JP2546059B2 - IC lead frame shape generator - Google Patents

Description

TECHNICAL FIELD The present invention relates to an IC lead frame shape generator, and more particularly to an apparatus for generating an IC lead frame shape for a multi-pin ceramic package.

[Conventional technology]

As a conventional technique, a manual design and drafting are mainly performed, and work is performed by trial and error so that the lead width and the lead interval are equal to or larger than a reference value.

[Problems to be Solved by the Invention]

It is an object of the present invention to provide a device that, when given an IC pin arrangement determined by the IC package and the number of pins, generates an IC lead frame shape according to the size of the IC pellet to be mounted in the IC package.

[Means for solving the problem]

The IC lead frame shape device of the present invention includes a display, a keyboard, a storage device, a plotter, and a central processing unit to which these are connected, and IC pin arrangement data input from the keyboard and stored in the storage device. ,I C
Based on the pellet shape data and the lead width and the lead interval width, the cavity line is positioned at a constant distance from the IC pellet in the central processing unit, and the bending auxiliary line is positioned at a constant distance from this cavity line to generate the IC lead frame shape, If the lead width and the lead interval are equal to or less than the reference value, the bending auxiliary line is moved in the direction of the cavity line to generate an IC lead frame shape again, and this IC lead frame shape is displayed on the display and drawn on the plotter. It is characterized by doing.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a system configuration diagram of an embodiment of the present invention.
In the figure, a central processing unit (hereinafter referred to as CPU) 1 is connected with a display 2, a storage device 3, a plotter 4, and a keyboard 5 as an input device.

FIG. 2 is an explanatory diagram showing an example of an IC lead frame.
As shown in the fourth quadrant in the figure, the leads 11 are wired from the IC pin 11 to the vicinity of the IC pellet 10. Although omitted in this figure, there are leads in quadrants other than the fourth quadrant. A set of leads is called an IC lead frame.

FIG. 3 is an explanatory view showing an example of the tip shape of the IC lead frame. As shown in the figure, one lead 12 is formed of a lead tip portion 21 and a lead peripheral portion 23, and the boundary between them is a bending auxiliary line 22. There is a cavity line 20 at a certain distance from the pellet 10, and the lead tips are on this line. The bonding point 24 is an important point where a wire (gold wire) is stretched to a pad (electrode) on the pellet.

FIG. 4 is a flow chart showing the operation for generating the shape of the IC lead frame.

Determined by various IC packages and pin numbers from the keyboard 5
When the IC pin arrangement (xy coordinate value of pin shape) is input, it is stored in the storage device 3. This operation may be performed once before using this device (step S0).

Next, the CPU 1 displays the type of the IC package registered in the storage device 3 on the display 2 and at the same time the keyboard 5
Display to input from. Items to enter are IC
The size of the pellet in the x direction and the y direction (only rectangular shape) and the type of IC package to be mounted (steps S1 to S3). CPU1 is the IC pellet shape and IC entered above
Display the package on display 2 (step S4),
A cavity line (only rectangular shape) is displayed at a certain distance from the pellet (step S5). Similarly, a bending auxiliary line (only rectangular shape) is displayed at a certain distance from the cavity line (step S6).

Since the IC lead frame is generally symmetrical vertically and horizontally, it is only necessary to design a specific quadrant and invert it with respect to the x and y axes. Here, the method of obtaining the lead tip position will be described below for the fourth quadrant. The lead frame design conditions are the lead width d of the lead tip and the bonding point 24.
The lead width d '(however, d'≥d), the lead width d "of the other portion, and the lead interval S in each of the above are equal to or larger than the reference values. Also, d'is made as uniform as possible for all the leads. The lead width is measured perpendicularly to the center line of the lead as shown in Fig. 3. The center line of the lead forms an angle α (unit: radian) with the cavity line 20. The lead width on the cavity line 20 Is defined as x, the following approximate expression holds at the lead tip.

Similarly, if the lead interval on the cavity line 20 is y, the following approximate expression holds.

In the lower half of the fourth quadrant, the lead or lead spacing tilt angle αi lies between π / 4 and π / 2 radians, And Here, n is the total number of leads and the number of lead intervals, and i is the number of leads or lead intervals counted from the central portion of the fourth quadrant. If the length of the cavity line 20 in the lower half of the fourth quadrant is C, That is, the following equation is established.

Here, if d to s ratio is given, d can be obtained from the above equation,
The lead tip position can be determined (step S7). Even on the bending auxiliary line, if the bending point of the lead is determined by the d: s ratio, the lead tip can be generated (step S8). The lead peripheral portion 23 can be generated by connecting a straight line from the bending point of the lead to the position of the pin (step S9).

It is checked whether or not the lead width d ″ and the lead interval S satisfy the reference values in the lead peripheral portion 23 (step S10), and if they are satisfied, the lead frame shape is displayed on the display 2 and output to the plotter 4 for printing. When the operation of the device is completed (step S11), if not satisfied, the bending auxiliary line 22 is moved in the direction of the cavity line 20 by a slight amount to alleviate the sudden bending of the lead (step S1).
2), return to step S10.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY As described in detail above, the present invention is useful for generating an IC lead frame shape according to the size of the IC pellet to be mounted in the IC package when given the IC pin arrangement determined by the IC package and the number of pins. Various devices can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a system configuration diagram showing an embodiment of the present invention, and FIG.
The figure is an explanatory view showing an example of the shape of the IC lead frame.
Explanatory drawing showing an example of tip shape of IC lead frame, 4th
The figure is a flow chart for explaining the operation of the embodiment shown in FIG. 1 ... CPU, 2 ... Display, 3 ... Storage device, 4
...... Plotter, 5 ...... Keyboard, 10 ...... Pellet, 11
...... Pin, 12 ...... Lead, 20 ...... Cavity line, 21
...... Lead tip part, 22 …… Bending auxiliary line, 23 …… Lead peripheral part.

Claims (1)

(57) [Claims] 1. A display, a keyboard, a storage device, a plotter, and a central processing unit to which these are connected, and IC pin arrangement data and IC pellet shape data input from the keyboard and stored in the storage device. Based on the lead width and the lead interval width, the cavity line is positioned at a constant distance from the IC pellet in the central processing unit, the bending auxiliary line is positioned at a constant distance from the cavity line, and the IC lead frame shape is generated. If the lead interval is less than the reference value, move the bending auxiliary line in the direction of the cavity line, and
An IC lead frame shape generator, which generates a lead frame shape, displays the IC lead frame shape on the display, and draws on the plotter.