Method of correcting a screen printer and a board inspection system using the same

Patent metadata

Field	Value
Publication number	US-9962926-B2
Application number	US-201314396545-A
Country	US
Kind code	B2
Filing date	Apr 29, 2013
Priority date	Apr 27, 2012
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

The present invention relates to a method of correcting a position of a stencil mask which comprises receiving fiducial information from a screen printer, extracting position information of a pad and position information of a solder formed on a board through measuring by a solder paste inspection apparatus, estimating an x, y offset value and a rotating amount of a stencil mask based on the fiducial information by using the position information of the pad and the solder, and transmitting the x,y offset value and the rotating amount of the stencil mask to the screen printer. Thus, a reliability of solder forming process may be increased by correcting a stencil mask position by transmitting a feedback of an x,y offset value and a rotating amount of the stencil mask from a solder paste inspection apparatus, in which the x,y offset value and the rotating amount are estimated based on fiducial information transmitted from the screen printer.

First claim

The invention claimed is:

1. A method of estimating offset values in a stencil mask for correcting a screen printer configured to deliver a board, the method comprising:
partitioning the board into plurality of blocks in a computer processing environment, by a solder paste inspection apparatus, wherein the board consists of the plurality of blocks;
obtaining a position of each of a plurality of pads and a position of each of a plurality of solders formed on the board for each block on a coordinate system of the board, by a solder paste inspection apparatus;
estimating one block-x, y offset values for each block and one block-rotating amount for each block from the positions of the pads and the positions of the solders for minimizing distances between the positions of the pads and the positions of the solders by coordinate matching between the coordinate system of the board and a coordinate system of the screen printer, by the solder paste inspection apparatus;
estimating one x, y offset value and one rotating amount of a stencil mask based on the estimated block-x, y offset values for blocks and block-rotating amounts for blocks, by the solder paste inspection apparatus; and
transmitting the estimated x, y offset value and the estimated rotating amount of the stencil mask from the solder paste inspection apparatus to the screen printer; and
correcting a printing condition of the screen printer based on the estimated x, y offset value and the estimated rotating amount of the stencil mask.

2. The method of claim 1 , wherein the x, y offset value and the rotating amount of the stencil mask are estimated by averaging the x, y offset value and the rotating amount of each block.

3. The method of claim 1 , when estimating the block-x, y offset value and the block-rotating amount of the stencil mask, wherein the error of the stencil mask is defined as following formula:

E
=

∑
i

⁢

(

position
⁢

⁢
of
⁢

⁢
measured
⁢

⁢
solder

-

estimated
⁢

⁢
opening
⁢

⁢
position
⁢

⁢
of
⁢

⁢
stencil
⁢

⁢
mask

)

⁢
2

wherein E means the error of the stencil mask, and i means each pad, and
the block-x, y offset value and the block-rotating amount of the stencil mask are estimated to minimize the defined error.

4. The method of claim 3 , wherein a weight corresponding to a reliability of a measured value of a solder is applied in defining the error of the stencil mask.

5. The method of claim 1 , before dividing a board into plurality of blocks in a computer processing environment, by a solder paste inspection apparatus,
further comprising receiving fiducial information from a screen printer, by the solder paste inspection apparatus,
wherein the coordinate system of the board is based on the fiducial information.

6. A method of estimating offset values in a stencil mask for correcting a screen printer configured to deliver a board, the method comprising:
obtaining an image of the board;
partitioning the board into plurality of blocks in a computer processing environment, by a solder paste inspection apparatus, wherein the board consists of the plurality of blocks;
obtaining a position of each of a plurality of pads and a position of each of a plurality of solders formed on the board for each block on a coordinate system of the board, by a solder paste inspection apparatus;
estimating one block-x, y offset values for each block and one block-rotating amount for each block from the positions of the pads and the positions of the solders for minimizing distances between the positions of the pads and the positions of the solders by coordinate matching between the coordinate system of the board and a coordinate system of the screen printer, by the solder paste inspection apparatus;
estimating one x, y offset value and one rotating amount of a stencil mask based on the estimated block-x, y offset values for blocks and block-rotating amounts for blocks, by the solder paste inspection apparatus;
transmitting the estimated x, y offset value and the estimated rotating amount of the stencil mask from the solder paste inspection apparatus to the screen printer; and
correcting a printing condition of the screen printer based on the estimated x, y offset value and the estimated rotating amount of the stencil mask,
wherein the partitioning the image of the board into a plurality of blocks follows the obtaining the image of the board.

Assignees

• Koh Young Tech Inc
• Kyungpook Nat Univ Ind Academic Coop Found
• Kyungpook Nat Univ Ind Academic Coop Found

Inventors

• Kim Min-Young
• Kim Min-Su
• Kim Ja-Geun

Classifications

• B41M1/12

  Stencil printing; Silk-screen printing · CPC title

• H05K1/0269

  for visual or optical inspection · CPC title

• H05K3/34

  by soldering · CPC title

• B41F15/12

  with auxiliary equipment, e.g. for drying printed articles · CPC title

• B41F15/08 Primary

  Machines · CPC title