好久没发帖，SIlist话题之PCB的损耗可否预测？

stupid

故事是这样开始的：有人问树脂含量和损耗的关系。

Date: Tue, 30 Oct 2012 08:52:23 +0800 (CST)

( X( ~! S# `9 EHello experts,
( L# d7 b% x* `& y>
> I'm from PCB house.  Recently we have producted some insertion loss test
> boards(16L, SET2DIL coupon, IS415/IT150DA/I-Speed Mid/low loss material with
. G5 ^3 S/ S! i$ W3 K> RTF copper foil). We found that the multiply core and high resin PP will
> result a lower loss result. It's a trouble to MI engineer.  I would like to
> know how to predict the loss base on stackup. Please help to suggest (papers,
+ `; d5 Y( o) l) O! b+ A> script, free software etc ). Thanks a lot!
; T0 E  _# R5 d7 R* G/ e! Z>
>
>
> Best regards,
>
> Terry Ho
: M9 |+ i* k" a" N1 u& d# G. K  H
然后 Scott McMorrow ,steve weir,Loyer Jeff 这些活跃分子开始依次发表意见.
7 d2 S- t( z* m6 t* a) M) E
From: Scott McMorrow <scott@xxxxxxxxxxxxx>
( ]3 }) n. F9 o; o2 EDate: Mon, 29 Oct 2012 21:02:36 -0400
# b# |: \1 ~# i
Hmmm...  I'm in the middle of the middle of Hurricane Sandy.  Power is out.
Storm surge is causing the river across the street to rise to unprecedented
levels.
1 m2 I$ {2 |, @' Z% h... and this guy wants us to do his job and suggest free software.

* T/ T1 B; R4 W) z$ Q, D( ?% g
From: steve weir <weirsi@xxxxxxxxxx>
% h# D$ Q" y4 }9 V0 I( |Date: Mon, 29 Oct 2012 21:23:22 -0700

5 P0 g4 |# _7 [3 P# V' oAs a PCB fabricator I think you need to develop in-house material
properties expertise.  Your competitors who understand the materials
they use and their process limits are positioned to get higher yield
percentages at lower cost because of their knowledge.
3 s2 @8 g9 R) o+ N( q4 {
2 A7 E0 G5 d+ D0 qI appreciate that you don't want to spend unnecessary money, but at
least spend the time to learn about what you are using.  I am troubled
that your engineer knows so little about the materials you use that he
- L* i; y4 j4 y. Mis surprised by common results.  Once your company understands materials
6 h% }0 D# ]" T! {9 @1 Zbetter you may well appreciate the value of commercial stack-up planning
% X6 T/ |6 Z- q8 W! Rsoftware.

Steve.

From: "Loyer, Jeff" <jeff.loyer@xxxxxxxxx>
) Y% K) K% _! ?1 F. w0 U4 _Date: Wed, 31 Oct 2012 21:33:48 +0000
$ c9 p- X- [) V, \& s( ?

I'm surprised at the tone of the responses to this posting (but perhaps I
shouldn't be, unfortunately); I don't see anything untoward in it.  I would
" S2 _4 p8 i1 s! j# J7 ^like to provide some context (with some assumptions on my part) for the message
lest other innocent postings meet with similar fates.  I'll also (eventually)
provide my answer to the question, as I understand it.

# \9 m( }- r' x7 h" E
There is a significant portion (majority?) of the industry which is extremely
cost constrained.  For instance, to them rotating a design 10 degrees is
- H! ~3 q2 |* U2 simpractical, much less 22 or 45 degrees.  Thus, they find other cost-effective
yet effective means of solving problems (such as zig-zag routing), even though
those don't appear efficient to others to whom cost is not an issue.
* @0 O3 L3 S) M6 X1 E

3 s" G. x1 h' Z; h- X! G
& @' {( J9 G( l! J2 bThere are new pressures being applied to this segment - designers are now not
- t) \, {; C* `9 m2 wonly requiring impedance control, but are also insisting on insertion loss
control.  This is a HUGE paradigm shift, very similar to what we encountered
when traceable impedance control was first introduced.  That was a very
) W0 K( _+ A% u9 D% J7 u, {challenging evolution, and this will be also.



As an example, PCB vendors are now being advised to smooth their copper, after
years of purposely roughening it for best mechanical integrity.  It should come
  y5 Y8 r3 L- Ras no surprise that this is not a trivial change, considering the effort that
4 R. A2 t2 F$ M; f; ~has gone into ensuring mechanically robust designs.
2 U+ |8 v# m1 _7 i3 y

/ ]7 U6 B0 J4 ~  c; ?' Q3 k
Likewise, many other basic assumptions that we've been able to apply for years
8 K/ Q3 {# q8 j+ b$ Hare now being drawn into question, and PCB vendors are looking for help to
intelligently and cost-effectively explore options - "How much effect does
rougher copper have on insertion loss?".   I believe Terry is highlighting the
) K7 h$ _) v/ i9 t7 R; u" \5 ofact that, while there are many tools available for impedance prediction,
; {# f) s& u# O+ Z5 sinsertion loss modeling is much less accessible.   I don't think it is
inappropriate to ask if there are cost-effective, reliable tools available to
4 p' ~5 Q  q6 ]3 wpredict insertion loss based on a proposed stackup.

! E: A& l! m: _" Q/ w. ]9 K) p. E

Unfortunately, I believe the answer to the question is that there are no
reliable, cheap (~free) modelers available to predict insertion loss.  And, the
( p1 p( ~2 B" i% _% A1 {ones that are available require a great deal more knowledge about the stackup
7 g# \7 {* C1 N7 ]# q! V9 Rthan impedance modeling does, and that information is not easily obtained.  
There are some of us working with a vendor to test their modeler against a
variety of stackups and we'll present results at DesignCon.  My personal goal
; p8 M/ o7 ]5 M! b  z' zis not so much to test a specific modeler but to judge how effective a modeler
can be given information that can reasonably be gleaned prior to building with
, v) P/ G) J0 |8 v, `# Jvarious materials, copper types, etc.
$ Y+ V* y. ?" Q/ ~% H

+ I! A) ~: v( Z- F% i+ v, d' V
" m5 ?6 s7 a# P5 T& P  j3 DIn the absence of a modeling tool, or in addition to one, I believe empirical
data is the best predictor of insertion loss.  To do this, however, you have to
build a stackup representing the final design, and it's not clear at this point
how broadly you can extrapolate those results to other stackups.  But, I know
many material vendors and PCB shops are engaged in similar efforts.
- e" c* L0 X$ Y, S% A

: U( a) r* E6 s% c
I think this is very similar to what we went through with impedance control -
the shops which most quickly were able to predict and control that
3 g. ~; t2 `+ N: x5 H( Tcharacteristic had an advantage.  I think successful PCB vendors will need
reliable modeling software and empirical data on insertion loss for their
( J2 p; r# o3 {1 i! C0 a6 P, M- [particular choices of materials, etc. - they will be able to find the most cost
' C" }+ {! b* t1 [6 Aeffective solution.



" \  k0 ?: s0 b8 }Bottom line: I doubt a reliable modeling tool is going to be cheap, but is
7 z. b) f, X) N% ggoing to be necessary, and you'll want to compare any tool you do purchase
against empirical data before you trust it.


+ O5 k! b9 s$ F) m
I hope this helps,

Jeff Loyer

; B; v4 O& s- z; L' T
From: steve weir <weirsi@xxxxxxxxxx>
Date: Wed, 31 Oct 2012 20:14:41 -0700

3 {# q' ^5 G7 ^7 ]
Jeff, given that the only two responses were Scott and mine, I am
+ C" s& S) z1 L8 }surprised that you are disappointed with both.
' |9 t4 x1 z( ?3 d9 T1 `' E3 P* D
* I# X$ a+ m; e5 b' FIn a fabrication market filled with intense competition it is up to
individual players to keep up with the technology requirements of the
market or get left behind.  The task is not simple. Depending on how far
9 O# A2 q. N* q5 B+ cup the frequency range one needs to go, dialing in cost effective
process requires substantial skills, time, effort and serious money.  It
3 w  j& H/ T9 }3 K4 g) R- Xrepresents competitive advantage to OEMs and their partner pcb fab
' |5 j; ]" b* ?9 P3 |; ]2 n0 Yhouses alike.  Neither who have invested are likely to hand over that
0 F8 `. U/ S4 skind of advantage especially when it is so costly to obtain.
# |, V0 ]  ?! f0 h0 G
3 A$ ^, H' x6 Q% b4 G, [  i- r: D: BI don't mind that Terry is looking for a solution on the cheap or free.  
7 h2 x+ z8 _! I0 _' r" TIf one could obtain such a sweet deal, one would be foolish not to take
it.   I am troubled that in this day in age, his organization hopes to
4 j. s" q/ Z' x9 I; q# Y5 k) v' paddress a sophisticated issue before his technical staff has a grip on
/ ?2 U6 q% e# Z7 T; w6 j+ {the basics.   I fail to understand what you find inappropriate about
that concern.  I would rather yell at someone headed for a cliff to stop
1 |! t1 Q( d2 @( b0 |3 Fthan smile and wave.
( b  Y6 }9 ~' H! d  A5 s
" l  r6 g( j9 N+ ?Best Regards,
6 @' M4 y: w4 E! @1 S: D
1 m  Z5 Q6 _2 q6 T/ \, [+ t! e
4 ~: i" C1 z0 E" ?  g- `Steve.
( P3 I: b* v% F, l2 [% ^% J/ t$ }
3 e3 e! z% G$ |$ @) S8 vFrom: "Loyer, Jeff" <jeff.loyer@xxxxxxxxx>
; D! `# s# g9 B" J2 m. e) F& EDate: Fri, 2 Nov 2012 15:37:46 +0000
6 S, p- [. K7 ~
2 Y' _7 \7 \" R4 p3 b2 s# ?; {) S6 c
  o  I4 q& Q0 F: EI realized we hadn't answered the basic question - "why does a high resin
prepreg give lower loss?"  The prediction of loss vs. resin content isn't
trivial; as Steve said, a tool which allows you to model loss for the various
# g& F0 Q# J8 A0 wscenarios should be on your Christmas wish list.  Here are the factors that I
9 K& C  `1 h5 p% Q9 f' N) bknow of (thanks to Richard Kunze for clarifying things for me, and I welcome
others' data/opinions):
  i2 z% e* D3 s+ b8 \* Resin has a lower Er than glass

7 q$ y+ j$ b& F3 Q  d  i     * loss is approximately proportional to Df * sqrt(Er), so lowering Er
lowers loss

     * lower Er allows wider traces for the same impedance - this may decrease
+ X0 w1 g+ H' T5 u3 p" h) nloss also

& g  w0 ?7 q/ A% _* But, resin is more lossy than glass, so Df may increase

+ s- p1 ?( j% z- g0 ~# s: z/ L7 s7 t     * for standard FR4 constructions, this is especially true.  The data sheet
for IS370HR, for instance, shows Df varying from 0.0177 to 0.0247 (1GHz),
depending on the resin content

% {  R; J$ I3 i2 T+ Q     * for low loss materials, this doesn't hold.  The data sheet for Meg6
9 ]: u/ f( n" Z7 c0 K. X, G7 d4 Z' jshows Df constant (0.002 @ 1GHz) for all its flavors of prepreg
% K" M! r. F6 a! p
* Where the factors dominate will depend on your relative conductor vs.
" W8 L( U/ T, Z  Z+ Adielectric loss effects: for FR4, dielectric loss dominates at >~1GHz; for
- _- a) ^, v% p1 d& p- M3 \low-loss materials, conductor loss dominates up to much higher frequencies (as
much as 10GHz).

$ w8 ~/ n4 s: {
1 M- T. k  X) d
In your particular (low loss) case, the lower Er of the resin-rich case is
9 A! J* s6 }5 ?# D- Rtrumping the Df change (or lack of) so you get lower loss.


, i4 I3 {5 L  E2 n8 Q1 V' j
Only a tool which takes into account the properties of the specific material
* J3 j* ]2 \" t, K2 T  u9 funder consideration can be expected to give an accurate prediction of insertion
loss for various resin contents.

- Y7 ^! i* _9 o4 o3 s" G9 \& x" ^& d
. P3 @0 V4 R8 F$ t2 `- c9 }
There are also environmental effects (I haven't heard or seen these stressed at
; x1 r7 ?! U+ Y0 Cthis point, though that may change soon):
" H, C4 ]; H+ i/ S; O: l
5 U4 p& d  J0 e  ^3 c7 c* Higher resin content will absorb more moisture, and thus your loss will be
( X2 B- M3 y9 Y) p! x. Mmore susceptible to humidity effects

* There's a difference in how the various materials' Df changes w/ temperature
  Y5 S- p7 s0 _7 x1 P. A2 s" F- more at DesignCon
" u! a6 |. W' ^, _/ x
8 A- f1 q+ ^) S

! c) J0 C5 ~- D* o5 I# [* m  }" ]I hope this helps,

Jeff Loyer
: M. O! x. X2 O
- f, `" Z% M  {* _- |4 q: iFrom: Scott McMorrow <scott@xxxxxxxxxxxxx>
Date: Thu, 8 Nov 2012 09:12:46 -0500
% |  ]2 y% {% F$ s. A

Jeff
A few quick comments.  Although the tanD of Meg 6 is stated to be flat, it
is not if you measure it.  The manufacturer reported characterization in
the data sheet is not correct.  Causality is violated when tanD is flat.
1 P9 n! _2 s7 O6 ~8 _( o- G2 ]- l" v
Loss is generally due to molecular dipole losses in the material.  It can
be low for high Er, as is the case with ceramic.

Hygroscopic loss is due to molecular polarity. Polar molecules "glom" on to
water molecules, which are also polar. Same property makes the material
extremely "sticky."

5 J7 s: C- E5 ^The paper that Jason Miller of Oracle and I wrote for DesignCon last year
) S5 C) }9 T  _# ocovers some of the impact of temperature and humidity on measured losses.
I don't have access to my storage server right now, otherwise I'd give a
: R9 Y! ]6 `0 M  o3 ~% z0 Ipaper citation.
# _. U1 w/ V3 _% Q+ _
regards,
# i$ ]5 p0 H) U1 a0 O$ }
Scott
) l" O7 \- ~7 _2 y3 ^; x9 K# G
# v3 t  l% z( a4 X3 `% @From: Kirby Goulet <kgoulet@xxxxxxxx>
$ S/ i, m! v% y. {# E7 LDate: Fri, 9 Nov 2012 11:08:49 -0800 (PST)
9 f: |  F  G# [! W8 e4 e
' J' ]6 T3 w! P1 H0 z$ a
It's not production quality software but you could try the mdtlc calculator to
! A' K) `& g8 [& L* I# w! t: ?experiment.  I tried Jeff's example and it seems to point to an explanation.
The source code is available so you might extend it to do what you want if you
0 H5 ?% _% v# Y6 _have more time than money.
It looks like a race between loss due to increasing loss due to resin and
decreasing loss due to wider traces.  There is a bigger increase in the resin
, L" ]' g( H) H/ g4 `content for the IS370 case over the IS415 case.  Not only that, but the IS370
" R( r- \( \% W8 R/ |2 r7 @resin is lossier: 0.0169 versus 0.02984 so the winner is increasing loss.  
1 G; [9 L% C. x7 [, r
6 Y8 [) i  _! h% i: O% {* GFrom the field solver,

IS370: the effective dielectric loss went up 14.7%.  The perimeter of the
1 p/ l5 n) j( S# r4 Qconductor went up 3.6%.  
9 Z8 h7 F8 x1 q1 N% hIS415: the effective dielectric loss went up 6.7%. The perimeter of the
conductor went up 5.7%.
6 R* i9 B% |4 P( H( N# v0 N
In the second case, overall dielectric loss is a smaller fraction than the
first case.  The missing bit of information you need to add is the conductor
loss.

INPUT PARAMETERS:
) \* \* X  R, s6 r, S
      Layer             Thick   Specifications
      Copper Plane Top   1.30    Opening w=0.0  offset=0.0
" S% o0 `- P. B3 A, J( n# t+ ]      Laminate Layer 1   3.90    Resin Content  57.0% 3.4-4.9
1 \2 G5 j* n1 s8 h9 x7 f, O        Signal Layer 1   1.20  4.3-7.2-4.3  Etchback=0.00
      Laminate Layer 2   3.90    Resin Content  57.0% 3.4-4.9
   Copper Plane Bottom   1.30    Opening w=0.0  offset=0.0

3 K: t5 c7 Y! ~2 [& L0 J      Layer             Thick   Er    Loss Tangent
      Copper Plane Top   1.30  3.20   
      Laminate Layer 1   3.90  4.02    0.02100
6 B, }& N  ]. j, M7 X        Signal Layer 1   1.20  3.38    0.02984
. ^- n! [9 A0 f      Laminate Layer 2   3.90  4.02    0.02100
! |' M& ~6 h$ s. {+ h& }   Copper Plane Bottom   1.30  3.20

) O2 O# x: y9 M3 ? DC resistance by dimensions:
Rdc_trace_1= 131.53      Rdc_trace_2 = 131.53  milliohms/in 20C
; C+ q7 v# u* W- R& n# M$ o
) r1 d7 c( d) r/ Y DC resistance by pixel count:
Rdc_trace_1= 131.531     Rdc_trace_2 = 131.531 milliohm/in
C_odd      =   4.221 pF/in    C_even =   3.968 pF/in
Er_odd     =   3.923         Er_even =   3.947
; `; w' B' }! u) o Loss_tan_o = 0.02212     Loss_tan_e  = 0.02184  
Delay_odd  = 167.801      Delay_even = 168.314  ps/in.
1 o" U7 B, V& R" k7 p Z_diff     =  79.501  ohms   Z_comm  =  21.209  ohms
# d; x6 S- v0 ^4 C- A* s4 ~  J
7 ~# h) Q4 ?( ^  d; ~/ `' [4 O5 hSimulation pix map 122 pixels high by 800 pixels wide.
293824 bytes allocated for bmp.

INPUT PARAMETERS:
/ B. T% d4 r7 J
      Layer             Thick   Specifications
      Copper Plane Top   1.30    Opening w=0.0  offset=0.0
      Laminate Layer 1   4.20    Resin Content  75.0% 3.4-4.9
        Signal Layer 1   1.20  4.5-7.0-4.5  Etchback=0.00
      Laminate Layer 2   4.20    Resin Content  75.0% 3.4-4.9
   Copper Plane Bottom   1.30    Opening w=0.0  offset=0.0
: f/ y% N) `+ A7 ?0 N& e
& W: H" R) h0 u' N1 h/ ~& R      Layer             Thick   Er    Loss Tangent
      Copper Plane Top   1.30  3.20   
      Laminate Layer 1   4.20  3.75    0.02470
        Signal Layer 1   1.20  3.38    0.02984
9 b3 h5 ?' {' ?2 y- r0 a: I      Laminate Layer 2   4.20  3.75    0.02470
   Copper Plane Bottom   1.30  3.20
& h/ Z; g( q3 L1 [/ q; E" @
DC resistance by dimensions:
# e5 v0 D; B2 Q, p0 @3 A Rdc_trace_1= 125.69      Rdc_trace_2 = 125.69  milliohms/in 20C

5 e/ z4 I( Z- X DC resistance by pixel count:
- C+ T' C% g& ` Rdc_trace_1= 125.685     Rdc_trace_2 = 125.685 milliohm/in
C_odd      =   3.929 pF/in    C_even =   3.624 pF/in
Er_odd     =   3.694         Er_even =   3.710
9 h: _4 X" L2 ^/ d: N& K Loss_tan_o = 0.02537     Loss_tan_e  = 0.02518  
Delay_odd  = 162.844      Delay_even = 163.195  ps/in.
: U$ n( j; ~) T& S9 G0 O Z_diff     =  82.900  ohms   Z_comm  =  22.519  ohms

Log file save name:
mdtlc_12100946383.txt

3 e& Y  C* \  ]! p% I" \0 j5 ]/ U8 bSimulation pix map 118 pixels high by 780 pixels wide.
8 {; h3 R) y$ I+ [* g277144 bytes allocated for bmp.

INPUT PARAMETERS:
& D1 o/ O1 K. Y7 a( [
2 s8 s) ~- k7 M3 ~' \: v) h      Layer             Thick   Specifications
. m8 M2 ]" z! h- t( @! W      Copper Plane Top   1.30    Opening w=0.0  offset=0.0
      Laminate Layer 1   4.00    Resin Content  45.0% 2.6-5.1
        Signal Layer 1   1.20  4.1-7.4-4.1  Etchback=0.00
- H$ x+ u' `! s4 a& h      Laminate Layer 2   4.00    Resin Content  45.0% 2.6-5.1
   Copper Plane Bottom   1.30    Opening w=0.0  offset=0.0

      Layer             Thick   Er    Loss Tangent
      Copper Plane Top   1.30  3.20   
      Laminate Layer 1   4.00  3.98    0.01140
        Signal Layer 1   1.20  2.64    0.01690
      Laminate Layer 2   4.00  3.98    0.01140
   Copper Plane Bottom   1.30  3.20
% m5 G' p0 B- y! q, I& L
DC resistance by dimensions:
* E- G2 E- e* t, I) V" | Rdc_trace_1= 137.95      Rdc_trace_2 = 137.95  milliohms/in 20C

DC resistance by pixel count:
Rdc_trace_1= 137.947     Rdc_trace_2 = 137.947 milliohm/in
# O1 p3 j# I7 R6 f0 V1 B4 s C_odd      =   3.910 pF/in    C_even =   3.695 pF/in
5 U& Y7 G5 @$ `5 s7 Y Er_odd     =   3.769         Er_even =   3.817
+ T2 M3 ~9 C: q0 X$ `6 W Loss_tan_o = 0.01202     Loss_tan_e  = 0.01189  
9 k& Z+ E5 Y+ I Delay_odd  = 164.490      Delay_even = 165.524  ps/in.
: E0 o/ c! h7 t& T, F2 \ Z_diff     =  84.134  ohms   Z_comm  =  22.396  ohms
. S8 g% S5 X, d
Simulation pix map 118 pixels high by 795 pixels wide.
282454 bytes allocated for bmp.

, J' m; B; C6 E7 RINPUT PARAMETERS:
1 j5 L& b! w/ g! l
      Layer             Thick   Specifications
      Copper Plane Top   1.30    Opening w=0.0  offset=0.0
, m: a& Q' d5 B4 ^& J, T/ P      Laminate Layer 1   4.00    Resin Content  54.0% 2.6-5.1
( w& w% E; a! P) b        Signal Layer 1   1.20  4.4-7.1-4.4  Etchback=0.00
      Laminate Layer 2   4.00    Resin Content  54.0% 2.6-5.1
   Copper Plane Bottom   1.30    Opening w=0.0  offset=0.0

6 f# R: b' e$ w8 ]  Q$ b      Layer             Thick   Er    Loss Tangent
* k+ u9 J& u9 e5 w' b      Copper Plane Top   1.30  3.20   
( @1 _5 F* G- d8 w      Laminate Layer 1   4.00  3.76    0.01230
        Signal Layer 1   1.20  2.64    0.01690
      Laminate Layer 2   4.00  3.76    0.01230
   Copper Plane Bottom   1.30  3.20
  `5 M! {3 f9 k4 P1 A/ a
DC resistance by dimensions:
6 w1 v2 k# V3 m! t) X# Q' c7 k Rdc_trace_1= 128.54      Rdc_trace_2 = 128.54  milliohms/in 20C

DC resistance by pixel count:
5 G3 u/ ?. ]! ~/ L" u; K$ y Rdc_trace_1= 128.542     Rdc_trace_2 = 128.542 milliohm/in
" G8 ^9 J1 H# ^, [- s9 b" O3 s/ o C_odd      =   3.865 pF/in    C_even =   3.623 pF/in
$ ~: ]  n, z. G" a2 Z Er_odd     =   3.588         Er_even =   3.631
$ u$ G" S& ~7 x3 f$ Z Loss_tan_o = 0.01283     Loss_tan_e  = 0.01270  
. p. z/ x* @7 o' |" l Delay_odd  = 160.480      Delay_even = 161.455  ps/in.
Z_diff     =  83.041  ohms   Z_comm  =  22.280  ohms

看完之后，我有一事不明，我总是分不清奇偶，不知道这两者到底如何区分，亲，你能告诉我吗？

Nelson

我以前也分不清奇偶，后来强行记住了even是偶，搞的后来一看到odd，就要先想even是“偶”，odd只好是“奇”了，很是麻烦！
你这一提醒，我以后可以换个记法了：odd是3个字母，“奇”数个字母；even是4个字母，“偶”数个字母。哈哈

hrb011011

晕， 版主居然转贴到这里来了！
7 n% t  o* e4 K( w4 z汗！！！{:soso_e110:}