HDI. HDI = High Density Interconnect. Kenneth Jonsson Bo Andersson. NCAB Group

Transcription

1 HDI HDI = High Density Interconnect Kenneth Jonsson Bo Andersson NCAB Group

2 Definitions / Standards (IPC) Pros & Cons Key equipment Build-ups Choice of material Design rules IPC HDI reliability (µvia stacked / filled) (Copper pillar technology) Topics

3 Definitions / Standards for HDI IPC-2221A Generic Standard on Printed Board Design (5/03) IPC-2222 Sectional Design Standard for Rigid Organic Printed Boards (2/98) Final draft A IPC-7095B Design and Assembly Process Implementation for BGAs (03/08) IPC-6011 Generic Performance Specification for Printed Boards (7/96) IPC-6012B Qualification and Performance Specification for Rigid Printed Boards (03/08) Final draft C IPC-4101C Specification for Base Materials for Rigid and Multilayer Boards (07/09)

4 Definitions / Standards for HDI IPC-DD-135 Qualification Testing for Deposited Organic Interlayer Dielectric Materials for Multichip Modules (8/95) IPC-2226 Sectional Design Standard for High Density Interconnect (HDI) Boards (04/03) IPC/JPCA-2315 Design Guide for High Density Interconnects (HDI) and Microvia (06/00) IPC-6016 Qualification & Performance Specification for High Density Interconnect (HDI) Layers or Boards (05/99) IPC-4104 Specification for High Density Interconnect (HDI) and Microvia Materials (5/99)

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6 Definitions / Standards for HDI HDI general description Printed circuit board with a higher wiring density per unit area than conventional printed circuit boards (PCB). They have finer lines and spaces ( 100 µm), smaller vias (<150 µm) and capture pads (<400 µm), and higher connection pad density (>20 pads/cm2) than employed in conventional PCB technology. IPC-2226 definition of microvia A blind hole with a diameter ( 150 µm) having a pad diameter ( 350 µm) formed by either laser or mechanically drilling. IPC-T-50H: High Density Interconnect (HDI) A generic term for substrates or boards with a higher circuit density per unit area than conventional printed boards.

7 IPC-2226 defines HDI in 6 classes Type I 1(C)0 or 1(C)1 Defines a single microvia layer on either one or both sides of core. Core can be multilayer, rigid or flex. Core is typically manufactured using conventional PWB techniques. Uses both plated microvias and plated through holes for interconnection. Employs blind, but not buried vias.

8 IPC-2226 defines HDI in 6 classes Type II 1(C)0 or 1(C)1 Defines a single microvia layer on either one or both sides of core. Core can be multilayer, rigid or flex. Core is typically manufactured using conventional PWB techniques. Uses both plated microvias and plated through holes for interconnection. Employs blind and buried vias.

9 IPC-2226 defines HDI in 6 classes Type III 2 (C) 0 Defines at least two layers of microvia layers on either one or both sides of core. Core can be multilayer, rigid or flex. Core is typically manufactured using conventional PWB techniques. Uses both plated microvias and plated through holes for interconnection. Employs blind and buried vias.

10 IPC-2226 defines HDI in 6 classes Type IV 1 (P) 0 Defines to have at least one microvia layer on either one or both sides of core. Core is typically manufactured using conventional PWB techniques. Uses both plated microvias and plated through holes for interconnection. Uses a passive core not electrically connected, used normally for CTE management.

11 IPC-2226 defines HDI in 6 classes Type V Coreless Uses thin cores which uses both plated microvias and conductive paste interconnections. Uses B-stage resin system prepreg where conductive material locally have been placed.

12 IPC-2226 defines HDI in 6 classes Type VI Constructions A construction where connections are buildup without normal plating. The connections are formed with conductive ink, or other type of conductive material. Examples as ALIVH (Any-Layer, Inner Via Hole )and PALAP (Patterned Prepreg Lay Up Process ) both Japanese inventions.

13 Pros & Cons HDI PCB Pros Increased interconnection density by miniaturization of holes, pads and conductors. Provides the possibility to have a via hole connect direct in the SMD or BGA pad. Improved signal integrity due to reduced tracklength. Improved possibility to maximization of ground connections. Opportunities of better thermal enhancement. Improved reliability by stepping up technology rather than compromising existing design rules.

14 Pros & Cons HDI PCB Cons Some technologies are at early stage yet. There are different ways to achieve similar technology (copper filling, drilling). Lower Yield. Most suppliers can do everything (risks costly experience). Limits available suppliers. Stepping up to advanced technology without proper need (or knowledge). Expensive equipment.

15 Production key equipment LDI Class 1000 clean room with auto alignment exposure units and LDI

16 Production key equipment Automatic lay-up Automatic lay up and high capacity lamination press with auto-loading

17 Production key equipment New generation of CO² laser drilling machines

18 Production key equipment Horizontal Cu plating line VCP line In processing Good HDI Cu plating solution with horizontal copper plating line plus vertical continuous plating line

19 Build-ups VOP Buildup 3 Buildup 2 Buildup 1 CCL Thru via Buried via Staggered via Triple stacked Microvia Stack via All the structure as above are available for mass production

20 Choice of Material

21 Choice of Material There are a wide range of materials that can be used for build-ups on HDI boards. RCC (Resin coated copper) LDP (Laser drillable prepreg) PP (prepreg) NWA (Non woven aramide) epoxy & polyimide Polyimide Speedboard C (Gore) The most common are RCC, LDP and PP

22 Choice of Material RCC (Resin coated copper) This is as the name indicates a copper foil which are treated with epoxy resin. It is normally applied in two layers one layer with fully cured epoxy (c-stage) and a layer with semi cured epoxy (b-stage). Normally values are 25 or 35µm of c-stage epoxy and 35µm of b-stage epoxy. Copper C-stage B-stage

23 Choice of Material RCC (Resin coated copper) Benefits Easy to drill Even surface for fine lines Disadvantages High CTE values Expensive Lower amount of resin Lower peel strength than LDP Requires an even surface that it s bonded to Mismatched Dk with the core layer Short shelf life

24 Choice of Material LDP (Laser Drillable Prepreg) This is as the name indicates a prepreg that has been more adopted for laser drilling, the fiber bundles are more uniformly distributed so the laser beam always drills in a uniform material. This is very important since the epoxy is very easy to drill, but the glass fibers are more difficult. The laser drillable prepregs are normally made only in 106, 1080 & 2116 style.

25 Choice of Material LDP (Laser Drillable Prepreg) Benefits Cheap Same CTE as core layer High amount of resin Same Dk as core layer High peel strength Woven material increased rigidity Long shelf life Disadvantages More difficult to drill then RCC

26 Choice of Material What material should be used? Since HDI boards are a more sensible in construction and we now have switched to lead-free soldering there is a need for better material than for conventional multilayer boards. They key parameters are: Total CTE in Z-axis Decomposition temperature T260 T288 Glass transition temp (Tg)

27 Choice of Material New materials according to IPC-4101C >2 min >15 min >30 min <3,0 % >340 C >170 C Yes FR4 HF 130 >2 min >15 min >30 min <3,5 % >340 C >170 C N/A FR >5 min >30 min <3,5 % >325 C >150 C Yes FR4 HF >5 min >30 min <4% >310 C >110 C Yes FR4 HF 127 >2 mi >1 mi >3 mi <3, % >34 C >17 C N/A FR HF >5 min >30 min <3,5 % >325 C >150 C N/A FR4 HF >5 min >30 min <4% >310 C >110 C N/A FR4 HF >15 min >5 min >5 min >5min >5min 88 Yes N/A N/A Yes Yes ers > >2 min >30 min >30 min >30 min >30 min >30 min 60 <3,0 % <3,5 % <4% <4% <3,5% E 50 0 C >340 C >325 C >310 C >310 C >325 C >170 C >150 C >110 C >110 C >150 C FR4 FR4 FR4 FR4 FR4 SI

28 Choice of Material Conclusions: Use LDP instead of RCC foil as material for µvia Use high quality FR4 in cores and Prepreg Specify the material according to IPC standard

29 Design rules

30 Design rules Always aim for symmetrical build-ups even if µvias not are needed on both sides. Aspect ratio on blind hole should be kept well below 1:1, preferred 0.7:1 When using 2 levels of µvias, keep the copper balance good, fill out empty areas with ground plane, so the amount of resin is enough to make a good encapsulation of the tracks. Example of to high aspect ratio on µvia

31 Design rules - HDI plus 1 A B C D No Description Recommendation Capability Remark A Entry pad size 300µm 250µm L1 B Microvia size 100µm 100µm STD C Dielectric thickness 60-80µm 60-80µm STD D Capture pad size 300µm 250µm L2

32 Design rules - HDI plus 2 (staggered µvia) B A B C C E D No Description Recommendation Capability Remark A Entry pad size 300µm 250µm L1 & L2 B Microvia size 100µm 100µm V1-2 & V2-3 C Dielectric thickness 60-80µm 60-80µm L1-L2 & L2-L3 D Capture pad size 300µm 250µm L2 & L3 E Microvia pitch 400µm 350µm STD

33 Design rules - HDI plus 2 (stepped µvia) F A B C C D E No Description Recommendation Capability Remark A Microvia size 200µm 200µm V1-2 B Microvia size 100µm 100µm V2-3 C Dielectric thickness 60-80µm 60-80µm L1-L2 & L2-L3 D Capture pad size 300µm 250µm L3 E Entry / Capture pad 400µm 350µm L2 F Entry pad size 400µm 350µm L1

34 Design rules - HDI plus 2 (skip µvia) B A E C D No Description Recommendation Capability Remark A Microvia size 200µm 200µm V1-3 B Entry pad szie 400µm 350µm L1 C Dielectric thickness 140µm 140µm L1-L3 Max D Capture pad size 400µm 350µm L3 E Anti pad size 400µm 350µm L2 Min

35 Design rules - HDI plus 2 (stacked µvia) A B C C D No Description Recommendation Capability Remark A Entry pad size 300µm 250µm L1 B Microvia size 200µm 200µm V1-2 & V2-3 C Dielectric thickness 60-80µm 60-80µm L1-L2 & L2-L3 D Capture pad size 400µm 350µm L2 & L3 µvia between L2-L3 need to be copper filled

36 Design rules - HDI plus 2 (µvia on pad) A B C E D No Description Recommendation Capability Remark A Entry pad size 300µm 250µm L1 B Microvia size 100µm 100µm V1-2 C Dielectric thickness 60-80µm 60-80µm L1-L2 D Capture pad size 500µm 450µm L2 E Buried hole size 250µm 200µm

37 Examples

38 Examples

39 IPC and reliability

40 IPC and reliability IPC standards are divided into three classes; 1, 2 and 3. 3 is divided into Space and Military/Avionics (A, B etc.)

41 IPC and reliability Class 1 General Electronic products: Includes consumer products, some computer and computer peripherals suitable for applications where cosmetic imperfections is not important, and the major requirement is function of the complete printed board. Class 2 Dedicated Service Electronic Products: Includes communications equipment, sophisticated business machines, and instruments where high performance and extended life is required, and for which uninterrupted service is desired, but is not critical. Certain cosmetic imperfections are allowed. Class 3 High Reliability Electronics Products: Includes equipment and products where continued performance or performance on demand is critical. Equipment downtime can not be tolerated, and the equipment must function when required, such as life support systems or flight control systems. Printed boards in this class are suitable for applications where high levels of assurance are required and service is essential.

42 IPC and reliability IPC 6016 divides the boards into five Slash sheet Categories A. Chip Carrier B. Hand Held (cell phones, pagers) C. High performance (avionics, military, medical) D. Harsh Environment (automotive, space) E. Portable (laptops, PDAs)

43 IPC and reliability Does HDI automatically need higher IPC class? (e.g. class3)

44 IPC and reliability Does HDI automatically need higher IPC class? (e.g. class3) No, IPCs different classes has nothing what so ever to do with how advanced the PCB is, but what reliability demands are placed on the endproduct.

45 IPC and reliability Does HDI automatically need higher IPC class? (e.g. class3) No, IPCs different classes has nothing what so ever to do with how advanced the PCB is, but what reliability demands are placed on the endproduct. Higher IPC class is not necessary advanced boards but always boards for advanced purposes!

46 IPC and reliability The standards and demands can be divided into three parts: 1. Design and Capability driven 2. Process control driven 3. Verification driven

47 IPC and reliability Design and Capability driven Annular rings Conductor imperfections

48 IPC and reliability Copyright by IPC Pictures by permission of IPC

50 IPC and reliability Process control driven Drilling and plating quality Surface finish thicknesses

53 IPC and reliability Verification driven To make likely the product will fulfil the demands

54 IPC and reliability IPC 6012 (Rigid), IPC 6013 (Flexible), IPC 6016 (HDI) Table 4-2 Sampling Plan Table 4-3 Acceptance Testing and Frequency Table 4-3, the part Structural Integrity Verification (Microsection), describes the verification level and number of microsections to test.

55 Copyright by IPC Pictures by permission of IPC IPC and reliability

56 Copyright by IPC Pictures by permission of IPC IPC and reliability

57 IPC and reliability Copyright by IPC Pictures by permission of IPC Copyright by IPC Pictures by permission of IPC

58 IPC and reliability Verification driven Cross sectioning Example: For a production lot of production panels of a four layer board, the verification only for the internal annular rings demands 250 cross-sectioning. It is important to understand that the verification is on a product level. Not to be mixed up with the cross sectioning for the ordinary process-control.

59 IPC and reliability This does not make sense!

60 IPC and reliability This does not make sense! NCAB suggest that the verification part should be separated and divided into several levels which will match to real life and make it possible to specify after the need of the product.

61 NCAB offers three different levels of IPC class boards NCAB level 1 Full verification Meeting end customer demands Limited numbers of manufacturers Extremely high cost NCAB level 2 Production and verification according to IPC A 600, IPC 6012, micro sectioning According to table 4-2 and 4-3 AQL 4.0, except for less than 26 panels, two micro Sections per production batch applies Meeting the majority of main end customers demands (also high reliability) Fairly cost effective Dual sourcing possible NCAB level 3 Production and verification according to IPC A 600, IPC 6012, two micro sections/production batch. Meeting a specific end customers demands Cost effective Multi sourcing possible IPC and reliability

62 The NCAB Group