User Manual
Contents
1. PROPERTY DuPont FERRO FERRO EMCA HERA Motorol DuPont 951 A6M A6 B T8800 TAPE a 943 CT700 T2000 Colour Blue White Black Blue Blue White Blue Available Fired 3 7 5 2 3 7 7 4 3 3 6 7 3 5 15 3 6 5 7 3 8 4 5 Thickness Mils 8 2 7 9 Dielectric Constant 7 8 5 9 6 5 7 2 7 9 9 1 7 5 K Loss Tangent 0 15 lt 0 2 lt 0 5 lt 0 2 lt 0 2 lt 0 3 lt 0 1 wave Insertion 18 lt 35 lt 5 0 12 Loss dB in 10GHz Insulation gt 10 gt 10 gt 10 gt 10 gt 10 gt 2x10 Resistance Ohms Ohms Ohms Ohms Ohms Ohms Breakdown gt 1000 gt 900 gt 1000 gt 1000 gt 1000 gt 1100 Voltage V Mil V Mil V Mil V Mil V Mil V Mil Electrolytic Leak lt 1 u lt 1 u Current amp cm amp cm Flexural Strength 28 3 17 1 17 1 40 6 36 33 4 kpsi 3 point test method Young s Modulus 15 12 12 27 kpsi Poisson Ratio 17 Fired Density 3 1 2 5 2 5 3 06 3 1 3 13 3 2 gm cc TCE ppm C 5 9 7 5 9 10 6 0 6 7 5 6 6 0 Surface Roughness lt 10 uin lt 15 uin lt 15uin lt 15puin lt 22 puin Camber Conforms to setter X Y Shrinkage 13 2 15 2 14 54 2 12 2 15 2 10 9 9 54 3 Z Shrinkage 15 5 254 5 35 5 14 5 25 5 14 7 10 3 5 Metallization Au Ag Au Ag Au Ag Au Ag Au Ag Au Ag Au Ag Ag Ag Au Ag Au Ag Au Ag Au Ag Au Ag Au Au Table 2 1 Tape properties of various LTCC tape manufacturers Electronic Packaging Group C MET Pu2. e Buy roll cutting sheets blanking machine machine LASER hi e Laser punching S poe LASER punching allows 3 Via formation e Programmable better flexibility in via i Programmable punching sizes punching Opening of via and via e Microscope lcrosconaand edge quality etc can be i e Automated verified The punched 4 Inspection Automated i Optical design can be directly Optical Inspection ae Inspection verified with the original design using AOI e Pressurized Pressurized Flexibility of process 5 Via filling chamber chamber and Availability of e Stencil printing Stencil Printing Screen stencil printer 6 Coneuelo e Screen printin Screen printin formation P 8 P 6 Zoa Automatic e Automatic video NA alignment and Better alignment accuracy 7 Stacking 18 Pin based available with automatic e Pin based alignment with alignment alignment F auto stacking 8 Stack shaping e Heated blade Heated blade Electronic Packaging Group C MET Pune 9 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 Laser cutting LASER cutting Punching of various geometries shapes of Open or an aa various sizes is possible CNC mill d 9 buried cavity P ce Lee B with the help of LASER amp formation uncuing using sister g CNC Power press with REWETpIESS P P die punch assembly can be used for high volumes Parallel plate lamination
3. which is a major advantage By virtue of such capabilities LTCC enjoys significant advantages in terms of package size reliability cost and manufacturability over the other multilayer circuit fabrication processes Figure 1 1 presents a schematic representation of typical LTCC package w Co fired Post fired Resistor Conductor Line eS a ee a ee Ce ell eee Meee asim oi Meee Figure 1 1 Schematic of LTCC Structure showing its capability to integrate with active devices In summary the specific advantages of LTCC can be listed as below e Reliable packaging due to ceramic processing e Multilayer or 3D circuit capability which is virtually unlimited e Low dielectric loss and better control over dielectric properties e HF capabilities in microwave and millimeter wave frequency range e High density integration due to smaller via and inclusion of buried passive elements Electronic Packaging Group C MET Pune 1 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 e Capability of packaging of Si chips along with any other technology devices e Hermetic sealing capability e Can handle fluidic optical mechanical and electrical signals simultaneously e Microsystems devices can be packaged as well as fabricated in LTCC e Close thermal expansion coefficient to Si GaAs allowing direct attachment of chips e Compatibility with flip chip wire bonding and SMT processes The following may b
4. Parallel plate Parallel plate provides opuon or Sa Aas E eae laminates without cavities ee lamination lamination and gt Mae 10 Lamination j Isostatic lamination gives Iso static Iso static r T Y better quality ability to lamination lamination prepare buried and closed cavities Both have individual Green stage Green stage 7 i advantages depending on 11 Singulation cutting cutting and post the end product Post fired cutting fired cutting requirement Free firin ot 6 X Free firing and Both choices expands 12 Co firing Constrained firing Pee i press sintering flexibility Press sintering LASER trimmin Provides complete Resistor g Both LASER and flexibility to the designer 13 Gin Buried resistor f i trimming Buried trimming for placing low tolerance trimming resistors BGA f ti i ere BGA formation vy 14 Contact Pin attachment and Pin Capability to have large formation KOVAR number of interconnects i n attachment Wire bonding Provid let Tube Soldering Soldering and Boh it aie a 15 tachment ee See flexibility to tube Cee g attachment Chi p Filp chip bonding attachment 16 zid Face up Not available yet bonding connections LASER sealing is required in only certain Seam sealing so aed F Hermetic Seam and solder applications such as using 17 Solder sealing F Sealing sealing SS lids etc The two LASER sealing choices made here cover most other applicat
5. systems C MET usually keeps stock of the Ag based materials along with the Au based wire bondable conductor paste C MET also keeps the brazing and some low value resistor materials Table 3 1 1 provides the complete list of materials usually available ex stock at C MET Other compatible materials are purchase as and when need arises Electronic Packaging Group C MET Pune 7 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 Material No Material type Green Tapes 951 PX 250 micron green tape 951 PT 100 micron green tape 951 C2 50 micron green tape Pastes 6141 Conductor Paste for via filling 6142D Inner Conductor Paste 6146 Outer Conductor Paste CFO11 Resister Paste 6135D Solderable conductor Paste Post fire 6138 Outer Conductor Paste QQ550 Encapsulant Paste 4195 Encapsulant Paste CFO21 Resister Paste 5092 D Resister Paste 9615 Dielectric Paste 5081 Conductor Paste adhesive brazing 5082 Conuctor Paste barrier brazing 5742 Solderable conductor paste 5087 Brazing Conductor paste Post fire Soldering Sealing brazing amp BGA pair attachment material 90Pb 10Sn Soldering Paste Type IV 99Sn 1Sb Soldering Paste Type III 63Sn 37Pb Soldering Paste Solder 96 5Sn 3 5Ag Ribbon 1 0 004 Solder 96 5Sn 3 5Ag Preforms 2 0 512 0 413 0 004 Solder ee nee for BGA l l ENE A 0 45mm dia 0 85mm head dia 10mm length Ni Au Plated
6. with cutting of green tape to the required processing size and pre baking at a specified temperature This step is however not mandatory After pre conditioning of tapes the package fabrication is initiated by preparing via holes cavities and alignment holes on each single individual layer separately The via holes are usually prepared by either mechanical punching or laser cutting process and the diameter varies typically between 100um and 250um Same processes are used for creating cavities which may vary from a few mm to a few 10 s of mm in size depending upon the design The via are intended to be used as electrical connections Between layers are then filled with silver or gold paste either by stencil printing method or by pressurizing the paste into the via holes The stencil printing is done using a hard polymer squeeze while vacuum is applied below the sample Once via are filled usual thick film screen printing is then employed to print metallization layer and buried passives The minimum line width of the printed conductors is usually about 100um Each single layer then passes through an optical inspection Next all such individually processed layers are aligned with help of registration pins and stacked after removing the supporting mylar sheet This method gives registration accuracy within 20um Automatic alignment is also employed sometimes which gives slightly better alignment accuracy of about 10um After cutting off the r
7. Table 3 1 1 LTCC materials usually available at C MET Other materials in this tape system can be purchased specifically for a particular implementation Electronic Packaging Group C MET Pune 8 Page User s Guide to LTCC and C MET s Fabrication Facility 3 2 Specific Process Choices Version 2 0 C MET has also made her own choices for processes Firstly C MET chose the about 6x6 tape format providing 4x4 tile area for circuit fabrication This aspect is based upon the available formats at the time of selection the size expectations for various applications and the cost of equipment for processing these tapes The aim of the facility of being a Prototyping Centre for LTCC was the guiding factor Table 3 2 1 provides details of available process choices for each process the choice made by C MET and the reasons of such selection Annexure I provides list of equipment used for LTCC process along with their important features and specifications Sr Process Process Options C MET Choice Remarks Standard CAD tool is useful in designing e Standard CAD Standard CAD tool packages but only the tools and Specialized LTCC design 1 Design Bat Tr e Specialized LTCC Specialized LTCC software can handle large design software design software number of interconnects dense circuits and layers with Automatic DRC e Purchase cut i sheets Purchase cut Saves investment on 2 Tape shaping
8. User s Guide to C MET s LTCC Fabrication Facility SORE Centre for Materials for Electronics Technology Panchawati Off Pashan Road Pune 411008 z S September 2013 o gt Contents 1 What is LTCC 2 LTCC Fabrication Process and Materials 3 C MET Materials Selection and Process Choices 3 1 Materials Selection 3 2 Specific Process Choices 3 3 C MET s Current Process Limitations Annexure Present Equipments amp Capabilities User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 1 What is LTCC The Low Temperature Co fired Ceramic LTCC is a multilayer interconnects fabrication process that uses glass ceramic tapes and conducting pastes for preparing the circuits The process ultimately produces multilayer ceramic circuits quite similar to the multilayer printed circuit boards with solder attached active and passive components on the outer surfaces with some differences The LTCC multilayer circuits are much denser and offer far better electrical properties The use of glass ceramic material allows reduced co firing temperature to below 900 C compared to the conventional ceramic firing temperatures This permits use of Ag Au and their alloys for interconnections which offer better stability during processing and are better conductors Such low firing temperature also allows use of other standard functional materials such as those for resistors capacitor dielectrics etc within the structures
9. ance or sample size Sample size and holder Large samples size with width 300mm amp height 500mm weight up to 15kg 4 axes manipulation 360 scanning Detector Combination of sintilator and visual range optics for high contrast Phase enhanced detector High contrast images possible of low atomic number materials such as Si or GaAs High speed data acquisition 1024 slices from 181 projections lt 3 min Continuous operation through automated multiple point tomography and repetitive scanning X ray leakage less than lt 1 uSv hr 38 Sputtering Machine Make Milman Thin Film Systems Pvt Ltd RF DC Magnetron System Two Target Substrate size of 6 Uniformity 5 Electronic Packaging Group C MET Pune 19 Page
10. bes for 4 x 4 area samples pad size min 200 x 200 um min distance between pads 150 um Control and software PC based menu driven with easy Graphic User Interface GUI 36 Dicing Machine Make Advanced Dicing Technologies Ltd Israel Samples Si Glass ceramic and Ceramic samples up to 7 x 7 with hardness 8 10 Gpa Sample holding Samples stuck on glass UV tapes and held by vacuum Cutting range and speed 200 mm 300 mm s or more Cutting depth parameters Stroke up to 30 mm or more accuracy 1 um resolution 0 2 um 0 axis maximum rotation angle 350 deg or more Indexing parameters Range 200mm positioning accuracy 3um Max chipping 25 and 40 um for samples up to 2 and 6 mm thickness Cutting blade Resin bonded diamond 45um grit wheel Dia 4 5 Spindle and drives 30000 rpm or more air bearing brushless dc motor drive amp lead screws in cutting direction stepper motor with lead screws in indexing direction Alignment With fiducials accuracy lum Electronic Packaging Group C MET Pune 18 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 37 X Ray Imaging Machine Make Xradia Inc USA X Ray tube Standard reflection type closed tube operating voltage from 40 150kV Tungsten target spot size lt 5um that does not limit the final resolution Submicron resolution lt 1um Spatial resolution lt 1 3m final resolution is independent of spot size sample working dist
11. cking Machine with LASER Alignment e Stacking using LASER peak detection technique e Alignment accuracy 15um e Automatic alignment and stacking process 33 Press Sinter Machine e Make Keje Thermoweld Equipments Pvt Ltd Pune e Samples Several 4 or 6 square LTCC unfired stacks with thickness up to 10 mm e Press up to 5kN min 100N accuracy 1 max stroke 150 mm e Furnace up to 1200 C control accuracy 0 5 uniformity 3 C e Atmosphere controllable gas line through MFC for air and other two gas lines for N2 other gas e PLCcontrol Full recipe programmability of pressure atmosphere and temperature 34 Wire Bonder e Make HYBOND Inc USA e Bonding Wedge wedge Ball wedge bumping ribbon 90 deep access 12 mm e Bonding mechanisms Ultrasonic thermosonic wedge Electronic Packaging Group C MET Pune 17 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 Bond force Variable between 15gf to 120gf X Y Stage 15x15mm or more mouse ratio 1 6 Z control motorized with 50mm travel 1um step resolution Wires Capability to bond Al and Au wires in the range 17 25um and ribbons about 25x250um Viewing 7 40X stereo zoom microscope or CCD camera with TFT viewing panel with fiber optic LED illuminator 35 Buried Resistance Trimmer Make Shalom Instruments Bangalore Resistance range 1 100 kQ Trimming Up to 30 higher accuracy settable up to 0 5 Probe station Two pro
12. e listed as disadvantages of LTCC although not all would matter in an intended application e High shrinkage after co firing and its tolerance cause process difficulties e Limited range and high tolerance for buried passive components due to materials limitations e Higher cost than polymeric packages e Low thermal conductivity of tapes as compared to ceramic materials e Non flexible packages Fortunately there are ways to overcome some of the disadvantages For example the heat can be routed through thermal via to the outer world thereby circumventing the difficulty of relatively low thermal conductivity Next there are some special processing methods which can make the shrinkage as low as zero in X Y direction More discussion about some of the process and applications related issues can be found further in this document Electronic Packaging Group C MET Pune 2 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 2 LTCC Fabrication Process and Materials The LTCC green tapes are prepared by uniformly casting the inorganic powder into polymeric materials using tape casting technique The slurry of the casting material is composed of glass ceramic mixture or composites in binders and organic solvent This as prepared slurry is cast to obtain glass ceramic green tape and is put together over a Mylar support These tapes are now commercially available The circuit package preparation process starts
13. egistration area whose utility is now over the stacks are laminated using uni axial heated press or an Isostatic laminator The latter process is usually preferred due to its ability to retain cavity and via shapes The individual circuits on the tiles are then singulated and co fired at 850 900 C peak temperature following the manufacturer recommended firing cycle Sometimes singulation is done after co firing using diamond wheel cutting machine The main Electronic Packaging Group C MET Pune 3 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 characteristic of sintered LTCC package is its all round shrinkage Free or un constrained sintering offers approximately 12 16 0 3 and 15 25 0 5 shrinkage in X Y and Z direction respectively depending on the composites used for preparation of LTCC green tape The integrated LTCC substrate is then available for post fire processing which may include usual print fire sequences for brazing attachment of external components BGA preparation etc After the completion of all such processing the substrate is ready for chip attachment and sealing Figure 2 1 presents the common process sequence for the preparation of LTCC structures Commercially different types of tape systems are available and there are a good number of manufacturers DuPont ESL Ferro Hearaus Nikko and Northrop Grumman are amongst the representative names All the commercial products are usuall
14. ignment mark detection e High precision heated vacuum table with X Y and O motion Electronic Packaging Group C MET Pune 12 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 5 Isostatic Laminator e Make Keko Slovenia e Thermal pressing up to 90 C of ceramic stacks in distilled water e Pressure up to 50Mpa can be given e Presses 4 x 4 stack e Programmable pressing cycle time up to 50 minutes 6 Programmable Batch furnace e Make ATV Germany e Furnace temperature up to 1000 C e Programming in 100 steps possible e Max 3 process gas connection and vacuum firing possible with pre defined time across available 100 steps e High cooling and heating ramp rate 7 High Temperature Reflow Oven e Make Sikama Falcon 5 C USA e Hot stage multi purpose reflow oven to melt high temperature solder up to 400 C e Appropriate gas flow 8 Mask Aligner amp Exposure System e Make ABM USA e 1000 watt near UV light source with expose time ranging from 0 1 to 999 9 seconds e Alignment tooling with standard X Y and O motion e Dual CCD camera for alignment system e Vacuum chuck to hold 4 sample e Accuracy 1pm 9 Package Seam Sealing Unit e Make Unitek Benchmark USA e Hermetically seam welds and solder seals ceramics SS Kovar and other metal packages from 3 17 mm to 203 mm to MIL SPEC 883E e Positioning accuracy of 0 038mm e High speed welding up to 38mm s 10 Thickness M
15. ion 2 0 Annexure Present Equipments amp Capabilities Following is a short description of the equipment added to the existing facility giving its important specifications capabilities and manufacturer 1 Via Puncher e Make Keko Slovenia e Punches green ceramic tapes with or without carrier film e Easy CAD CAM programming via DXF e Punching area up to 5 x 5 e Punching capabilities min 80 um amp max 5mm e C MET s Present Capabilities Circular punch 200um 1mm less than 1mm variable and 3mm Square punch 2mm e Alignment to previous punching 2 Screen Printer with Visual Aligner e Make DEK J Japan e Printing by Stencil and Screen printing method e SS made screens and stencils for X Y printing and Z filling respectively e CCD camera equipped visual aligner for better alignment and accuracy 3 Green Ceramic Foil Stacker e Make Keko Slovenia e Stacking of printed and via filled Green LTCC tape layers on carrier blocks to form multilayered structure e Layer alignment by positioning pins Three different stacks can be processed simultaneously e Two parallel hot plates pressing technique temperature 120 C max e Pressing surface area 160 x 160 mm e Pressing force 200 kN max adjustable 4 Green Stack Cutter e Make Keko Slovenia e Cutting of green ceramic stacks into individual components e Cutting by SS or Silicon carbide blade with heating option for smooth cut e 2 CCD cameras for al
16. ions In situ inspection of the fired samples Non Inspection destructive inspection is 18 abe X ray tomograph after firing Atay inspection y BARY possible for alignment verification or other issues Table 3 2 1 Process choices made by C MET Electronic Packaging Group C MET Pune 10 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 3 3 C MET s Current Process Limitations The description in Table 3 2 1 above indicates that C MET has already established a full fledged LTCC processes for most of multilayer LTCC design can be implemented With the availability of such facilities and processes there are a very few limitations which are listed in the following e Passive and active device placement and attachment Presently the LTCC multilayer circuits or packages can be fabricated but circuit or package cannot be assembled populated with passive active components as C MET does not have any SMT pick and place machines and chip attachment facilities e Laser Sealing Presently only seam and solder sealing are available LASER sealing is useful for applications such as pressure sensors where stainless steel may be required for sealing Recently new advanced machines have been inducted in C MET s facility which has significantly eliminated many of the limitations Electronic Packaging Group C MET Pune 11 Page User s Guide to LTCC and C MET s Fabrication Facility Vers
17. l 3D EM field simulator based on FDTD Simulation of microwave passive components and many more utilities packaged with this software Belt Furnace e Make BTU USA e Thick film Belt type firing furnace up to 1000 C e Appropriate gas flow Electronic Packaging Group C MET Pune 14 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 20 Vacuum Evaporation Unit e Make Hind Hi Vacuum India 21 Stereo Microscope e Make Olympus Japan e Digital Photographic attachment with measurement software e Computer interfacing 22 Potentiostat Galvanostat e Make Autolab USA e Includes GPES and FRA analysis 23 Measuring Microscope e Make Nikon Corporation Japan e Up to 1000 X magnification e Digital Photographic attachment with measurement software 24 Specialized Design Software e Make Electronic Packaging Designer EPD by CAD Design Software CDS e Large Via density up to 2500 sq inch e BGA designing and placement e 3D package development e DRC amp Advanced DRC ADRC with unlimited checking capability and configurable design rules definitions e Auto as well as Manual Routing option with online DRC e Supports popular output formats like GerbOut DXF which are needed to make Gerber Punch and Nibble files for LTCC fab process 25 Measuring Microscope e Make Olympus Corporation Japan e Up to 500 x magnification e Sample Stage 170x170 mm with 100 mm travel in X amp Y e Digital Photog
18. ne 6 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 3 C MET Materials Selection and Process Choices As the previous section briefly describes the generic LTCC process offers several choices at individual process steps Likewise one has to choose from a host of materials systems that are commercially available This section provides a brief description of such choices made by C MET while setting up the LTCC process and reasons behind making certain choices 3 1 Materials Selection The selection of the tape system and its manufacturer has to be done carefully depending upon the requirements of the targeted applications For C MET the choice of applications is wide ranging from devices device packaging HF circuits biomedical applications etc Therefore a tape system that is most suitable for all the possible applications was required to be selected C MET has presently chosen the DuPont 951 tape system for its LTCC operations because of its versatility wide acceptance and availability of a wide range of materials for buried components brazing etc Additionally this tape system provides option of Ag Au and mixed metal system for the conductor fabrication Further the DuPont materials are easily available in India Annexure 1 provides the list of complete set materials available for the 951 Green Tape system along with their intended application Amongst the available materials with the 951 Green Tape
19. onitoring Unit e Make Taylor Hobson UK e Thickness profiling by three gauge CLA confocal gauge 300um to 3mm Electronic Packaging Group C MET Pune 13 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 11 12 13 14 15 16 17 18 19 LASER gauge up to 10mm range Inductive gauge range of 2 5 mm e 3D profiling Manual Probe Station e Make Cascade Microtech USA e DC prober with microwave probes e Equipped with stereo microscope Shear Strength Tester DAGE Singapore make shear strength tester with only ball shear option is available presently Underfill Dispenser DIMA The Netherlands make Automatic programmable dispenser Dotmaster for high and low viscous solder paste adhesive underfill and glob top applications with maximum dispensing area of 320 x 420 mm Pulse Plating Power Supply Pulse plating power supply specially designed for electroplating of solder for BGA preparations having forward and reverse current mode Lapping and Polishing Machine Speedfam make Single side lapping and polishing machine Sample size max 50 mm Millipore Water Purification System 10 15MQ and 18 MQ water 3 and 10 litres per hour Diamond Wheel Cutter Specially designed for cutting of fired LTCC ceramic structures for inspection only Design and Analysis Software e Design software AutoCAD and Ganymede IMST Germany e Analysis software Ganymede with Empire ful
20. raphic attachment with measurement amp analysis software 26 LASER Micromachining and Trimming Machine e Make Process Photonics Canada e Nd YAG 355nm with focused beam diameter 15um and 7W power Electronic Packaging Group C MET Pune 15 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 Micromachining via and cuts of various shapes and size of green tapes and stacks engraving scribing over fired LTCC Resistance trimming of thin and thick film resistors in the range 10 Q to 10 MQ with better than 1 trimming tolerance 27 CNC Milling Machine Make LPKF Germany Materials Glass ceramic tapes with thickness varying from 25 um to 700 um and dimensions up to 170 x 170 mm and pressed and laminated stacks of such tapes 170 x 170 mm with thickness up to 10 mm Accuracy of position shape and dimensions and control 5 um Vacuum Holding Arrangements No use of coolant for un fired tapes and stacks Programmed drilling using DXF files 28 Hydraulic Press for Die Punching A hydro pneumatic power press for punching out portions of LTCC tapes stacks with the help of a precision die punch stripper assembly LTCC tapes and stacks of size 6 625 with thickness from 300 um to 8 mm 29 Automated Optical Inspection Make SIBCO BV The Netherlands Samples LTCC tapes with via filled via and screen printed green LTCC tapes up to 7 screens and stencils with frame size 320 x 320 mm Ill
21. umination from front and back with appropriate wavelength and intensity for useful contrast pixel size 5um or lower Faults can be detected Before screen printing Scratches cracks contamination and debris on blank unprocessed tapes missing via channels improper shapes of channel and cuts in the un fired tapes invalid distances between via channels unintentional via or structures improper dimensions of via channels or any other cuttings Faults can be detected after printing Missing tracks Interrupted tracks bridges voids missing pads invalid dimensions and shapes of lines pads filled via or any other printed shape invalid distances between interconnects pads filled via passive structures unintentional Electronic Packaging Group C MET Pune 16 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 interconnects pads passive structures fault finding like cracks contamination and debris on processed tapes 30 Pressurized Via Filling e Pressure up to 6 Bar e Porous Plate for holding and vacuum pull e Filling capability up to 100um via 31 Screen Cleaning Machine e Make Sonictron Sdn Bhd Malaysia e Ultrasonic generator 1500 2000W at 40kHz e Ultrasonic cavitations in IPA bath followed by CDA blow for drying e Capable of cleaning printing screens and stencils made of silk stainless steel cloths or stainless steel sheets frame size from 300 x 300 mm to 750 x 750mm 32 Automated Sta
22. y having similar properties with differences in their dielectric constant loss tangent thickness and shrinkage A partial list of commercial tape systems is presented in Table 2 1 One important point regarding LTCC materials is worth mentioning All the commercial LTCC tapes have to be used with the compatible pastes or tapes made available by the same manufacturer Here by compatibility one mean that the shrinkage and materials interaction properties especially during firing have to be tailored to match with each other Therefore due to the uncertainty about compatibility issues and thus the final properties mixing of materials system from different manufacturers is generally avoided Electronic Packaging Group C MET Pune 4 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0 Green Tape Pre conditioning Layer 2 Via Punching Layer 1 Via Punching Layer n Via Punching Layer 1 Via filling amp Conductor printing Layer 2 Via filling amp Conductor printing Layer n Via filling amp Conductor printing Stacking 1 to n Layer Lamination Post fire Processes Final Package Figure 2 1 Process steps for manufacturing of LTCC modules Electronic Packaging Group C MET Pune 5 Page User s Guide to LTCC and C MET s Fabrication Facility Version 2 0
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