CN112141411A - Tension-free film pasting device and method for lead frame - Google Patents

Abstract

The invention discloses a tension-free film pasting device and method for a lead frame, and relates to the technical field of semiconductor packaging testing. The invention comprises a cantilever film sticking main bracket with a movable position, a left guide wheel, a film carrying cylinder, a film depletion detection sensor, a release layer winding drum, a film pulling and releasing force application cylinder, a film pulling and releasing meshing roller module, a film and release layer separation position control optical fiber, an upper film supporting plate, an ion fan, a middle guide wheel, a lower film supporting plate, a right guide wheel, a linear cutting knife, a film end surface adsorption rod, a film sticking roller and a film supporting air pipe, wherein the left guide wheel is arranged on one side part of the cantilever film sticking main bracket. The invention can realize the tension-free film pasting, and can not cause the thin and soft lead frame to warp due to the tension of the film paper; the film-pulling and meshing roller set in the device clamps the release layer instead of the clamped film paper, so that the damage to the glue layer of the film paper is avoided; the invention adopts double-workbench film pasting, so that the working efficiency can reach more than 300 pieces/hour.

Description

Tension-free film pasting device and method for lead frame

Technical Field

The invention belongs to the technical field of semiconductor packaging test, and particularly relates to a tension-free film sticking device and a tension-free film sticking method for a lead frame.

Background

The integrated circuit is a miniature electronic device or component, and is prepared by interconnecting the required elements of transistor, resistor, capacitor and inductor in a circuit and wiring, making them on one or several small semiconductor wafers or medium substrates, and packaging them in a tube shell to obtain the miniature structure with the required circuit function; all the components are structurally integrated, and the integrated circuit makes the electronic components advance toward miniaturization, low power consumption, intellectualization and high reliability.

The lead frame is used as a chip carrier of an integrated circuit, is a key structural member for realizing the electrical connection between a lead-out end of an internal circuit of a chip and an external lead by means of bonding materials to form an electrical circuit, plays a role of a bridge connected with an external lead, and is an important basic material in the electronic information industry. The lead frame is subjected to back protection before high-temperature baking or injection molding, so that the layer of yellow film for back protection is required to be resistant to high temperature and accurate in position relative to the lead frame, preferably, the yellow film is completely located in a designated area of the range of the lead frame, accurate positioning and effective clamping and fixing are required before film pasting, and in the action process, an operator and equipment do not need to touch a chip on the front face of the lead frame, and people currently conduct research on the aspect. For example, the applied chinese patent with application number CN201811326498.5 discloses a film sticking device composed of a film carrying cylinder, a release layer winding cylinder, a film feeding mechanism, a waste film collecting and guiding mechanism, a film placing and guiding mechanism, a lead frame workbench, a swinging film sticking mechanism, etc.; but it has the following problems: 1. the attaching force between the film paper and the release layer cannot be released in advance, the separating force is still relatively large for partial film paper, and for an extremely soft and extremely thin lead frame, the separating force can also be reflected on the frame to which the film is attached, so that the frame is warped along with the tension of the film, and subsequent processes such as chip mounting, bonding and the like are influenced; 2. the film feeding mechanism can complete the active film feeding action only by clamping the film, and the film feeding mechanism is arranged before the release layer is separated from the adhesive tape and can certainly damage the adhesive film. Based on the problems, the tension-free film sticking device and the film sticking method for the lead frame are significant for solving the problems.

Disclosure of Invention

The invention provides a tension-free film sticking device and a film sticking method for a lead frame, which solve the problems.

In order to solve the technical problems, the invention is realized by the following technical scheme:

the invention discloses a tension-free film sticking device for a lead frame, which comprises a cantilever film sticking main support with a movable position, a left guide wheel, a film carrying cylinder, a film depletion detection sensor, a release layer winding drum, a film pulling and releasing meshing force application air cylinder, a film pulling and releasing meshing roller module, a film and release layer separation position control optical fiber, an upper film supporting plate, an ion fan, a middle guide wheel, a lower film supporting plate, a right guide wheel, a linear cutting knife, a film end surface adsorption rod, a film sticking roller and a film supporting air pipe, wherein the left guide wheel is arranged on one side part of the cantilever film sticking main support;

the film carrying cylinder is wound with a film with an unseparated release layer, the film is sequentially pressed and stuck on the left guide wheel and the middle guide wheel, the release layer and the adhesive surface film are separated by pulling at the middle guide wheel, and the release layer is connected with a pull-release film meshing roller module with a pull-release film meshing force application air cylinder through an upper supporting film plate and then is rewound and stretched in a release layer rewinding cylinder for winding and recovery; after the adhesive film is supported by the lower film supporting plate, the adhesive film is guided to the position of the film end surface adsorption rod by the right guide wheel;

the cantilever pad pasting main support is located at the lower part of the membrane end surface adsorption rod and is provided with an inner pad pasting workbench and an outer pad pasting workbench which are in a double-workbench type and can independently move along the X axial direction.

Further, the ion fan is installed on the cantilever pad pasting main support, and the wind direction mouth faces the upper support membrane plate and the lower support membrane plate, and is used for removing static electricity generated when the glue film is separated from the release layer.

Further, the membrane uses a depletion detection sensor to indicate when the membrane is about to be depleted and to suspend operation of the device, employing a photosensor.

Furthermore, the cantilever film-sticking main support is installed on the Y-axis moving mechanism, and switching is achieved between the inner film-sticking workbench and the outer film-sticking workbench.

Further, the film pasting idler wheel is arranged on the side part of the film end surface adsorption rod and used for rolling and pasting the film.

Further, the support straight line cutting knife is positioned on the side part of the support membrane air pipe and used for cutting off the adhesive membrane.

Furthermore, the film supporting air pipe is located below the film end face adsorption rod and used for supporting the broken adhesive surface film when the adhesive surface film is cut off and preventing the adhesive surface film from falling onto the lead frame under the action of gravity.

A non-tension film pasting method for a lead frame comprises the following steps:

s01, penetrating the film according to the structure and the positional relation description of the film;

s02, moving the inner film pasting workbench from right to left along the X-axis direction to the position below the film end face adsorption rod, then downward placing a section of adhesive film by the film pulling and releasing meshing roller module, simultaneously rotating the film end face adsorption rod clockwise by 90 degrees, moving the position where the adhesive film is separated from the release layer to the first position between the film pulling and releasing meshing roller module and the middle guide wheel, and enabling the film at the right end of the film end face adsorption rod to be in a downward convex shape as shown by the second position;

s03, pressing the film end face adsorption rod downwards by 20mm, attaching the section of the adhesive film to the left end of the lead frame on the inner film pasting workbench, cutting off the vacuum adsorption force, lifting the film end face adsorption rod at the adhesive film end by 20mm, and rotating the end part upwards clockwise;

s04, pressing the film pasting roller down by 10mm, moving the film pasting roller to the right by 50mm, and pressing the end face of the adhesive film on the lead frame;

s05, moving the inner film pasting workbench leftwards along the X axis, and meanwhile, downwards putting films on the film drawing and releasing meshing roller module at the same speed as the inner film pasting workbench until the separation position of the adhesive film and the release layer is close to the third position of the middle guide wheel;

s06, the pulling and releasing film meshing roller module pulls the release layer to peel the adhesive film from the release layer until the peeling position is pulled to the lower initial position of the control optical fiber at the position where the film is separated from the release layer;

s07, clockwise rotating a film end face adsorption rod of the end face of the adhesive film to an initial position, adsorbing the adhesive film on the bottom face of the film end face adsorption rod, blowing air to the left upper side of a film supporting air pipe below, moving a linear cutting knife to the left, puncturing the adhesive film under the support of a knife avoiding groove of the film end face adsorption rod, then cutting the adhesive film in the knife avoiding groove by the linear cutting knife, sucking the end face above the adhesive film by the film end face adsorption rod, and reversely wrapping a film attaching roller on the film surface below under the action of airflow of the film supporting air pipe;

s08, the inner film pasting workbench continues to move left along the X axis, the adhesive surface film floating above the film pasting roller is pasted on the lead frame, then the film pasting roller moves left by 50mm and then rises by 10mm to return to the initial position, and the film supporting air pipe stops blowing air;

s09, the cantilever film-pasting main support integrally moves to the position above the X-axis track of the outer film-pasting workbench, and meanwhile, the inner film-pasting workbench automatically completes the feeding and blanking actions of the lead frame;

s10, the outer film pasting workbench carries out the same film pasting steps as the steps S02-S08;

s11, moving the cantilever film sticking main bracket to the position above the X-axis track of the inner film sticking worktable integrally, and then circulating the inner film sticking worktable to exchange the film sticking between the two workbenches.

Compared with the prior art, the invention has the following beneficial effects:

1. the tension-free film sticking device and the film sticking method for the lead frame can realize tension-free film sticking, and the film paper has no tension when sticking the film, so that the thin and soft lead frame cannot be warped due to the tension of the film paper.

2. The film-pulling and film-engaging roller set in the device of the invention clamps the release layer instead of the clamped film paper, thereby avoiding damaging the adhesive layer of the film paper

3. The double-workbench film pasting in the device enables the working efficiency to reach more than 300 sheets/hour.

Of course, it is not necessary for any product in which the invention is practiced to achieve all of the above-described advantages at the same time.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a lead frame film bonding apparatus without tension according to the present invention;

FIG. 2 is a schematic diagram of step S01 of a method for attaching a lead frame to a film without tension according to the present invention;

FIG. 3 is a schematic diagram of step S02 of a method for attaching a lead frame to a film without tension according to the present invention;

FIG. 4 is a schematic diagram of step S03 of a method for attaching a lead frame to a film without tension according to the present invention;

FIG. 5 is a schematic diagram of step S04 of the method for attaching a lead frame to a film without tension according to the present invention;

FIG. 6 is a schematic diagram of step S05 of a method for attaching a lead frame to a film without tension according to the present invention;

FIG. 7 is a schematic diagram of step S06 of a method for attaching a lead frame to a film without tension according to the present invention;

FIG. 8 is a schematic diagram of step S07 of a method for attaching a lead frame to a film without tension according to the present invention;

FIG. 9 is a schematic structural diagram of a lead frame film laminating apparatus according to the prior art;

in the drawings, the components represented by the respective reference numerals are listed below:

1-left guide wheel, 2-film carrying cylinder, 3-film depletion detection sensor, 4-release layer winding drum, 5-film pulling and releasing engagement force application air cylinder, 6-film pulling and releasing engagement roller module, 7-film and release layer separation position control optical fiber, 8-upper supporting film plate, 9-ion fan, 10-cantilever film pasting main support, 11-middle guide wheel, 12-lower supporting film plate, 13-right guide wheel, 14-inner film pasting workbench, 15-outer film pasting workbench, 16-linear cutting knife, 17-film end surface adsorption rod, 18-film pasting roller, 19-film, 20-release layer, 21-film and release layer separation position, 22-adhesive film, 23-lead frame, 24-section before release layer and film are separated, 25-first position, 26-second position, 27-third position, 30-tropism air pipe.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "side," "lower," and the like refer to an orientation or positional relationship merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referenced components or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

In the related art, the content of the conventional lead frame attachment method is summarized in the patent application No. CN201811326498.5, as shown in fig. 9: the device comprises a film carrying cylinder 1, a release layer winding drum 2, a film feeding mechanism 6, a waste film collecting guide mechanism 9, a film placing guide mechanism 8, a lead frame workbench 25 and a swinging film pasting mechanism 55. The film pasting step is as follows:

fixing a lead frame on a lead frame workbench, keeping the back of the lead frame upward, enabling the lead frame workbench to enter a film pasting position, swinging a film pasting mechanism to swing left, and pasting a yellow film on the front section of the lead frame;

swinging the film sticking mechanism to the right, and sticking a yellow film to the middle section of the lead frame;

thirdly, the swing film sticking mechanism cuts the film at the right swing position;

fourthly, the swing film pasting mechanism pastes films on the tail end of the lead frame at the right swing position;

and fifthly, swinging the film pasting mechanism, returning the lead frame workbench to the loading position, and finishing the work.

The above prior art has the following disadvantages:

1. the attaching force between the film paper and the release layer cannot be released in advance, the separating force is still relatively large for partial film paper, and for the extremely soft and extremely thin lead frame, the separating force can also be reflected on the frame to which the film is attached, so that the frame is warped along with the tension of the film, and subsequent processes such as chip mounting, bonding and the like are influenced.

2. In fig. 9, the film feeding mechanism 6 must clamp the film to complete the active film feeding operation, and before the release layer is separated from the tape, the film feeding mechanism will certainly damage the adhesive film.

The invention provides a lead frame film sticking device which can completely eliminate the tension of film sticking paper, does not damage a glue film and has high efficiency (the sticking film UPH can reach more than 300 pieces/hour), and can be applied to a full-automatic lead frame film sticking machine;

the technical scheme of the invention is as follows: referring to fig. 1, the tension-free film sticking device for lead frames of the present invention includes a cantilever film sticking main support 10 with a movable position, a left guide wheel 1 installed at one side portion of the cantilever film sticking main support 10, a film carrying cylinder 2, a film exhaustion detection sensor 3, a release layer winding drum 4, a film pulling and releasing meshing force application cylinder 5, a film pulling and releasing meshing roller module 6, a film and release layer separation position control optical fiber 7, an upper film supporting plate 8, an ion fan 9, a middle guide wheel 11, a lower film supporting plate 12, a right guide wheel 13, a linear cutting knife 16, a film end surface adsorption rod 17, a film sticking roller 18, and a film supporting air duct 30;

a film 19 with a release layer 20 which is not separated is wound on the film carrying cylinder 2, the release layer on the film 19 and a section 24 before the film is not separated are sequentially pressed against the left guide wheel 1 and the middle guide wheel 11, the release layer 20 and the adhesive film 22 are separated by pulling at the position of the middle guide wheel 11, the release layer 20 is connected with a pull-release film meshing roller module 6 with a pull-release film meshing force application cylinder 5 through a supporting film plate 8, and then is rewound and stretched in a release layer rewinding cylinder 4 for winding and recycling; after the adhesive film 22 is supported by the lower film supporting plate 12, the adhesive film is guided to the position of the film end surface adsorption rod 17 by the right guide wheel 13;

the cantilever film sticking main support 10 is positioned at the lower part of the film end surface adsorption rod 17 and is provided with an inner film sticking workbench 14 and an outer film sticking workbench 15 which are in a double-workbench form and can independently extend the X axial direction to move side by side, and the cantilever film sticking main support 10 switches the film sticking mechanism between the two film sticking workbench.

The left guide wheel 1, the middle guide wheel 11 and the right guide wheel 13 are used for guiding the film paper to prevent the film paper from being stuck obliquely in the film sticking process;

wherein, the film carrying cylinder 2 is used for placing the roll film paper with a release layer;

wherein, the ion fan 9 is installed on the cantilever pad pasting main support 10 and the wind direction mouth faces the upper pad film plate 8 and the lower pad film plate 12, and is used for removing the static generated when the glue film 22 is separated from the release layer 20.

Wherein, the film depletion detection sensor 3 is used for prompting when the film 19 is about to be depleted, and suspending the operation of the device, and adopts a photoelectric sensor;

wherein the release layer is rewound to the reel 4 for rewinding the release layer 20.

Wherein, the cantilever film sticking main bracket 10 is arranged on the Y-axis moving mechanism, and realizes the switching between the inner film sticking worktable 14 and the outer film sticking worktable 15;

an inner film lamination stage 14; the outer film sticking workbench 15 is provided with double-workbench film sticking, so that the working efficiency of the full-automatic film sticking machine is improved, and the working efficiency can be improved by 1 time basically. And a linear cutting knife 16 for cutting the film paper. And the film end face adsorption rod 17 is used for adsorbing the film paper end face and attaching the film paper end face to the left end face of the lead frame. And a film pasting roller assembly 18 for rolling and pasting the film. And the film supporting air pipe is used for supporting the broken film when the film is cut off and preventing the film from falling onto the lead frame under the action of gravity.

Wherein, the film sticking roller 18 is arranged at the side part of the film end surface adsorption rod 17 and used for rolling and sticking the film.

The film pulling and releasing meshing force application cylinder 5 is used for applying meshing force to the film pulling and releasing meshing roller module during film pasting and releasing the applied force during film threading so as to facilitate film threading; the film pulling and releasing meshing roller module 6 is used for pulling the film out for a certain distance before film pasting, reversely releasing the film during film pasting and eliminating the pulling force generated on the film paper when the film paper is separated from the release layer; the film and release layer separation position control optical fiber 7 is used for controlling the separation position of the film paper and the release layer;

the upper supporting membrane plate 8 and the lower supporting membrane plate 12 are used for supporting the membrane paper and preventing the membrane paper from being blown by the ion fan to be shaken.

Wherein, the support straight line cutting knife 16 is positioned at the side part of the support membrane air duct 30 and is used for cutting off the adhesive membrane 22.

The film supporting air duct 30 is located below the film end surface adsorption rod 17 and is used for supporting the broken adhesive film 22 when the adhesive film 22 is cut off, so as to prevent the adhesive film 22 from falling onto the lead frame under the action of gravity.

As shown in fig. 2-8, a method for non-tension lamination of lead frame includes the following steps:

s01, threading the film 19 according to the structure and the positional relation description of the film 19, and pulling the separation position of the film 19 and the release layer 20 below the film 19 to the separation position 21 of the film and the release layer in the figure, as shown in figure 2;

s02, moving the inner film pasting workbench 14 from right to left along the X-axis direction to the position below the film end face adsorption rod 17, then downwards placing a section of adhesive film 22 by the film pulling and releasing meshing roller module 6, simultaneously clockwise rotating the film end face adsorption rod 17 by 90 degrees, moving the position where the adhesive film 22 is separated from the release layer 20 to the first position 25 between the film pulling and releasing meshing roller module 6 and the middle guide wheel 11, and enabling the film at the right end of the film end face adsorption rod 17 to be in a downward convex shape as shown by the second position 26;

s03, pressing the film end face adsorption rod 17 downwards by 20mm, attaching the section of the adhesive film 22 to the left end of the lead frame 23 on the inner film pasting workbench 14, cutting off the vacuum adsorption force, lifting the film end face adsorption rod 17 at the adhesive film 22 end by 20mm, and rotating the end part clockwise to be upward;

s04, pressing the film pasting roller 18 down by 10mm, then moving the film pasting roller to the right by 50mm, and pressing the end face of the adhesive film 22 on the lead frame 23;

s05, moving the inner film sticking worktable 14 to the left along the X axis, and simultaneously, pulling and releasing the film engaging roller module 6 to release the film downwards at the same speed as the inner film sticking worktable 14 until the position where the film 22 is separated from the release layer 20 is close to the third position 27 of the middle guide wheel 11;

s06, pulling the release layer 20 by the film pulling and releasing meshing roller module 6, so that the adhesive surface film 22 is peeled from the release layer 20 until the peeling position is pulled to the lower initial position of the control optical fiber 7 at the film and release layer separation position;

s07, rotating the film end face adsorption rod 17 of the end face of the adhesive film 22 clockwise to an initial position, adsorbing the adhesive film 22 on the bottom face of the film end face adsorption rod 17, blowing air to the left upper side by the film supporting air pipe 30 below, moving the linear cutting knife 16 leftward at the same time, piercing the adhesive film 22 under the support of the knife avoiding groove of the film end face adsorption rod 17, cutting the adhesive film 22 by the linear cutting knife 16 in the knife avoiding groove, sucking the end face above the adhesive film 22 by the film end face adsorption rod 17, and reversely wrapping the film attaching roller 18 by the film surface below under the air flow action of the film supporting air pipe 30;

s08, the inner film pasting workbench 14 continues to move left along the X axis, the adhesive surface film 22 floating above the film pasting roller 18 is pasted on the lead frame 23, then the film pasting roller 18 moves left by 50mm and then rises by 10mm to return to the initial position, and the film supporting air pipe 30 stops blowing air;

s09, the cantilever film-pasting main support 10 integrally moves to the position above the X-axis track of the outer film-pasting workbench 15, and meanwhile, the inner film-pasting workbench 14 automatically completes the feeding and blanking actions of the lead frame 23;

s10, the outer film pasting workbench 15 carries out the same film pasting steps as the steps S02-S08;

s11, the cantilever film-pasting main bracket 10 integrally moves to the upper part of the X-axis orbit of the inner film-pasting worktable 14, and then circulates between the two worktables to exchange the film.

The principle of eliminating the film sticking tension of the film paper is described in the fifth step, and the film paper is not separated from the release layer in the whole film sticking process through the control of the film sticking speed and the reverse film releasing speed, so that the film paper is not pulled by the separating force between the film paper and the release layer, and the warping deformation of the lead frame due to the pulling force on the film paper is avoided after the film paper is stuck on the lead frame.

The principle of not damaging the film is that the release layer is clamped by the film pulling and placing meshing roller module 6, so that the film paper can not be directly clamped to cause film paper damage. When the film sticking device is applied to a full-automatic film sticking machine, the film sticking efficiency UPH can reach more than 300 pieces/hour, because double film sticking working tables are adopted, one working table can synchronously complete the feeding and discharging actions while sticking films, and the other working table can synchronously complete the feeding and discharging actions.

Has the advantages that:

1. the tension-free film sticking device and the film sticking method for the lead frame can realize tension-free film sticking, and the film paper has no tension when sticking the film, so that the thin and soft lead frame cannot be warped due to the tension of the film paper.

2. The film-pulling and film-engaging roller set in the device of the invention clamps the release layer instead of the clamped film paper, thereby avoiding damaging the adhesive layer of the film paper

3. The double-workbench film pasting in the device enables the working efficiency to reach more than 300 sheets/hour.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims (8)

1. A tension-free film sticking device for a lead frame is characterized by comprising a cantilever film sticking main support (10) with a movable position, a left guide wheel (1) arranged on one side part of the cantilever film sticking main support (10), a film carrying cylinder (2), a film exhaustion detection sensor (3), a release layer winding drum (4), a film pulling and releasing meshing force application air cylinder (5), a film pulling and releasing meshing roller module (6), a film and release layer separation position control optical fiber (7), an upper film supporting plate (8), an ion fan (9), a middle guide wheel (11), a lower film supporting plate (12), a right guide wheel (13), a linear cutting knife (16), a film end surface adsorption rod (17), a film sticking roller (18) and a film supporting air pipe (30);

a film (19) with a release layer (20) which is not separated is wound on the film carrying cylinder (2), the film (19) is sequentially pressed against the left guide wheel (1) and the middle guide wheel (11), the release layer (20) and the adhesive surface film (22) are separated by pulling at the position of the middle guide wheel (11), and the release layer (20) is wound and stretched in the release layer winding cylinder (4) for winding and recovery after being supported by the upper film supporting plate (8) and connected with the release film engaging roller module (6) with the release film engaging force applying cylinder (5); the adhesive film (22) is supported by the lower film supporting plate (12) and then guided to the position of the film end surface adsorption rod (17) by the right guide wheel (13);

the cantilever film sticking main support (10) is positioned at the lower part of the film end surface adsorption rod (17) and is provided with an inner film sticking workbench (14) and an outer film sticking workbench (15) which are in a double-workbench form and can independently move along the X axial direction in parallel.

2. The lead frame tension-free film sticking device as claimed in claim 1, wherein the ion fan (9) is mounted on the cantilever film sticking main support (10) and has an air direction opening facing the upper film sticking plate (8) and the lower film sticking plate (12) for removing static electricity generated when the adhesive film (22) is separated from the release layer (20).

3. The lead frame tension-free film sticking device as claimed in claim 1, wherein the film is provided with a depletion detection sensor (3) for indicating when the film (19) is about to be depleted and suspending the operation of equipment, and a photoelectric sensor is adopted.

4. The lead frame tension-free film pasting device of claim 1, wherein the main cantilever film pasting bracket (10) is mounted on a Y-axis moving mechanism to realize switching between an inner film pasting workbench (14) and an outer film pasting workbench (15).

5. The lead frame tension-free film sticking device as claimed in claim 1, wherein the film sticking rollers (18) are arranged at the side parts of the film end surface adsorption rods (17) and used for rolling the film.

6. The lead frame tension-free film sticking device as claimed in claim 1, wherein the support straight line cutting knife (16) is positioned at the side part of the support film air duct (30) and is used for cutting off the adhesive film (22).

7. The lead frame tension-free film sticking device according to claim 1, wherein the film supporting air pipe (30) is positioned below the film end surface adsorption rod (17) and is used for supporting the broken adhesive film (22) when the adhesive film (22) is cut off so as to prevent the adhesive film from falling onto the lead frame under the gravity.

8. The method for non-tension lamination of lead frames according to claim 1, characterized by comprising the following steps:

s01, penetrating the film (19) according to the structure and the positional relation description of the film (19);

s02, moving the inner film pasting workbench (14) to the position below the film end face adsorption rod (17) from right to left along the X axial direction, then placing a section of adhesive film (22) downwards by the film pulling and releasing meshing roller module (6), rotating the film end face adsorption rod (17) clockwise by 90 degrees, moving the position where the adhesive film (22) is separated from the release layer (20) to the first position (25) between the film pulling and releasing meshing roller module (6) and the middle guide wheel (11), and enabling the right end film of the film end face adsorption rod (17) to be in a downward convex shape as shown by the second position (26);

s03, pressing the film end face adsorption rod (17) downwards for 20mm, attaching the section of the adhesive film (22) to the left end of the lead frame (23) on the inner film pasting workbench (14), cutting off the vacuum adsorption force, lifting the film end face adsorption rod (17) at the adhesive film (22) end for 20mm, and rotating the end part clockwise to be upward;

s04, pressing the film pasting roller (18) down by 10mm, then moving the film pasting roller to the right by 50mm, and pressing the end face of the adhesive film (22) on the lead frame (23);

s05, the inner film pasting workbench (14) moves leftwards along the X axis, and meanwhile, the film stretching and releasing meshing roller module (6) stretches the film downwards at the same speed as the inner film pasting workbench (14) until the separation position of the adhesive film (22) and the release layer (20) is close to the third position (27) of the middle guide wheel (11);

s06, pulling the release layer (20) by the pull-release film meshing roller module (6) to peel the adhesive film (22) from the release layer (20) until the peeling position is pulled to the lower initial position of the control optical fiber (7) at the film and release layer separation position;

s07, rotating a film end face adsorption rod (17) on the end face of a glue film (22) clockwise to an initial position, adsorbing the glue film (22) on the bottom face of the film end face adsorption rod (17), blowing air to the left upper side of a lower film supporting air pipe (30), moving a linear cutting knife (16) leftwards, puncturing the glue film (22) under the support of a knife avoiding groove of the film end face adsorption rod (17), cutting the glue film (22) in the film avoiding groove by the linear cutting knife (16), adsorbing the glue film (22) by the film end face adsorption rod (17) on the upper end face of the glue film (22), and reversely wrapping a film attaching roller (18) under the air flow action of the film supporting air pipe (30) on the lower film;

s08, the inner film pasting workbench (14) continues to move left along the X axis, the adhesive film (22) floating above the film pasting roller (18) is pasted on the lead frame (23), then the film pasting roller (18) moves 50mm left and then rises 10mm to return to the initial position, and the film supporting air pipe (30) stops blowing air;

s09, the cantilever film-pasting main support (10) integrally moves to the position above the X-axis track of the outer film-pasting workbench (15), and meanwhile, the inner film-pasting workbench (14) automatically completes the feeding and blanking actions of the lead frame (23);

s10, the outer film pasting workbench (15) carries out the same film pasting steps as the steps S02-S08;

s11, the cantilever film sticking main bracket (10) integrally moves to the position above the X-axis track of the inner film sticking worktable (14), and then the film sticking is circularly exchanged between the two workbenches.

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