www.smthelp.com CONTENTS 1. SHIPPING, STORAGE and PRODUCTION ENVIRONMENT..............................................................2 1.1 General shipping and storage conditions.......................................................................................... 2 1.2 Storage and handling conditions for solder paste............................................................................ 2 1.3 Storage conditions for underfill epoxy materials...............................................................................3 1.4 Storage and handling conditions for printed wiring boards [PWBs].............................................. 4 1.5 Shelf life time for different component categories............................................................................ 5 1.6 Drying (baking) moisture sensitive devices....................................................................................... 6 2. PASTE SPECIFICATIONS......................................................................................................................... 7 3. STENCIL PRINTING PROCESS SPECIFICATIONS............................................................................. 8 3.1 Squeegee............................................................................................................................................... 8 3.2 Stencil...................................................................................................................................................... 8 3.3 Support tables........................................................................................................................................ 9 3.4 Printing process parameters (stencil printing)................................................................................ 10 4. STATISTICAL PRINTING PROCESS CONTROL, SPPC................................................................... 11 4.1 Alarm and control limit settings......................................................................................................... 11 4.2 Actions when the machine alarms.................................................................................................... 12 4.3 Handling of statistical process information...................................................................................... 12 5. AUTOMATED OPTICAL INSPECTION, AOI......................................................................................... 12 5.1 Location of the machine in the production line............................................................................... 12 5.2 Utilisation of inspection results.......................................................................................................... 12 5.3 Component and paste alarm limits................................................................................................... 12 6. REFLOW SOLDERING PROCESS SPECIFICATION........................................................................ 13 6.1 Profile measurement equipment....................................................................................................... 13 6.2 Reflow profile measurement method............................................................................................... 13 6.3 Reflow profile specification................................................................................................................ 14 6.4 Recommended reflow oven settings................................................................................................ 15 7. MANUAL SOLDERING PROCESS AND WORKMANSHIP CRITERIA............................................15 7.1 Manual and semi-automatic hot gas soldering and rework.......................................................... 15 7.2 Manual soldering and rework using soldering iron........................................................................ 16 7.3 CSP rework.......................................................................................................................................... 16 7.4 Specifications for visual inspection; error criteria, faults classification and training material.. 17 8. UNDERFILL PROCESS............................................................................................................................ 17 8.1 General................................................................................................................................................. 17 8.2 Dispencing pattern for CSP components........................................................................................ 18 9. PLACEMENT PROCESS SPECIFICATIONS....................................................................................... 19 9.1 Nozzles................................................................................................................................................. 19 9.2 Feeders................................................................................................................................................. 19 9.3 NC-Programs....................................................................................................................................... 19 9.4 Part Data / Vision processing............................................................................................................ 20 9.5 Placement process management data compatibility table........................................................... 20
Transcript
www.smthelp.com
CONTENTS1. SHIPPING, STORAGE and PRODUCTION ENVIRONMENT..............................................................2
1.1 General shipping and storage conditions..........................................................................................21.2 Storage and handling conditions for solder paste............................................................................21.3 Storage conditions for underfill epoxy materials...............................................................................31.4 Storage and handling conditions for printed wiring boards [PWBs]..............................................41.5 Shelf life time for different component categories............................................................................51.6 Drying (baking) moisture sensitive devices.......................................................................................6
2. PASTE SPECIFICATIONS......................................................................................................................... 73. STENCIL PRINTING PROCESS SPECIFICATIONS.............................................................................8
3.1 Squeegee............................................................................................................................................... 83.2 Stencil......................................................................................................................................................83.3 Support tables........................................................................................................................................93.4 Printing process parameters (stencil printing)................................................................................10
4. STATISTICAL PRINTING PROCESS CONTROL, SPPC...................................................................114.1 Alarm and control limit settings.........................................................................................................114.2 Actions when the machine alarms....................................................................................................124.3 Handling of statistical process information......................................................................................12
5. AUTOMATED OPTICAL INSPECTION, AOI.........................................................................................125.1 Location of the machine in the production line...............................................................................125.2 Utilisation of inspection results..........................................................................................................125.3 Component and paste alarm limits...................................................................................................12
7. MANUAL SOLDERING PROCESS AND WORKMANSHIP CRITERIA............................................157.1 Manual and semi-automatic hot gas soldering and rework..........................................................157.2 Manual soldering and rework using soldering iron........................................................................ 167.3 CSP rework..........................................................................................................................................167.4 Specifications for visual inspection; error criteria, faults classification and training material..17
8. UNDERFILL PROCESS............................................................................................................................178.1 General................................................................................................................................................. 178.2 Dispencing pattern for CSP components........................................................................................18
9. PLACEMENT PROCESS SPECIFICATIONS.......................................................................................199.1 Nozzles................................................................................................................................................. 199.2 Feeders.................................................................................................................................................199.3 NC-Programs.......................................................................................................................................199.4 Part Data / Vision processing............................................................................................................209.5 Placement process management data compatibility table........................................................... 20
1.3 Storage conditions for underfill epoxy materials
Material name andtype
Loctite 3566 Namics Ohmcoat 1572
Max transportationtime
Goods must be receivedwithin 4 days after shipment
Goods must be receivedwithin 4 days after shipment
Package type Syringe, EFD compatible 50cc or 6oz,173cc Semco
Syringe, EFD compatible 50cc or 6oz,173cc Semco
Storage condition Syringes must be transferredimmediately fromtransportation package tointermediate storage (freezer,-40 C)Following items must berecorded:- product type, package size- color (white) withoutdeformation- lot number- date of shipment- amount of dry ice
Syringes must be transferredimmediately fromtransportation package tointermediate storage(freezer, -40 C)Following items must berecorded:- product type, package size- color (black) withoutdeformation- lot number- date of shipment- amount of dry ice
Max storage time 6 months @ -40C 12 months @ -40C or
6 months @ -20 C frommanufacturing date and keptin closed syringes
Pot life Once opened syringe must beused within 8-12 hours
Once opened syringe mustbe used within 24 hours
Special attention This is flammable liquid.Keep out of ignition sources.Cured waste is harmless.Uncured, liquid epoxy ishazardous waste. Read"Material Safety Data Sheet"and wear protective clothingand face mask.
This is flammable liquid.Keep out of ignition sources.Cured waste is harmless.Uncured epoxy is hazardouswaste. Read "MaterialSafety Data Sheet" andwear protective clothing andface mask.
1.4 Storage and handling conditions for printed wiring boards [PWBs]
Standard PWBs Micro via and Aramid (ALIVH) PWBs
Deliverypackage andstorage
Air evacuated plasticpacking50 panels/bag fromsame manufacturing lotHIC and desiccantoptional
Air evacuated Moisture Barrier Bag(MBB) according EIA-583 class 2, 50panels/bag, all from samemanufacturing lotHumidity Indicator Card (HIC),5 levels, on the top of PWB stackDesiccant optional
Incominginspection
Check that MBB is not broken or HICreading is 40% RHActions if NOK:-return to vendor or
-bake in 60 C, 5 hours, RH 5%,soldering within 24 hours
The components that typically are moisture sensitive are all PWBs having microvias onpads or having Aramid fibre reinforcement, most QFP components with lead count higherthan 50, all CSP components regardless of ball count, most optical devices based onacrylic plastics (IR modules, all LEDs), special plastic integrates structures (plastic powerdevices including polyimide tape or equivalent interfaces).
The purpose of NMP baking is to decrease amount of water from plastic packages priorsoldering. As absorbed water vaporise in reflow, internal cracks and failures may becreated.
Note standards and instructions for moisture sensitive components regardingprotective packing in shipping and storage together with this specification.
Moisture sensitive componentunprotected exposure time in ambient
Preventative action required
More than 48, but less than 168 hours,In case JEDEC class 5a or 6, more than24 h
bake condition: 12 (+10,-2)h @60 5C,RH 5%
More than 168 hours bake condition: 168h@605C, RH 5%
Note! Prevent direct contact of reels to drying chamber side and bottom walls,since these may be at significantly higher temperature than oven controllerindicates. Verify feasibility of drying oven to component moisture removal andeffect of various loading conditions by careful study of oven temperature controlsystem.
Stencil thickness (0402 or min 0.4mm pitchQFP, min 0.75mm pitch CSP)
0.12mm 0.01mm
Stencil materialElectro formed nickel orlaser cut stainless steel
Recommended stencil area of frame innerarea
60% 10%
Stencil rejection criteria by tension inproduction measured at screen at anypoint*
20N/cm or less
Fiducials 2x1mm dia sphere etched half-wayon stencil
*) Method of measurement: Fabric Tension Gauge, for example ZBF Tetkomat, CH-8803Rüschlikon, Switzerland, fax. 01/724 15 25, or equivalent.
3.3 Support tables
Property SpecificationMaterial Machined construction metal as steel or anodized Al
alloy. High friction surface on the top recommended.
Support table parallelity to stencil frameclamps
Max 0.2mm
Supporting surface smoothness 0.025mm on whole area
Machining depth* Max component height + min 5 mm
Module edge support* Module edge supported 1.5mm 0.5mm from edgetowards module center, max edge span aroundcritical areas without support max 15mm
Module inner area support (supportpins)*
Max PWB span without support 35mm
Support pins* Machined in dedicated workholder, M3x15 setscrews or equivalent
Vacuum holes on support table Primarily locate at non-printable area and preventvacuum leakage to print area. If vacuum can belimited to 100-200 mbar reliably, vacuum assistanceover whole area may be possible with carefulprocess adjustment.
3.4 Printing process parameters (stencil printing)
Parameter SettingPrint speed 100mm/s recommended, min 70mm/s, max
120mm/sNote: Under non-conforming situations causedby technical problems, lower than specifiedspeeds are temporarily accepted.
Squeegee pressure for 200mm widesqueegee** in constant force mode(force automatically adjusted, print headfloating)
minimum pressure that will wipe stencilsurface clean +5N as safety margin, normallybetween 40 – 50 N
Squeegee adjustment for MPM printers(constant squeegee distance (negative)from PWB surface, force against downstops)
Minimal adjustment that will wipe stencilsurface clean +0.5mm as safety margin
Snap-off distance -0.5 - 0.0mm on whole panel area (negativesnap-off recommended to give margin againstmachine misadjustments)
Separation speed Max. 20 mm/sec until stencil has released,then maximum speed.
Automatic wipe rate After every 10 5 prints Note: Under non-conforming situations caused by temporarytechnical problems more frequent wipe maybe applied.
Wipe cycle recommendation 1 dry with vacuum or 1 dam followed by 1 dryfor printers without vacuum option
Recommended cleaning fluid for printerautomatic wiping
Multicore Prozone SC-01 or equivalent highflash point solvent officially accepted by printermanufacturer. Use of isopropanol (IPA) orequivalent solvents is not recommended dueto fire safety.
Recommended cleaning fluid forcleaning of misprinted boards
Multicore Prozone SC-02 is preferred (SC-02will attack slightly acrylics and some rubbersused in protective gloves)Use of isopropanol (IPA) is allowed but notrecommended. Waste must be handledproperly.Note! Components that are not designed forliquid cleaning process, have to be removedand changed after cleaning.PWB with laser (micro) vias, OSP plating orwhich are totally or partly Aramid based, ARENOT ALLOWED TO BE WASHED! Cleaningsolvent traps into PWB structures and reducesesp. CSP components joint reliability.
Support table vacuum OFF while printing, unless dedicatedworkholder is of such construction that novacuum is created between PWB and stencilOR vacuum is limited to 100-200mbar.Vacuum ON during loading and tablemovements (activate special 1043 in AP-25SW 6.1 or later).
Kneading1 8 kneads after every 20min or longer pause inprinting process and recommended afteraddition of paste. Otherwise not needed.
Solder paste amount on stencil 150 – 160 g + paste attached to squeeze(200mm )
Printing accuracy +/- 0.05 mm
*) Sometimes referred as ”squeegee pressure” and force given in KGs, 1kg=9.81N
**) Depends linearly on squeegee width1) Automatic procedure to soften paste and dissolve partly dried paste residues at stencilaperture opening edges instead of stencil manual cleaning. The panel used for kneadingcan be fed to production line as normally printed board. After pauses beyond 120mincareful stencil cleaning in dedicated cleaner is recommended.
4. STATISTICAL - PRINTING - PROCESS CONTROL, SPPC
4.1 Alarm and control limit settings
In order to determine alarm and control limits for the SPPC machine at least 5.000 boardsmust be measured in normal process conditions. Successive boards must be processedas subgroups of about 10 pcs. Ideally subgroups should match with a board batch printedbetween stencil cleaning. Alarm limits for Area and Bridge parameters equal to 3 xstandard deviation of collected data (5.000 boards).
Control limit SpecificationControl limit for Area 3Area
Control limit for Bridge 3Bridge
In order to make sure that too low value isn't accepted as a control limit following minimumvalues are requested for both Area and Bridge.
Minimum values for each limit are:Control limit for Area 70%
The acquired data can be analysed and limits defined by the software called SPC-PC-IVwhich is included in system software package of SPPC equipment.
4.2 Actions when the machine alarms
When the SPPC machine alarms the paste printing process must be verified immediatelyby checking board – stencil alignment, amount of paste and condition of stencil. Moredetailed troubleshooting information is available from local process support team. When aproblem is fixed the alarm will be automatically reset after 5 to 10 boards.
4.3 Handling of statistical process information
Reports from SPPC system must be printed out and analysed on weekly basis.Corrective actions must be agreed and implemented when remarkable deviations fromnominal values exist.
5. AUTOMATED OPTICAL INSPECTION, AOI
5.1 Location of the machine in the production line
In most cases the best location for AOI machine is after high speed placement machines.In this stage all chip components are placed and paste deposites of integrated circuits arestill visible.
5.2 Utilisation of inspection results
Primary purpose of use of AOI machines is monitoring of paste printing and placementprocesses. This can be done by using the SPC software package delivered with themachine or by supplying inspection results to dedicated process monitoring software ifavailable.It is also possible to rationalise rework by sending AOI failure information to rework station.
5.3 Component and paste alarm limits
Next table describes recommended alarm limit values for different component types andfor paste printing. The objective is to detect placement errors that can't be fixed by selfaligment during reflow process and to avoid unnecessary alarms.
Component type Placement alarm limit specification0402 150 m for X and Y, 10 for Theta
0603 and bigger chip components 200 m for X and Y, 10 for Theta
Leaded components 150 m for X and Y, 5 for Theta
Paste printing accuracy 50 m for X and Y
Paste printing Area coverage 70 - 125% of nominal value
The profiling equipment shall be calibrated regularly according to the maintenanceinstructions by the supplier.
Only the thermocouples recommended and approved by the measurement equipmentsupplier shall be used.
6.2 Reflow profile measurement method
Item Oven calibration and verificationPurpose To evaluate oven functionality to specified profile and settings
(preventive maintenance)
Measurementfrequency
Once in two weeks, after every major maintenance or wheneverdeviation is suspected
Measurement piece Plain PWB100x100x1 mm plain FR4 laminate recommended
Number ofthermocouples
2
Position ofthermocouples
1 thermocouple attached to PWB (PWB temperature). This profile shallconform to specification in section 6.3.1 thermocouple 2…3 mm above the PWB surface (air temperature nearthe PWB).
Thermocoupleattachment method
PWB thermocouple shall be attached reliably by glue, screw or highmelting point solder.Repeatability and Reproducibility (Gage R&R) of thermocoupleattachment shall be verified when taking new thermocouples in use.Critical parameters are time above 179°C (ref. 5), peak temperature (ref.6) and temperature gradients in preheat (ref. 1) and reflow (ref. 4)
The following settings shall verified for each oven using oven calibration method (section6.2) and settings shall be adjusted if necessary to achieve a profile within the specificationin section 6.3.
7. MANUAL SOLDERING PROCESS AND WORKMANSHIP CRITERIA
7.1 Manual and semi-automatic hot gas soldering and rework
Parameter SpecificationMax air temperature measuredat PWB surface
+260°C
Recommended method of airtemperature calibration
Use light weight NiCr/Ni thermocouple or calibrator such asERSA DTM100* or equivalent
Max air velocity 10m/s
Max exposure time 30s
Nozzle size and shapeSelect according to application to create selective heatingat joint areas. Especially for larger components, adedicated nozzle has to be used.
Warning! A visual change in PWB surface characteristics during heating is a signof too high a temperature and/or too long exposure time and must result inrejection of module.
7.4 Specifications for visual inspection; error criteria, faults classification and trainingmaterial
Applicable internationalstandard
ANSI/IPC-A-610B, class 2, telecommunications
Error criteria and faultclassification
“SMD Workmanship Standard”, MES00055.
Training package NMP training package “SMD Workmanship Standard”,MES00055 or equivalent training material conformingto ANSI/IPC-A-610B.
8. UNDERFILL PROCESS
8.1 General
Process phase SpecificationMethod of application: Dispensing; positive displacement pump
type valve is recommended.Automatic dispenser: Asymtek M-600 or Cam/alot 3700
Needle: Gage 21 or 22, ¼" or ½" long needle.
Preheat of PWB: PWB surface temperature 40..70Cdepending on underfill material anddispensing pattern. Note: Loctite 3566underfill material requires 60 - 70 CPWB surface temperature for bettercapillary flow and fill
Temperature of PWB and underfill: PWB: 50..70C. Note: Too hightemperature might cause gelling.Underfill: 20..40C. Note: If thetemperature too high the viscosity insidesyringe starts to rise too fast.
Postheat of PWB: PWB temperature 40..70C. Note:Postheat is not required if PWB goesdirectly to curing oven after dispensingprocess
Flow rate: 9..35mg/sec depending on dispensingpattern
Dispensing speed: Max. 25mm/sec.
Fiducials: Two fiducial marks from PWB need to beused.
Height sense: Two measurements need to be done tomake sure that the needle is on right
height. Measurements need to be donefrom first and third blocks. If the tooling isnot straight enough the height senseneeds to be done from all four blocks.
Needle height: 0.5mm from the PWB surface for 0.8mmpitch CSP's (0.5mm bumps)0.3mm from the PWB surface for 0.5mmpitch CSP's (0.3mm bumps)Note: If some 0402 or 0201 componentsare closer that 1.1mm from the CSPcomponent the needle height must be0.7mm.
Right fill If underfill can be seen from all foursides.MAD: 52-54mg (Note: Variation betweendifferent PWB's causes variation torequired amount of underfill.)
Curing 150C/3min for Namics Ohmcoat 1572and 150C/5min for Loctite 3566.Note: Time is minimum time. Must not beless, otherwise insufficient cure.
8.2 Dispencing pattern for CSP components
From process cycle time point of view it is recommended to use L-patterns. To avoid voidsthe pattern needs to start and end 1.3mm from the corner (picture 3.). This way the risk ofvoids is little and the dispensing speed is as fast as possible.
Recommended nozzle sizes for some package types:0201 (0603) Fuji CP series: 0.4 mm circular nozzle
Panasert MV2V: type SXSiplace: type 702
0402 (1005) Fuji CP series: 0.7 mm circular nozzlePanasert MV2 RSS mininozzles, part no 10224781 86 and MSH2: special small nozzles, partno M1023 8-10-500-00Siplace: type 901 or 925
As large nozzle as possible shall be used (usuallymin diameter 5mm /area min 20mm 2 ) in order tomaintain placing speed and accuracy
9.2 Feeders
High Speed machines 7” Tape&Reel is a standard for both Fuji andPanasert. 13” reels can be used for 0402 resistorsand capacitors (13” with paper tape, blister tapenot allowed).For Siplace 13" and 15" Tape&Reel can be used.
Low Speed machines 13” Tape&Reel is a standard, 7” and 15” may alsobe used. Sticks and trays are not allowed.
9.3 NC-Programs
Placing sequence of 0402 In high-speed machines it is generallyrecommended to assembly first all low parts(0402 resistors 0.3mm), then parts, the height ofwhich is 0.3 - 0.5 mm (usually 0402 capacitors)and then the rest of the components.
Independent / connected feedertables
It is always recommended to use feeder tablesindependently in high-speed machines, thuseliminating undesirable stoppages when a partruns out. If connected tables must be used, it isadvisable to use “Next Device” or “Master Z-Number” functions or/and 13” reels to decreasecomponent shortages of “high-runner” codes
NC-program optimization / Allmodules mixed
This is usually the fastest way to assembly apanel (all modules assembled mixed at the sametime as one big PCB) and is thus recommended.
NC-program optimization / Stepand repeat
If “step and repeat” mode (offset) is used, thenevery other module must be assembled usingreverse placement sequence, so that the feedertable doesn’t have to move unnecessarily fromleft to right at each offset.
Chip components Fuji CP-series uses binary vision processing, Panasertuses gray scale for 0402 chips. This is due to the actualnozzle size behind the component body. With smallernozzles Panasert can use both. Binary vision isrecommended.
IC-type components Every lead shall be checked for pitch and lead length.CSP components As general recommendation use outermost balls for
component alignment.Complex connectors As general recommendation use outermost leads for
component alignment. Pls, check “lead insertion depthtolerance” from component’s specifications, since thisaffects in positioning of component body.
Placing speed 100 % placing speed is always the target. This can beachieved with most package types by selecting theproper nozzle (see 11.1, Nozzles).
9.5 Placement process management data compatibility table
Fuji Readings from F4G (Production Data -> Analyzer ->Device) shall be used to manually generate followingrates:
Pick-up Rate = 1- Total Errors / Total Parts
Mount Rate = 1- Total Errors / (Total Parts - TotalErrors)
Panasert Rates from “Production Control Data”:
Pick-up Numbers = Total Number of Pick-upsMount Numbers = Pick-up Numbers - Total Errors
