CN106126848A - The method for building up of impedance computation model, impedance matching methods and device thereof - Google Patents

Abstract

The invention discloses the method for building up of impedance computation model, impedance matching methods and device thereof, impedance matching methods comprises the steps: A1, obtains the impedance measured value of several difference through holes；A2, the bimetallic conductor resistance value A3 being obtained several difference through holes by bimetallic conductor formula of impedance, the linear relationship that obtains between several impedance measured values and several bimetallic conductor resistance values, obtain difference through hole impedance formula, described difference through hole impedance formula is the bimetallic conductor formula of impedance revised, the prediction resistance value of difference through hole is tried to achieve, so that obtaining difference through hole more accurately according to prediction resistance value by difference through hole impedance formula.It is an advantage of the current invention that to predict a difference through hole impedance more accurately by difference through hole impedance computing formula, so that the line impedance that the difference through hole impedance that making obtains gives with client is mated more accurate.

Description

The method for building up of impedance computation model, impedance matching methods and device thereof

Technical field

The present invention relates to impedance matching methods, particularly relate to the method for building up of impedance computation model, difference through hole impedance and Line impedance matching process and device thereof.

Background technology

Along with electronic product high frequency, high speed development, signal integrity requires more and more higher, and it is right that signal integrity requires The impedance control of PCB requires more and more stricter.In high-speed PCB, Via Design is a key factor, and via plays The effect of connection PCB difference interlayer cabling, under high frequency, high-speed condition, via can not simply regard electrical connection effect as, it is necessary to Consider that signal integrity is affected by it；Via Design is dealt with improperly, signal can be caused reflection, affect signal integrity.

Differential signal because of its there is suppression common-mode noise, the significant advantage that improves noise margin and blue or green by PCB design person Looking at, PCB design person is many can be selected difference through hole to carry out turning layer to design to improve PCB layout density, therefore difference through hole impedance and Differential line impedance coupling is particularly important.PCB difference through hole impedance design at present uses emulation mode to be designed mostly, But for PCB manufacturing firm, for meeting the particular requirement of client, via can be compensated accordingly, add production The impact made, can cause and there is deviation between emulation and actual through hole impedance, time serious, can cause customer complaint.

Owing to difference through hole and bimetallic conductor are structurally similar, general by bimetallic conductor impedance in prior art Computation model predicts the resistance value of difference through hole, and the patent of Publication No. CN1901366A discloses a kind of difference through hole impedance With the method for differential conductor impedance matching, it utilizes bimetallic conductor impedance computation formula to replace difference through hole impedance to calculate public affairs Formula, the relation further according to difference through hole impedance with differential conductor impedance matching calculates the distance at via center and crosses the pass of pore radius System, to obtain the structure of difference through hole；But it is simply similar, by difference mistake from structure due to bimetallic conductor and difference through hole It is inaccurate that hole is fully equivalent to bimetallic conductor model, and actually difference through hole impedance value is deposited with bimetallic conductor resistance value In bigger error, it is inaccurate for directly using bimetallic conductor impedance computation formula to substitute difference through hole impedance computing formula.

Summary of the invention

In order to overcome the deficiencies in the prior art, an object of the present invention is to provide the foundation side of impedance computation model Method, it can obtain a difference through hole impedance computing formula more accurately.

The two of the purpose of the present invention are to provide difference through hole impedance and line impedance matching process, its can more accurately by Difference through hole impedance mates with line impedance.

The three of the purpose of the present invention are to provide difference through hole impedance and line impedance coalignment, its can more accurately by Difference through hole impedance mates with line impedance.

An object of the present invention realizes by the following technical solutions:

The method for building up of impedance computation model, comprises the steps:

A1, detect the impedance of several difference through holes, thus obtain the impedance measured value of several difference through holes；

A2, calculate the bimetallic conductor resistance value of several difference through holes according to bimetallic conductor formula of impedance, described double Plain conductor formula of impedance is:Wherein Z₀For bimetallic conductor impedance, ε_rFor relative dielectric constant, D is difference through hole center distance, and D is difference through hole diameter；

A3, according to several impedance measured values and several bimetallic conductor resistance values, obtain impedance measured value and double gold Belong to the relation between conductor impedance value, according to described relation, bimetallic conductor formula of impedance is modified, thus obtains difference Through hole impedance formula, described difference through hole impedance formula is for calculating the prediction resistance value of difference through hole, thus hinders according to prediction Difference through hole is compensated by anti-value accordingly.

Preferably, in A3, described relation is linear relationship, and described difference through hole impedance formula is:Wherein Z_diffFor prediction resistance value, d is difference through hole center distance, D≤ 0.35mm。

Preferably, in A1, TDR impedance instrument is used to detect the impedance of several difference through holes.

Preferably, in A2, described bimetallic conductor formula of impedance is:

Wherein stray inductanceParasitic capacitanceMagnetic permeability μ=μ_r*μ₀, DIELECTRIC CONSTANT ε=ε_r*ε₀；

Wherein, relative dielectric constant μ_r≈ 1, absolute permeability μ₀=4 π * 10^-7H/m, absolute dielectric constant ε₀=8.85* 10^-12F/m。

The two of the purpose of the present invention realize by the following technical solutions:

Impedance matching methods, comprises the steps:

S1, acquisition design parameter；

S2, calculate the pre-of difference through hole according to design parameter and difference through hole impedance formula as claimed in claim 1 Survey resistance value, further according to prediction resistance value, difference through hole is compensated accordingly.

Preferably, in S1, design parameter includes difference through hole center distance d, difference through hole diameter D and relative dielectric constant ε_r, the difference through hole impedance formula stated in S2 is:

Wherein Z_diffFor prediction resistance value, D≤0.35mm.

Preferably, in S2, corresponding compensation is: adjusts the aperture of difference through hole, pad according to prediction resistance value and counter welds One or more size in dish.

The three of the purpose of the present invention realize by the following technical solutions:

Impedance-matching device, including:

Acquisition module, it is used for obtaining design parameter；

Processing module, poor for calculating according to design parameter and difference through hole impedance formula as claimed in claim 1 Divide the prediction resistance value of via, further according to prediction resistance value, difference through hole is compensated accordingly.

Preferably, described design parameter includes difference through hole center distance d, difference through hole diameter D and relative dielectric constant ε_r, the difference through hole impedance formula described in processing module is:Wherein Z_diffFor in advance Survey resistance value, D≤0.35mm.

Preferably, corresponding compensation is: adjust the aperture of difference through hole, pad and anti-pad according to prediction resistance value In one or more sizes.

Compared to existing technology, the beneficial effects of the present invention is: can be predicted by difference through hole impedance computing formula One difference through hole impedance more accurately, mates more so that making the line impedance that the difference through hole impedance obtained gives with client Precisely.

Accompanying drawing explanation

Fig. 1 is the flow chart of the method for building up of the impedance computation model of the present invention；

Fig. 2 is impedance measured value and the linear fit of bimetallic conductor resistance value of the present invention；

Fig. 3 is the difference through hole impedance flow chart with line impedance matching process of the present invention；

Fig. 4 is the difference through hole impedance module map with line impedance coalignment of the present invention.

Detailed description of the invention

Below, in conjunction with accompanying drawing and detailed description of the invention, the present invention is described further:

Difference through hole is similar to bimetallic conductor model, difference through hole can be equivalent to bimetallic conductor model and grind Studying carefully, can obtain bimetallic conductor impedance computation formula according to mutual inductance formula and mutual tolerance formula, its mutual inductance formula is:

$L=\frac{\mathrm{\μ}}{\mathrm{\π}}{\cosh }^{-1}\left(\frac{d}{D}\right);$

Its mutual tolerance formula is

$C=\frac{\mathrm{\π}\mathrm{\ϵ}}{{\cosh }^{-1}(d/D)};$

Wherein, L is stray inductance, and C is parasitic capacitance, and μ is pcrmeability, and ε is dielectric constant, d be in difference through hole in the heart Away from, D is difference through hole diameter；

μ=μ_r*μ₀；

Wherein μ_rFor relative dielectric constant, for metallic copper, μ_r≈1；μ₀For absolute permeability, pcb board is come Say, μ₀=4 π * 10^-7H/m；

ε=ε_r*ε₀；

Wherein ε_rFor relative dielectric constant, the relative dielectric constant of different materials is different, and client is at customization pcb board Time material requirements can be provided, just can obtain the relative dielectric constant ε of material customized in client simultaneously_r；ε₀Normal for absolute dielectric Number, ε₀=8.85*10^-12F/m；

So

$L=\frac{\mathrm{\μ}}{\mathrm{\π}}{\cosh }^{-1}\left(\frac{d}{D}\right)=\frac{{\mathrm{\μ}}_r*{\mathrm{\μ}}_0}{\mathrm{\π}}{\cosh }^{-1}\left(\frac{d}{D}\right)=4*{10}^{-7}{\cosh }^{-1}\left(\frac{d}{D}\right);$

$C=\frac{\mathrm{\π}\mathrm{\ϵ}}{{\cosh }^{-1}(d/D)}=\frac{{\mathrm{\π\ϵ}}_0*{\mathrm{\ϵ}}_r}{{\cosh }^{-1}\left(d/D\right)}=\frac{2.78*{10}^{-11}*{\mathrm{\ϵ}}_r}{{\cosh }^{-1}\left(d/D\right)};$

Meanwhile, bimetallic conductor impedance computation formula is:

$Z_0=\sqrt{\frac{L}{C}=}\frac{120}{\sqrt{{\mathrm{\ϵ}}_r}}{\cosh }^{-1}\left(\frac{d}{D}\right);$

Owing to difference through hole and bimetallic conductor model are simply structurally similar, and can not by difference through hole completely etc. With with bimetallic conductor model, so bimetallic conductor impedance and actual difference through hole impedance exist certain error, therefore need The computing formula of bimetallic conductor impedance is optimized, the practical impedance of difference through hole could be mated.

As it is shown in figure 1, the method for building up of impedance computation model, comprise the steps:

Step 11, detect the impedance of several difference through holes, thus obtain the impedance measured value of several difference through holes Z_d′_iff；

It is specially the impedance using TDR impedance instrument to detect several difference through holes；

Step 12, calculate the bimetallic conductor resistance value of several difference through holes according to bimetallic conductor formula of impedance, institute Stating bimetallic conductor formula of impedance is:Wherein Z₀For bimetallic conductor impedance, ε_rFor relative dielectric Constant, d is difference through hole center distance, and D is difference through hole diameter；

This impedance measured value is following (table 1) with the concrete numerical value of bimetallic conductor resistance value:

Table 1

Bimetallic conductor resistance value/ohm	Impedance measured value/ohm
		127.076	97.2
149.863	106
		170.038	113
104.669	90
		128.054	101
148.487	105
		117.118	98.2
138.119	105
		156.713	110
96.466	89.3
		118.019	96.4
136.851	101
		127.43	103
150.28	109
		170.511	115
104.96	93.6
		128.41	101
148.9	107

Step 13, according to several impedance measured values and several bimetallic conductor resistance values, obtain impedance measured value and Relation between bimetallic conductor resistance value, is modified bimetallic conductor formula of impedance according to described relation, thus obtains Difference through hole impedance formula, described difference through hole impedance formula is used for calculating the prediction resistance value of difference through hole, thus according in advance Survey resistance value difference through hole is compensated accordingly.

According to the difference of impedance measured value Yu the result of bimetallic conductor resistance value, bimetallic conductor model is carried out linearly Matching, fitting result as in figure 2 it is shown, can discrete from Fig. 2 from the point of view of to impedance measured value and bimetallic conductor resistance value Relation forms a regular trend, and this impedance measured value and bimetallic conductor resistance value discrete values are carried out Linear Quasi Close, obtain impedance measured value Z_d′_iffWith bimetallic conductor resistance value Z₀Between linear relationship be:

Z′_diff=0.33*Z₀+57.79；

Obtain impedance measured value Z_d′_iffWith bimetallic conductor resistance value Z₀Between linear relationship be not necessarily intended to by linearly Matching, it is also possible to obtain by other means, uses linear fit to obtain impedance as a preferably mode in the present embodiment Measured value Z_d′_iffWith bimetallic conductor resistance value Z₀Between linear relationship.

The Pearson's correlation coefficient R of this linear relationship²=0.951.

So difference through hole impedance value formula is:

$Z_{diff}=0.33*Z_0+57.79=\frac{39.6}{\sqrt{{\mathrm{\ϵ}}_r}}{\cosh }^{-1}(d/D)+57.79;$

Wherein Z_diffFor prediction resistance value, ε_rFor relative dielectric constant, d is difference through hole center distance, and D is difference through hole Diameter.

Verifying difference through hole impedance formula, the result is as shown in table 2, result display impedance measured value Z_d′_iff With the prediction resistance value Z obtained by difference through hole impedance formula_diffBetween comparison, for different types of material, via During diameter D≤0.35mm, it was predicted that within the difference of resistance value and impedance measured value can be controlled in 3.127%, difference through hole is described Formula of impedance can be applicable to the prediction of the through hole impedance value of different materials, and described prediction resistance value is consistent with impedance measured value, Can apply to difference and cross the prediction of resistance value.

Table 2

As it is shown on figure 3, difference through hole impedance and line impedance matching process, comprise the steps:

Step 01, acquisition design parameter；Described design parameter is provided by client, and design parameter includes in difference through hole in the heart Away from d, difference through hole diameter D, relative dielectric constant ε_rAnd line impedance；

Step 02, calculate the prediction resistance value Z of difference through hole according to design parameter and difference through hole impedance formula_diff； Described difference through hole impedance formula is:

$Z_{diff}=\frac{39.6}{\sqrt{{\mathrm{\ϵ}}_r}}{\cosh }^{-1}(d/D)+57.79,$

Wherein d is difference through hole center distance, and D is difference through hole diameter, D≤0.35mm；Further according to calculated pre- Survey resistance value difference through hole is compensated accordingly；So that prediction resistance value mates with line impedance.

As shown in Figure 4, difference through hole impedance and line impedance coalignment, including:

Acquisition module, obtains design parameter；Described design parameter is provided by client, and design parameter includes difference through hole center Spacing d, difference through hole diameter D, relative dielectric constant ε_rAnd line impedance；

Processing module, calculates the prediction resistance value of difference through hole according to design parameter and difference through hole impedance formula Z_diff；Described difference through hole impedance formula is:

$Z_{diff}=\frac{39.6}{\sqrt{{\mathrm{\ϵ}}_r}}{\cosh }^{-1}(d/D)+57.79,$

Wherein d is difference through hole center distance, and D is difference through hole diameter, D≤0.35mm；Further according to calculated pre- Survey resistance value difference through hole is compensated accordingly, so that prediction resistance value mates with line impedance.

It will be apparent to those skilled in the art that can technical scheme as described above and design, make other various Corresponding change and deformation, and all these change and deformation all should belong to the protection domain of the claims in the present invention Within.

Claims (10)

1. the method for building up of impedance computation model, it is characterised in that comprise the steps:

A1, detect the impedance of several difference through holes, thus obtain the impedance measured value of several difference through holes；

A2, calculate the bimetallic conductor resistance value of several difference through holes according to bimetallic conductor formula of impedance, described bimetallic Conductor impedance formula is:Wherein Z₀For bimetallic conductor impedance, ε_rFor relative dielectric constant, d is Difference through hole center distance, D is difference through hole diameter；

A3, according to several impedance measured values and several bimetallic conductor resistance values, obtain impedance measured value and bimetallic led Relation between impedance values, is modified bimetallic conductor formula of impedance according to described relation, thus obtains difference through hole Formula of impedance, described difference through hole impedance formula is used for calculating the prediction resistance value of difference through hole, thus according to prediction resistance value Difference through hole is compensated accordingly.

2. the method for building up of impedance computation model as claimed in claim 1, it is characterised in that in A3, described relation is linear Relation, described difference through hole impedance formula is:

Wherein Z_diffFor prediction resistance value, D≤0.35mm.

3. the method for building up of impedance computation model as claimed in claim 1, it is characterised in that in A1, use TDR testing impedance Instrument detects the impedance of several difference through holes.

4. the method for building up of impedance computation model as claimed in claim 1, it is characterised in that in A2, described bimetallic is led Line impedence formulaWherein stray inductanceParasitic capacitanceMagnetic permeability μ=μ_r*μ₀, DIELECTRIC CONSTANT ε=ε_r*ε₀；

Wherein, relative dielectric constant μ_r≈ 1, absolute permeability μ₀=4 π * 10^-7H/m, absolute dielectric constant ε₀=8.85*10^-12F/ m。

5. impedance matching methods, it is characterised in that comprise the steps:

S1, acquisition design parameter；

S2, calculate the prediction resistance of difference through hole according to design parameter and difference through hole impedance formula as claimed in claim 1 Anti-value, compensates difference through hole accordingly further according to prediction resistance value.

6. impedance matching methods as claimed in claim 5, it is characterised in that in S1, design parameter includes difference through hole center Spacing d, difference through hole diameter D and relative dielectric constant ε_r, in S2, described difference through hole impedance formula is:

Wherein Z_diffFor prediction resistance value, D≤0.35mm.

7. impedance matching methods as claimed in claim 5, it is characterised in that in S2, corresponding compensation is: according to prediction impedance Value adjusts the one or more size in the aperture of difference through hole, pad and anti-pad.

8. impedance-matching device, it is characterised in that including:

Acquisition module, it is used for obtaining design parameter；

Processing module, for calculating difference mistake according to design parameter and difference through hole impedance formula as claimed in claim 1 The prediction resistance value in hole, compensates difference through hole accordingly further according to prediction resistance value.

9. impedance-matching device as claimed in claim 8, it is characterised in that described design parameter includes in difference through hole in the heart Away from d, difference through hole diameter D and relative dielectric constant ε_r, the difference through hole impedance formula described in processing module is:

Wherein Z_diffFor prediction resistance value, D≤0.35mm.

10. impedance-matching device as claimed in claim 8, it is characterised in that corresponding compensation is: according to prediction impedance Value adjusts the one or more size in the aperture of difference through hole, pad and anti-pad.