1. A method for determining the optimal alignment value of a solder mask 8-point CCD is characterized by comprising the following steps:

uniformly arranging n welding-proof CCD points on the upper part and the lower part of the material object plate and the film along the length direction;

step two, pressing CCD points on the object plate and the film according to phasesThe same sequence is numbered as 1, 2.. 2 n; measuring the distance between the ith welding-proof CCD point and the jth welding-proof CCD point on the object plate in the X-axis direction, wherein i is more than or equal to 1 and less than or equal to 2n, and j is more than or equal to 1 and less than or equal to 2 n; obtaining the distance between any two anti-welding CCD points of the object plate in the X-axis direction; measuring the distance between the ith welding-proof CCD point and the jth welding-proof CCD point on the film in the X-axis direction; obtaining the distance between any two solder mask CCD points on the film in the X-axis direction; let a_xijThe distance between the ith welding-proof CCD point and the jth welding-proof CCD point on the object plate on the X axis, b_xijThe distance between the ith and jth welding-proof CCD points on the film on the X axis is delta X ═ a_xij-b_xijL, |; obtaining max delta X, wherein the max delta X is the maximum value of the delta X;

measuring the distance between the ith welding-proof CCD point and the jth welding-proof CCD point on the physical plate in the Y-axis direction to obtain the distance between any two welding-proof CCD points of the physical plate in the Y-axis direction; measuring the distance between the ith welding-proof CCD point and the jth welding-proof CCD point on the film in the Y-axis direction; obtaining the distance between any two solder mask CCD points on the film in the Y-axis direction; let a_YijThe distance between the ith welding-proof CCD point and the jth welding-proof CCD point on the material board on the Y axis, b_yijThe distance between the ith anti-welding CCD point and the jth anti-welding CCD point on the film on the Y axis is delta Y ═ aYij-byij |; obtaining max delta Y, wherein the max delta Y is the maximum value of delta Y;

and step four, the optimal alignment value delta max is sqrt ((max delta X/2)2+ (max delta Y/2) 2)).

2. The method for determining the optimal alignment value of a solder mask 8-point CCD as claimed in claim 1, wherein n is 4.

3. The method for determining the optimal alignment value of the solder mask 8-point CCD as claimed in claim 1, wherein the film is determined to be available when Δ max < windowing of the pad, and the film is determined not to be available otherwise.

4. The method for determining the optimal alignment value of the solder mask 8-point CCD as claimed in claim 1, wherein the moving range of the CCD light spot and the moving distance of each movement are set, the CCD light spot is moved according to the moving distance in the moving range, the optimal alignment value Δ max is adjusted, the moving range of all the CCD light spots is traversed, and the obtained minimum Δ max is the actual optimal alignment value.

Background

The existing solder mask exposure machine (620.5mm x 725mm) is 4 point (4 corners of the board) alignment, when the PCB size is increased to (620.5mm x 1092mm), the 4 point alignment can not meet the requirement due to uneven expansion and contraction, and the situations are as follows: the periphery can be aligned, but the middle is misaligned, so that the alignment condition in the middle of the Panel cannot be monitored.

In addition, at present, the harmomegathus contraposition can only be more than or equal to +/-1.0mil, so that a plurality of boards with fine circuit design cannot be split into large makeup boards, and the production efficiency is influenced; solder mask PAD directly results in PCB rejection.

Disclosure of Invention

In order to solve the problems, the invention discloses a method for determining the optimal alignment value of a solder-resisting 8-point CCD. The method simulates the maximum deviation of the film and the actual PCB by a mathematical method, and obtains the optimal PE value of the solder mask exposure machine according to the solder mask windowing value and the cover line value, thereby effectively preventing the PCB from being scrapped due to exposure deviation, saving the cost and improving the production efficiency.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a method for determining the optimal alignment value of a solder mask 8-point CCD (charge coupled device) comprises the following steps of:

uniformly arranging n welding-proof CCD points on the upper part and the lower part of the material object plate and the film along the length direction;

secondly, numbering CCD points on the material object plate and the film as 1, 2.. 2n according to the same sequence; measuring the distance between the ith welding-proof CCD point and the jth welding-proof CCD point on the object plate in the X-axis direction, wherein i is more than or equal to 1 and less than or equal to 2n, and j is more than or equal to 1 and less than or equal to 2 n; obtaining the distance between any two anti-welding CCD points of the object plate in the X-axis direction; measuring the distance between the ith welding-proof CCD point and the jth welding-proof CCD point on the film in the X-axis direction; obtaining the distance between any two solder mask CCD points on the film in the X-axis direction; let a_xijThe distance between the ith welding-proof CCD point and the jth welding-proof CCD point on the object plate on the X axis, b_xijThe distance between the ith and jth welding-proof CCD points on the film on the X axis is delta X ═ a_xij-b_xijL, |; obtaining max delta X, wherein the max delta X is the maximum value of the delta X;

measuring the distance between the ith welding-proof CCD point and the jth welding-proof CCD point on the physical plate in the Y-axis direction to obtain the distance between any two welding-proof CCD points of the physical plate in the Y-axis direction; measuring the distance between the ith welding-proof CCD point and the jth welding-proof CCD point on the film in the Y-axis direction; obtaining the distance between any two solder mask CCD points on the film in the Y-axis direction; let a_YijThe distance between the ith welding-proof CCD point and the jth welding-proof CCD point on the material board on the Y axis, b_yijThe distance between the ith anti-welding CCD point and the jth anti-welding CCD point on the film on the Y axis is delta Y ═ aYij-byij |; obtaining max delta Y, wherein the max delta Y is the maximum value of delta Y;

and step four, the optimal alignment value delta max is sqrt ((max delta X/2)2+ (max delta Y/2) 2)).

In a further improvement, n is 4.

And further improving that the film is judged to be available when the delta max is less than the windowing of the bonding pad, and the film is judged not to be available otherwise.

Further improvement, the moving range of the CCD light spots and the moving distance of each moving are set, the CCD light spots are moved in the moving range according to the moving distance, the optimal alignment value delta max is adjusted, the moving ranges of all the CCD light spots are traversed, and the obtained minimum delta max is the actual optimal alignment value.

The invention has the advantages that:

1. and (3) simulating the maximum deviation of the film and the actual PCB by a mathematical method, and obtaining the optimal PE value of the solder mask exposure machine according to the solder mask windowing value and the cover line value.

2. And obtaining the specific expansion and contraction offset among the SET in the Panel, and solving the expansion and contraction problem of any type of PCB.

Drawings

FIG. 1 is a schematic view of solder mask CCD dots in a film and physical plate of example 1;

FIG. 2 is a schematic view of solder mask CCD spots in a film and physical plate according to example 2;

FIG. 3 is a schematic view of solder mask CCD spots in a film and physical plate according to example 3;

FIG. 4 is a schematic view of solder mask CCD dots in the film and physical plate of example 4;

FIG. 5 is a schematic view of solder mask CCD dots in the film and physical plate of example 5;

FIG. 6 is a schematic view of solder mask CCD dots in the film and physical plate of example 6;

FIG. 7 is a schematic view of solder mask CCD dots in the film and physical plate of example 7;

FIG. 8 is a schematic view of the film and physical plate of example 7 after adjustment of the solder mask CCD dots.

Detailed Description

The technical means of the present invention will be specifically described below by way of specific embodiments.

The 25"x43" (620.5 mm. 1092mm) solder mask exposure machine had 8 registration points, 4 each in the length direction, and the best registration values for the film and board were now calculated.

Example 1

Firstly, as shown in FIG. 1, starting from one dimension, assume 4 welding-proof CCD points, and only expand and contract in X direction

Firstly, measuring the distance between any two points of 4 CCD points of the real object plate and the film to obtain the deviation value delta of the distance between the corresponding points of the real object plate and the film

Second, find out two endpoints with the maximum corresponding deviation value delta

Bold characters in the above figure indicate that the deviation value Δ is maximum (Δ max is 2), and corresponds to A3-a4 and a1-A3, respectively.

Thirdly, delta max/2 is the optimal deviation value of the single point of the film and the material plate

Equation 1: the optimal deviation value of a single point is equal to the maximum deviation value/2 of the distance between any two points is equal to 1

Equation 2: the single-point optimal deviation value is min (max Δ Aij), i is the number of CCD points, j is the number of shifts, for example, the CCD light spot is shifted within 3x3mil,

if the unit of distance moved is set to 0.1mil, j is 900, and the smaller the unit of distance is set, the larger the movement range is, and the more accurate the formula is.

Note that equation 1 does not apply fully to two-dimensional non-linear variation of the harmomegathus, but one reference value can be calculated and then equation 2 can be applied

Fine tuning is performed.

And fourthly, moving the gray points A3-A4 to be aligned with the centers of the black points A3-A4, so that the optimal alignment of the film and the plate is realized.

Black A3-A4 with a length of 10 and gray A3-A4 with a length of 12 will suffice no matter how the gray A3, A4 translate

| Δ A3| + | Δ a4| ≧ 2, and | Δ Ai, i ═ 3,4 ≦ 1 only when | Δ A3| ═ Δ a4| ═ 1

And (4) conclusion:

1. and calculating the optimal alignment position and the optimal single-point deviation value of the film and the material object plate according to the method.

2. And obtaining deviation values of all CCD light spots under the condition of optimal alignment, and determining whether the film is available or not according to the minimum resistance welding windowing and cover line in the unit.

Example 2

The expansion and contraction gradually increase from one side to the other side, and the sizes of the film and the real plate are consistent as shown in figure 2:

example 3

The middle swell and shrink are the largest, the two swell and shrink are equal, and the film and the real plate have the same size, as shown in figure 3:

example 4

The middle expansion and contraction is the largest, the expansion and contraction on the two sides are unequal, and the size of the film is consistent with that of the real object plate, as shown in figure 4:

example 5

The left and middle expansions are small, the right expansion and contraction is large, and the film and the object plate are not consistent in size, as shown in FIG. 5:

example 6

Irregular harmomegathus, as shown in fig. 6:

example 7

Suppose that: 1. the expansion and contraction of each interval are inconsistent 2. the overall size of the film and the material plate is inconsistent.

At this time, the maximum deviation value of Δ max cannot be directly deduced by using a formula, and only a step-by-step derivation method can be adopted.

The derived principle is as follows: priority is given to the most extreme cases of expansion and contraction.

The first step is to calculate the maximum offset between every two points of 8 CCD points in the X direction

The second step is to calculate the maximum shift between each two points of 8 CCD points in Y direction

Thirdly, calculating the theoretical optimal deviation value of delta max

As shown in fig. 7: theoretical values of 3.01 for A5, 2.65 for A3 and 2.46 for A4

As shown above, A5 is the point where the positional difference between the film and the real plate is the greatest, and A3 and A4 are the second and third points of positional difference.

We also find a law:

when the gray point is moved rightward as a whole, the offset distance of a5 decreases, the offset distance of A3 decreases, and the offset distance of a4 increases.

When Δ max.a5 is Δ max.a4, Δ max is the smallest,

the equation (2.25-x) (2.25-x) +4 ═ 2.25+ x) ((2.25 + x) +1

Solving the equation x is 1/3 Δ max.5 Δ max.a4 is 2.77 Δ max.a3 is 2.45

When the gray dot is moved upward as a whole, the offset distance of a5 decreases, the offset distance of A3 increases, and the offset distance of a4 increases

When Δ max.a5 is Δ max.a3, Δ max is the smallest,

the equation (2-x) × (2-x) +2.25 × 2.25 ═ 2+ x (2+ x) +1.75 × 1.75

Solving the equation x is 0.25, Δ max.5 is Δ max.3 is 2.85 Δ max.4 is 2.57

The left side 2.25 represents the x-axis distance of the A5 gray dot from the black dot, and the x represents the movement of the gray dot to the right by x, the x-axis distance from the black dot is 2.25-x

The right side 2.25 represents the x-axis distance of the A4 gray dot from the black dot, and + x represents the gray dot moving to the right by x, the x-axis distance from the black dot is 2.25+ x

The y-axis distance between the black dots and the gray dots of A5 is 2, and the square is 4; the y-axis distance between the black dot and the gray dot of a4 is 1, and the square is 1 equation, which indicates that when x is moved, the distances between the black dot and the gray dot of a5 and a4 are equal (the offset value is the smallest), so that (2.25-x) × (2.25-x) +4 ═ 2.25+ x) ((2.25 + x) +1 according to the pythagorean theorem

(2.25-x) (2.25-x) +4 represents the square of the distance between the black and gray dots of A5,

(2.25+ x) (2.25+ x) +1 represents the square of the distance between the black and gray dots of A4,

it is also possible to explain (2-x) × (2-x) +2.25 × 2.25 ═ 2+ x (2+ x) +1.75 × 1.75, although this x is shifted towards the y axis.

The adjusted Δ max theoretical maximum offset value min (2.77,2.85) 2.77 is obtained, see fig. 8 below

As shown in fig. 8-fine tuning based on the theoretical optimum offset of 3.01, resulting in an adjusted offset of 2.77

While embodiments of the invention have been disclosed above, it is not limited to the applications set forth in the specification and the embodiments, which are fully applicable to various fields of endeavor for which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.