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October 1997

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Subject:
From:
Jan Vercammen <[log in to unmask]>
Reply To:
TechNet Mail Forum.
Date:
Wed, 1 Oct 1997 12:17:26 +0200
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hello,

I am working on a tool to build virtual PCBs. Other people or organisations
are probably also working on this. I have tried to use the most simple
models for the dimensional and the electrical analysis. The dimensional
analysis involves weight and thickness, the electrical part concerns
impedances, xtalk, ...

My background is in electronics and EMC engineering. It is only lately that
I have began to explore PCB manufacturing. So forgive me my expressions
for I am not used to the slang used in PCB manufacturing. Also I apologize
for this lengthy mail. I appreciate you going through this text.

I have some first results on the dimensional part. We actually have build 10
6-layer test boards and we have a simulation run using some detailed data
on preg, core laminate and foil. Of these we have used very specific data
of the reinforcement, of the resin and of the copper. Also included is
the copper area/layer, mask data (or coating), plating details, plated
perimeter of vias and the board dimensions.

The preg is an Isola with 1080 reinf., the core is an Isola with 3x7628
reinf. The average finished resin content of the preg is 65+/-3%.

The buildup is described below at the end of this email bewteen
** example ** and *** example done ** and although you do not know the
exact input syntax, you should be able to figure out the data and the
buildup intuitively (note: a comment line starts with ; or *, all
other lines do something, e.g. introduce the resin, do an analysis, ...)

At the bottom of the example you will the results of the weight and thickness.
They are repeated here (the board is renamed to XYZ6):

***************** build summary for XYZ6 *****************
                  mean       max        min        sdev
preg weight:    5.09E-02 | 5.33E-02 | 4.88E-02 | 6.40E-04
core weight:    1.22E-01 | 1.26E-01 | 1.18E-01 | 1.16E-03
foil weight:    4.33E-02 | 4.76E-02 | 3.90E-02 | 1.28E-03
plate weight:   9.83E-03 | 1.25E-02 | 7.44E-03 | 7.17E-04
                -----------------------------------------
total weight:   2.27E-01 | 2.33E-01 | 2.19E-01 | 2.00E-03

preg thick:     5.12E-04 | 5.41E-04 | 4.88E-04 | 7.64E-06
core thick:     1.02E-03 | 1.07E-03 | 9.68E-04 | 1.40E-05
foil thick:     6.26E-05 | 7.01E-05 | 5.57E-05 | 2.16E-06
                -----------------------------------------
final thick.:   1.59E-03 | 1.66E-03 | 1.53E-03 | 1.60E-05

The colomns give the mean, the maximum, the minimum and the
standard variation of the weight and thickness of the simulated
buildup (in kg and m). You can also see the contibutions of the
induvidual materials.

The weight of the 10 test boards we build is 227.12g with a stand. dev of 1.79g.

The simulation fits the measured data good with a simulated weight of 227g
and a standard dev of 2g.


These are my questions:

(q1) Is this analysis useful? Or is this just a coincidence that the
     match is good?

If the answer to q1 is affirmative:

(q2) Does anyone use these kind of tools?
(q3) Can someone supply me with the specific weight of typical FR4
     resins (and also their variations) or give me directions were
     I can find data on these things.
(q4) Is it possible to get an estimate of the thickness of a PCB by
     just weighing it? If a do another analysis with an overall
     finished resin content of 70+/-3% the weight and thickness data
     looks like below. The mean weight is 7g larger and the mean
     thickness is now 1.7mm. This simulation indicates that it is
     feasable! (Is this reasoning correct?)


                  mean       max        min        sdev
preg weight:    5.93E-02 | 6.26E-02 | 5.66E-02 | 8.59E-04
core weight:    1.22E-01 | 1.26E-01 | 1.18E-01 | 1.16E-03
foil weight:    4.33E-02 | 4.76E-02 | 3.90E-02 | 1.28E-03
plate weight:   9.97E-03 | 1.27E-02 | 7.53E-03 | 7.27E-04
                -----------------------------------------
total weight:   2.35E-01 | 2.42E-01 | 2.27E-01 | 2.08E-03

preg thick:     6.16E-04 | 6.56E-04 | 5.83E-04 | 1.03E-05
core thick:     1.02E-03 | 1.07E-03 | 9.68E-04 | 1.40E-05
foil thick:     6.26E-05 | 7.01E-05 | 5.57E-05 | 2.16E-06
                -----------------------------------------
final thick.:   1.70E-03 | 1.77E-03 | 1.63E-03 | 1.74E-05



***************** example *************************************
***************** example *************************************
BUILD V1.0: build from file 'test.bui', Fri Sep  5 11:43:37 1997

;file test.bui for initial test build code
;example XYZ 6 layer type 1
;model  type  nstat
model   1     3000

******************** material data ********************
; Isola core 510 micron, 3x7628, class 2 (+/-10%) 510 (561-459) micron
; Isola preg 1080, RC% 65 +/- 3%
; E-glass fabric 1080  46.8 g/m2, level 2 ->  45.4- 48.5 g/m2
; E-glass fabric 7628 204.4 g/m2, level 2 -> 210.0-199.4 g/m2
; E-glass data spw 2540 kg/m3, dk 6.1, variations unknown
; foil 18 micron 153 g/m2, level 2 -> 168.3-137.7 g/m2
; foil 35 micron 305 g/m2, level 2 -> 335.5-274.5 g/m2
; foil spw 9860 kg/m3, conductivity copper 17.8E-9 S/m, variations unknown
; resin data not exactly known, estimated spw 1300 kg/m3 and dk 3.6
; mask data spw 1300 kg/m2, 1350-1250 kg/m3, estimated dk 3.0
;  thickness_over_conductor > 8 micron, thickness_over_substrate 40 micron
;plating data copper spw 9860 kg/m3, thicknes 35 micron,  (25-50) micron
******************** material data ********************


******************** build data input ********************
;resin name    spw,+,-,sdv       dk,+,-,sdv
resin  EPON12  1300,1300,1300,0  3.6,3.6,3.6,0
;rinf name     w,+,-,sdv                    spw,+,-,sdv       dk,+,-,sdv
rinf  E_1080   0.0468,0.0485,0.0454,0.0005  2540,2540,2540,0  5.8,5.8,5.8,0
rinf  E_7628   0.2044,0.2100,0.1994,0.0025  2540,2540,2540,0  5.8,5.8,5.8,0

;foil name      w,+,-,sdv                   spw,+,-,sdv       [conductivity]
foil  ELF_17um  0.153,0.1683,0.1377,0.0075  9860,9860,9860,0  17.8E-9
foil  ELF_35um  0.305,0.3355,0.2745,0.0150  9860,9860,9860,0  17.8E-9

;preg name        rc%,+,-,sdv    resin   rinf
preg  ISOLA_1080  65,68,62,1.0  EPON12  E_1080

;core   name       t,+,-,sdv                    resin   rinf1 ... rinfn
core ISOLA_3X7628  510E-6,561E-6,459E-6,10E-6  EPON12  E_7628 E_7628 E_7628

;plate  name    t,+,-,sdv               spw,+,-,sdv
plate   OUTER   35E-6,50E-6,25E-6,2.5E-6  9860,9860,9860,0

;mask  name  spw,+,-,sdv        dk,+,-,sdv     toc,+,-,sdv          tos,+,-,sdv
mask   POLY  1300,1350,1250,15  3.0,3.0,3.0,0  10E-6,10E-6,10E-6,0  40E-6,40E-6,40E-6,0
******************** build data input done ********************


******************** the actual build ********************

;job number
job  100789

;build  name  www    hhh
build   XYZ  0.2945  0.215

;signal name      layer_name  area
signal  ELF_17um  L1          0.01077
;preg   name
preg    ISOLA_1080
preg    ISOLA_1080
signal  ELF_35um  L2          0.0059
;core   name
core    ISOLA_3X7628
;plane  name      layer_name  area
plane   ELF_35um  P1          0.05944
preg    ISOLA_1080
preg    ISOLA_1080
plane   ELF_35um  P2          0.05916
core    ISOLA_3X7628
signal  ELF_35um  L3          0.00021
preg    ISOLA_1080
preg    ISOLA_1080
signal  ELF_35um  L4          0.01183

;mask   name  area
mask    POLY  0.075
mask    POLY  0.075

;plate  name   top_area  bottom_area  perimeter
plate   OUTER  0.01077   0.01183      3.701

;hole  area
hole   0.00113
******************** the actual build done ********************



******************** dimensional analysis ********************
;end, start the analysis

*** STARTING BUILDUP for job 100789 ***

***************** build summary for XYZ6 *****************
                  mean       max        min        sdev
preg weight:    5.09E-02 | 5.33E-02 | 4.88E-02 | 6.40E-04
core weight:    1.22E-01 | 1.26E-01 | 1.18E-01 | 1.16E-03
foil weight:    4.33E-02 | 4.76E-02 | 3.90E-02 | 1.28E-03
plate weight:   9.83E-03 | 1.25E-02 | 7.44E-03 | 7.17E-04
                -----------------------------------------
total weight:   2.27E-01 | 2.33E-01 | 2.19E-01 | 2.00E-03

preg thick:     5.12E-04 | 5.41E-04 | 4.88E-04 | 7.64E-06
core thick:     1.02E-03 | 1.07E-03 | 9.68E-04 | 1.40E-05
foil thick:     6.26E-05 | 7.01E-05 | 5.57E-05 | 2.16E-06
                -----------------------------------------
final thick.:   1.59E-03 | 1.66E-03 | 1.53E-03 | 1.60E-05

********************* end of example ***********************

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