JPH03294077A - Apparatus for cutting tie bar - Google Patents

Abstract

PURPOSE:To cut a tie bar into the suitable shape by detecting shrinkage rate on frame surface near the tie bar on a lead frame after sealing with resin, correcting laser beam irradiation position to the tie bar and executing the laser beam irradiation. CONSTITUTION:Picture of marks 5a, 5b for detecting shrinkage shifting rate arranged on the lead frame 2 is taken in an ITV camera through an image forming lens, and each picture position is detected with picture processing. Positional information of the detected marks 5a, 5b is transferred to a correction arithmetic device and the shifting rate from the laser beam irradiation position beforehand programed is calculated and the accurate laser beam irradiation position is decided. Then, with the decided accurate laser beam irradiation positional information, the irradiating angle to the tie bar 4 is controlled to cut the tie bar 4.

Description

DETAILED DESCRIPTION OF THE INVENTION r Industrial Application Field The present invention relates to a tie bar cutting device for manufacturing resin-sealed semiconductor devices, and more particularly to a tie bar cutting device using laser light.

[Prior Art] Conventionally, in a tie bar cutting device using a laser beam, as is clear from the drawings referred to in FIG. 5 and FIG. The alignment is performed by a mechanical mechanism that inserts the positioning hole 20 of the lead frame 2 into a positioning bin (not shown) on the laser irradiation stage 1. That is, a method is used that depends entirely on the mechanical precision of the lead frame 2. Here, 3 is the sealing resin of the semiconductor device transferred onto the laser irradiation stage 1, 6, 7, 13 and 14 are large diameter lenses of the laser irradiation system, half mirrors,
A carbano mirror and a laser oscillator, and 17 and 18 indicate external leads and lead frame perforations arranged at a pitch P on the lead frame 2, respectively.

[Problems to be Solved by the Invention] As described above, in the conventional tie bar cutting device, the positioning of the tie bar 4 with respect to the laser beam 15 is performed by inserting the positioning hole 20 of the lead frame 2 into the positioning bin of the laser irradiation stage 1. After that, the laser beam 15 is sequentially irradiated according to the irradiation position coordinates that have been programmed in advance.

However, in this type of semiconductor device, shrinkage stress of the encapsulating resin that occurs after resin encapsulation causes the lead frame to bend.
In many cases, waviness is generated and the external lead pitch P is reduced below a specified value. Moreover, the degree of this reduction varies within individual frames, so it is not suitable for normal lead pitches, but when used for fine lead frames with a lead pitch of 0.5 mm or less designed for high-density board mounting. , the conventional tie bar cutting device that relies only on the mechanical precision of the frame is
This causes the problem that the center of the fusing portion 16 of the tie bar must be removed from the normal center position shown by the dotted line. In other words, a deep cut and a wide protrusion are formed in the external lead 17, so the next lead forming step is not necessary. This method has the drawback of causing bending or twisting of the lead, resulting in frequent defects in the lead shape.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a tie bar cutting device that solves the conventional problem of displacement of the fusing portion caused by bending and waviness of the lead frame.

[Means for Solving the Problems] According to the present invention, the tie bar cutting device detects the amount of shrinkage of the frame surface near the tie bars of the lead frame after the resin sealing process is completed, and determines the program content of the laser irradiation position with respect to the tie bars. and a laser irradiation position control means that controls the irradiation position of the laser beam output from the laser oscillator with respect to the tie bar based on the corrected laser irradiation position information from the optical system means. .

[Function J According to the present invention, the shrinkage of the lead pitch that occurs in the lead frame during resin sealing is quantitatively measured in the vicinity of the closest tie bar, thereby accurately determining the laser irradiation position with respect to the tie bar. Therefore, the problem of irregularly fused tie bars that conventionally occurred in the tie bar cutting process of fine lead frames is completely solved.

[Example 1 Next, one embodiment of the present invention will be explained in detail with reference to the drawings.

FIG. 1, FIG. 2, and FIG. 3 are a block diagram of a tie bar cutting device showing one embodiment of the present invention, and a partial plan view of a glued frame to be cut with tie bars, respectively. According to this embodiment, the tie bar cutting device includes a laser irradiation stage 1 and a lead frame 2 conveyed on the stage 1, which has two or four shrinkage and snow detection marks 5a and 5b provided near the tie bars 4. Or a large diameter lens 6, dichroic mirror 7, half mirror 8, and imaging lens 9 for accurately measuring the positions of 5a to 5d. I
The program content of the laser irradiation position is corrected based on the optical measurement system consisting of the TV camera, the image recognition device 11i5, and the light projecting device 19, and the position information of the marks 5a and 5b output by the image recognition device 11, and the contraction position shift is corrected. A correction calculation device 12 that accurately irradiates the laser beam 15 to the raised tie bar 4. It includes a laser irradiation system consisting of a laser oscillator and a calparameter 13. According to the present embodiment, the marks 5a, 5 for detecting shrinkage/slip snow provided on the lead frame 2
The images b or 5a to 5d are sent to IT through the imaging lens 9.
The images are captured by the V camera 10, and the image positions are detected by image processing by the image recognition device 11. The position information of the detected marks 5a, 5b or 5a to 5d is transferred to the correction calculation device 12, where the amount of deviation from the pre-programmed laser irradiation position is calculated to determine the accurate laser irradiation position. It will be done. This accurate laser irradiation position information determined in this way drives the calparameter 13 and controls the irradiation angle of the laser beam 15 oscillated by the laser oscillator 14 with respect to the tie bar 4.
As shown in the figure, the centers of the fusing portions 16 of all tie bars can be cut at once by aligning them with the regular center positions. Therefore, even for a fine lead frame with a lead pitch P of 0.5 s+s or less, it is possible to cut the tie bar into an appropriate shape with less cutting deviation. In particular, when the amount of positional deviation information of the lead pitch P is increased using four shrinkage deviation snow detection marks as shown in Fig. 3, the size of the sealing resin 3 is large and the multi-bin lead is greatly affected by resin shrinkage. It can have a great effect on the frame.

[Effects of the Invention] As described in detail above, according to the present invention, the positional deviation of the lead pitch that occurs during resin sealing can be quantitatively detected in the vicinity of the tie bar, and the laser irradiation position with respect to the tie bar can be accurately determined. After that, laser irradiation is performed, so it is possible to cut a tie bar into an appropriate shape with less cutting deviation for a fine-pitch lead frame with a lead pitch of 0.5+s■ or less.

In particular, it can sufficiently cope with the trend of increasing the size of the sealing resin layer due to the increase in the number of bottles in semiconductor devices, and is therefore highly effective in stabilizing quality.

[Brief explanation of the drawing]

1, 2, and 3 are a block diagram of a tie bar cutting device showing one embodiment of the present invention, and a partial plan view of a lead frame to be cut with tie bars, and FIG. 4 is a tie bar according to the present invention. 5 and 6 are respectively a block diagram of a conventional tie bar cutting device and a partial plan view of a lead frame to be cut with tie bars, and FIG. 7 is a diagram of a fine lead frame cut by a conventional tie bar cutting device. FIG. 3 is a diagram showing a state in which the tie bar is cut. 1... Laser irradiation stage, 2-... Lead frame, 3... Sealing resin 4...
Tie bars 5a, 5b, 5c, 5d - Shrinkage deviation snow detection mark,
6...Large diameter lens, 7...Dichroic mirror 8...Half mirror-19--Imaging lens, 10--
ITV camera, 11--Image recognition device, 12--Correction calculation device, 13--Carbal meter, 14--Laser oscillator, 15--Laser light, 16--Tie bar fused portion, 17.・-External lead, 18... Lead frame feed hole, 19... Light projector, 20... Positioning hole, P
-...Lead pitch. Figure 2

Claims (1)

[Claims] optical system means for detecting the amount of shrinkage of the frame surface near the tie bars of the lead frame after the resin sealing process is completed and correcting the program content of the laser irradiation position with respect to the tie bars, and corrected laser irradiation position information from the optical system means; 1. A tie bar cutting device comprising: laser irradiation position control means for controlling an irradiation position of a laser beam output from a laser oscillator on the tie bar based on the laser oscillator.