prof. fritz j. neff l m h snefr0001/ensmmlessonsfjn/... · prof. fritz j. neff director of the...
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Micro mechatronics 1part 6: soldering and glueing
Prof. Fritz J. NeffDirector of the Laboratory for Micro mechatronics and Hybrid integrated thick film circuitSat the University of AppliedSciences Karlsruhe (FH), 16. August 2004
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 2
Introduction
After the thick film structures havebeen manufacturedAnd controlledThe Surface-Mount-Technology SMT occurs
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 3
Characteristics of soldering
Remove of disturbing layers on thesurfaceWetting of the surfaces and spreadingof the solder(with flux)Interdifusion and establishing of alloysystemsCrystalisation of solder
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 4
Soldering process
main requirements:- connection between substrate, solder and SMD- no damage of SMDs- live long reliability of the soldered product
Two different methods:- bringing liquid solder to the point of connection- soldering paste dispensed on the soldering pad
and then treated by reflow soldering
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 5
Soldering temperature
ca. 260°C
ca. 183°C
group
solders
225°C205°C
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 6
Temperature problems
260 °C: Maximal on electronic groups235 °C: Maximal on BGA (Ball Grid Array)225 u. 235 °C: Minimal necessary for leadfree
solders205 °C: Minimal necessary on electronic group
examples:- SnAg3,8Cu0,7-alloys, melting temperatures at
216°C – 221°C - Sn63Pb37-alloys, melting temperature at 183°C
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 7
Problems with/without lead
Restriction On Substances(ROS-guideline)
of EU-commissionlast day for solders with lead
01.01.2008Japanese electro industrie has changed yet also for
consumer goods!
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 8
Soldering technologies for printedcircuit boards (PCB)
local soldering technologies:- with soldering hammer, by LASER
automated soldering process for groups(PCBs):- wave soldering (1 wave, double wave)- Reflow soldering (Infra red)- Convection soldering (need of gaz)
Problem: small elements become earliermax. of temperature than big elements
- vapour phase soldering
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 9
Parameters for soldering
solderflux
combination of materials withsolder
thermal energyphase of increasing temperature
soldering phasecooling phase
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 10
Process steps
selection of soldering pastestencil printing or dispensing of
solder pasteFine-Pitch-assembly
Soldering process- Reflow or- vapour phase
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 11
Application of soldering pastes•Dispensing•Stencil Printing Technologie•Screen Printing
Granular size of soldering pastes10 µm < d < 45 µm
Granular size for microdots5 < d < 25 µm.
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 12
Stencil manufacturing
by LASER cutting or by etchingaccuracy < 0,1µm
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 13
SMT-sideA
SMT-sideB
THT
Siemens
Soldering line forelectronic groups
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 14
Vapour phase soldering
also known as condensation solderingtransfer of thermal energy according to second law of thermodynamics
the more is the temperature difference themore ist the energy transfertemperature increases more if the thermal capacity is small
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 15
Vapor phase solderingtransfer time for thermal energyτ = c x m / (A x h)mit A = contact arear and h = coefficient of thermal conduction(Wm-2 K-1)end temperature Te
TD = vapour temperature, T0 = surface temperature,
⟩−⟩⟨−⟨+=−
eTTTTt
Deτ100
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 16
Vapour phase soldering
Gesättigter Dampf215 °C
Medium
Sensor
FBG >20 °CFBG >20 °C
FBG >20 °C (< 215 °C)
FBG ≤ 215 °C
FBG < 215 °C
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 17
Characteristics of vapor phase soldering
Homogenous heating of group (PCB)small ΔT on the PCB in peak temperatureContinuous condensating processO2-free conditionsLowest possible energy transfer to the PCBExceeding of peak temperature is not possibleBoiling point of perfluorised Polyether 230°C
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 18
Convection soldering
Important parameters:- control of the different heating zones- control of processing time
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 19
BGA-soldering
Examples for Ball Grid ArraysBGA: 560 connections, pitch: 1,27mmBGA: 480 connections, pitch: 1,27mmBGA: 728 connections, pitch: 1,00mmBGA: 400 connections, pitch: 1,27mm
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 20
Comparisionvapour phase - convection
BGA-Ball soldered in vapor phase BGA-Ball soldered
in convection oven
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 21
Parameters leading to decision
quantity of heat during liquidus timethermal mass of elementsused solder
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 22
Intermetallic phase
smallintermetallicphaseCu/Sn
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 23
steps of soldering SMDs
Dispensing or screen printing of solder
surface mount technology(Fine-Pitch-Placement)
soldering process(Reflow-, convection-, or vapour phasesoldering)
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 24
Pick-and-place with reflow soldering
Solderapplication,Pick-and-place,Thermal treatment
LotkugelnFlußmittel
AgPd-Lötpad
Keramiksubstrat
Geschmolzenes Lot
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 25
Preparation of soldering
Mounting plan for the controlwith amplifier of an elctrocardiographicsystem made on Al2O3-ceramic-substrate
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 26
Dispencing and SMD-fine-pitch-placement
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 27
placementVacuum gripper withSMD-elementoverhead theLanding positionElectronic elementsor devices (SMD)
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 28
Temperatur profile reflow soldering
260
240
220
200
180
160
140
120
100
80
60
40
20
Temperatur / °C
10 20 30 40 50 60 70 80 90 100 110
15s 25s 25s 8s 47s
73s65s
1.Phase 2.Phase 3.Phase Vorheiz-phase
Schmelzen der Lotpaste
Vorheizen Lötphase
Zeit / s
Aufheizen des Ofeninnenraumes Erwärmen der Bauelemente
Preheat-Time(Timer)
Soldering-Time (Timer)
Abkühl-phase
120
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 29
Reflow oven in the LMHS
Beschickungsseite
Reflowprozessprotection of sensibel elementswith ceramic hut
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 30
basics of glueing
soldered- Peak temperature 220°C- energy for melting anddiffusion necessary
Lot Kleber
Bauelement
a.) b.)
glued- Peak temperature 170°C- energy for hardening ofth glue
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 31
Types of gluesgeneraly:
Single component, Two components, Containing solvents, Without solvents,Activated by light,Theraml activation.
Important for micro technicsinsulating,isotrop electric conducting,anisotrop electricconducting,thermal conducting.
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 32
Advantages of conducting glues
Low temperature treatment of the electronic devicesno fluxerOptimal comportment by temperature change stressSimple handling and using by dispensing or screen printingOptimal for systems with very small dimensionsGood electrical conductors are also good thermal conductors
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 33
Isotropic conducting glues
61
0,60,2
0
1
2
3
4
5
6
7
8
9
10
72 74 76 78 80 82 84
Ag - Anteil in %
spez
.Wid
erst
and
in 1
0-3
Ohm
cm
Spezific resistant is depending ofthe relative amount of conducting
particles within the mass of the glue
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 34
Silver ion migration
Ag is hydrolisatingby warm and humid climate to Ag+-Ionsby migration to theanodes in theneigbourhoodfollows the short cut
+ -
Silberdentriden
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 35
Anisotropic conducting glues
lower contact pad on substrate
upper contact ball of electronic device
Conducting particles
By compression deformed buttherefore, conducting particles
Particle-diameter 6,5µm
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 36
Possibility with Flip-Chip-Bonding
Prof. Fritz J. Nef, Steinbeis TZ Mechatronik-Karlsruhe 37
Decision aidEpo-Tek-Kleber E2101 E3116 E3116
-5H20E-PFC
H70E-4
SMD X X X
Flip-Chip X X
Dispenser X X
Siebdruck X X X X X
Stempeldruck X
Scherfestigkeit (N/cm²) 1050 970 >1030 830 790Wärmeleitfähigkeit
(W/m*K) 2,1 2,0 2,0 1,64 1,43
Max. Dauerbetriebs-temp. (°C) 150 175 175 200 150
Isotrop X X X
Anisotrop X XSpez. el. Vol.widerstand
(Ù*cm) 1-4*10-4 1-5*10-4 1-5*10-4 1-4*10-4 1*1014