'MicroStar BGA Packaging Reference Guide' - TI.com

1 microstar BGA PackagingReference GuidePrinted on Recycled PaperPrinted on Recycled PaperLiterature Number: SSYZ015 BThird Edition September 2000 microstar BGA is a trademark of Texas Instruments NOTICET exas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinueany product or service without notice, and advise customers to obtain the latest version of relevant informationto verify, before placing orders, that information being relied on is current and complete. All products are soldsubject to the terms and conditions of sale supplied at the time of order acknowledgment, including thosepertaining to warranty, patent infringement, and limitation of warrants performance of its semiconductor products to the specifications applicable at the time of sale inaccordance with TI s standard warranty. Testing and other quality control techniques are utilized to the extentTI deems necessary to support this warranty.

2 Specific testing of all parameters of each device is not necessarilyperformed, except those mandated by government are responsible for their applications using TI order to minimize risks associated with the customer s applications, adequate design and operatingsafeguards must be provided by the customer to minimize inherent or procedural assumes no liability for applications assistance or customer product design. TI does not warrant or representthat any license, either express or implied, is granted under any patent right, copyright, mask work right, or otherintellectual property right of TI covering or relating to any combination, machine, or process in which suchsemiconductor products or services might be or are used. TI s publication of information regarding any thirdparty s products or services does not constitute TI s approval, warranty or endorsement 2000, Texas Instruments IncorporatediiiMicroStar BGA Packaging Reference GuideIntroductionThe parallel pursuit of cost reduction and miniaturizationin recent years has given rise to an increasing emphasison very small integrated circuit (IC) package is particularly evident in consumer-based endequipment using digital signal processor (DSP) solutionssuch as wireless telephones, laptop computers, andhard-disk drives.

3 Despite the formal definition, packageswith an area similar in size to the IC they encapsulate areloosely referred to as chip scale packages (CSPs).Figure 1 illustrates this 1. Packaging TrendsPackage mm pitchBGA (ball grid array) mm ball pitchFine pitch mm pitchBare chip(flip chip) Infra. issue (KGD) Soldering difficulties PWB/ASSY cost upCSP (chip scale pkg.) solutionFine pitch BGA( , , mm ball pitch) chip (bump)Pin countPackage trend (customer requirement)Chip scale packages are in many ways an ideal solutionto the cost reduction and miniaturization offer enormous area reductions in comparison toquad flat packages (QFPs) and have increasing potentialto do so without adding to system-level cost. In the bestcase, CSPs compete today on a cost-per-terminal basiswith QFPs. For example, various CSPs from TexasInstruments (TI) are now available at cost parity with Instruments produces a polyimide film-basedfamily of CSPs called microstar BGA.

4 Like most otherCSPs, microstar BGAs use solder alloy balls as theinterconnect between the package substrate and theboard on which the package is soldered. The MicroStarBGA family comes in a range of solder ball pitch ( mm, mm, and mm). Currently, TI s most popularpackages are 64- and 144-ball packages. Figure 2shows the structure of TI s microstar BGA 2. Structure of TI s microstar BGACu pattern(30 m line/40 m space)Flex substrate(polyimide)(Single electrical layer) mm mm ball pitchSn/Pb: near eutecticVia( mm DIA.)Wire bondConforms to JEDEC Outlines: MO-192 and MO-205-AEncapsulantChip(11 mils) mmpitchPWBD iepasteMicroStar BGA is a trademarks of Texas BGA Packaging Reference GuideTexas Instruments addressed several key issues inpackage assembly in order to produce a CSP that is notonly physically and mechanically stable butcost-effective for a wide variety of applications.

5 Figure 3demonstrates how microstar BGAs resolve reliabilityand cost issues. An overall view of the flow used toproduce TI microstar BGA packages is shown inFigure 4. The process for solder ball attachment isshown in Figure 3. microstar BGA Package AssemblyIssuesSubstrate Ceramicselection Glass-epoxy Polyimide Interconnection Bump (flip chip) Wire bond Solder ball form Solder jet Stud bump Paste print Pick and place Encapsulation Potting Transfer mold TransducerMoltensolderOrificePrinting maskSolderpasteVacuumSolder wireCapillary These are the processes used by 4. microstar BGA Package Assembly FlowSame as QFP assemblyDie attachWire bondEncapNon-Ag pasteShort loopX fer modeBall attachIR reflowFlux mm cleanLaser symboland singulationTestTrayBGA unique processFigure 5. Solder Ball AttachmentSolder ball attachPick and placeSqueegeePrinting maskSolderpasteVacuumSubstrateSolder ballBall pads (via)Solder paste printSolder ball attach(12 mil DIA.)

6 Solder ball shear testsSSFailAve. Reading1250668 g1250734 g144 GGU, pitch, mm DIA. ball TI spec. is 400 g minThe microstar BGA package has been fully qualified innumerous applications and is being used extensively inmobile phones, laptops, modems, handheld devices,and office environment equipment. Your local TI fieldsales office can give you more information on usingreliable and cost-effective microstar BGA Packaging inyour guide is designed to give you technical backgroundon microstar BGA packages as well as how they can beused to build advanced board layouts. Any additionalhelp desired with your specific design is also availablethrough your local TI field sales BGA Packaging Reference GuideContents1 PCB Design Considerations1 1.. Solder Land Areas1 2.. Conductor Width/Spacing1 2.. High-Density Routing Techniques1 3.. Via Density1 3.. Conventional PCB Design1 4.

7 Advanced Design Methods1 4.. 2 Reliability2 1.. Daisy-Chained Units2 2.. Reliability Data2 2.. Reliability Calculations2 4.. Package Characteristics2 6.. Thermal Modeling2 6.. Electrical Modeling2 6.. 3 Surface-Mounting microstar BGA Packages3 1.. Design for Manufacturability (DFM)3 2.. Solder Paste3 2.. Solder Ball Collapse3 3.. Reflow3 3.. Inspection3 4.. 4 Packing and Shipping4 1.. Trays4 2.. Tape-and-Reel Packing Method4 4.. Tape Format4 4.. Device Insertion4 5.. Packaging Method4 5.. 5 Sockets5 1.. The Design Challenge5 2.. Contacting the Ball5 2.. Establishing Contact Force5 3.. Conclusions and Future Work5 3.. 6 Lead-Free Solutions6 1.. Moisture Sensitivity6 4.. Board Land Finishes and Solder Paste6 5.. Summary 6 9.. 7 References7 1.. Appendix AFrequently Asked QuestionsA 1.

8 Package QuestionsA 1.. Assembly QuestionsA 2.. Appendix BPackage Data SheetsB 1.. 80 GJK(Pitch = mm; Size = 6 x 6 mm)B 2.. 167 GJJ(Pitch = mm; Size = 8 x 8 mm)B 3.. 151 GHZ(Pitch = mm; Size = 10 x 10 mm)B 4.. 100 GGM(Pitch = mm; Size = 10 x 10 mm)B 5.. 64 GGV(Pitch = mm; Size = 8 x 8 mm)B 6.. 80 GGM(Pitch = mm; Size = 10 x 10 mm)B 7.. 100 GGF(Pitch = mm; Size = 10 x 10 mm)B 8.. 100 GGT(Pitch = mm; Size = 11 x 11 mm)B 9.. 144 GGU(Pitch = mm; Size = 12 x 12 mm)B 10.. 179 GHH(Pitch = mm; Size = 12 x 12 mm)B 11.. 176 GGW(Pitch = mm; Size = 15 x 15 mm)B 12.. 208 GGW(Pitch = mm; Size = 15 x 15 mm)B 13.. viMicroStar BGA Packaging Reference GuideContents (continued)240 GGW(Pitch = mm; Size = 15 x 15 mm)B 14.. 196 GHC(Pitch = mm; Size = 15 x 15 mm)B 15.. 257 GHK(Pitch = mm; Size = 16 x 16 mm)B 16.. 257 GJG(Pitch = mm; Size = 16 x 16 mm)B 17.. viiMicroStar BGA Packaging Reference GuideList of FiguresFigurePage1 Packaging Trendsiii.

9 2 Structure of TI s microstar BGAiii.. 3 microstar BGA Package Assembly Issuesiv.. 4 microstar BGA Package Assembly Flowiv.. 5 Solder Ball Attachmentiv.. 6 Package Via to Board Land Area Configuration1 2.. 7 Effects of Via-to-Land Ratios1 2.. 8 Optimum Land Configurations1 2.. 9 PCB Design Considerations (Conventional)1 3.. 10 Microvia Structure1 3.. 11 Dog Bone Via Structure1 4.. 12 Buried Vias1 4.. 13 Daisy-Chained Pinout List2 2.. 14 General Net List2 2.. 15 PCB Layout for Daisy-Chained Unit2 2.. 16 Daisy-Chain Test Configuration2 3.. 17 Board-Level Reliability Test Boards2 4.. 18 Board-Level Reliability Test Data2 4.. 19 Thermal Modeling Process2 6.. 20 Electrical Modeling Process2 6.. 21 Solder Ball Collapse3 3.. 22 Ideal Reflow Profile3 4.. 23 Shipping Tray Detail4 2.. 24 Packing Method for Trays4 3.. 25 Single Sprocket Tape Dimensions4 4.. 26 Reel Dimensions4 5.. 27 Tape-and-Reel Packing4 5.

10 28 Approaches for Contacting the Solder Ball5 2.. 29 Pinch Contact for Solder Balls5 2.. 30 Contact Area on Solder Ball5 3.. 31 Witness Marks on Solder Ball5 3.. 32 Effect of Burn-in on Probe Marks5 3.. 33 Assembly Testing of Eutectic vs. Pb-free Solder Balls6 3.. 34 Standard Reflow Profile for Pb/Sn Alloy Solder6 3.. 35 Proposed Reflow Profile for Non-Pb Alloy Solders6 4.. 36 Typical SAM Pictures After Moisture Sensitivity Testing6 5.. 37 Broad-Level Reliability Study(Solder Paste: Sn/Pb Eutectic)6 6.. viiiMicroStar BGA Packaging Reference GuideList of Figures (continued)FigurePage38 Broad-Level Reliability Study(Solder Paste: Pb-free-1)6 6.. 39 Broad-Level Reliability Study(Solder Paste: Pb-free-2)6 7.. 40 Key Push Test Apparatus6 8.. 41 Typical Key Push Test Results6 8.. 42 Key Push Test Performance6 9.. 43TI s Strategic Package Line-UpB 1.. List of TablesTablePage1 Package-Level Reliability Tests2 3.