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DfX	Engineering	
A Design for Cost approach to PCB Layout
www.dfxengineering.com
Design	For	Cost	Process	
Material	Selec+on	and	part	size	–	Driven	by	Material	Type	(cost	vs.	performance	trade	offs),	
Size...
Design	Goal		
•  What	is	your	producIon	volume	and	how	does	it	compare	to	
capacity?	Are	you	in	the	right		producIon	site	...
Robust	Market		
Know	your	suppliers	capabiliIes,	and	material	vendors	
DfX	Engineering,	LLC,	2016
MATERIAL	SELECTION	
Performance,	Dk	and	size
BOM	Cost	Analysis	Basis	
As	Material	is	the	most	significant	factor	in	PCB	we	will	talk	about	building	a	cost	
model	from	t...
1	Ghz	–	Df	Resin	Rich,	Resin	Poor	
0.000		
0.005		
0.010		
0.015		
0.020		
0.025		
Std.	
Loss	
Upper	Mid	Loss	 Low	Loss	 V...
4	Ghz	–	Df	Resin	Rich,	Resin	Poor	
0.000		
0.005		
0.010		
0.015		
0.020		
0.025		
Std.	
Loss	
Upper	Mid	Loss	 Low	Loss	 V...
8	Ghz	–	Df	Resin	Rich,	Resin	Poor	
0.000		
0.005		
0.010		
0.015		
0.020		
0.025		
0.030		
Std.	
Loss	
Upper	Mid	Loss	 Low...
Material	SelecIon	Decision	Tree	
Tg	Decision	
Point	
Key	Factor	
Considera+ons:	
•  Overall	Thickness	
•  Aspect	RaIo	
•  ...
Material	SelecIon	Cost	Impact	
Cost	
Factor	
1X	
2X	
3X	
150	
Tg	
170	
Tg	
>200	
Tg	
3.7Dk	
3.5Dk	
<3.0Dk	
STD	
RTF	
VLP	o...
Material	Cost	v	Performance	Analysis	
UIlize	an	extensive	material	tesIng	program	to	
provide	a	comprehensive	cost	v.	perf...
MATERIAL	OPTIMIZATION	
Best	Fit	Panel
Material	OpImizaIon	
DFM	and	DFC	analysis	will	opImize	part	size,	array	and	working	panel	to	provide	the	lowest	cost,	
mos...
Panel	U+liza+on	
PCB	Laminate	material	is	
purchased	in	Master	sheets	and	
then	cut	into	working	panels.		
The	Master	shee...
Panel	U+liza+on	
Typical	Working	Panel	Sizes:	
18x24	
20x24	
21x24	
	
	
36”	
24”	
18”	
48”	
	
*	There	are	many	op+ons	depe...
Panel	U+liza+on	-	cross	cuRng	
Cross	cunng	is	a	working	panel	opIon	in	some	cases.		It	relies	on	cunng	material	
in	differe...
PPSI	–	Price	Per	
Square	Inch	
.	
Since	this	is	the	unit	of	shipment;	when	we	use	the	comparaIve	term	price	per	
square	in...
Panel	U+liza+on	 In	this	example	the	red	boxes	show		
6	PCB’s	or	PCB	arrays	panelized	on	
an	18	x	24.		We	would	divide	the...
FUNCTION	ANALYSIS	
How	many	funcIons	are	Ied	in	one	board
How	many	FuncIons	
Main	logic	board	
Processor	
4G	 Wi-Fi	BT	
PCB	budget	combined	
Processor	
4G	
Wi-Fi	
BT	
PCB	budget	se...
Same	Device	Designs,	Different	
Cost	ConstrucIons	
PCB	budget	combined	
Processor	
4G	
Wi-Fi	
BT	
PCB	budget	separate	
Main...
PanelizaIon	Differences	
DfX	Engineering,	LLC,	2016
PanelizaIon	Differences	
DfX	Engineering,	LLC,	2016
PanelizaIon	Differences	
DfX	Engineering,	LLC,	2016
PROCESS	PARAMETER	SELECTION	
OpImize	features	for	the	center		not	the	limit
Reference	Plane	SelecIon	
S	
P	
S	
P	
S	
Split	
RP	
P	
SelecIng	the	right	reference	plane	
arrangement	can	opImize	feature...
BOM	Cost	Analysis	
DFM/DFC	analysis	will	break	down	every	layer	in	the	stack-up	for	comparaIve	cost	
analysis.			Glass	Sty...
HDI	vs.	ConvenIonal	
Inner	 Lam	 Drill	 Plate	
Outer	
Etch	
SES	
SM/	
Finish	
Test	
ConvenIonal	
HDI	
Inner	 Lam	 Drill	 P...
Device	SelecIon	
0.4mm	Pitch,	0.0157”	
0.5mm	Pitch,	0.0196”	
0.6mm	Pitch,	0.0236”	
MicroVia	–	Hole	Size	.004,	Pad	.010”,	
...
RouIng	Guidelines	
Source:	HDI	Handbook	
DfX	Engineering,	LLC,	2016
Decision	Tree	For		
Design	Choices	
Feature	Size	 1.0	Cpk	 1.3	Cpk		 2.0	Cpk	
Line	width	
(HDI	Layer)	
45um	 53um	 63um	
L...
Cpk	Feature	Analysis	
All	criIcal	features	should	be	staIsIcally	analyzed		and	reviewed	to	ensure	
yield	performance	is	ma...
Surface	Finish	ConsideraIons	
Surface	Finish	 Cost	 Considera+ons	 Benefits	
OSP	 1	 Shelf	Life	Limits	 Flatness,	ease	of	
...
PROCESS	OVERVIEW	
Flow	Chart	for	cost	opImizaIon
Process	Overview	
Start	with	
Interconnect	
budget	
Review	material	
selecIon	for	type	
and	size	
opImizaIon	
OpImize	stac...
Process	Cost	Driver	Decisions	
•  AddiIonal	LaminaIons	versus	addiIonal	layers	
•  Drill	Size	versus	Pad	size	opImizaIon	
...
HIGH	COST	CHOICES	
Performance,	Dk	and	size
High	Cost	Choices	
•  VIPPO	–	AddiIonal	Steps	Epoxy	Fill,	PlanarizaIon,	Dual	plaIng	passes,	masking	
MulIple	drilling	pass...
HDI	Types	Explained	
Source:	HDI	Handbook	DfX	Engineering,	LLC,	2016
HDI	Types	Explained	
DfX	Engineering,	LLC,	2016				
Source:	HDI	Handbook
SequenIal	LaminaIon	
Take	careful	consideraIon	on	adopIng	these	design	choices	due	to	the	impact	
on	cost.		Analyze	and	qu...
Back-Drilling	
Take	careful	consideraIon	on	adopIng	these	design	choices	due	to	the	impact	
on	cost.		Analyze	and	quanIfy	...
Process	Overview	
Cost	Adder	impact	from	Design	Choices	
	
	Design	Choice	 Added	Processes	 Approximate	Cost	
Factor	on	MF...
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Dfx design for_cost

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A design for cost approach to PCB design. This presentation lays out a generic process for cost optimization in typical PCB design. This work is licensed under a Creative Commons Attribution 4.0 International License.

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Dfx design for_cost

  1. 1. DfX Engineering A Design for Cost approach to PCB Layout www.dfxengineering.com
  2. 2. Design For Cost Process Material Selec+on and part size – Driven by Material Type (cost vs. performance trade offs), Size related to master sheets not working panels and pre-preg selecIon opImizaIon (how does glass style affect BOM cost, and Stack-up / Construc+on Type: This is where you are focusing with your quesIons on both how are we rouIng out of devices and how many devices are we trying to rout in a single board, can we do it less expensively by making separate smaller boards, what interconnect scheme is the best cost. Cpk Op+miza+on On Capability: Here we review how do the rouIng of trace choices drive the feature size relaIve to the market’s capability at 2.0Cpk, and is there an alternate way to meet that to drive feature size to the center of the capability. What is the guide for HDI vs. ConvenIonal. If we chose a below 1.0Cpk Design feature is our detecIon system adequate for the volume we are producing. The design for cost process has three major areas to focus on for opImizing the cost features in a design. These three areas should interact repeatedly to refine to the best cost vs. performance trade off DfX Engineering, LLC, 2016
  3. 3. Design Goal •  What is your producIon volume and how does it compare to capacity? Are you in the right producIon site for your size. •  What Environmental CondiIons will you operate in? •  What reliability level do you require? •  What is your cost priority ranking? •  What are your tesIng requirements? •  Is delivery Ime and proximity a significant factor? •  Use FMEA to inform the decision process. DfX Engineering, LLC, 2016
  4. 4. Robust Market Know your suppliers capabiliIes, and material vendors DfX Engineering, LLC, 2016
  5. 5. MATERIAL SELECTION Performance, Dk and size
  6. 6. BOM Cost Analysis Basis As Material is the most significant factor in PCB we will talk about building a cost model from the base material, up. Early Ime spent in the areas of material type, and material uIlizaIon will pay the biggest returns. Pre-preg FR4 Cost index % 1078/1086 1.2 1080 1,0 1067 1.75 106 2.35 2116 1.20 1501/1506 1.65 3313/2113 1.55 7628 1.25 DfX Engineering, LLC, 2016 * Prices shown are examples only and need to be updated to specific circumstances
  7. 7. 1 Ghz – Df Resin Rich, Resin Poor 0.000 0.005 0.010 0.015 0.020 0.025 Std. Loss Upper Mid Loss Low Loss Very Low Loss Material SelecIon is More Complex DfX Engineering, LLC, 2016
  8. 8. 4 Ghz – Df Resin Rich, Resin Poor 0.000 0.005 0.010 0.015 0.020 0.025 Std. Loss Upper Mid Loss Low Loss Very Low Loss Material SelecIon is More Complex Vendor Base and Material choices have grown dramaIcally. Know your needs. DfX Engineering, LLC, 2016
  9. 9. 8 Ghz – Df Resin Rich, Resin Poor 0.000 0.005 0.010 0.015 0.020 0.025 0.030 Std. Loss Upper Mid Loss Low Loss Very Low Loss Material SelecIon is More Complex As Microwave Journal says: Frequency MaCers! DfX Engineering, LLC, 2016
  10. 10. Material SelecIon Decision Tree Tg Decision Point Key Factor Considera+ons: •  Overall Thickness •  Aspect RaIo •  Assembly condiIons including rework •  Reliability Useful Life Target Dk Range Df Range Key Factor Considera+ons: •  Impedance Goals •  Layer Constraints •  Resin Content (fill) •  Glass Styles Key Factor Considera+ons: •  OperaIng Frequency •  Loss SensiIvity •  Copper Roughness Profile Pick the Best Fit in each of these to find the ideal meaterial cost DfX Engineering, LLC, 2016
  11. 11. Material SelecIon Cost Impact Cost Factor 1X 2X 3X 150 Tg 170 Tg >200 Tg 3.7Dk 3.5Dk <3.0Dk STD RTF VLP or HVLP CriIcal areas are reliability, yield loss, and availability AddiIonal ConsideraIon of Halogen Free or Not 0.011 Df 0.009 Df <0.005Dk 0.006 Df DfX Engineering, LLC, 2016
  12. 12. Material Cost v Performance Analysis UIlize an extensive material tesIng program to provide a comprehensive cost v. performance analysis specific to your applicaIon. Main variables to consider, Tg, Dk, Df 0 1 2 3 4 5 6 Laminate Cost Final PCB Cost 16L Final PCB Cost 20L DfX Engineering, LLC, 2016
  13. 13. MATERIAL OPTIMIZATION Best Fit Panel
  14. 14. Material OpImizaIon DFM and DFC analysis will opImize part size, array and working panel to provide the lowest cost, most efficient soluIon. Depending on material selecIon master panel’s offered can vary, opImizing to the material provides the lowest uIlized square inches per part. DfX Engineering, LLC, 2016
  15. 15. Panel U+liza+on PCB Laminate material is purchased in Master sheets and then cut into working panels. The Master sheets come in sizes that are easy for the laminate suppliers to manufacture. The working panels are selected to fit on the equipment in the PCB factory. Laminates are sold in Price per square foot, so the bigger the panel the more expensive Typical Master Sheet Sizes: 36 x 48 40 x 48 42 x 48 * Special Order sizes are available in some cases Standard Master Panel Sizes PanelizaIon DfX Engineering, LLC, 2016
  16. 16. Panel U+liza+on Typical Working Panel Sizes: 18x24 20x24 21x24 36” 24” 18” 48” * There are many op+ons depending on tech and tooling Standard Panel Sizes Working Panels are then cut out of the master sheet, evenly if possible to maximize the uIlizaIon of the material. The more parts on a working panel the lower the unit cost. Both working and master panel do factor into material cost. We can express working and master panel uIlizaIons Working Panel Development DfX Engineering, LLC, 2016
  17. 17. Panel U+liza+on - cross cuRng Cross cunng is a working panel opIon in some cases. It relies on cunng material in different direcIons which can impact scale factors. Density and construcIon consideraIons need to be evaluated, and if available can be a good way to reduce the effecIve square inches per part. Working Panel AlternaIves DfX Engineering, LLC, 2016
  18. 18. PPSI – Price Per Square Inch . Since this is the unit of shipment; when we use the comparaIve term price per square inch we need to compare unit price to area shipped. Forumla PPSI = Unit Price / (Array Area/Array number up) Unit price is divide Unit Price by the area of the array divide by the array number up. This way we capture the Unit Part plus it’s porIon of the rails. Effec+ve square inches per part is the best compara+ve index when analyzing PCB op+ons. Shown here is a 6-up array or 6 single PCB Images that are connected by tabs, and two assembly rails are apached. Oqen the PCB’s are sold as an array. (A no x-out array assumes all images on the array are Good) PanelizaIon – Array Design DfX Engineering, LLC, 2016
  19. 19. Panel U+liza+on In this example the red boxes show 6 PCB’s or PCB arrays panelized on an 18 x 24. We would divide the RED area by the BLUE area to calculate Panel uIlizaIon as a percentage. Since PCB labor costs are applied to working panels the more parts on a panel the lower the unit cost. Number up per working panel is the number of total 1 up images on the working panel (Array number up x array’s per WPNL) We can never reach 100% uIlizaIon because we need space between parts for cunng tools to separate them, we need a panel border to apach to some electroplaIng equipment, and we need some room for destrucIve tesIng coupons. ComparaIve analysis should be used to assess the quality of your pricing and designs. 24” 18” PanelizaIon DfX Engineering, LLC, 2016
  20. 20. FUNCTION ANALYSIS How many funcIons are Ied in one board
  21. 21. How many FuncIons Main logic board Processor 4G Wi-Fi BT PCB budget combined Processor 4G Wi-Fi BT PCB budget separate Can sizes and rouIng be opImized to break out PCB’s into more manufacturable lower cost unit with different interconnect scheme camera camera compare DfX Engineering, LLC, 2016
  22. 22. Same Device Designs, Different Cost ConstrucIons PCB budget combined Processor 4G Wi-Fi BT PCB budget separate Main logic board Processor 4G Wi-Fi BT camera camera compare Total Layers = 10 HDI (2+6+2) Number Up 18 x 24 = 16 (4”X5”) BOM Cost = $20 Material Part Cost = $1.25 Total Layers = 10 HDI (2+6+2) Number Up 18 x 24 = 44 (2” x 4”) BOM Cost = $20 Material Part Cost = $.23 Main Board Total Layers = 6 HDI (2+2+2) Number Up 18 x 24 = 154 BOM Cost = $12 Material Part Cost = $.07 Total Layers = 4 HDI (1+2+1) Number Up 18 x 24 = 300 BOM Cost = $10 Material Part Cost = $.02 4G Card Acc Card (2X) PCB Budget Significantly Reduced DfX Engineering, LLC, 2016
  23. 23. PanelizaIon Differences DfX Engineering, LLC, 2016
  24. 24. PanelizaIon Differences DfX Engineering, LLC, 2016
  25. 25. PanelizaIon Differences DfX Engineering, LLC, 2016
  26. 26. PROCESS PARAMETER SELECTION OpImize features for the center not the limit
  27. 27. Reference Plane SelecIon S P S P S Split RP P SelecIng the right reference plane arrangement can opImize feature size. Consider reference planes two layers away or lower Dk Material selecIon to improve feature size. Other important stack-up consideraIons for best manufacturing cost are: •  Balanced copper cores •  Good ref. distance for L/W OpIzaIon •  Reduce variaIon in pre-preg selecIon to avoid layup error yeild impact. DfX Engineering, LLC, 2016
  28. 28. BOM Cost Analysis DFM/DFC analysis will break down every layer in the stack-up for comparaIve cost analysis. Glass Style, core construcIon and resin content will have cost impact on the BOM cost. Cost factors dynamically adjust based on use over Ime and new market entrants like 1037, 1027 glass will change price based on usage, so need to maintain conInual updates for Imely cosIng in your model. Pre-preg FR4 Cost index % 1078/1086 1.2 1080 1,0 1067 1.75 106 2.35 2116 1.20 1501/1506 1.65 3313/2113 1.55 7628 1.25 DfX Engineering, LLC, 2016 * Prices shown are examples only and need to be updated to specific circumstances
  29. 29. HDI vs. ConvenIonal Inner Lam Drill Plate Outer Etch SES SM/ Finish Test ConvenIonal HDI Inner Lam Drill Plate Outer Etch SES Plate/Cu fill SM/ Finish Test Lam Laser Drill Outer Etch SES Repeat for number of build up layers In lower layer count boards, material can be 30-45% of cost leaving the majority of price for processing cost and OH. HDI adds significant criIcal steps. Analysis on BOM cost savings and feature size should be reviewed when selecIng HDI, target to save at least 2 cores reducIon in total layers or if device pitch absolutely requires it for rouIng. DfX Engineering, LLC, 2016
  30. 30. Device SelecIon 0.4mm Pitch, 0.0157” 0.5mm Pitch, 0.0196” 0.6mm Pitch, 0.0236” MicroVia – Hole Size .004, Pad .010”, Copper filled to get full .010 pad area for solder assembly. .0057” rouIng Space = 1 Track rouIng 48um at (0.0019”) trace and space .0096” rouIng Space = 1 Track rouIng at 75um .013” rouIng Space = 2 Track rouIng at 65um Best Aspect RaIo on MV is 1:1 so max dielectric on outer layer is . 004”. If ConvenIonal drilling smallest drill is .008” and will need .018” pad size DfX Engineering, LLC, 2016
  31. 31. RouIng Guidelines Source: HDI Handbook DfX Engineering, LLC, 2016
  32. 32. Decision Tree For Design Choices Feature Size 1.0 Cpk 1.3 Cpk 2.0 Cpk Line width (HDI Layer) 45um 53um 63um Line Space 55 um 65um 70um Aspect RaIo 0.9:1 0.8:1 Min. Mech Drill Size 0.15mm (.006”) 0.20mm (.008”) 0.25mm (.010”) Min Capture Pad HDI 150um 180um 220um Min Capture Pad STD D+8 D+8 D+10 1:1 Understand the cri+cal change over points at your fabrica+on site DfX Engineering, LLC, 2016
  33. 33. Cpk Feature Analysis All criIcal features should be staIsIcally analyzed and reviewed to ensure yield performance is maximized reducing overall process cost and providing long term cost reducIon opportuniIes. DfX Engineering, LLC, 2016
  34. 34. Surface Finish ConsideraIons Surface Finish Cost Considera+ons Benefits OSP 1 Shelf Life Limits Flatness, ease of use ENIG 1.1 Process Controls ConducIvity, flatness Immersion Silver 1.05 Environmental Cost, Flatness Immersion Tin 1.2 Capacity Flatness LF HASL 1.4 Capacity, Uniformity Robust Electroplated Gold 2.0 Buss Scheme, Minimize area Bondability, Compression contacts Major ConsideraIons: Assembly site familiarity. Avoid dual surface finish, compounded effect of cost, masking and defect risk. DfX Engineering, LLC, 2016
  35. 35. PROCESS OVERVIEW Flow Chart for cost opImizaIon
  36. 36. Process Overview Start with Interconnect budget Review material selecIon for type and size opImizaIon OpImize stack- up for BOM cost OpImize feature size for Cpk management and ConstrucIon type Review FuncIons in a given board design DfX Engineering, LLC, 2016
  37. 37. Process Cost Driver Decisions •  AddiIonal LaminaIons versus addiIonal layers •  Drill Size versus Pad size opImizaIon •  Pad Size versus Trace Size opImizaIon •  Move finer lines to inner non-plated layers •  Do you need both through and microvias? Microvia counts can be increased without cost impact. Avoid addiIonal plaIng steps. •  Stacked or Staggered Vias (Filled or not) •  Matched Glass Styles to reduce Layup Error, Increase Economy of Scale DfX Engineering, LLC, 2016
  38. 38. HIGH COST CHOICES Performance, Dk and size
  39. 39. High Cost Choices •  VIPPO – AddiIonal Steps Epoxy Fill, PlanarizaIon, Dual plaIng passes, masking MulIple drilling passes for filled and non-filled holes. •  Signal integrity Benefits (No Dogbone), Assembly Land Increase, Supported Via with material that expands at same rate. Take careful consideraIon on adopIng these design choices due to the impact on cost. Analyze and quanIfy the benefit to jusIfy the cost. DfX Engineering, LLC, 2016
  40. 40. HDI Types Explained Source: HDI Handbook DfX Engineering, LLC, 2016
  41. 41. HDI Types Explained DfX Engineering, LLC, 2016 Source: HDI Handbook
  42. 42. SequenIal LaminaIon Take careful consideraIon on adopIng these design choices due to the impact on cost. Analyze and quanIfy the benefit to jusIfy the cost. DfX Engineering, LLC, 2016
  43. 43. Back-Drilling Take careful consideraIon on adopIng these design choices due to the impact on cost. Analyze and quanIfy the benefit to jusIfy the cost. DfX Engineering, LLC, 2016
  44. 44. Process Overview Cost Adder impact from Design Choices Design Choice Added Processes Approximate Cost Factor on MFG cost AddiIonal STD Layer Inner Layer Processing, RegistraIon Budget 8% AddiIonal HDI Layer AddiIonal, Lam, Laser, Plate 20% Dual Surface Finish Mask, Strip, Coat 15% (plus metal area CaclulaIon) VIPPO Epoxy Fill, PlanarizaIon, PlaIng 30% SequenIal LaminaIon Three LaminaIon Cycles RegistraIon 50% Back Drilling Drilling, Alignment, Cleaning 15% (based on hole count) DfX Engineering, LLC, 2016

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