One. Integrated consideration

 

1. easy generation applies the parts of an apparatus of dependability problem

 

The parts of an apparatus with sensitive to outside stress ①

 

CMOS circuit: Sensitive to electrostatic, latch, surge;

 

Small signal amplifier: Opposite voltage, noise, interference is sensitive;

 

Plastic enclose parts of an apparatus: Sensitive to loop of damp, thermal shock, temperature.

 

② job stress is close to circuit the parts of an apparatus of the greatest stress

 

Power parts of an apparatus: Power approachs limiting value;

 

High-pressured parts of an apparatus: Voltage approachs limiting value;

 

Power source circuit: Voltage and electric current approach limiting value;

 

High frequency parts of an apparatus: Frequency approachs limiting value;

 

Exceed large-scale chip: Power comsumption approachs limiting value.

 

The parts of an apparatus with ③ frequency and great power

 

Clock outputs circuit: Lead in whole circuit intermediate frequency highest, and want drive module of circuit of almost all number;

 

Bus line control and drive circuit: Drive capability is strong, frequency is tall;

 

Wireless the catapult in sending and receive circuit: Power and frequency approach limiting value.

 

2. chooses yuan of parts of an apparatus to want the 10 gist white of the consideration

 

① report is characteristic: Yuan parts of an apparatus asks besides contented equipment function besides, want to be able to be endured the biggest the electric stress that bring to bear on;

 

Limits of ② job temperature: Yuan the limits of rated job temperature of parts of an apparatus should is equal to or wide the working temperature range that should experience at place;

 

③ craft quality and producibility: Yuan craft of parts of an apparatus is mature and stability can accuse, n should prep above provides a value, enclose should assemble look of craft condition look with equipment;

 

④ stability: Below the circumstance of the change such as temperature, humidity, frequency, ageing, parameter change is inside permission range;

 

⑤ life: Working life or reserve life should not short the predicting life of the equipment at using them;

 

⑥ environmental suitability: Should work goodly at all sorts of use environments, be like the special environment such as mist of hectic fever, salt, sand and dust, acid rain, mould, radiate, high height above sea level especially;

 

⑦ failure mode: Be opposite the typical failure mode of yuan of parts of an apparatus and failure mechanism are due and sufficient understanding;

 

⑧ but maintainability: Installation of Lv of take an examination, disassemble, change to whether go to the lavatory and needs tool and skilled grade

 

⑨ usability: Supplier 1 over, for commodity cycle contented equipment makes plan rate of progress, when can assuring invalidation of yuan of parts of an apparatus change in time the requirement;

 

⑩ cost: The condition is restricted to fall in the function that can satisfy a requirement at the same time, life and environment, the consideration uses sexual price to compare yuan of tall parts of an apparatus.

 

Failure mode reachs 3. its distributing

 

Yuan is parts of an apparatus how of invalidation? Yuan parts of an apparatus why invalidation?

 

Yuan although the use person of parts of an apparatus cannot understand failure mechanism, also should understand failure mode.

 

Failure mode distributings: If yuan parts of an apparatus has a variety of failure mode, criterion the probability that all sorts of failure mode produce is the premise that undertakes invalidation is analysed.

 

 

 

 

4. Gao Ke relies on the feature of yuan of parts of an apparatus

 

Manufacturer attestation: The manufacturer passed the conformity certification of authoritative branch;

 

Product line attestation: The product can be produced on the special product line of attestation qualification only;

 

Dependability examines: The product undertakes and passed a series of function and dependability experiment, 100% choose and quality consistency examines;

 

Craft controls a standard: The manufacturing process of the product gained strict control, n is tall;

 

Standardize degree: The production of the product and examine accord with international, country or industry current standard and detailed and normative requirement.

 

Of 5. breed model preferential choose regulation

 

Preferential those who choose a level, general, yuan of parts of an apparatus of seriation, careful reelect is mixed with new breed nonstandard parts of an apparatus, the breed norms that utmost ground compresses yuan of parts of an apparatus and bear the amount that makes an unit;

 

Preferential choose include yuan of parts of an apparatus actor choosing list, preferential the product that chooses parts of an apparatus to make a technology mature, choose can long-term, successive, stable, big batch to offer money and the calm point with high n offers money unit;

 

Preferential choose the manufacturer product that can offer perfect craft to control data, dependability applies a guideline or use a standard;

 

Below the premise that comparatives in quality grade, preferential choose compositive degree of tall parts of an apparatus, little choose schism parts of an apparatus.

 

 

The dependability information that 6. supplier should provide

 

Detailed standard reachs the level that accord with: Mark of mark of national army mark, GB, travel, look forward to;

 

Attestation circumstance: QPL, QML, PPL, IECQ;

 

Quality grade and dependability level: Failure rate, life (MTTF) , combat electrostatic strength, fight irradiation water equality;

 

Dependability test data: Quicken with the spot, environment and life, the near future and before, uses experiment method and data processing method;

 

N data: Measure in (naked piece) , always measure (after enclosing) etc;

 

Quality consistency data: Between batch, between brilliant circle, between chip, average, variance, distributing;

 

Craft stability data: Statistical craft is controlled (SPC) data, batch produces a situation;

 

Adoption technology and material: Best the main parameter index that can provide critical process and data;

 

Use manual and operation are normative: Representative application circuit, dependability defends the method.

 

2. Craft consideration

 

It is with integrated circuit exemple:

 

The smallest line: 0.35, 0.25, 0.18, 0.13μm;

 

Underlay material: Si>SOI>SiGe>GaAs>SiC;

 

Interrelate material: Cu>Al (foreign advanced technology) Al>Cu (home has technology) ;

 

Passivation material: SiN>PSG> gets together Xi inferior amine is inorganic > organic;

 

Bond data: Au>Cu>Al(Si) ;

 

Circuit form: Several / the model is detached > several / modular syncretic RF/BB is detached > RF/BB syncretic.

 

The relation of CMOS chip n and dependability

 

N (call quality sometimes) : Leave factory or the eligible parts of an apparatus that ageing sieve pitch on discovers in batch parts of an apparatus counts dependability: Those who experience a year of above go up the number of invalidation parts of an apparatus after machine time

 

Generally speaking, the quality of parts of an apparatus and n are taller, dependability is better, but the parts of an apparatus with quality and identical n, dependability is not identical

 

 

SPC data: The token of percent of pass

 

Statistical craft is controlled

 

Craft accuracy and craft stability are the main factor that decides product n and dependability, usable statistic craft is controlled (SPC, statistical Process Control) data comes mensurable token.

 

The token parameter of percent of pass

 

N (Yield) : The qualification in approving a product tastes place to hold percentage;

 

Ppm (Parts Per Million) : The amount of the reject in 1 million each products, agree with batch the product token with stability of big, quality, tall n;

 

The token of craft deflection and disperse:

 

The generation of reject basically comes from yuan of deflection that workmanship of parts of an apparatus is existing inevitably and disperse, of craft parameter distributing to satisfy normal school normally, its all are worth it is σ for deviation of μ , standard.

 

3. Enclose a consideration

 

Model of 1. parasitism parameter is worth

 

Have the element that cite a base: Parasitism inductance 1nH/mm/ cites a base (shorter better) , parasitism capacitance 4pF/ cites a base;

 

Without the component that cite a base: Port of parasitism inductance 0.5nH/ , port of parasitism capacitance 0.3pF/ ;

 

Different enclose a form to send those who give birth to effect to compare (parasitism parameter by small to big) ;

 

Without bring a foot to stick outfit > the surface is stuck outfit > radiative shape cites a base > meridional plane parallel cites a base;

 

CSP>BGA>QFP>SMD>DIP.

 

 

The parasitism inductance of capacitor returns with capacitor enclose a form to concern: Pin is wide long bigger than jumping over, parasitism inductance is smaller.

 

 

2. is helpful for dependability

 

Down-lead is extremely short: Reduced distributinging inductance and electric capacity, raised interference rejection ability and circuit rate;

 

Mechanical intensity is high: Raised circuit to fight vibration and percussive ability;

 

It is good to assemble consistency: N is tall, parameter disperse sex is small.

 

3. goes against dependability

 

Material does not match a gender to increase: The SMT component of base material of certain pottery and porcelain (like certain resistor, capacitor, without LCC of down-lead chip carrier) the hot coefficient of expansion with glass of oxygen of PCB substrate annulus does not match, cause thermal stress invalidation;

 

Pollute more easily: SMT component and PCB board between not easy cleanness, be stationed in the contaminant that leaves welding flux easily, need to use special processing technique;

 

The surface is stuck installing is benefit to dependability ambitious at fraud, already held the proportion of 90 ％ at present.

 

4. encloses the comparison of material:

 

Plastic enclose

 

Advantage: Cost is low (the 55 ％ that enclose for pottery and porcelain about) , weight is light (the 1/2 that encloses for pottery and porcelain about) , pin number is much, effect of high frequency parasitism is weak, facilitating automation is produced;

 

Defect: Air-tightness is poor, suck tide, come loose not easily hot, easy ageing, right electrostatic and sensitive;

 

Applicability: Parts of an apparatus of most semiconductor schism and product of integrated circuit convention.

 

Pottery and porcelain is enclosed

 

Advantage: Air-tightness is good, medicinal powder heat energy force is powerful (thermal conductance is tall) , high frequency insulation property is good, bear power is great, wiring density is high;

 

Defect: Cost is high;

 

Applicability: The high-end market such as aviation, spaceflight, military affairs.

 

The metal is enclosed

 

Advantage: Air-tightness is good, medicinal powder heat energy force is powerful, have electromagnetism screen capacity, reliability is high;

 

Defect: Cost is high, pin number is limited;

 

Applicability: Miniature Gao Ke relies on parts of an apparatus.

 

Call model Feng Weifei hermetic seal outfit normally, pottery and porcelain and metal are hermetic seal to install.

 

Attract wet sex issue

 

Plastic enclose place to use itself of epoxy resin material to have sex suction tide, damp is in easily its surface is adsorptive, lunt can cause model to seal the creep of material oneself, if inbreak chip is in-house, can bring about corrode and problem of exterior flyblow air-tightness.

 

The difference of the hot coefficient of expansion of the material such as chip of plastic envelope and metallic down-lead frame, semiconductor should be gotten greatly more (reach metallic envelope photograph to compare with pottery and porcelain) the meeting when → temperature changes produces interface of quite big mechanical stress → to be in generation gap → to bring about air-tightness deterioration lunt in material interface.

 

The temperature when PCB sheds solder again can rise to 205 ～ 250 inside 5 ～ 40s ℃ , ascendant gradient achieves ℃ of 1 ～ 2 / S, produce afore-mentioned effect easily.

 

Temperature adaptability problem

 

The vitrification critical temperature that model seals material is 130 ～ 160 ℃ , the model after exceeding this temperature seals material meeting bate, also have adverse effect to air-tightness

 

The temperature limits that business seals parts of an apparatus with model is 0 ～ 70 commonly ℃ , – 40~+85 ℃ , – 40 ～ + 125 ℃ , reach range of temperature of for military use hard – 55~+125 ℃ .