True Position GD&T With respect to the MXM Application

Transcription

1 True Position GD&T With respect to the MXM Application

2 Agenda Introduction MXM specification 1.3 PCB & Connector Fab Specification Old & New comparison ASME Y14.5M 2004 GD&T with respect to MXM PCB information Integrity MXM PCB Certification Plan MXM Connector Specification Analysis MXM Connector Certification Plan MXM Connector Inspection per GD&T MXM PCB Inspection per GD&T MXM PCB First Article Inspection Q&A

3 MXM

4 MXM PCB Fab Finger

5 MXM PCB Fab Finger

6 Old Specification

7 Old Tolerance

8 Notes on the Old Fab Drawing

9 MXM Connector Specification

10 The New PCB Fab Drawing

11 MXM Fab Drawing

12 Gold Finger Dimensioning

13 Gold Finger Dimensioning

14 Gold Finger Dimensioning

15 The Update Description

16 The GD&T Standard ANSI & ASME ASME Y14.5M 1994 Geometric Dimensioning & Tolerance 形位公差 ( 形狀位置公差 ) ISO ISO ISO ISO ISO ISO ISO China (PRC) GB/T 形状和位置公差通则 定义 符号和图样表示法 GB/T 公差原则 GB/T 几何公差位置度公差注法 GB/T 形状和位置公差最大实体要求 最小实体要求和可逆要求 GB/T 形状和位置公差非刚性零件注法

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18 Overview Basic Dimensions ( 理論正確尺寸 ) True Position ( 位置度 ) Material Conditions ( 實體狀態 ) The Feature Control Frame ( 形位公差框格 ) Positional Tolerance in the Feature Control Frame ( 位置公差 ) How Positional Tolerance is Derived ( 位置公差的換算 ) Bonus Tolerance ( 公差帶 ) The MXM Specification (MXM 標準 ) True Position Slot Tolerance ( 狹長孔的公差 ) How Datum D is Established ( 基準 D 之建立 ) Image & Etch Registration ( 成像及蝕刻精準度 ) Clarification of the MXM Spec (MXM 標準的解讀 )

19 Basic Dimensions: Basic dimensions appear on the drawing as a number in a rectangular box. A basic dimension has NO TOLERANCE and is only intended to establish the theoretical centerline from which the standard deviation is to be measured. In the MXM Spec, the 2.33 (.092"), 2.67 (.105") top side and 2.08 (.082"), 2.17 (.085") bottom side are the basic dimensions.

20 Geometric Characteristic Symbols

21 True Position

22 Material Conditions: In GD&T the tolerance applied is relative to the material conditions. True Position with respect to M controls interference. If the failure would occur when the largest peg cannot fit into the smallest hole, then this is considered the Maximum Material Condition. An M in the feature control frame would indicate that the true position tolerance is with respect to the max material condition. MMC = largest Pin or the smallest Hole 最大實體要求 最小實體要求 True Position with respect to L controls alignment. If the failure would occur when the smallest pin falls off the smallest track, then this is considered the Least Material Condition. An L in the feature control frame would indicate that the true position tolerance is with respect to the least material condition. LMC = smallest Pin or largest Hole 獨立原則 True Position with respect to S controls balance. Here the tolerance in the feature control frame must be followed regardless of feature size.

23 Example of Interference Control by MMC At MMC (the smallest hole) has the least amount of Positional tolerance As you move away from the MMC towards the LMC (the largest hole) you gain additional positional tolerance

24 Example of Alignment Control by LMC Contact Pad Nominal At LMC (the narrowest pad) has the least amount of Positional Tolerance As you move away from LMC towards the MMC (the widest pad) you gain additional Positional Tolerance

25 The Feature Control Frame M True Position Positioned From Parallel To Perpendicular To At Maximum Material Condition Positional Tolerance With Respect To the Material Condition In the example shown, the first box defines the function of the feature control frame which is true position. The second box defines the tolerance with respect to the condition and the 3rd, 4th & 5th boxes define the datum s. The best practice is to ensure that datum s are always in the order of perpendicularity, parallelism and then position. So, for that reason the datum s may not always be in alphabetical order.

26 Positional Tolerance in the Feature Control Frame The tolerance shown in the feature control frame is the total tolerance window which means that the center line of the feature must be within a.123 tolerance window established by the centerline of the basic dimension. This is NOT a +/- tolerance.

27 How Positional Tolerance is Derived Example # A A B / B / M A B C M A B C MMC for the female part is: = MMC for the male part is: = So, the available positional tolerance at MMC =.000

28 How Positional Tolerance is Derived. Example # A A B / B / M A B C M A B C MMC for the female part is: = MMC for the male part is: = So, the available positional tolerance at MMC =.010 Note: The positional tolerance is NOT (+/-). It is a total window (of.010 in this case)

29 Bonus Tolerance A B / M A B C The part at MMC is and at MMC then only the.010 tolerance window is available to meet the specification. As the actual parts move away from the Maximum Material Condition, then bonus tolerance becomes available. Example 1: If the actual part feature size is then it is.005 away from the MMC of =.005 This is the bonus tolerance The bonus tolerance is added to the positional tolerance in the feature control frame =.015 is the true position tolerance window for this part Example 2: If the actual part feature size is then it is.010 away from the MMC of =.010 This is the bonus tolerance The bonus tolerance is added to the positional tolerance in the feature control frame =.020 is the true position tolerance window for this part

30 Bonus Tolerance (continued) The part at MMC is and at MMC then only the.000 tolerance window is available to meet the specification. As the actual parts move away from the Maximum Material Condition, then bonus tolerance becomes available. Example 1: If the actual part feature size is then it is.005 away from the MMC of =.005 This is the bonus tolerance The bonus tolerance is added to the positional tolerance in the feature control frame =.005 is the true position tolerance window for this part Example 2: If the actual part feature size is then it is.010 away from the MMC of =.010 This is the bonus tolerance The bonus tolerance is added to the positional tolerance in the feature control frame =.010 is the true position tolerance window for this part

31 Is this spec manufacturable? YES, it tells the part supplier to stay away from MMC to attain the necessary bonus tolerance.

32 The MXM Specification How the Feature Control Frame Tolerance was Derived At the Maximum Material Condition of the PCB Slot is =.037 The Connector Male Key Feature is /-.02mm ( / ) MMC = = light interference fit when both parts are at MMC, for this design this is acceptable. The amount of lateral shift caused when both parts are at LMC determines the failure mode. The slot.041 key.0358 =.0052 which is very close to a disconnect. If the working film is registered to the slot the positional tolerance can be.002 at LMC

33 How The Slot is Formed with Accuracy The Slot is formed in the drilling process, as shown above. That is why the feature control frame indicates the datums perpendicular to A, parallel to B and positioned from hole C. Registration of the working film to the PCB is based on the drilled pattern, which can maintain a tolerance tighter than +/-.05mm (+/-.002 ). This can not be done based on the routing process which can only maintain +/-.13mm (+/-.005 ).

34 True Position Slot Tolerance LMC defines the failure mode caused by lateral shift, which will cause a disconnect. There is little concern if the slot fits tightly because the mounting holes have a liberal tolerance. By avoiding the LMC you gain the maximum true position tolerance. At LMC =.041 the positional tolerance is.002 and there is no bonus tolerance. At nominal =.039 the p. t bonus tolerance.002 =.004 true position tolerance At MMC =.037 the p.t bonus tolerance.004 =.006 true position tolerance The slot forms a new datum D for the positional control of the gold finger patterns

35 Working Film to Key Slot Registration If the working film is simply registered to the datum C tooling hole then the positional tolerance with respect to the LMC is.000 If the working film is registered to the datum D slotted hole by utilizing the dummy pad provided in the gerber file, then the positional tolerance with respect to the LMC is.002 This Pad is to be used for working film registration to the pre-drilled slot / L A B C

36 Image & Etch Registration

37 Image & Etch Registration (continued) The failure condition is based on the most narrow connector contact pin in relation to the most narrow gold finger pad. This requires the use of Least Material Condition (LMC) tolerance control to define the failure mode when the pin and pad lose connection. The gold finger is defined as /-.03mm feature size. At LMC 0.32mm the gold finger has no bonus tolerance. At nominal 0.35mm the gold finger has 0.03mm bonus tolerance. At MMC 0.38mm the gold finger has 0.06mm bonus tolerance. The positional tolerance in the feature control frame is.15mm at LMC with respect to the center of the slot datum D Example of feature size, bonus tolerance + positional tolerance = true position tolerance True Position at 0.32 is =.15mm ( This is a.006 window = +/-.003 ) True Position at 0.35 is =.18mm ( This is a.007 window = +/ ) True Position at 0.38 is =.21mm ( This is a.008 window = +/-.004 ) Note: If.15mm (+/-.075mm) is difficult to manufacture, then optimize the working film to avoid the Least Material Condition. By producing wider gold fingers you can gain more Bonus Tolerance.

38 Clarification of the MXM Spec The purpose of the true position specified here is for connectivity only. Therefore, we are not concerned with the areas of the feature below the top contact surface. Note that Datum A is not in the feature control frame, so there is no requirement for perpendicularity from the PCB surface. Per 0.15 at Least Material Condition, every pad in the array must be centered within the true position tolerance with respect to the slot datum D The 0.50mm Pitch needs to be balanced and therefore controlled by S (regardless of feature size) at S means that each pad must be centered within.05mm of the centerline of the adjacent pads on either side of it.

39 Thank You on behalf of NVIDIA Author: George A. Sorensen NVIDIA Corp. PCB/PCA Process Eng. Mgr Document Number: Revision A, Date

40 PCB information Integrity Note: The design is base on NVIDIA Reference design PXXX (180-XXXXX-XXXX REV XXX)

41 MXM PCB Fab Certification Plan GD&T training Understand GD&T Controlled Build Have Good Yield instead of ~70%

42 MXM PCB Fab Supplier Certified Tripod (PingCheng Plant) Unimicron (ShanYing Plant, ShenZhen Plant) Topsearch (ShenZhen Plant) E&E (GuangZhou Plant) Viasystem (GuangZhou Plant) GCE (ChungLi Plant) Under Certification OPC (SYE, DMC) CCTC (Shantou) As of October 2006

43 MXM Failure Mode Mating Open or Short? How to Verify?

44 MXM Connector Supplier ACES EDAC FOXCONN QUASAR SPEEDTEC TYCO (List for illustration only as of October 2006)

45 MXM Connector Study what it should look like 2.08mm.0366" +/-.0008".001" L A B 0.03 L A B Alignment Key Rib C / C.082" 230 X.25mm +/-0.03mm 0.08mm L A 230 X.010" +/-.001" C.003" L A C D D Contact Well Contact Surface -A - 0.5mm Pitch X.XX /-.01mm (.008" +/-.0004") 0.1mm M A C D Solder Tail Portion ONLY.06mm M A Solder Tail Coplanarity

46 0.15 mm Contact Width (MMC)

47 0.15 mm Contact Width (LMC)

48 0.20 mm Contact Width (LMC)

49 0.20 mm Contact Width (MMC).2mm Contact Width (.008").2mm Contact Width (.008") Adjacent Pad.32mm (.013") Minimum Gold Finger Width.38mm (.015") Maximum Gold Finger Width Max. Shift Right.003" Potential Short at +/-.001" pad to pad Adjacent Pad Max. Shift Left.003" Adjacent Pad Adjacent Pad Max. Shift Left.004" Potential Short at +/-.001" Pad to pad Connector Contact MMC P.T. window is.0038" (~+/-.0019") Gold Finger P.T. window is.006" (~+/-.003) Connector Contact LMC P.T. window is.0085" (~+/-.0042") Gold Finger P.T. window is.008" (~+/-.004) Proper Contact Well Spec 230 X.25mm +/-0.03mm 0.08 M Y Z X = 230 X.010" +/-.001".004" M Y Z X Proper Spec Tolerance Per GD&T For 0.20mm Contact Width Contact Slop = contact well size -.2mm (.008") contact width Contact Well, True Position, Contact Slop, Total Positional Tolerance MMC.22mm, 0.08mm mm = 0.10mm (+/-0.05mm) MMC.009",.003" " =.0038" (+/-.0019") LMC.28mm, 0.14mm mm = 0.22mm (+/-0.11mm) LMC.011",.0055" +.003" =.0085" (+/-.0042") SPECIFICATION WRITTEN BY: A: George Sorensen SPECIFICATION RELEASE DATE: A: NVIDIA CORPORATION 2701 SAN TOMAS EXPRESSWAY, SANTA CLARA, CA SIZE FSCM NO DWG NO REV A A SCA MXM CONTACT STUDY SHE 1 : 1 LE 06.VSD ET 1 OF 7

50 MXM Connector Study Example ACES

51 MXM Connector Study Example SpeedTech

52 MXM PCB at MMC.014" +/-.001" gold finger.006" M Y Z Adjacent Pad X.2mm Contact Width (.008").38mm (.015") Maximum Gold Finger Width Max. Shift Right.003" Gold fingers at MMC Pcb Supplier is rewarded by getting best yield by holding to Smallest gold finger PCB supplier needs +/-.004" Tolerance for Manufacturability No Short at +/-.001" pad to pad Plenty of margin.2mm Contact Width (.008").32mm (.013") Minimum Gold Finger Width Adjacent Pad PCB Supplier will aviod this condition. Proper Contact Well Spec Max. Shift Left.003" Connector Contact LMC P.T. window is.006" (~+/-.003") 230 X.25mm +/-0.03mm 0.08 L Y Z X Adjacent Pad Gold Finger P.T. window is.006" (~+/-.003) Contact Slop = contact well size -.2mm (.008") contact width Contact Well, True Position, Contact Slop, Total Positional Tolerance LMC.28mm, 0.08mm mm = 0.16mm (+/-0.08mm) LMC.011",.003" +.003" =.006" (+/-.003") MMC.22mm, 0.14mm mm = 0.18mm (+/-0.09mm) MMC.009",.0055" " =.0063" (+/-.0031") = Adjacent Pad Max. Shift Left.004" Gold Fingers at LMC.014" +/-.001" gold finger 230 X.010" +/-.001".006" M Y Z.003" L Y Z SPECIFICATION WRITTEN BY: A: George Sorensen SPECIFICATION RELEASE DATE: A: Connector Contact MMC P.T. window is.0063" (~+/-.0031") X X No Short at +/-.001" Pad to pad Gold Finger P.T. window is.008" (~+/-.004) Proper Spec Tolerance Per GD&T For 0.20mm Contact Width With PCB Control by MMC NVIDIA CORPORATION 2701 SAN TOMAS EXPRESSWAY, SANTA CLARA, CA SIZE FSCM NO DWG NO REV A A SCA MXM CONTACT STUDY SHE 1 : 1 LE 06.VSD ET 1 OF 8

53 MXM Connector Inspection

54 MXM Connector Inspection

55 MXM Connector Inspection Set Zero at the basic datum. Move to the basic dimension 7.28mm ( ) Move to the center line of the feature. In this example: = from center

56 MXM Connector Inspection Measure the feature size. Add the bonus tolerance to the positional tolerance and verify if the part is within spec mm (.0366 ) has bonus tolerance of 0.02mm (.0008 ) + positional tolerance of.03mm (.001 ) =.05mm (.002 ) True position.05mm (.002 ) = +/-.025mm (+/-.001 ) so.025mm (-.001 ) is within spec.

57 MXM Connector Inspection -C - -D -

58 MXM Connector Inspection Move to the New Feature Datum center / 2 = zero the CMM Note: we are measuring the contact well because the actual contact can have some positional shift within the well. Move the CMM to the basic dimension 2.08mm (.082 ) and zero the CMM Then move the CMM to center of the same contact well and read the deviation. This is the first contact from the alignment rib

59 MXM Connector Inspection Verify the bonus tolerance and positional tolerance to see if the part meets the true position requirement. Measure the contact well opening size 0.23mm (.009 ) has bonus tolerance of 0.05mm (.002 ) + positional tolerance of.08mm (.003 ) =.13mm (.005 ) True position.13mm (.005 ) = +/-.065mm (+/ ) so.035mm ( ) is within spec. 102 contacts at 0.5mm pitch = 51mm (2.008 ) mm (.082 ) basic dimension = 53.08mm (2.090 )

60 MXM Connector Inspection 2.08mm.082" 230 X.25mm +/-0.03mm 0.08mm L A C 230 X.010" +/-.001".003" L A C D D Contact Well Contact Surface 0.5mm Pitch /-.01mm (.008" +/-.0004") 0.1mm M A C D Solder Tail Portion ONLY.06mm M A Solder Tail Coplanarity

61 MXM Connector Inspection 53.08mm (2.090 ) mm (2.092 ) =.05mm (.002 ) Measure the contact well opening size. Verify the bonus tolerance and positional tolerance to see if the part meets the true position requirement. 0.25mm (.010 ) has bonus tolerance of 0.025mm (.001 ) + positional tolerance of.08mm (.003 ) =.105mm (.004 ) True position.105mm (.004 ) = +/-.052mm (+/-.002 ) so.05mm (-.002 ) is within spec.

62 MXM PCB Inspection

63 MXM PCB Inspection

64 MXM PCB Inspection Typical MXM PCB Gold Finger design Set the CMM to zero on the Datum Pad

65 MXM PCB Inspection = Move CMM to Basic Dimension from Fab drawing Then move to the center of the slot. Measure the feature size Add the bonus tolerance to the positional tolerance and verify if the part is within spec. 0.99mm (.039 ) has bonus tolerance of 0.05mm (.002 ) + positional tolerance of.05mm (.002 ) =.10mm (.004 ) True position.10mm (.004 ) = +/-.05mm (+/-.002 ) so -.055mm (-.002 ) is within spec.

66 MXM PCB Inspection Move the CMM to the center of the slot to establish the new Datum D (.0396 / 2 =.0187 ) and set to Zero. Move the CMM to the Basic Dimension 2.33mm (.092 ) per the fab drawing.

67 MXM PCB Inspection Set the CMM to zero then move the CMM to the center line of the pad and take the reading (example.0014 ) Measure the feature size and add the bonus tolerance to the positional tolerance. 0.33mm (.013 ) has bonus tolerance of 0.00mm (.000 ) + positional tolerance of.15mm (.006 ) =.15mm (.006 ) True position.15mm (.006 ) = +/-.075mm (+/-.003 ). So -.036mm ( ) is within spec.

68 MXM PCB Inspection Move the CMM to the last gold finger. Zero the CMM at the theoretical location 51.83mm (2.041 ) 99 contacts at 0.5mm pitch = 49.5mm (1.949 ) mm (.092 ) basic dimension = 51.83mm (2.041 ) Measure the actual size of the gold finger and add the bonus tolerance to the positional tolerance 0.35mm (.014 ) has bonus tolerance of 0.025mm (.001 ) + positional tolerance of.15mm (.006 ) =.175mm (.007 ) True position.175mm (.007 ) = +/-.0875mm (+/ ). So -.031mm ( ) is within spec

69 MXM PCB Fab 1st Article Inspection

70 Thank You on behalf of NVIDIA Author: George A. Sorensen NVIDIA Corp. PCB/PCA Process Eng. Mgr Document Number: Revision A, Date