Classifications

• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B19/00—Programme-control systems
  • G05B19/02—Programme-control systems electric
  • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
  • G05B19/406—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by monitoring or safety
  • G05B19/4065—Monitoring tool breakage, life or condition
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/37—Measurements
  • G05B2219/37253—Fail estimation as function of lapsed time of use

Definitions

• the present invention relates to a method and an apparatus for predicting a life expectancy of a product comprising at least two components.
• the life expectancy is determined as a function of a specifiable load of the product.
• the invention relates to a computer program which is executable on a computing device, in particular on a microprocessor, a data processing system.
• a product comprises several components.
• a product can be a personal computer (PC), the components then the electrical components (power supply, motherboard, hard disk, Floppy disk drive, CD-ROM drive, DVD drive, etc.) of the PC. It would also be conceivable to consider, for example, the motherboard as the product, in which case the various electrical components, solder joints etc. on the board are the components.
• a product could also be any motor vehicle component, in particular a motor vehicle control device, the components then being the various electrical components (for example resistors, capacitors, coils, operational amplifiers), solder joints, conductor tracks, etc.
• a motor vehicle control device for example, which is arranged in the vicinity of an internal combustion engine of a vehicle, is exposed to a significantly higher thermal load than a control device arranged in the passenger compartment of the vehicle.
• the thermal load can be an absolute temperature but also a temperature fluctuation.
• the same control unit would therefore have a shorter service life in the engine area than in the passenger compartment.
• the testing for providing the proof can be carried out on a plurality of identical products, so that the result of the proof is more representative.
• the known method provides after testing a plurality of identical products, for example, statements such as: "The product achieved at absolute
• the present invention based on the object to design a method and an apparatus of the type mentioned in such a way and further that within the shortest possible time and as close to the field as possible a particularly meaningful proof of reliability for the product provided or the lifetime of the product can be determined.
• the following method steps are proposed starting from the method of the type mentioned: the components of the product are subjected to different loads; the components are operated at the different loads each to their failure; the downtimes achieved are stored for the respective component as a function of the load; depending on the load-dependent
• Downtime of a component is added to an end-of-life (EoL) curve of the component; an EoL curve of the product is determined so that, at the various loads, it comprises that of the EoL curves of the components which, at the respective load, each have the shortest downtime; and the expected life of the product being determined as the functional value of the EoL curve of the product as a function of the given load on the product.
• EoL end-of-life
• each component of a product is first considered individually. Based on the EoL curves recorded for the individual components, an EoL curve is determined for the entire product. This corresponds to the different loads, so to speak, always the EoL curve of the worst component, ie the component with the lowest life at a given load. This results from the consideration that a product in its entirety fails as soon as only one of the components fails.
• the consideration of the individual components has the advantage that if the structure of the product changes (replacement of one component by another, omission of a component, addition of a new component) it does not have to be determined again for the entire product, if the product of the given load for the given
• Duration can withstand. It is sufficient if the EoL curve for the new or modified component is included and taken into account in the determination of the EoL curve of the entire product. When omitting a component, simply determining the EoL curve for the product simply ignores the EoL curve of the omitted component.
• the EoL curve of the component can simply be passed through or approximated to the calculated values for the load-dependent downtime for that component.
• the points of the EoL curve of a component between the determined values for the load-dependent downtimes of the component can be interpolated according to any method known per se. At the edge, d. H. at the beginning and end, the EoL curve can be extrapolated.
• the method according to the invention enables particularly rapid checking of the durability of a product, in particular when the EoL curves for the individual components have already been recorded in advance of the check, stored in a database and, if necessary, only retrieved.
• irrelevant errors due to excessive burden for the proof of reliability can be prevented.
• the various burdens that are placed on the individual components are largely in the range of an assumed one
• the loading of the components or of the entire product with the assumed field load was separated from the determination of the lifetime of the product and the examination of the durability. While the loading of the components with the assumed field load may take place in advance of the actual determination of the life and / or reliability of the product, the actual life of the product is determined based on the previously determined EoL curves during the running time of the method according to the invention.
• the consideration of the individual components also has the advantage that, based on the EoL curves for the individual components, it can be checked whether the components are suitable for withstanding the assumed field load. If a component can not withstand the field load, it will be immediately recognized by the EoL curve of the component and the component can then be swapped for a more stable one. On the other hand, it is also possible components that are clearly much more stable than actually required (because the EoL curve of these components significantly above assumed field load) to replace with less stable less expensive components, without running the risk that the product of the assumed field load can no longer withstand.
• the assumed EoL curve of the product can be used to determine an assumed field load (by magnitude of load and duration of load) which, from the point of view of minimizing the test duration and field irrelevant errors, allows optimal verification of product reliability.
• the assumed field load is chosen so that the duration of the stress has a representative value (this corresponds to approximately 50 to 3,000 cycles).
• the value for the field load is then selected as the load at which the selected duration of the load is just below the EoL curve of the product.
• the duration and the stress are set for optimal test conditions. For safety reasons, it is not necessary to carry out the test at a higher load or to carry it out for longer than the determined duration.
• the method according to the invention is not only suitable for determining the life of the product (how long does the product withstand a given load?) But can also be used to provide proof of the reliability of the product (keeps the product at a predetermined load for a given period of time was standing ?) . Therefore, it is proposed according to an advantageous embodiment of the invention that the method is used to provide a proof of reliability for the product and it is checked whether the EoL curve of the product is above a predetermined load for a predetermined period of time.
• the proof of reliability for the Product is considered to be provided if the EoL curve of the product is above the load in the Statement of Reliability. In this case, at the given load, the failure of the component therefore occurs at a later point in time than the component has to withstand according to the specifications of the proof under this load.
• the EoL curves of the components be extrapolated towards smaller loads.
• a very long service life of the component up to its failure can occur, in particular for small loads, ie the test duration can be very long.
• the test duration can be reduced and thus the detection accelerated by the failure time of the component is taken at higher loads and is extrapolated to smaller loads and longer test periods out.
• the recorded downtimes at different loads put an approximation function, which is continued beyond the recorded downtimes to smaller loads and longer test periods.
• an arbitrary exponential function e A (A + Bx); A (le A (-Bx)) + C; Ae A (B / x)
• an equalizing polynomial of the xth order may be considered.
• the EoL curves of the components be interpolated between the discrete values for the downtime at certain loads at which the EoL curves were taken.
• the number of component tests to be performed operation of the component with a certain load to failure of the component
• the component downtime only at a few discrete loads and interpolating the EoL curve therebetween.
• interpolation there are a plurality of methods known per se. It is conceivable, for example, that one places an approximation function through the recorded failure durations at different loads, which is, for example, an arbitrary exponential function, a spline function or an offset polynomial of the xth order.
• the load of the component can be any type of load, in particular a mechanical, thermal, chemical, electrical, magnetic or electromagnetic load.
• Each kind of load has a life-changing, usually life-shortening, effect on the considered component.
• the load is a certain absolute operating temperature of the component and / or a temperature fluctuation of a certain size within a certain period of time.
• the downtime of the components of the product is absorbed at various discrete loads. Between the recorded downtimes, the EoL curve can be interpolated and extrapolated beyond the recorded downtime.
• a first temperature class covers for example the temperature range from 100 0 C to 12O 0 C
• a second temperature class the range from 12O 0 C to 14O 0 C.
• the product must be 120 hours and in the first temperature class endure in the second temperature class for 20 hours. For example, if the tested product could run 150 hours to failure in the first temperature class and only 10 hours to failure in the second class, the product or component of the product would not meet the customer's specifications.
• At least the under-dimensioned component needs to be replaced by a more stable one. Even if the product in the second temperature class can be operated for up to 25 hours before failure, ie longer than specified by the customer, the total allowable load of the product will be exceeded, so that it will reach the customer's required level minimum life of for example 180 hours fails.
• the distance of the duration of a predetermined load (for example, the assumed field load) of a component to the corresponding value on the EoL curve of the component that is the corresponding downtime the component is determined and added to Palmgren-Miner.
• Palmgren-Miner damage accumulation hypothesis the quotients from the value of the duration of a given load on the component and the corresponding downtime are summed up for all load classes. The component only meets the requirements if the sum is less than 1. If the sum is greater than or equal to 1 must be with the premature failure of the component can be expected.
• the product the proof of reliability can provide.
• the EoL curve of the product is determined.
• a damage accumulation according to Palmgren-Miner is carried out.
• the EoL curve of the product can even be used to determine a different (usually higher) load than the customer's intended load for a shorter period of time to still meet the required proof of reliability. In this way, the required time for providing the reliability proof can be reduced without disadvantages of the validity of the proof.
• the finished product is exposed over its entire lifetime seen a certain load profile, that is, the product is loaded with different load classes each for a certain duration.
• the actual load profile can not be traversed for reasons of time. For this reason, accelerated tests are used in which the load is increased and the duration of the test is reduced accordingly.
• a certain temperature which is above a predeterminable field load of the product, for a a certain period of time, which is below the duration of the field load, an accelerated proof of reliability is carried out, wherein the determined temperature and the determined time period are coordinated with one another such that a mechanical test
• Load of the product and a thermomechanical load of the product can be accelerated by about the same factor.
• an EoL curve of a component includes at least two points resulting from the downtime of the component at different loads. If, for example, the load is the operating temperature of the component, the downtime of the component is recorded at at least two different discrete temperatures or in at least two different temperature classes, for example at 100 ° C. and 175 ° C.
• the device comprises:
• EoL end-of-life
• each component is subjected to different loads individually and each operated until their failure. It can also be said that the components are operated in different load classes until failure. This results in load-dependent downtimes for each component, which are the interpolation points of the EoL curve
• the interpolation points are interpolated or extrapolated in advance and the complete EoL curves for the components are stored.
• the complete EoL curves for the components of the product are then immediately available, without first having to wait between runtimes during runtime
• the at least one EoL curve for a component has been recorded in advance as a function of determined load-dependent downtimes of the component by a manufacturer of the component.
• the EoL curve of a component can then be a manufacturer of the entire product, for example a datasheet or online.
• the manufacturer of the product can then use the EoL curves of the various components that he may receive from different manufacturers to determine the EoL curve of the entire product and verify that the overall product meets the requirements set by his customers.
• the device according to the invention serve to provide a proof of reliability for the product and means for checking whether the EoL curve of the product is above a predeterminable load for a predefinable period of time, and, if so, the proof of reliability for the product is considered to be supplied.
• the method according to the invention can be realized in the form of a computer program that can run on a computing device, for example on a microprocessor or a microcontroller.
• the computer program runs on the computing device and performs the inventive method fully automatically.
• the invention is realized by the computer program, so that this computer program in the same way represents the invention as the method to whose execution the program is programmed.
• the method according to the invention is divided into two parts.
• a first part is responsible for recording the EoL curves for each component of the product. This can be done for example by the manufacturers of the components.
• a second part of the method according to the invention is responsible for determining the EoL curve for the entire product and for determining the life expectancy of the product. This can be done, for example, by the manufacturer of the product, following his calculations based on component manufacturers' EoL curves.
• Figure 1 is a method known from the prior art for providing a proof of reliability for a product at a given assumed field load
• FIG. 2 shows a first embodiment of a method known from the prior art for providing a reliability check in the case of an assumed field load increased compared with the embodiment of FIG. 1;
• FIG. 3 shows a second embodiment of a method known from the prior art for providing a reliability check in a compared to the embodiment of Figure 1 increased assumed field load;
• Figure 5 is an end-of-life curve for a component of a
• FIG. 8 shows the end-of-life curve for a component of a product from FIG. 5 with a distance plotted in a certain stress class between a predetermined duration of the field load and the corresponding downtime of the component for producing a lifetime prediction of the Palmgren-Miner component;
• Figure 9 ways to define failure criteria and to design components of a product
• FIG. 10 Realistic acceleration of the testing of a
• the testing of products or certificates of reliability for products is carried out according to the state of the art using standards and standardized procedures proposed by customers or standards bodies. These standards describe accelerated tests that must be performed on a product for a specific service life t or a certain number of cycles N in order to demonstrate the reliability of the product. A test is said to be accelerated if it is performed under higher loads than the loads that occur in the field and only for a lesser time t or number of cycles N. The evaluation criterion for passing the reliability test is then usually proof of the functioning of the product after completion of the test. In this way, a yes / no statement can be made as to whether the product withstands the required load for the required period of time or not. However, a statement about the life of the product under any load can not be made in this way.
• the assumed field load (AFB) is designated by the reference numeral 1 and the load specified in the reliability report (BZN) by the customer is designated by the reference numeral 2.
• the load is plotted on the x-axis in the form of an operating temperature T or an operating temperature deviation ⁇ T and on the y-axis the duration of the load as time t or number of cycles N.
• the assumed field load 1 corresponds to an estimated or empirically determined load of the product during normal operation.
• the load 2 in the reliability check is an estimated load which is above the assumed field load 1.
• the load 2 in the reliability check is an estimated load which is above the assumed field load 1.
• the load is formed as an absolute operating temperature T or as a temperature deviation .DELTA.T.
• T absolute operating temperature
• ⁇ T temperature deviation ⁇ T
• N Number of cycles
• FIG. 2 shows the case in which the assumed field load 1 has been extended by an additional period of time 3 at different load values.
• the burden 2 in the reliability check is increased by an additional time period 4, i.
• the product must be operated for a longer period of time with the load 2 in the proof of reliability.
• the additional increased field load 1, 3 is taken into account by not extending the time duration of the reliability check, but rather by increasing the load T, ⁇ T.
• This is shown in Figure 3 on the basis of the new load 5 in the proof of reliability.
• the field irrelevant failure mechanisms can prevent the release of the product, although they do not occur in practical operation.
• An important aspect of the invention is the fact that several components of a product, preferably all components, are initially considered individually.
• the components of the product are subjected to a predeterminable load. It is not necessary to apply all the components of the product, but it is advisable to include at least those components of the product in the process according to the invention and consequently to apply a predeterminable load which has an effect on the life of the product.
• the components are operated at different loads (so-called load classes) until their failure. This results in load-dependent downtime for the various components.
• Temperature range (eg up to 175 0 C, 200 0 C or 233 0 C).
• the measurement of the downtimes is carried out in each load class preferably at the corresponding highest load, these are the points 19 in Figure 5. Of course, the measurement could also be at an average load within the respective load class or at a low load within the load class.
• the measured values for the downtime of the component are shown as points 7. All measured and recorded in this way downtime 7 are on a so-called end-of-life (EoL) curve 8 of the component.
• EoL end-of-life
• the values of the EoL curve 8 between the measured downtimes 7 are determined by means of an interpolation. Some of the interpolated values are designated by reference numeral 9 in FIG.
• the EoL curve 8 is extrapolated over the measured downtimes 7 in the direction of lower loads.
• the extrapolated values of the EoL curve 8 are designated by the reference numeral 10 in FIG.
• the component is accelerated from near field to strong at different loads, ie at higher loads, which shortens the test duration, up to operated their failure.
• defect images are analyzed and combined so that a defect-specific EoL curve 8 is created for the component, which makes possible correlations to the field, ie for practical use of the component.
• defects are cracking and creeping in solders, diffusion in boundary layers (eg Kirkendal in bonding wires), delamination of a so-called MoId compound, bond fatigue, increasing a transient thermal resistance Z_th, leakage in electrolytic capacitors, etc.
• the various fault patterns are expressed in different EoL curves 8 of the components, as shown in FIG. There, the various EoL curves are exemplified for four components Kl, K2, K3 and K4. Of course, the inventive method can be used for less than four components or for any number of components Kl, K2, K3 to Kn. It can be clearly seen in FIG. 6 that the EoL curve 8 for the fourth component K4 can not withstand a load which lies approximately in the middle load range over the required period of time. The component K4 is thus unsuitable for the planned use in the field. Before using the product in the field, the component K4 must be replaced by a more stable or durable one.
• an EoL curve 11 of the product is determined.
• the EoL curve 11 of the product always comprises the EoL curves 8 of those components K1, K2,... K4, which have the shortest downtimes in the various load classes.
• the EoL curve 8 for the fourth component K4 has the shortest downtimes in all load classes. For this reason, the EoL curve 11 of the product includes only the EoL curve 8 of the fourth
• the EoL curve 11 of the product at low load classes comprises the EoL curve 8 of the fourth component K4, for medium load classes the EoL curve 8 of the first component K1, and finally for high Load classes of the EoL curve 8 of the second component K2.
• the EoL curves 8 of all components Kl, K2,... K4 and the EoL curve 11 of the product all run at a distance from the assumed field load 1 or the additional field load 3, so that a first approximation can be assumed in that the components Kl, K2, ... K4 and the product meet the reliability requirements.
• the proof of reliability would therefore be provided for all components Kl, K2, ... K4 (or Kl, K2, ... Kn) and thus also for the entire product.
• failure criteria can be set product-specifically and adapted to the application.
• the failure criteria need not be known a priori, but may even be determined after the end of the determination of the downtime and the EoL curves 8, 11 for the components and the product.
• the optimal load 12 for the proof of reliability can be determined. What constitutes a major problem in the prior art, namely the determination of the load 12 in the reliability report (see Figure 2: relatively low load 2, 4, therefore too time-consuming; see Figure 3: relatively high load 5, therefore issue field irrelevant error) , According to the invention can be carried out without problems.
• the load 12 in the proof of reliability must be chosen so that it lies below the EoL curve 11 of the product.
• care should be taken that the test duration is chosen to be long enough (for example, between 50 and 3,000 hours or cycles N) that the test result is representative.
• a specific load profile to which a finished product is exposed over its entire service life is designated by reference numeral 14.
• the stress profile 14 is either estimated or simulated or recorded under realistic conditions.
• the load profile 14 comprises in the simplified embodiment shown here relatively short periods of time .DELTA.ti, during which a relatively low load Ti is applied.
• the load profile 14 includes longer periods of time ⁇ t2, during which a higher load T 2 is applied.
• the load section 14 comprises a so with a certain frequency (1 / ( ⁇ ti + At 2)) recurring load change ⁇ Ti.
• the stress on the product with the load profile 14 leads to both a thermal load and to a thermomechanical load of the product, with thermal and thermomechanical load in a certain relationship to one another.
• the thermal stress occurs, for example, in the form of recrystallization or diffusion on the product.
• the thermomechanical load is mainly due to different coefficients of thermal expansion of the substances and components of the product (so-called TCE mismatch).
• the reference numeral 15 is an accelerated
• Designated loading profile which includes in the simplified embodiment shown here, the relatively short periods of time .DELTA.ti, during which the relatively low load T 1 is applied.
• the load profile 15 includes the longer periods of time ⁇ t 2 , during which a higher load T 3 is applied, which is greater than the load T 2 of the first load profile 14.
• the exposure profile 15 thus comprises a at a specific frequency (1 / ( ⁇ ti + .DELTA.t 2)) recurring larger load change .DELTA.T.
• the accelerated load profile 15 means that the thermal load is over-emphasized compared to the thermomechanical load.
• the resulting acceleration factor of the thermal load or the degree of increase of the probability of failure due to the thermal load of the load profile 15 can be calculated according to the Arrhenius rule.
• Reference number 16 in FIG. 10 designates a further accelerated load profile which, in the simplified exemplary embodiment illustrated here, comprises relatively short durations ⁇ t 3 during which the relatively low load Ti is present.
• the time duration ⁇ t 3 is shorter than the time duration ⁇ ti of the load profiles 14 and 15.
• the load profile 16 includes longer periods of time ⁇ t 4 during which the higher load T 2 is applied.
• the time duration ⁇ t 4 is shorter than the time duration ⁇ t 2 of the load profiles 14 and 15.
• the load profile 16 one with a higher frequency (1 / (At 3 + At 4 )) includes periodically recurring loading stroke ⁇ Ti.
• the accelerated load profile 16 results in that the thermomechanical load is over-emphasized compared to the thermal load. The resulting
• Acceleration factor of the thermomechanical load or the degree of increase in the probability of failure due to the thermo-mechanical loading of the load profile 16 can be calculated according to the Coffin-Manson rule. In order to provide a proof of reliability, the actual load profile 14 can not be completely traversed for reasons of time. For this reason, accelerated tests (see load profiles 15 and 16) are used in which the load is increased and the duration of the test is correspondingly reduced.
• this method can not only be used for absolute loads (eg temperature T 1 ) but also for load cycles or load strokes (eg temperature strokes AT 1 ).
• a certain temperature lift AT 3 which is greater than a predeterminable field load ATi of the product, with a specific frequency 1 / (At 5 + At 6 ) which is greater than the frequency 1 / ( ⁇ ti + At 2 ) the field load ATi is performed, an accelerated proof of reliability.
• the increased temperature lift AT 3 and the greater frequency 1 / (At 5 + At 6 ) are coordinated in such a way that a mechanical load and a thermomechanical load of the product are accelerated by approximately the same factor.
• the resulting acceleration factor for the thermal load is first determined according to Arrhenius. According to Coffin-Manson, the resulting reduced duration At 5 , At 6 or increased frequency 1 / (At 5 + At 6 ) for the test is then determined on the basis of the determined acceleration factor for the thermal load such that the acceleration factor for the thermomechanical load is approximately is equal to the acceleration factor for the thermal load.
• test times can be shortened and the product costs can be reduced.
• reliability can be increased.
• accurate predictions can be made about the life expectancy of a component or the entire product.
• the test conditions are chosen as close to the field as possible in order to be able to represent the correlation to the product in real terms. The generation of defect images that can not occur in the field is prevented as much as possible.
• the termination criteria can be dynamically adapted to the respective site after the end of the test and need not be known a priori. This is a cost-effective, product-specific design of the products possible, at the same time increased reliability with sufficient life expectancy. So-called over- or under-engineering can be prevented. By avoiding recursions, the delivery quality of the products can be improved at the same time.
• the evidence of reliability may be due to scalability (previously performed measurements and
• the load 12 is determined in the proof of reliability BZN.
• the determination of this load 12 can be optimized in the manner shown in FIG. 6 and described above, so that the optimum load 12 is obtained in the reliability statement BZN.
• test load EB demanded by him, which the product must withstand from the perspective of the customer to secure a given quality standard.
• the test load EB required by the customer is also greater than the burden on the proof of reliability BZN determined by the supplier.
• the supplier had no arguments as to why the load 12 determined by the supplier was completely sufficient for the BZN certificate of reliability so that the product could meet the requirements demanded by the customer
• observables observable quantities
• these can be Delamination MoId Compound or Bonder Fatigue for an active device. Further examples are summarized in the following list. Of course, further observables are possible.
• Microprocessor a microcontroller, a MOSFET, etc
• MoId compounds which can be detected by means of ultrasound.
• it could be a bonder fatigue or an increase in a thermal resistance Z th , an increase in the current I SU bthreshoid or an increase in the internal resistance R 0n .
• the capacitance, the loss factor tan ⁇ or an electrical series resistance ESR is an observable variable; as well as the insulation resistance R 1SO at -40, +25, +125 and + 150 ° Celsius or other freely selectable temperatures. Also faulty images could be detected by optical control or by the drift evaluation of characteristics. In printed circuit boards, a resistance measurement, eg. The insulation resistance R 180 ⁇ be performed. Likewise, as observable quantities, delamination, cracks in the insulating lacquer or cracks in the glass fiber structure can be recognized optically.
• connection technique AVT for example, in soldering
• a resistance measurement, a shear force measurement or an X-ray inspection can be carried out to determine typical defect images.
• the pulsed operation can be superimposed on the passive and active heating.
• the operation of the components during the detection is limited to periodic processes and fixed corner temperatures.
• varying temperatures and temperature strokes can be interleaved.
• two near-field corner temperatures T bottom and T are selected above .
• the mean minimum temperature in winter is averaged over populous regions with high motor vehicle content, resulting in -15.degree.
• upper corner temperatures T above for the various EoL experiments for example, 100, 125, 150, 175 and 200 ° Celsius are selected.
• the results obtained can be used in the development departments of the supplier or customer for:
• the present invention has been further described in the context of a high temperature application. But it is also applicable to all other evidence of reliability at "normal" temperatures, mechanical stress, exposure to moisture and / or chemicals.
• a device according to the invention is designated by the reference numeral 20.
• EoL curves 8 are available for many different components from a database 21.
• the database 21 can be connected to the device 20 directly or via a client-server network, for example the Internet.
• the device 20 can access desired EoL curves 8 in the database 21 and load the desired EoL curves 8 in whole or in part.
• an input 22 of the device 20 is a predetermined load collective or load profile for a particular component or a specific product.
• the applied load profile is, for example, the assumed field load AFB 1 and optionally an additional load 3 in the sense of FIGS. 2 and 3.
• An output 23 of the device 20 is connected to an output signal that provides information about the reliability and / or service life of a particular load Component or the entire product. While the evidence of reliability provides only "yes” or “no" statements, ie the component or the product may or may not provide evidence, the lifespan will provide an accurate statement of the durability of the component or product. For example, the life provides a value in hours, or a cycle number, after which the component or product is likely to fail when subjected to a given load.
• Components are added and delivered to the customer together with the product, for example as additional information on a data sheet or as retrievable via the Internet information.
• the customer can then use the device 20 according to the invention to assemble any products from the available components and to determine a corresponding EoL curve 11 for the components from these components from the EoL curves 8 of the components.
• the provided or self-determined assumed field load 1 (AFB) and the additional field load 3 by means of a predetermined load 2 in the proof of reliability or a previously determined optimal load 12 in the proof of reliability can be checked whether the product meets the requirements.
• a storage element 24 is provided, which is designed for example as a flash memory.
• a computer program 25 is stored on a
• Computing device 26 of the device 20 is executable.
• the computing device 26 is designed, for example, as a microcontroller or as a microprocessor.
• determined data can be transmitted in the opposite direction via the data link 27 from the computing device 26 to the memory element 24 and stored there.
• the computer program 25 When the computer program 25 is executed on the computing device 26, it carries out the method according to the invention. In the illustrated embodiment, the computer program executes in particular the following method steps:
• an EoL curve 11 is determined for a particular product, so that the EoL curve 11 at the various loads T, .DELTA.T includes that of the loaded into the device EoL curves 8 of the components which has the shortest downtime t, N at the respective load T, ⁇ T, respectively; and the expected life of the product is determined as the functional value of the EoL curve 11 of the product as a function of the load 1, 3 of the product given at the inlet 22.
• a proof of reliability for the product can be provided by checking that the EoL curve 11 of the product is above a load 2 set at input 22; 12 for a predetermined period of time t; N is, and, if so, the
• the following method steps can be carried out for the determination of the EoL curves 8 for the components K1 through Kn: the components K1 to Kn of the product are subjected to a predeterminable load T, ⁇ T; the components Kl to Kn are operated at different loads T, ⁇ T, respectively, until their failure; - The achieved downtime t, N are stored for each component Kl to Kn as a function of the load T, .DELTA.T;
• an associated end-of-life (EoL) curve 8 of the component Kl to Kn is added and stored in the database 21.

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• 2004
  • 2004-12-16 DE DE102004060528A patent/DE102004060528A1/de not_active Withdrawn
• 2005
  • 2005-11-25 US US11/793,342 patent/US7831396B2/en not_active Expired - Fee Related
  • 2005-11-25 CN CN2005800433276A patent/CN101443735B/zh not_active Expired - Fee Related
  • 2005-11-25 JP JP2007546010A patent/JP4629735B2/ja not_active Expired - Fee Related
  • 2005-11-25 EP EP05813679A patent/EP1828894A2/de not_active Ceased
  • 2005-11-25 WO PCT/EP2005/056217 patent/WO2006063923A2/de active Application Filing

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