What is New in IPC-7351C. by Tom Hausherr CEO & Founder of PCB Libraries, Inc.

Transcription

1 by Tom Hausherr CEO & Founder of PCB Libraries, Inc.

2 Through-Hole Technology

3 3-Tier IMD (Inserted Mount Device) The original IPC-7251 Concept for 3-Tier Pad Stack Joint Characteristics Maximum (Most) Density Level A Median (Nominal) Density Level B Minimum (Least) Density Level C Hole Diameter Factor (over max lead) Int. & Ext. Annular Ring Excess (added to hole dia.) Anti-pad Excess (added to hole dia.) Courtyard Excess from Component Body and/or Pads (which ever is greater) Courtyard Round-off factor Round up to the nearest even two place decimal, i.e., 1.00, 1.01, 1.02, 1.03 etc.

4 3-Tier Pad Stack Concept Proportional Pad Stack Small Hole Same Annular Ring Large Hole Proportional Annular Ring

5 No 3-Tier Library System IPC-7351C Proportional Pad Stacks

6 IPC-7351C Proportional Pad Stacks

7 Rounded Rectangle Pad Shape Most Component Manufacturer s Recommended Pad Shape is Rectangle IPC-SM-782 and IPC-7351B Recommended Pad Shape is Oblong IPC-7351C Rounded Rectangle Pad Land Width = Shortest Side Corner Radius = 25% Land Width 1 Mil (0.01 mm) Round-off Maximum Radius = 10 Mil (0.25 mm)

8 Surface Mount Component Lead Styles Ball Grid Array Bump Grid Array Land Grid Array Column Grid Array Pillar Grid Array Flat Lug Flat Side Convex Side Concave Side Corner Concave Inward L Flat Bottom Gull Wing Outward L J-Lead End Cap Under Body L No-Lead

9 Lead Styles and Rounded Rectangle Pads Under Body L End Cap Gull Wing PQFN D-Shape Corner Concave QFN D-Shape Sharp Corner pads are not good for RF design

10 Lead Styles Exempt from Rounded Rectangle Pads Under Body Terminal Leads where a Periphery Pad is required: Ball Grid Array Column Grid Array Land Grid Array Dual Flat No-lead Thermal Pads

11 Guidelines for Drafting Items Silkscreen Outline and Polarity Marking Assembly Outline and Polarity Marking Courtyard Outline Land Pattern Origin Marker Component Outline Terminal Lead Outline

12 Silkscreen Outline Guidelines 1. No silkscreen outline under the component body; these get covered up during assembly and don t provide any useful purpose (waste of good ink) 2. Silkscreen outlines visible after assembly process and provide a functional use as alignment marking for assembly registration accuracy 3. Silkscreen outlines should be inside placement courtyard 4. Silkscreen outlines should be mapped to the Maximum Component Body with one exception, the Silkscreen to Pad spacing rule overrides the Component Body Mapping 5. Silkscreen outlines should map the component body and not go around pads. Excess silkscreen outlines should be avoided to make room for ref des locations. Silkscreen outlines should perform a hatch outline along the component package body. 6. Pin 1 is identified by extending the silkscreen along Pin 1 length of pads when component leads extend outward. Bottom only terminals Pin 1 is identified by a missing line.

13 3-Tier Silkscreen Outlines The recommended guidelines for 3-Tier line widths and Silkscreen to Pad Gap are illustrated in the pictures below representing a SOT23-6 component package The Silkscreen to Pad Clearance is the same as the Line Width Least Density Level 0.10 mm Line Width Nominal Density Level 0.12 mm Line Width Most Density Level 0.15 mm Line Width

14 IPC-7351B Rectangular Courtyards The recommended courtyard outline line widths are 0.05 mm or 0.01 mm

15 IPC-7351C Contour Courtyard Outlines The recommended courtyard outline line widths are 0.05 mm or 0.01 mm

16 IPC-7351C Contour Courtyard Outlines

17 Silkscreen Outline Pkg. Body Hatching The Maximum Component Body tolerance is the starting place for mapping a silkscreen outline inside edge Silkscreen should only be applied to edges of the plastic component package or hatched (corner cropping) larger component packages like BGA, CGA and LGA packages It is not recommended to map silkscreen outlines to land pattern pads Quad Flat Package QFP Pull-back Quad Flat No-lead PQFN Ball Grid Array BGA

18 Silkscreen Polarity Marking Gull Wing & J-Lead, Bottom Only & Chip Gull Wing & J-Lead Polarity Bottom Only Polarity Absence of Silkscreen 2-pin Component Polarity 2-pin Component Non-polarity

19 Silkscreen Visible After Assembly Quad Flat No-lead (QFN) Ball Grid Array (BGA) Quad Flat Pack (QFP) SOT23 Axial Resistor

20 Alternate Silkscreen Polarity Marking Assembly Shops Like Dots but, They Consume Space Gull Wing & J-Lead Polarity Bottom Only Polarity Outside Courtyard 2-pin Diode/LED Polarity 2-pin Capacitor Polarity

21 Assembly Outline & Polarity Guidelines Non-polarized Chip, Crystal, Molded Body Polarized Chip, SOD, LED, SOT. Molded Body 0.10 mm Line Width Small Outline Package SOP, SON, QFN, QFP 1.00 mm Plastic Leaded Chip Carrier PLCC, LCC, 4-sided Chip Array 1.00 mm 1.00 mm

22 Component Body & Terminal Outlines The Nominal Component Body and Terminal Lead Outlines Output to CAD tool on a mechanical layer

23 REFDES 3-Tier Silkscreen Reference Designators Silkscreen reference designators are normally placed inside the courtyard during library construction and typically located on the land pattern origin. After part placement has been approved, the silkscreen ref des are relocated outside the component body so they are visible after assembly. The ref des line width is normally 10% of the text height In the past, we made all silkscreen reference designators 1.50 mm height. Fabrication technology has improved it s time to support a 3-Tier reference designator option New recommendations for the 3-Tier ref des Least Density Level: 1.00 mm Height Nominal Density Level: 1.20 mm Height Most Density Level: 1.50 mm Height

24 Assembly Reference Designators The default assembly Ref Des height is 2.00 mm For miniature components the text height must be scalable to fit The default rotation of the assembly reference designator is associated with the component body length 0.6 x x x x REFDES Ref Des Height 0.50 mm REFDES Ref Des Height 0.70 mm REFDES Ref Des Height 1.00 mm REFDES Ref Des Height 0.12 mm These Chip assembly Ref Des are scaled down to fit inside assembly outlines

25 Land Pattern Origin Guidelines The land pattern origin is typically located at the center of gravity of the component, but sometimes this is difficult to calculate with irregular shaped components, so Pin 1 is used in these cases. Also Pin 1 in most through-hole connectors. The centroid origin marking in the picture below is an unfilled 0.50 mm diameter circle with a 0.05 line width with a 0.70 crosshair for cursor alignment.

26 Snap Grid & Feature Round-off 0.01 mm Footprint Features in 0.01 mm increments *Japanese 80% rule for 0.65 pitch Line Widths Corner Radius 0.01

27 3-Tier Local Fiducials Local Fiducials have been used only on fine pitch QFP and BGA Land Patterns Fine pitch QFP = Less than 25 mil (0.635 mm) pitch Fine pitch BGA = Less than 32 mil (0.8 mm) pitch Future Local Fiducial sizes will be: Level A (Most) = 40 mil (1.0 mm) with 80 mil (2.0 mm) solder mask & keep-out Level B (Nominal) = 30 mil (0.75 mm) with 60 (1.5 mm) solder mask & keep-out Level C (Least) = 20 mil (0.5 mm) with 40 mil (1.0 mm) solder mask & keep-out

28 Zero Component Orientation Levels A & B Zero Orientation with Pin 1 in Upper Left Corner Introduced in 2007 in the IPC-7351A Publication IPC-7351C Level A Zero Orientation with Pin 1 in Lower Left Corner Introduced in 2009 in the IEC publication IPC-7351C Level B

29 EIA & JEDEC EIA Component Dimensions vs: JEDEC Dimensional Letters

30 JEDEC Dimensional Characters

31 Land Pattern Naming Convention Extended Names Eliminate Duplication I The original IPC-7351 footprint naming convention does not include Gull Wing component lead tolerances, Thermal Pad sizes, BGA Ball sizes or Chip Terminal Lead Width into account. Therefore, the same component with different tolerances can produce a different land size and spacing with the same footprint name. A footprint name of SOP50P710X120-14N can have version A, B, C, D which do not indicate the variances in Thermal Tab or Lead Length There are 3 component features that affect the footprint name Square/Rectangle Thermal Tab Size = SOP50P710X120-14T300/T300X500 Gull Wing Lead Length Tolerance = SOP50P710X120-14L50 BGA Ball Size = BGA121C50P11X11_600X600X100B23 Chip Terminal Lead Width = CAP3216X135L45 For component mfr. recommended footprint drop the environment level character after the pin qty. - SOP50P710X120-14

32 Land Pattern Naming Convention Extended Names Eliminate Duplication II The existing IPC-7351 land pattern naming convention does not take into consideration component package tolerances. Package tolerances affect the pad, silkscreen and courtyard sizes You can have several packages with the same dimensions but different tolerances but the IPC-7351 naming convention will name all the parts with the same land pattern name In order to save the IPC-7351 naming convention and eliminate duplicate land pattern names for parts with different tolerances, we need to add the component manufacturer abbreviation as a prefix to the IPC-7351 name Example: SOP50P710X120-14L50T300X500 will become these names TI_SOP50P710X120-14L50T300X500 MAXIM_SOP50P710X120-14L50T300X500 ANALOG_SOP50P710X120-14L50T300X500

33 New Land Pattern Naming Convention Extended Names Eliminate Duplication III Component manufacturer s apply different tolerances on the package dimensions which creates a different footprint pattern. So a new Naming Convention must be created for each mfr. Case Code Standard Packages MfrNameAbr_MfrCaseCode Unique Packages MfrNameAbr_MfrPartNumber This new naming convention is exclusive to all footprints, so instead of having one naming convention for Standard Packages and a different naming convention for Unique packages, a universal naming convention is needed

34 New Land Pattern Naming Convention Manufacturer Names and Abbreviations Abbreviation Manufacturer s Name Abbreviation Manufacturer s Name TI Texas Instruments LATTICE Lattice Semiconductor AMD Advanced Micro Devices SA State of the Art ST ST Microelectronics CDE Cornell Dubilier Electron TE TE Connectivity CTS CTS KOA KOA Speer Electronics MOLEX Molex NXP NXP Semiconductors ALD Advanced Linear Devices HTK Honda Tsushin Kogyo CYPRESS Cypress Semiconductor JAE Japan Aviation Electron.. FOX Fox Electronics IQD IQD Frequency Products IDT Integrated Device Tech.. KEMET Kemet DIODES Diodes, Inc.

35 New Solder Joint Goal Recommendations Proportional SMD Pad Stack 25% Pitch 30% Pitch 5% Pitch 20% Pitch Gullwing Lead Shape Toe Heel Side Courtyard Excess 2.54 mm Pitch (DPAK) mm Pitch mm Pitch mm Pitch mm Pitch mm Pitch mm Pitch mm Pitch Component Families Small Outline IC (SOIC) Small Outline Package (SOP) Quad Flat Package (QFP) Small Outline Transitor (SOT23) Small Outline Transitor (SOT223) Small Outline Transitor (SOT143) Small Outline Diode (SOD) Ceramic Flat Package (CFP) Ceramic Quad flat Package (CQFP) TO (DPAK) Pad Length = Nominal Lead Length + Toe + Heel Pad Width = Nominal Lead Width + Side

36 Old/New Solder Joint Goal Recommendations 1.00 pitch 0.35 Toe / Heel 1.00 pitch 0.25 Toe / 0.35 Heel 0.80 pitch 0.35 Toe / Heel 0.80 pitch 0.20 Toe / 0.30 Heel Toe Heel 0.65 pitch 0.35 Toe / Heel 0.65 pitch 0.16 Toe / 0.20 Heel 0.50 pitch 0.35 Toe / Heel 0.50 pitch 0.13 Toe / 0.15 Heel Toe Heel 0.40 pitch 0.35 Toe / Heel 0.40 pitch 0.10 Toe / 0.12 Heel 0.35 pitch 0.35 Toe / Heel 0.35 mm pitch 0.09 Toe / 0.10 Heel Toe Heel

37 Solder Joint Goals for Gull Wing Perfect Pad Centering Visible Wetting Under Lead Heel Larger Than Toe Bad Pad Centering Wetting Under Lead Unachievable Possible Short Circuit with Trace

38 New Pad Center Calculation Nominal E Nominal L Heel Toe Pad Length CL Pad Centers Pad Length = Nom L + Heel + Toe Pad Centers = Nom E + 2 Toes Pad Length

39 Solder Joint Goals for Chip Components Chip Non-polarized Diode Chip Inductor Chip Varistor Chip Fuse Chip Resistor Chip Capacitor Chip Thermistor Chip LED Polarized Chip Capacitor Chip Diode

40 Solder Joint Goals for Chip Components < 0603 Lead Part Maximum (Most) Median (Nominal) Minimum (Least) Density Level A Density Level B Density Level C Toe (J T ) Heel (J H ) Side (J S ) Round-off factor Round off to nearest two place decimal, i.e., 1.00, 1.01, 1.02 Courtyard excess Rectangular Chip Components Smaller than 1608 (0603) (unit: mm) Toe (J T ) Toe (J T ) Toe (J T ) Heel (J H ) 0.00 Side (J S ) 0.00 Round-off factor Round off to nearest two place decimal, i.e., 1.00, 1.01, 1.02 Courtyard excess 0.15

41 New Solder Joint Goal Recommendations Proportional SMD Pad Stack 50% Height 10% Height 15% Height Package Dimensions 40% Height Rectangular End Cap Toe Heel Side Length Width Height Courtyard Inch 01005, Metric mm 0.20 mm 0.25 mm 0.10 Inch 0201, Metric mm 0.30 mm 0.30 mm 0.12 Inch 0402, Metric mm 0.50 mm 0.40 mm 0.16 Inch 0603, Metric mm 0.80 mm 0.50 mm 0.20 Inch 0805, Metric mm 1.25 mm 0.60 mm 0.24 Inch 1008, Metric mm 2.00 mm 0.65 mm 0.25 Inch 1206, Metric mm 1.60 mm 0.70 mm 0.25 Inch 1210, Metric mm 2.50 mm 0.70 mm 0.25 Inch 1806, Metric mm 1.60 mm 0.75 mm 0.25 Inch 1812, Metric mm 3.20 mm 0.80 mm 0.25 Inch 2010, Metric mm 2.50 mm 0.80 mm 0.25 Inch 2512, Metric mm 3.20 mm 0.80 mm 0.25 Inch 2920, Metric mm 5.10 mm 0.80 mm 0.25 Limit Maximum Courtyard setting to 0.25 mm but make it User Definable

42 J-STD-001 Chip Component Solder Joints Visible Wetting Evident on the vertical surfaces of the component termination Minimum End Solder Fillet 25% of Height or 0.50 mm Whichever is Less Class 3 Minimum End Solder to be 75% of the Length. The Pad Width is Critical Class 3 The Side and Heel are Nominal Values But Must Insure Centering The Pad Spacing Center to Center is Critical To Avoid Excess Heel

43 New Pad Center Calculations Toe Nominal E Nominal L Heel Pad Length Pad Centers C L Pad Length = Nom L + Heel + Toe Pad Centers = Nom E + 2 Toes Pad Length

44 Old BGA Solder Joint Goal Recommendations Nominal Ball Diameter Reduction Nominal Land Diameter Land Variation % % % % % % % % % % %

45 New Collapsing BGA SJG Recommendations A Single Simple Ball Diameter to Pad Size Calculation Proportional SMD Pad Stack Collapsing Ball Grid Array (BGA) Pin Pitch Adj. % New Pad SizeOld Pad Size Pad Round-off Courtyard Excess Nominal Ball (mm) Fixed Fixed 80% of Pin Pitch % % % % % % % % %

46 New Non-collapsing BGA SJG Recommendation Proportional SMD Pad Stack Non-Collapsing Ball Grid Array Pin Pitch Adj. % Pad Size Pad Round-off Courtyard Excess Nominal Ball (mm) Fixed Fixed 80% of Pin Pitch % % % % % % % % % % %

47 Chapters 8 & 9 Total Rewrite Component Family Grouping by Pin Quantity 3D Model Picture of Each Component Land Pattern Pictures with Level A & B Rotations Updated Solder Joint Goal Tables Naming Convention: Mfr. Part Number or Case New Chapter on Aspects of 3D Modeling Appendix Introduces Drafting Outline Guidelines Relocating all Assembly Related Data to the new IPC-7070 Component Mounting Issues and Recommendations

48 PCB Library Expert

49 The Footprint (FP) Designer Module Traditional footprint software only calculates standard parts, constraining usage to only 50% of the components in the industry. PCB Library Expert also creates mfr. recommended footprints for components with the following characteristics: Asymmetrical Various sizes of pads Different pad shapes

50 PCB Library Expert CAD Tool Interfaces Allegro OrCAD PCB Editor OrCAD Layout Board Station Expedition PADS Layout Altium Designer P-CAD CADSTAR CR-5000 Eagle Ultiboard Pantheon Other formats in development

51 Questions?