TWI481081B - Encapsulation material forming method - Google Patents

Description

Sealing material forming method

The present invention relates to a method of forming a sealing material for a semiconductor wafer, and more particularly to a method of forming a sealing material suitable for forming a sealing material for a light-emitting diode package product.

A technique of forming a sealing material with a resin to encapsulate a wafer is used to manufacture a packaged product including a semiconductor wafer such as a light emitting diode wafer. According to the technical level and characteristics of the latest products and market demand, semiconductor packages such as light-emitting diode packages are becoming lighter, thinner, shorter, and smaller. In view of this trend, in order to reduce the consumption of raw materials, active research has been conducted on the formation of a sealing material in order to minimize the amount of resin used to form the sealing material.

As a sealing material forming technique, transfer molding, injection molding, and overmolding (or compression molding) are well known in the art.

In the case of transfer molding, in order to fill a cavity for performing molding with an uncured resin used as a raw material, the resin is first supplied to a port (s) formed in a mold, and then An external force is applied to the port in a state where the upper mold and the lower mold are closed, so that the resin can sequentially enter the cavity through a runner and a gate. When the cavity is completely filled with the resin, the resin flowing through the gate is cured for a predetermined time. The sealing material or the product including the sealing material is separated from the mold. At this time, the remaining resin remaining in the port, the launder, and the gate is separated from the product and then discarded.

As described above, since the resin is to be transferred in a long path in transfer molding (or injection molding), it is necessary to use a resin having a large flow rate. In addition, since the port, the launder, and the gate have a larger volume than the cavity forming the sealing material, and the resin remaining in the port, the launder, and the gate is discarded, there is excessive increase in resin loss. Shortcomings. Therefore, although transfer molding has many advantages, such as good molding accuracy and high dimensional stability, it also has an inherent problem that its economic efficiency is greatly reduced due to excessive resin consumption.

In contrast, unlike transfer molding, the overmolding provides the resin directly to the cavity without the use of a port, runner or gate, and then compresses the resin to form a sealing material. As a result, the secondary molding is economically advantageous because the consumption of the resin is greatly reduced. However, in the conventional overmolding, since the cavity volume is reduced or changed along the molding thickness direction during the compression of the resin, the molding thickness varies depending on the supply of the resin. Further, conventional overmolding is advantageous when forming a sealing material for a plurality of components in a batch form, but the problem is that it is difficult to produce a specific product by conventional secondary molding. Specifically, when a conventional overmolding is used to form a sealing material for a semiconductor wafer on a lead frame substrate having a plurality of through-holes, the resin passes through the through holes. Flow out. Therefore, the conventional overmolding must be performed, for example, by pretreatment, and the through hole is blocked by an article such as a leakage preventing tape, which is very inconvenient and troublesome.

In the case of surface mounted device (SMD) type light emitting diode packages, which account for the majority of the LED package products, a retroreflective sheeting around the light emitting diode chip is required to enhance optical efficiency. The reflector is a product formed by injection molding and integrating phenylpropanolamine (PPA) on a lead frame substrate, wherein the lead frame substrate is formed by patterning a metal, and the reflector has a Opening, which is used to house a semiconductor wafer. For overmolding to be used in such applications, a sealing material or lens should be formed to cover the opening. Therefore, if the resin is applied to the entire cavity of the lower mold, an unnecessary region of the lead frame including the outer periphery of the reflector also forms a sealing material. Thus, the greater the gap or pitch between the devices or packages, the greater the consumption of the desired repellent resin, which further poses additional problems in the molding process or any subsequent process. In addition, if a thin layer of sealing material is formed in order to reduce the consumption of the repellent resin, the adhesion between the reflector and the sealing material may be deteriorated, so that the sealing material may be in any subsequent process after the molding process. Will separate, causing other problems.

At the same time, after the sealing material is formed, in order to separate the product, an expensive release film is currently used. Typical examples of the release film include a fluorine compound resin film such as PTFE, PFA, FEP, and ETFE (manufactured by Asahi Glass Co., Ltd., trademark Fluon) ETFE), all of these release films contain a non-viscous fluorine component. In the prior art, the use of expensive release films results in reduced economic benefits. In addition, there are problems in that excess solid resin adheres to a mold or a block opposite the release film, that is, a mold or a block that supports the product, making them difficult to separate. To remove these extra solid resin, you have to do some more troublesome work. Further, if the mold or the block in which the excess solid resin is not completely removed is used again to compress and form other sealing materials, the molding quality of the sealing material is lowered, thereby causing more defects.

The present invention has been made to solve the above problems of the prior art. It is an object of the present invention to provide an improved method of forming a sealing material which can easily remove excess solid resin after formation of the sealing material.

According to an aspect of the present invention which is provided for the purpose of the present invention, there is provided a method of forming a sealing material, the method comprising: an insert cavity block configuration step, an embedded cavity block having a resin inlet and a molding cavity Disposed on the substrate; a resin loading space forming step for forming a resin loading space, which is surrounded by a film on the side embedded in the cavity block; and a sealing material forming step to bring the bottom of the resin loading space close to the embedded cavity a block so that the resin in the resin loading space fills the molding cavity via the resin inlet; and the film separating step, after the resin is cured, the excess solid resin remaining on the surface of the embedded cavity block adheres to the film The film is separated from the embedded cavity block and removed.

Preferably, in the step of embedding the cavity block, the release agent is applied to the surface of the cavity facing the resin loading space.

Preferably, the step of embedding the cavity block includes: mounting the substrate on the first mold; and mounting the embedded cavity block on the substrate.

Preferably, in the resin loading space forming step, the second mold facing the first mold and having a concave space is covered by the film to form a resin loading space, and the second mold includes a cavity compression block and a compression block surrounding the cavity In the case of the configured cavity holding block, the concave space is formed by the difference in height between the cavity holding block and the cavity compressing block.

Preferably, in the sealing material forming step, the cavity holding block is moved up or down until the cavity holding block contacts the embedded cavity block. In a state where the cavity holding block stops moving, the cavity compression block continues to move up or down to inject the resin in the resin loading space into the molding cavity, wherein in the film separation step, the second mold is de-embedded The cavity block causes the film and excess solid resin adhered to the film to be detached from the cavity block.

The first mold may be an upper mold or a lower mold. If the first mold is the upper mold, the second mold is the lower mold. Conversely, if the first mold is the lower mold, the second mold is the upper mold.

According to the present invention thus constructed, when a compression molding technique is used to form a sealing material for packaging a semiconductor such as a light-emitting diode wafer on a substrate, it is not necessary to use an expensive release film, so that economic efficiency can be improved. Further, according to the present invention, since the excess solid resin can be easily removed from the embedded cavity block and the sealing material, the cost for manufacturing the product can be greatly reduced. Further, many conventional quality deterioration problems caused by the phenomenon that the release film and the excess solid resin are not easily separated from the sealing material of the formed product can be solved.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail in conjunction with the drawings. Further, the embodiments are provided to enable those skilled in the art to better understand the present invention, and the present invention is not limited to the embodiments.

1 to 3 are cross-sectional views of a sealing material forming apparatus corresponding to a first position at an initial stage of molding, a second position corresponding to a mid-molding period, and a final position corresponding to the molding stage, respectively, according to an embodiment of the present invention. The third position, and Fig. 4 is an enlarged cross-sectional view showing an important part of the sealing material forming device shown in Fig. 3. Fig. 5 is a cross-sectional view showing a state in which the excess solid resin is separated after the sealing material is completely formed.

As shown in FIGS. 1 to 5, the sealing material forming device of the present embodiment is a secondary molding or extrusion-molding forming device including an upper mold 20, a lower mold 30, and The cavity block 40 is embedded between the two. A resin compression-mold is performed in order to move the lower mold up or down, for example, a lifting mechanism such as a press compressor may be used, but this is not shown in the drawings.

The upper mold 20 and the lower mold 30 are respectively disposed at an upper end portion and a lower end portion of a lifting mechanism such as a pressure compressor, and are located opposite to each other. The upper mold 20 and/or the lower mold 30 may have heating elements (not shown) for heating the resin to a predetermined temperature. In the present embodiment, a sealing material is formed on the substrate 10 having the lead frame 11, and the substrate 10 includes: a light emitting diode wafer 12 mounted on the lead frame 11; and a plurality of light reflecting plates 13 having a plurality of The openings respectively accommodate the respective light emitting diode chips 12. In addition, after the sealing material is formed, the substrate 10 is cut to be divided into a plurality of surface mount component (SMD) type light emitting diode packages, wherein the substrate 10 has a plurality of through holes, which is caused by the pattern of the lead frame 11. . Throughout the specification, the term "substrate" is defined to include all types of articles that are mounted on the upper mold 20 or the lower mold 30 to form a seal material. Further, as shown in the respective drawings, the substrate, which is formed as a sealing material, is produced by mounting a light-emitting diode wafer on a lead frame, but the present invention is not limited to this case.

The substrate 10 is supplied to the upper mold 20 by a separately provided substrate supply device (not shown), and is mounted on the upper mold 20. In order to mount the substrate 10 on the upper mold 20, a vacuum absorption method or a clamping method may be used, but any other method may be used to mount the substrate 10 on the upper mold 20. The substrate supply device supplies the substrate 10 by a pressure driving unit in a state where the upper mold 20 and the lower mold 30 are spaced apart from each other by a predetermined distance. The substrate 10 mounted on the upper mold 20 is configured such that the wide surface of the substrate 10 used to form the sealing material faces the lower mold 30.

Further, the embedded cavity block 40 is mounted on the substrate 10, wherein the substrate 10 is mounted on the upper mold 20. As further shown in FIG. 4, the embedded cavity block 40 has a plurality of molding cavities 41 on one surface and a plurality of resin inlets (or gates) 42 respectively connected to the molding cavities 41 on the other surface. Further, the embedded cavity block 40 is mounted on the substrate 10 such that the plurality of molding cavities 41 face the substrate 10, and the plurality of resin inlets 42 face the resin loading space 38 located on the lower mold 30.

As described above, one surface of the substrate 10 includes the light emitting diode chip 12 and the light reflecting plate 13, each of the reflecting plates 13 having an opening for accommodating its corresponding light emitting diode wafer 12, and the opening of the light reflecting plate 13 Must be filled with sealing material. To this end, the reflector 13 is to be substantially rigidly fitted into the corresponding shaped cavity 41 of the cavity block 40. Therefore, in the molding cavity 41, only the opening of the reflecting plate 13 can be filled with the resin R. In order to form the sealing material into a desired shape, the molding cavity 41 can be designed to have a convex lens shape or other desired shape. The resin in the resin loading space of the lower mold 30 is pressed by the cavity compression block 31, flows into the molding cavity 41 via the resin inlet 42 in a pressurized manner, and is then solidified, thereby forming an opening for enclosing the reflector 13 The sealing material of the LED wafer 12 . If the substrate 10 does not include the reflector 13 unlike the present embodiment, the space occupied by the reflector 13 in the drawing is also filled with resin.

Referring again to FIGS. 1, 2, 3, and 5, the lower mold 30 includes a cavity compression block 31 and a cavity holding block 36 disposed on a base 3. The substrate 3 is configured to be coupled to a lifting mechanism (not shown) for being driven by the lifting mechanism in a vertical direction. The cavity compression block 31 is fixed to a central portion of the upper surface of the substrate 3, and the cavity holding block 36 is elastically supported by the elastic member 37 mounted on the substrate 3. If the substrate 3 is moved up by operation, the cavity compression block 31 and the cavity holding block 36 are moved up together. Then, if the cavity holding block 36 stops moving up due to contact with another member (in this embodiment, the embedded cavity block 40), only the cavity compressing block 31 moves up with the compression of the elastic member 37. The predetermined height.

According to the present embodiment, since the outer periphery of the cavity compression block 31 is always lower than the cavity holding block 36, a concave space defined by the cavity compression block 31 and the cavity holding block 36 is formed above the lower mold 30. .

Meanwhile, the sealing material forming device of the present embodiment includes a film, particularly a non-separating film 50, which is installed in a concave space formed by the cavity compression block 31 and the cavity holding block 36. The film 50 defines a variable-capacity resin loading space 38 that accommodates the molten resin according to the contour of the concave space. The film 50 can prevent the molten resin from directly contacting the lower mold 30, and can prevent the molten resin from leaking under the lower mold 30.

The film 50 is adhered in a vacuum manner (a vacuum is applied through a narrow gap between the cavity compression block 31 of the lower mold 30 and the cavity holding block 36), so that the resin loading space which can prevent the resin portion from leaking out during the compression process 38 can be formed by the above procedure. A predetermined amount of solid or liquid resin is equally loaded into the resin loading space 38.

When the film 50 covers the upper end portion of the lower mold 30, the film 50 is vacuum-bonded to the upper end portion of the lower mold 30 by a vacuum member (not shown) mounted on the lower mold 30. Unlike the existing release film, when the sealing material is formed, the film 50 is adhered to the resin (as shown in FIG. 5), so that even when the sealing material is formed, the excess solid resin is firmly fixed. Adhered to the film 50. Therefore, if the film 50 is separated, the excess solid resin is also separated together with the film 50. The film 50 may be a conventional heat-resistant film that can be used in a temperature range capable of forming a sealing material (for example, a temperature range from 130 ° C to 200 ° C), and the film 50 may be, for example, polyethylene (PE). Polypropylene (PP), polyethylene terephthalate (PET), etc., which are cheaper than conventional release films. In particular, polyethylene terephthalate (PET) film has been used in various fields such as general industrial, electrical and electronics, packaging, graphics, and display industries, and is therefore easily available at low prices.

At the same time, at least one surface of the cavity block 40 (the surface in which the cavity block 40 is in contact with the resin when the sealing material is formed) has an interface separation property. In order to provide the interface separation property, it is preferred to apply a release agent 401 (see Fig. 4) on the surface of the cavity block 40 in contact with the resin.

The process of forming a sealing material on a substrate using a sealing material forming device will be further explained below with reference to Figs. 1, 2, 3 and 5, respectively.

Referring to FIG. 1, the substrate 10 is first mounted on the upper mold 20, and then the embedded cavity block 40 is mounted on the substrate 10. At this time, a release agent may be applied to at least a portion of the surface embedded in the cavity block 40.

Further, the heat-resistant film 50 is adhered to the upper end portion of the lower mold 30 in a vacuum manner, and the lower mold 30 has a concave space due to the difference in height between the cavity compression block 31 and the cavity holding block 36, thereby forming a resin loading space. 38. At this time, the resin loading space 38 is located on the side facing the cavity block 40. Preferably, the film 50 can withstand the temperature required to form the sealing material, and when the sealing material is formed, the adhesion of the film 50 to the excess solid resin can be greater than the amount of excess solid resin embedded in the cavity block 40. Surface adhesion. As described above, in order to make the adhesion force of the embedded cavity block 40 to the surface of the resin relatively small, a release agent may be applied.

The process of arranging the cavity block 40 on the substrate 10 and the process of forming the resin loading space 38 can be reversed. Or both processes can be performed simultaneously.

In the first position shown in Figure 1, all of the elements of the lower mold 30 are spaced from all of the elements of the upper mold 20.

Referring to FIGS. 2 and 3, when the resin loading space 38 containing the liquid or gel type resin is placed close to the cavity block 40, the molding cavity 41 embedded in the cavity block 40 is filled with the liquid loaded by the resin loading space 38. Filled with a type or gel type resin. The resin fills the molding cavity 41 via the resin inlet 42, and therefore, it is preferable that the plurality of resin inlets 42 may be connected to a plurality of corresponding molding cavities 41 to be connected to one resin loading space 38, respectively.

As shown in FIG. 2, if the substrate 3 is moved up by the operation of the lifting mechanism, the cavity holding block 36 of the lower mold 30 first contacts the embedded cavity block 40 and stops moving. As a result, between the lower mold 30 covered by the film 50 and the embedded cavity block 40 facing the lower mold 30, the resin loading space 38 defined by the film 50 is completely closed.

As shown in FIG. 3, if the substrate 3 continues to move up under the operation of the elevating mechanism, the cavity compression block 31 continues to move up with the compression of the elastic member 37, thereby causing compression of the resin in the resin loading space 38. This compression causes the resin loading space 38 to become smaller and smaller. As shown in FIG. 4, if the dam bar surface 43 where the reflector 13 is in contact with the cavity block 40 is further pressed, the transfer of the resin to the cavity region may be inhibited, and the sealing performance may be further improved. . As described above, as the resin loading space 38 becomes smaller and smaller, the resin is directly pressed, and the pressed resin is injected into the molding cavity 41 via the resin inlet 42 provided by the cavity block 40.

Further, in order to effectively remove the bubbles (voids) left or generated in the above process and to improve the formability, a vacuum passage, that is, a vent hole may be formed. The vent hole is selectively formed along a surface in which the cavity block 40 is in contact with the upper surface of the light reflecting plate 13 and an upper surface of the periphery of the cavity holding block 36 constituting the resin loading space 38. The surface that is in contact.

Further, as shown in FIG. 3, the pressed liquid type resin is cured after a predetermined time, and then a sealing material having a lens shape (shaped by the molding cavity 41 embedded in the cavity block 40) is formed on the substrate 10. At this time, the excess solid resin that should be removed remains between the embedded cavity block 40 and the film 50 via the resin inlet 42.

Referring to FIG. 5, the lower mold 30 is moved downward to separate the upper mold 20 from the lower mold 30. The substrate 10 mounted on the upper mold 20 and the embedded cavity block 40 mounted on the substrate 10 are separated from the lower mold 30 and the film 50 mounted on the upper surface of the lower mold 30. At this time, the excess solid resin R' (except for the resin which has been solidified in the molding cavity 41 to form the sealing material) is firmly adhered to the film 50, and will be detached from the film 50 together into the cavity block 40. As a result, the excess solid resin R' can be removed from the surface embedded in the cavity block 40 and the surface of the sealing material.

As described above, the present invention is made of a heat-resistant film having a strong adhesive force which can be firmly adhered to a solid resin, and is not made of a release film. In addition, a material having a strong interfacial separation property (for example, a release agent) is applied to the surface of the cavity block 40 that is in contact with the resin, so that when the sealing material is formed, the excess solid resin is formed. R' can be removed from the sealing material and the embedded cavity block 40 along with the film 50.

At the same time, a material supply device (not shown) can be used to unpack the substrate 10 and embed the cavity block 40 in a bundle so that they are detached from the mold in a packaged manner. In other cases, the embedded cavity block 40 may be removed first and simultaneously separated, and then the substrate on which the sealing material has been formed may be separated.

Figure 6 presents a film that is separated and removed from the mold and the embedded cavity block after the process illustrated in Figure 5 is performed. Referring to Figure 6, it will be appreciated that the film is removed along with the excess solid resin attached to the film. At this time, it is also understood that some of the excess solid resin used to fill the resin inlet or gate is also separated while they retain the shape of the resin inlet or gate.

7 and 8 are views showing a method of forming a sealing material performed using a sealing material forming device in accordance with another embodiment of the present invention.

Fig. 7 is substantially the same as the sealing material forming method of the foregoing embodiment, except that the substrate 10 is mounted in the opposite direction.

Referring to FIG. 7, the movable mold 300 is located at the upper portion to configure the upper mold, and the fixed mold 200 is located at the lower portion to configure the lower mold. The substrate 10 is mounted on the lower mold (i.e., the fixed mold 200), and the embedded cavity block 400 is placed on the substrate 10. A molding cavity 410 is provided on one surface of the embedded cavity block 400, wherein the molding cavity 410 opens toward the substrate 10 mounted on the lower mold (i.e., the stationary mold 200). The resin loading space 380 and the resin inlet 420 connecting the resin loading space 380 and the molding cavity are formed on the other surface of the facing movable mold 300 that is embedded in the cavity block 400. The film 500 is located below the movable mold 300 or embedded above the cavity block 400 to be positioned below the resin loading space 380. Similar to the foregoing embodiment, the film 500 surrounds the resin loading space 380. The movable mold 300 is first moved down such that the cavity holding block 360 of the movable mold 300 contacts the embedded cavity block 400 with the film 500 interposed therebetween. Further, the cavity compression block 310 continues to move down accompanying the compression of the elastic member 370, thereby causing compression of the resin in the resin loading space 380. Under great pressure, resin is injected into the molding cavity from the resin loading space 380 via the resin inlet. The liquid type resin in the molding cavity is solidified to form a dense and thick-dimensionally stable sealing material in the molding cavity. Although vacuum adhesion is not performed, the film 500 may remain on the lower fixed mold 200 (i.e., the lower mold), and thus may not include a vacuum member for vacuum bonding the film 500.

As shown in FIG. 8, after the sealing material is formed, if the film 500 is detached from the cavity block 400, the excess solid resin R' remaining on the surface of the cavity block 400 after the sealing material is formed is also separated from the embedded cavity. The surface of the block 400 while the excess solid resin R' remains adhered to the film 500. Similar to the previous embodiment, a release agent can be applied to the surface of the cavity block 400. The movable mold above is not shown in FIG.

3. . . Base

10. . . Substrate

11. . . Lead frame

12. . . Light-emitting diode chip (or semiconductor wafer)

13. . . Reflector

20. . . Upper mold

30. . . Lower mold

31, 310. . . Cavity compression block

36, 360. . . Cavity holding block

37,370. . . Elastic member

38,380. . . Resin loading space

40, 400. . . Embedded cavity block

41, 410. . . Molded cavity

42,420. . . Resin inlet

43. . . Dam railing surface

50, 500. . . film

200‧‧‧Fixed mould

300‧‧‧ movable mold

401‧‧‧ Release agent

R‧‧‧Resin

R’‧‧‧Excess solid resin

1 to 3 are cross-sectional views of a sealing material forming apparatus according to an embodiment of the invention taken from a first position, a second position, and a third position, respectively.

Figure 4 is an enlarged cross-sectional view showing a portion of the sealing material forming device of Figure 3 in accordance with an embodiment of the present invention.

Figure 5 is a cross-sectional view showing a process of forming a sealing material and then separating and removing excess solid resin together with the film in accordance with an embodiment of the present invention.

Figure 6 is a photograph of a film which is separated and removed together with the excess solid resin in the process shown in Figure 5.

7 and 8 are views of a method of forming a sealing material in accordance with another embodiment of the present invention.

3. . . Base

10. . . Substrate

11. . . Lead frame

12. . . Light-emitting diode chip (or semiconductor wafer)

13. . . Reflector

20. . . Upper mold

30. . . Lower mold

31. . . Cavity compression block

36. . . Cavity holding block

37. . . Elastic member

38. . . Resin loading space

40. . . Embedded cavity block

41. . . Molded cavity

42. . . Resin inlet

50. . . film

Claims (5)

A sealing material forming method comprising: embedding a cavity block arranging step, disposing an embedded cavity block on a substrate, the embedded cavity block having a resin inlet and a molding cavity; and a resin loading space forming step for forming a resin a loading space that is surrounded by a film on a side of the embedded cavity block; a step of loading a resin into the resin loading space; and a sealing material forming step to bring the bottom of the resin loading space closer to the Embedding a cavity block such that the resin loaded into the resin loading space fills the molding cavity via the resin inlet; and a film separation step, after the resin is cured, remaining in the The excess solid resin embedded in the surface of the cavity block is adhered to the film, and the film is separated from the embedded cavity block and removed. The method of forming a sealing material according to claim 1, wherein in the step of disposing the cavity block, a release agent is applied to the resin loading space of the embedded cavity block. On the surface. The method of forming a sealing material according to claim 1 or 2, wherein the step of embedding the cavity block comprises: mounting the substrate on a first mold; and embedding the cavity block Mounted on the substrate. The method of forming a sealing material according to claim 3, wherein in the resin loading space forming step, a second mold facing the first mold and having a concave space is covered by the film to form a a resin loading space, the second mold comprising a cavity compression block and surrounding The cavity holding block is configured by the cavity compression block, and the concave space is formed by a height difference between the cavity holding block and the cavity compression block. The method of forming a sealing material according to claim 4, wherein in the sealing material forming step, the cavity holding block is moved up or down until the cavity holding block contacts the Embedding the cavity block, and then, in a state where the cavity holding block stops moving, the cavity compression block continues to move up or down to inject the resin in the resin loading space into the molding space In the cavity, and wherein, in the film separating step, the second mold is detached from the embedded cavity block such that the film and the excess solid resin adhered to the film are detached from the embedded cavity Cavity block.