanical assemblies.
While this service can be completely independent of other services, the input from those activities are recommended and can be discussed.
Electrical and mechanical design can be accomplished without the inputs from any other listed service.
Please e-mail info@cennamoelectronics.com or call (614) 600-7634 for more information.
Cennamo Electronics, LLC is a limited liability company formed in the state of Ohio.