4.3.22 · D1Packaging and wire bonding - flip-chip
Ek tiny fragile chip ko connect , protect , aur cool karna hota hai — aur jitne wires attach kar sakte ho wahi make-or-break bottleneck hai. Wire bonding sirf edge ke around wires lagate hai (ek line), jabki flip-chip puri face par bumps lagate hai (ek area) — aur area hamesha line ko beat karta hai jab chip itni badi ho jaye.
Is page par assume kiya hai ki tumne parent note ki koi bhi notation nahi dekhi . Hum har letter, ratio, aur symbol zero se build karenge, har ek ko ek picture se anchor karenge, aur tabhi use karenge. Upar se neeche padho: har idea ek rung hai jis par agla idea khada hai.
Kisi bhi symbol se pehle, hume scale ka feel chahiye, kyunki poori story smallness se ladai hai.
Definition Micrometre (µm) aur millimetre (mm)
Ek millimetre (mm
Ek micrometre (μ m 1000 1 70 μ m
Hume yeh kyun chahiye: ek chip ka connection pad lagbhag 50 μ m 500 μ m = 0.5 mm das guna bada . Yahi size gap hai jis ki wajah se "fan-out" (connections ko bahar ki taraf spread karna) exist karta hai.
Die ek single finished chip hai, silicon ka ek flat square tile jo ek badi wafer se kata jaata hai (cutting step ke liye Wafer Dicing dekho). Ek chhoti glass floor tile socho: flat, square, ek top face jis par circuitry hai aur ek plain back face .
Definition Bond pad (I/O pad)Ek bond pad die ki top face par metal ka ek chhota square hota hai — "landing spot" jahan ek wire ya bump attach hoti hai. "I/O" ka matlab hai In/Out (signals aur power chip ke andar ya bahar jaana). Socho chhote metal buttons tile ke upar bichhe hue hain.
Topic ko yeh kyun chahiye: packaging mein sab kuch is baare mein hai ki in pads se electricity ko bahar ki duniya mein bina fragile tile todte kaise pahunchaye.
L L letter hai jo ek number ki jagah khada hai : square die ke ek edge ki length, millimetres mein measure ki gayi. Agar ek chip "10 mm on a side" hai, to L = 10 mm
Picture: square tile ke bottom edge ki length. Kyunki die square hai, chaaro edges ki length same L
Number ki jagah letter kyun? Kyunki hum chahte hain ek formula jo kisi bhi chip ke liye kaam kare. L
L L letter L do bilkul alag cheezoan ke liye reuse karta hai : die side length (mm) aur, bahut baad mein, inductance (ek magnetic quantity). Yeh unrelated hain — context batata hai kaun sa. Hum inductance ko section 8 mein handle karenge aur usse apne dimag mein "the coily L
p Pitch do neighbouring pads ya bumps ke beech ka centre-to-centre distance hai. Agar pads har 0.25 mm p = 0.25 mm
Fence posts ki ek row socho: pitch ek post ke centre se agले post ke centre tak ki doori hai — unke beech ka gap nahi, balki repeating spacing.
Hume yeh kyun chahiye: pitch batata hai ki ek given length mein kitne connections fit honge. Chhoti pitch = tightly packed = zyada connections. Yahi counting ki kunji hai.
Yeh maths ka pehla asli tukda hai, aur yeh pure division hai.
Intuition Division "kitne fit hote hain?" ka jawab kyun deta haiAgar ek shelf L = 12 cm p = 3 cm 12 ÷ 3 = 4 Division woh tool hai "size p L Yahi sawaal hum baar baar poochte hain, isliye p L
Ratio p L dimensionless hai — ek plain count, koi units nahi — kyunki millimetres, millimetres ko cancel karte hain. Hamesha sanity-check karo: yeh pads ki ek whole-ish number aani chahiye.
Yeh page par sabse important picture hai.
Definition Perimeter aur area
Perimeter = square ke chaaro taraf edge ki total length: L 4 L Area = square ki poori flat surface : L × L = L 2
Intuition One-dimensional vs two-dimensional resourcesEdge ek line hai — ek 1-D resource. Chip ko do guna wide karo aur edge double hoti hai.
Face ek surface hai — ek 2-D resource. Chip ko do guna wide karo aur face char guna badi ho jaati hai (2 × 2 linearly badhna vs ek area quadratically badhna — literally isliye flip-chip banaya gaya.
2 2 (ek exponent ) ka matlab hai "cheez ko ek baar khud se multiply karo." Isliye x 2 = x × x rows aur columns hote hain — tum donon counts ko multiply karte ho. Jab bhi koi squared quantity dekho, "ek 2-D grid" ya "ek area" socho.
Parent ke headline claim ko L = 10 mm p = 0.25 mm p L = 40
Wire: 4 × 40 = 160
Flip: 4 0 2 = 1600 das guna zyada connections.
> A > B A B "flip-chip ki count wire bonding ki count se kab zyada hoti hai?"
x x x = p L L > 0 p > 0 x
Parent teen energy terms add karta hai. Notation decode karte hain.
E E energy ke liye khada hai (ek store of "kuch karne ki ability," joules mein measure hoti hai). Ek subscript — neeche chhota word — label karta hai kaun si energy: E thermal E mechanical E ultrasonic
k T e − E a / k T
T temperature (kitna hot, absolute Kelvin scale par).k Boltzmann's constant , ek fixed number jo temperature ko energy-per-atom mein convert karta hai. Isliye k T T e ≈ 2.718 e − E a / k T Arrhenius factor ) jawab deta hai: "kitne fraction atoms mein barrier E a Zyada hot T
Topic ko yeh kyun chahiye: yeh explain karta hai kyun heat ek bond banane mein help karta hai (zyada atoms barrier clear karte hain) — aur, "too much heat" wali mistake mein, kyun yeh galat bhi ho sakta hai.
Mnemonic Teen energies = "Heat, Hug, Hum"Heat (thermal), Hug (mechanical squeeze), Hum (ultrasonic vibration). Thermosonic bonding teeno use karta hai.
Yeh electrical reason hai ki flip-chip kyun jeetta hai. Har symbol, ek ek karke.
ℓ r ℓ length (connecting thread kitna lamba hai). r radius (thickness ka aadha). Ek wire bond lamba hota hai (1 3 mm ≈ 0.1 mm
L L inductance hai: ek wire ki tendency current mein achanak aane wale changes ka resist karna , kyunki current khud ko ek magnetic field mein wrap kar leta hai. Socho ek lambi hose mein paani — yeh instantly nahi rukta ya shuru hota; uske paas "momentum" hai. Inductance electrical momentum hai.
μ 0 μ 0 ki ek given current empty space mein kitna strong magnetic field banata hai . Yeh "current" aur "magnetic field" ke beech conversion factor hai. Tum ise derive nahi karte; tum ise look up karte ho.
ln ln ( x ) "e x Yeh section 7 ke e power undo hai. Yeh bahut slowly badhta hai, isliye inductance formula mein ln distance 1 distance 1
d t d i i t d t d i "current kitni fast badal raha hai, per unit time" (amps per second). Socho current-vs-time graph ki slope: steep slope = fast switching. Fast digital chips current bahut fast switch karte hain, isliye d t d i
Feel karne ke liye quick numbers: d t d i = 5 × 1 0 8 A/s 2 nH V = 2 × 1 0 − 9 × 5 × 1 0 8 = 1.0 V 1 V 0.05 nH 0.025 V
Definition CTE (Coefficient of Thermal Expansion)CTE measure karta hai ki koi material garam hone par kitna badata hai . Silicon aur plastic/ceramic substrate ke different CTEs hote hain, isliye jab chip garam aur thandi hoti hai, yeh different amounts expand karte hain aur tiny solder bumps ko shear karte hain. Socho do alag materials ke rulers ko glue karke warm karna — woh joint par ek doosre ke against slide karte hain.
Underfill epoxy gap bharta hai aur us stress ko share karta hai taaki bumps crack na hon. Coefficient of Thermal Expansion (CTE) Mismatch aur Intermetallic Compounds and Bond Reliability dekho.
Right side cover karo aur khud test karo — tum parent note ke liye tabhi ready ho jab har ek cleanly reveal ho.
Millimetres mein ek micrometre kya hota hai? Ek millimetre ka ek hazarwan hissa (1 μ m = 0.001 mm
Counting formulas mein letter L Square die ki side length (mm mein).
Pitch p Neighbouring pads ya bumps ke beech centre-to-centre spacing.
p L Division batata hai ki size p L
Ek die edge ek 1-D resource kyun hai aur face ek 2-D resource kyun hai? Edge ek line hai (as L L 2
Yahan exponent 2 Rows aur columns wala ek grid — ek area, isliye squared.
Flip-chip wire bonding ko count mein kab beat karta hai? Jab L > 4 p
> "Greater than"; choda munh bade side ko face karta hai.
E Yeh name tags hain jo batate hain kaun si energy (thermal/mechanical/ultrasonic) — koi maths nahi.
ln ( x ) Yeh e power e x
d t d i Current per unit time kitni fast change hoti hai (current vs time ki slope).
Ek lamba wire ek bump se zyada ground bounce kyun cause karta hai? Inductance L ∝ ℓ V = L d t d i
CTE kya hai aur yeh underfill kyun force karta hai? Garam hone par material kitna expand karta hai; mismatched expansion bumps ko shear karta hai, isliye underfill us stress ko spread karta hai.
