CN103237418B - The determination methods of printed circuit slab warping - Google Patents

Abstract

The invention discloses a kind of determination methods of printed circuit slab warping, comprise the following steps: according to the production model of printed circuit board, obtain the information of its processing dimension, folded composition and process of surface treatment; Using the every one deck prepreg in laminated construction as analysis cutpoint, split successively from ground floor prepreg to last one deck prepreg, using as this layer of prepreg of cut-point as an analytic unit, prepreg upper portion is as an analytic unit, and lower portion is as an analytic unit; According to modulus of elasticity and the thermal coefficient of expansion information of each analytic unit obtained, calculate the curvature of each cutting unit and ask algebraical sum; Calculate the angularity of printed circuit board and Output rusults according to total curvature, the numerical value of angularity comprise on the occasion of and negative value, stick up to CS layer on the occasion of representing printed circuit board, negative value represents printed circuit board and sticks up to SS layer.

Description

The determination methods of printed circuit slab warping

Technical field

The present invention relates to printed circuit board technology field, particularly relate to a kind of determination methods of printed circuit slab warping.

Background technology

Along with the progress of mounting technology, propose harsher requirement to the evenness of printed circuit board, in order to meet Full Vision requirement, angularity has been put into one of whether qualified test item of printed board.Because angularity design factor is many, complicated mechanism, angularity problem becomes the puzzlement of printed circuit board manufacturer, and for solving this problem, the method taked at present has: the first, and rule of thumb the regular warpage providing different structure accepts standard; The second, warpage difficulty to be controlled or warpage receives the high printed board of standard, strengthen production management and control, cold pressing and carry out pressurization baking after time, boring as extended lamination and process and carry out hot pressing leveling before shipment.The defect of above method is to design the warpage degree that end can not predict its project organization before manufacture, manufacture process once warpage exceeds standard, need to scrap to mend and throw, the warpage issues caused for structural design needs to manufacture experimently first plate and can determine warpage scope and improvement measure, extend the process-cycle, production cost also can increase.

Summary of the invention

Based on this, for the problems referred to above, the present invention proposes a kind of determination methods can predicting the printed board warpage of printed circuit board angularity before manufacture.

Technical scheme of the present invention is: a kind of determination methods of printed circuit slab warping, comprises the following steps:

According to the production model of printed circuit board, obtain the information of its processing dimension, folded composition and process of surface treatment;

Using the every one deck prepreg in laminated construction as analysis cutpoint, split successively from ground floor prepreg to last one deck prepreg, using as this layer of prepreg of cut-point as an analytic unit, prepreg upper portion is as an analytic unit, and lower portion is as an analytic unit;

According to modulus of elasticity and the thermal coefficient of expansion information of each analytic unit obtained, calculate the curvature of each cutting unit and ask algebraical sum;

Calculate the angularity of printed circuit board and Output rusults according to total curvature, the numerical value of angularity comprise on the occasion of and negative value, stick up to CS layer on the occasion of representing printed circuit board, negative value represents printed circuit board and sticks up to SS layer.

In a preferred embodiment, further comprising the steps of: when the numerical value of the angularity calculated exceeds default numerical value, provide according to warp direction and optimize folded structure.

In a preferred embodiment, test different materials is from room temperature to the modulus of elasticity of solidification summit temperature, and the modulus of heat treatment process base material calculates as follows:

$E_{\mathrm{xb}}=\frac{E_{T1}+E_{T2}}{2}$

Wherein, E _xbfor the average elastic modulus of base material, ET1 is the modulus of elasticity under base material room temperature, E _t2for the modulus of elasticity of base material solidification summit temperature.

In a preferred embodiment, prepreg is made up of glass fabric and resin, and the modulus of heat treatment process prepreg calculates as follows:

$E_{\mathrm{pp}}=\frac{E_g+E_{\∞}}{2}$

$E_z=\frac{\mathrm{\Σ}\left(E_{\mathrm{xb}}{h}_{\mathrm{xb}}\right)+\mathrm{\Σ}\left(E_{\mathrm{pp}}{h}_{\mathrm{pp}}\right)+\mathrm{\Σ}\left(E_{\mathrm{cu}}{h}_{\mathrm{cu}}\right)}{\mathrm{\Σ}{h}_{\mathrm{xb}}+\mathrm{\Σ}{h}_{\mathrm{pp}}+\mathrm{\Σ}{h}_{\mathrm{cu}}}$

Wherein, E _ppfor the average elastic modulus of semi-solid preparation, E _gmodulus of elasticity during gel for semi-solid preparation, E _∞for modulus of elasticity when prepreg solidifies completely, E _zfor total mixing modulus of elasticity of base material, prepreg and Copper Foil, h _xbfor the thickness of base material, h _ppfor the theoretic throat of prepreg, h _cufor copper thickness.

In a preferred embodiment, the process formula of thermal coefficient of expansion CTE is:

$\mathrm{CTE}=\frac{\mathrm{\Σ}{\mathrm{CTE}}_{\mathrm{xb}}{h}_{\mathrm{xb}}+\mathrm{\Σ}{\mathrm{CTE}}_{\mathrm{pp}}{h}_{\mathrm{pp}}}{\mathrm{\Σ}{h}_{\mathrm{xb}}+\mathrm{\Σ}{h}_{\mathrm{pp}}}$

Wherein, CTE _xbfor the CTE of base material, CTE _ppfor CTE when prepreg solidifies completely, h _xbfor the thickness of base material, h _ppfor the theoretic throat of prepreg.

The invention has the beneficial effects as follows: the warpage that printed board can be predicted before manufacture, the printed board serious to the warpage doped, the optimization laminated construction improving warpage can be provided, improve product qualified rate, shorten process-cycle and processing cost.

Accompanying drawing explanation

Fig. 1 is the flow chart of determination methods described in the embodiment of the present invention;

Fig. 2 is a structural analysis figure of printed circuit board in the embodiment of the present invention;

Fig. 3 is another structural analysis figure of printed circuit board in the embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing, embodiments of the invention are described in detail.

Embodiment:

As shown in Figure 1, a kind of determination methods of printed circuit slab warping, comprises the following steps:

Step S101, according to the production model of printed circuit board, obtains the information of its processing dimension, folded composition and process of surface treatment;

Step S102, using the every one deck prepreg in laminated construction as analysis cutpoint, split successively from ground floor prepreg to last one deck prepreg, using as this layer of prepreg of cut-point as an analytic unit, prepreg upper portion is as an analytic unit, and lower portion is as an analytic unit;

Step S103, according to modulus of elasticity and the thermal coefficient of expansion information of each analytic unit obtained, calculates the curvature of each cutting unit and asks algebraical sum;

Step S104, calculates the angularity of printed circuit board and Output rusults according to total curvature, the numerical value of angularity comprise on the occasion of and negative value, stick up to CS layer on the occasion of representing printed circuit board, negative value represents printed circuit board and sticks up to SS layer.

Step S105, when the numerical value of the angularity calculated exceeds default numerical value, provides according to warp direction and optimizes folded structure.

In the present embodiment, test different materials is from room temperature to the modulus of elasticity of solidification summit temperature, and the modulus of heat treatment process base material calculates as follows:

$E_{\mathrm{xb}}=\frac{E_{T1}+E_{T2}}{2}$

Wherein, E _xbfor the average elastic modulus of base material, E _t1for the modulus of elasticity under base material room temperature, E _t2for the modulus of elasticity of base material solidification summit temperature.

In the present embodiment, prepreg is made up of glass fabric and resin, and the modulus of heat treatment process prepreg calculates as follows:

$E_{\mathrm{pp}}=\frac{E_g+E_{\∞}}{2}$

$E_z=\frac{\mathrm{\Σ}\left(E_{\mathrm{xb}}{h}_{\mathrm{xb}}\right)+\mathrm{\Σ}\left(E_{\mathrm{pp}}{h}_{\mathrm{pp}}\right)+\mathrm{\Σ}\left(E_{\mathrm{cu}}{h}_{\mathrm{cu}}\right)}{\mathrm{\Σ}{h}_{\mathrm{xb}}+\mathrm{\Σ}{h}_{\mathrm{pp}}+\mathrm{\Σ}{h}_{\mathrm{cu}}}$

Wherein, E _ppfor the average elastic modulus of semi-solid preparation, E _gmodulus of elasticity during gel for semi-solid preparation, E _∞for modulus of elasticity when prepreg solidifies completely, E _zfor total mixing modulus of elasticity of base material, prepreg and Copper Foil, h _xbfor the thickness of base material, h _ppfor the theoretic throat of prepreg, h _cufor copper thickness.

In the present embodiment, the process formula of thermal coefficient of expansion CTE is:

$\mathrm{CTE}=\frac{\mathrm{\Σ}{\mathrm{CTE}}_{\mathrm{xb}}{h}_{\mathrm{xb}}+\mathrm{\Σ}{\mathrm{CTE}}_{\mathrm{pp}}{h}_{\mathrm{pp}}}{\mathrm{\Σ}{h}_{\mathrm{xb}}+\mathrm{\Σ}{h}_{\mathrm{pp}}}$

Wherein, CTE _xbfor the CTE of base material, CTE _ppfor CTE when prepreg solidifies completely, h _xbfor the thickness of base material, h _ppfor the theoretic throat of prepreg.

As shown in Figure 2, label 2 is the first layer of prepreg, label 4 is the second layer of prepreg, always has 2 layers of prepreg and need split 2 times, when splitting the first layer of prepreg 2, label 1 is upside analytic unit, label 3,4,5 is common as downside analytic unit, then information extraction from 3 analytic units, as thick in core thickness, residual copper rate, copper, sheet material type, prepreg model, size, obtain modulus of elasticity and thermal coefficient of expansion, calculate the curvature 1 formed.

When second layer of prepreg 4 is split, as shown in Figure 3, label 1,2,3 is upside analytic unit, label 5 is downside analytic unit, then information extraction from 3 analytic units, as thick in core thickness, residual copper rate, copper, sheet material type, prepreg model, size, obtain modulus of elasticity and thermal coefficient of expansion, calculate the curvature 2 formed.

Below for 6 layers of printed circuit board plate 6a49403xa3, be illustrated:

1. design before producing

(1) input production model 6a49403xa3, automatically obtain data: processing dimension 18*16inch, finished size 200mm*160mm from ERP, surface treatment is turmeric, and folded structure situation is as follows:

Laminated information is as follows:

(2) the maximum angularity of program computation is-0.756% by analysis, and warp direction is SS face, and client accepts maximum warpage is 0.75%, has the risk exceeded standard.According to warp direction, the laminated construction situation of optimization is as follows:

Laminated information is as follows:

(3) the maximum angularity of the laminated construction of program computation optimization is by analysis-0.459%.

2. structure after determining routinely production method produce, complete production process is as following table:

3. warpage test: client accepts standard: maximum angularity≤0.75%, tests this batch according to IPC-TM-650, qualification rate 100%.

The above embodiment only have expressed the specific embodiment of the present invention, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.

Claims (5)

1. a determination methods for printed circuit slab warping, is characterized in that, comprises the following steps:

According to the production model of printed circuit board, obtain the information of its processing dimension, folded composition and process of surface treatment;

Using the every one deck prepreg in laminated construction as analysis cutpoint, split successively from ground floor prepreg to last one deck prepreg, using as this layer of prepreg of cut-point as an analytic unit, prepreg upper portion is as an analytic unit, and lower portion is as an analytic unit;

According to modulus of elasticity and the thermal coefficient of expansion information of each analytic unit obtained, calculate the curvature of each cutting unit and ask algebraical sum;

Calculate the angularity of printed circuit board and Output rusults according to total curvature, the numerical value of angularity comprise on the occasion of and negative value, stick up to CS layer on the occasion of representing printed circuit board, negative value represents printed circuit board and sticks up to SS layer.

2. the determination methods of printed circuit slab warping according to claim 1, is characterized in that, further comprising the steps of:

When the numerical value of the angularity calculated exceeds default numerical value, provide according to warp direction and optimize folded structure.

3. the determination methods of printed circuit slab warping according to claim 1 and 2, is characterized in that, test different materials is from room temperature to the modulus of elasticity of solidification summit temperature, and the modulus of heat treatment process base material calculates as follows:

$E_{\mathrm{xb}}=\frac{E_{T1}+E_{T2}}{2}$

Wherein, E _xbfor the average elastic modulus of base material, E _t1for the modulus of elasticity under base material room temperature, E _t2for the modulus of elasticity of base material solidification summit temperature.

4. the determination methods of printed circuit slab warping according to claim 1 and 2, is characterized in that, prepreg is made up of glass fabric and resin, and the modulus of heat treatment process prepreg calculates as follows:

$E_{\mathrm{pp}}=\frac{E_g+E_{\∞}}{2}$

$E_z=\frac{\mathrm{\Σ}\left(E_{\mathrm{xb}}{h}_{\mathrm{xb}}\right)+\mathrm{\Σ}\left(E_{\mathrm{pp}}{h}_{\mathrm{pp}}\right)+\mathrm{\Σ}\left(E_{\mathrm{cu}}{h}_{\mathrm{cu}}\right)}{\mathrm{\Σ}{h}_{\mathrm{xb}}+\mathrm{\Σ}{h}_{\mathrm{pp}}+\mathrm{\Σ}{h}_{\mathrm{cu}}}$

Wherein, E _ppfor the average elastic modulus of semi-solid preparation, E _gmodulus of elasticity during gel for semi-solid preparation, E _∞for modulus of elasticity when prepreg solidifies completely, E _zfor total mixing modulus of elasticity of base material, prepreg and Copper Foil, h _xbfor the thickness of base material, h _ppfor the theoretic throat of prepreg, h _cufor copper thickness.

5. the determination methods of printed circuit slab warping according to claim 1 and 2, is characterized in that, the process formula of the thermal coefficient of expansion of analytic unit is:

$\mathrm{CTE}=\frac{\mathrm{\Σ}{\mathrm{CYE}}_{\mathrm{xb}}{h}_{\mathrm{xb}}+\mathrm{\Σ}{\mathrm{CTE}}_{\mathrm{pp}}{h}_{\mathrm{pp}}}{\mathrm{\Σ}{h}_{\mathrm{xb}}+\mathrm{\Σ}{h}_{\mathrm{pp}}}$

Wherein, CTE is the thermal coefficient of expansion of analytic unit, CTE _xbfor the thermal coefficient of expansion of base material, CTE _ppfor thermal coefficient of expansion when prepreg solidifies completely, h _xbfor the thickness of base material, h _ppfor the theoretic throat of prepreg.