Electron yuan parts of an apparatus chooses principle and project
Electron yuan the inherent dependability of parts of an apparatus depends on the dependability design of the product, accordingly, should be in electron yuan mount of parts of an apparatus before overall, equipment, be about to try to try yuan of parts of an apparatus that has early failure as far as possible to eliminate, be about to be opposite for this yuan of parts of an apparatus undertake filtration. So yuan is parts of an apparatus chosen what plan to have? What is the principle? What does common sieve options order have?
Arrangement test chooses early or late two kinds of plan when order:
A) plan 1: The failure mode that will not produce interlink to cause the effect is chosen put in front, choose the failure mode that can produce interlink to cause the effect with other failure mode put at the back. B) plan 2: Choose the failure mode that can produce interlink to cause the effect with other failure mode put in front, the failure mode that will not produce interlink to cause the effect is chosen put at the back.
If choose plan 1, meeting discovery will be OK the failure mode that causes the effect with interlink of generation of other failure mode is chosen when be being put at the back, occurrence itself failure mode was not sparked, when the circumstance that the relevant failure mode of other correlation is sparked, this kind contains yuan of parts of an apparatus of blemish to cannot be located by accurate ground, eliminate, because of this kinds of failure mode detect had been done in front. And choose plan the 2 happening that can avoid afore-mentioned problems effectively, make choose a course high grade, economy and efficient.
The definition is as follows:
Choose defective goods of eliminate of efficiency W ＝ to count / number of practical substandard products
It is good to choose loss to lead L ＝ taste attaint to count / actual good taste number
Choose wash out get rid of of the ＝ that lead Q to fall defective goods is counted / the sum of products that undertakes filtration
Ideal dependability is chosen should make W=1, l= 0, such ability achieve the goal that dependability chooses. Q value size reflected the volume that these products are producing problem of the existence in the process. Q value is greater, the dependability before stating this approves a product to choose is poorer, the question that i.e. exists in manufacturing process is bigger, the n of the product is low.
Option of sieve options order is more, stress requirement is stricter, bad is tasted fall into disuse more thoroughly, its choose efficiency taller, level of yuan of dependability of parts of an apparatus that the sieve singles is more adjacent also the inherent dependability level at the product. But should pay higher cost, longer cycle, the dependability of the product that still can make nonexistent blemish, performance good at the same time is reduced.
Reason chooses a condition exorbitant can create needless waste, conditional option is too low criterion bad is tasted fall into disuse not complete, the utilization reliability of the product is couldn’t get assure. This shows, choose intensity insufficient or choose a condition to father to be opposite too whole batch the dependability of the product is adverse.
To undertake dependability is chosen correctly, must decide a sieve to option looks and choose stress reasonably, for this, must understand the failure mechanism of the product. The type of the product is different, manufacturing unit is different and when raw material and technological process are different, its failure mechanism is the same as with respect to differ phasing, the condition that consequently dependability chooses also should differ somewhat.
Accordingly, must make dependability experiments and be chosen in great quantities in the light of all sorts of particular products try to find out the real intention experiment, master the relation between product failure mechanism and sieve options order thereby.
Yuan the formulate that parts of an apparatus chooses plan should master the following principle:
Choose the product that wants effectively eliminate early failure, but should not make normal product raises failure rate;
Choose efficiency to rise, can undertake strong stress is chosen, but the failure mode that should not make product generation new;
Logical choice can expose the optimal stress order of invalidation;
To be being chosen the failure mode with potential target should master somewhat;
For the filtration with reasonable and effective formulate plan, the character that must know each to concern yuan of parts of an apparatus, material, enclose reach production technology.
In addition, in abide by above 5 principles while, should combine manufacturing cycle, reasonable make choose time.
A few kinds of commonly used sieve option look
High temperature keep in storage
Electron yuan because all sorts of with the surface physico-chemical change place inside body are caused,the invalidation great majority of parts of an apparatus is, they and temperature have close relationship. After temperature is elevatory, chemistry reacts speed is accelerated greatly, invalidation process also gets acceleration. Make defective yuan parts of an apparatus can be exposed in time, give eliminate.
High temperature is chosen be used extensively on semiconductor device, it can be effective ground eliminate has exterior buy corrupt, layer of undesirable, oxidation has bond the parts of an apparatus of the failure mechanism such as blemish. Be in normally highest knot is lukewarm hours of next 24~168 of keep in storage.
High temperature is chosen go easily simply, fee is not big, in make yuan of many parts of an apparatus go up to be able to apply. After carrying high temperature reserve, still can make the parameter function stability of yuan of parts of an apparatus comes down, reduce the parameter drift in using. All sorts of yuan the thermal stress of parts of an apparatus and choose time to want proper alternative, lest produce new failure mechanism.
Power cable is ageing
When choosing, below the joint action of pyroelectricity stress, can expose a variety of yuan of with the surface potential defect inside body of parts of an apparatus well, it is a when dependability chooses main item.
All sorts of electrons yuan parts of an apparatus falls in rated power condition normally ageing come a few hours 168 hours, some products, be like integrated circuit, cannot change a condition casually, but can use way of high temperature work to increase the job the knot is lukewarm, achieve tall stress status, all sorts of yuan the electric stress of parts of an apparatus should choose appropriately, can be equal to or tallish at rated condition, but cannot fetching new failure mechanism.
Power is ageing the test equipment with special need, its cost is higher, reason chooses time to should not be too long. Civil product is a few hours normally, expensive reliable product can choose for military use 100, 168 hours, space navigation class yuan parts of an apparatus can choose longer even cycle 240 hours.
Temperature circulates
Electronic product can encounter different environmental temperature condition in use process, bilge in heat cold below the stress action that shrink, yuan of parts of an apparatus that heat matchs function to differ is easy invalidation. Temperature is chosen circularly used the heat between extreme high temperature and extreme low temperature to bilge cold shrink stress, can effective eliminate has the product of hot property blemish. Yuan the filtration with commonly used parts of an apparatus the condition is – 55 ～ + 125 ℃ , circular 5~10 second.
Centrifugal acceleration
Centrifugal acceleration experiment says again constant stress acceleration experiments. This is chosen undertake on semiconductor device normally, use high speed to rotate the centrifugal master piece of generation is used on parts of an apparatus, can too weak, lead matchs eliminate bond intensity undesirable with the parts of an apparatus with outfit undesirable wearing, choose 20000 G centrifugal acceleration to experiment one minute continuously normally.
Monitoring vibration and concussion
Monitor in what undertake vibration to the product or electric property has while concussion experiments often be called monitoring vibration or monitoring concussion experiment. This experiment can environment of the vibration in imitate product use process, concussion, effectively eliminate instantaneous yuan of parts of an apparatus with the rigid undesirable structure such as short, open circuit and overall the breakdown such as medium empty solder. Relay leans in Gao Ke, in receiving plug-in unit and facility of electron of for military use, monitoring vibration and concussion are a main sieve option item.
Typical oscillatory condition is: Frequency 20 ～ 2000 Hz, acceleration 2~20 G, scanning 1~2 is periodic, want to keep period of time more around resonance dot. Typical concussion chooses a condition is 1500^ -3000g, pound 3~5 second, this experiment applies to yuan of parts of an apparatus only.
Monitoring vibration and concussion need specialized test equipment, cost is high, do not use commonly in civil electron product.
Outside choosing a project except above, commonly used still check of leak hunting of degree of finish, lens, linear differentiate is chosen, nicety is chosen etc.
Arrangement test chooses early or late two kinds of plan when order:
A) plan 1: The failure mode that will not produce interlink to cause the effect is chosen put in front, choose the failure mode that can produce interlink to cause the effect with other failure mode put at the back. B) plan 2: Choose the failure mode that can produce interlink to cause the effect with other failure mode put in front, the failure mode that will not produce interlink to cause the effect is chosen put at the back.
If choose plan 1, meeting discovery will be OK the failure mode that causes the effect with interlink of generation of other failure mode is chosen when be being put at the back, occurrence itself failure mode was not sparked, when the circumstance that the relevant failure mode of other correlation is sparked, this kind contains yuan of parts of an apparatus of blemish to cannot be located by accurate ground, eliminate, because of this kinds of failure mode detect had been done in front. And choose plan the 2 happening that can avoid afore-mentioned problems effectively, make choose a course high grade, economy and efficient.
The definition is as follows:
Choose defective goods of eliminate of efficiency W ＝ to count / number of practical substandard products
It is good to choose loss to lead L ＝ taste attaint to count / actual good taste number
Choose wash out get rid of of the ＝ that lead Q to fall defective goods is counted / the sum of products that undertakes filtration
Ideal dependability is chosen should make W=1, l= 0, such ability achieve the goal that dependability chooses. Q value size reflected the volume that these products are producing problem of the existence in the process. Q value is greater, the dependability before stating this approves a product to choose is poorer, the question that i.e. exists in manufacturing process is bigger, the n of the product is low.
Option of sieve options order is more, stress requirement is stricter, bad is tasted fall into disuse more thoroughly, its choose efficiency taller, level of yuan of dependability of parts of an apparatus that the sieve singles is more adjacent also the inherent dependability level at the product. But should pay higher cost, longer cycle, the dependability of the product that still can make nonexistent blemish, performance good at the same time is reduced.
Reason chooses a condition exorbitant can create needless waste, conditional option is too low criterion bad is tasted fall into disuse not complete, the utilization reliability of the product is couldn’t get assure. This shows, choose intensity insufficient or choose a condition to father to be opposite too whole batch the dependability of the product is adverse.
To undertake dependability is chosen correctly, must decide a sieve to option looks and choose stress reasonably, for this, must understand the failure mechanism of the product. The type of the product is different, manufacturing unit is different and when raw material and technological process are different, its failure mechanism is the same as with respect to differ phasing, the condition that consequently dependability chooses also should differ somewhat.
Accordingly, must make dependability experiments and be chosen in great quantities in the light of all sorts of particular products try to find out the real intention experiment, master the relation between product failure mechanism and sieve options order thereby.
Yuan the formulate that parts of an apparatus chooses plan should master the following principle:
Choose the product that wants effectively eliminate early failure, but should not make normal product raises failure rate;
Choose efficiency to rise, can undertake strong stress is chosen, but the failure mode that should not make product generation new;
Logical choice can expose the optimal stress order of invalidation;
To be being chosen the failure mode with potential target should master somewhat;
For the filtration with reasonable and effective formulate plan, the character that must know each to concern yuan of parts of an apparatus, material, enclose reach production technology.
In addition, in abide by above 5 principles while, should combine manufacturing cycle, reasonable make choose time.
A few kinds of commonly used sieve option look
High temperature keep in storage
Electron yuan because all sorts of with the surface physico-chemical change place inside body are caused,the invalidation great majority of parts of an apparatus is, they and temperature have close relationship. After temperature is elevatory, chemistry reacts speed is accelerated greatly, invalidation process also gets acceleration. Make defective yuan parts of an apparatus can be exposed in time, give eliminate.
High temperature is chosen be used extensively on semiconductor device, it can be effective ground eliminate has exterior buy corrupt, layer of undesirable, oxidation has bond the parts of an apparatus of the failure mechanism such as blemish. Be in normally highest knot is lukewarm hours of next 24~168 of keep in storage.
High temperature is chosen go easily simply, fee is not big, in make yuan of many parts of an apparatus go up to be able to apply. After carrying high temperature reserve, still can make the parameter function stability of yuan of parts of an apparatus comes down, reduce the parameter drift in using. All sorts of yuan the thermal stress of parts of an apparatus and choose time to want proper alternative, lest produce new failure mechanism.
Power cable is ageing
When choosing, below the joint action of pyroelectricity stress, can expose a variety of yuan of with the surface potential defect inside body of parts of an apparatus well, it is a when dependability chooses main item.
All sorts of electrons yuan parts of an apparatus falls in rated power condition normally ageing come a few hours 168 hours, some products, be like integrated circuit, cannot change a condition casually, but can use way of high temperature work to increase the job the knot is lukewarm, achieve tall stress status, all sorts of yuan the electric stress of parts of an apparatus should choose appropriately, can be equal to or tallish at rated condition, but cannot fetching new failure mechanism.
Power is ageing the test equipment with special need, its cost is higher, reason chooses time to should not be too long. Civil product is a few hours normally, expensive reliable product can choose for military use 100, 168 hours, space navigation class yuan parts of an apparatus can choose longer even cycle 240 hours.
Temperature circulates
Electronic product can encounter different environmental temperature condition in use process, bilge in heat cold below the stress action that shrink, yuan of parts of an apparatus that heat matchs function to differ is easy invalidation. Temperature is chosen circularly used the heat between extreme high temperature and extreme low temperature to bilge cold shrink stress, can effective eliminate has the product of hot property blemish. Yuan the filtration with commonly used parts of an apparatus the condition is – 55 ～ + 125 ℃ , circular 5~10 second.
Centrifugal acceleration
Centrifugal acceleration experiment says again constant stress acceleration experiments. This is chosen undertake on semiconductor device normally, use high speed to rotate the centrifugal master piece of generation is used on parts of an apparatus, can too weak, lead matchs eliminate bond intensity undesirable with the parts of an apparatus with outfit undesirable wearing, choose 20000 G centrifugal acceleration to experiment one minute continuously normally.
Monitoring vibration and concussion
Monitor in what undertake vibration to the product or electric property has while concussion experiments often be called monitoring vibration or monitoring concussion experiment. This experiment can environment of the vibration in imitate product use process, concussion, effectively eliminate instantaneous yuan of parts of an apparatus with the rigid undesirable structure such as short, open circuit and overall the breakdown such as medium empty solder. Relay leans in Gao Ke, in receiving plug-in unit and facility of electron of for military use, monitoring vibration and concussion are a main sieve option item.
Typical oscillatory condition is: Frequency 20 ～ 2000 Hz, acceleration 2~20 G, scanning 1~2 is periodic, want to keep period of time more around resonance dot. Typical concussion chooses a condition is 1500^ -3000g, pound 3~5 second, this experiment applies to yuan of parts of an apparatus only.
Monitoring vibration and concussion need specialized test equipment, cost is high, do not use commonly in civil electron product.
Outside choosing a project except above, commonly used still check of leak hunting of degree of finish, lens, linear differentiate is chosen, nicety is chosen etc.