GB2280144A - Apparatus for sealing semiconductor devices - Google Patents

Abstract

Apparatus for sealing semiconductor devices 27, 27a by resin-transfer moulding has mould cavities 10, 20, resin-supply pots 9 holding resin pellets 17, resin supply paths 25, 26 and ejector pins 12a, 22a provided in chase blocks 7, 8 mounted in upper and lower mould parts 1, 2 and means 5, 6, 11, 21 for heating the lower periphery of resin pellets 17 causing their upward expansion, facilitating removal of air and water from the pellets under vacuum applied via line 39 and vent 43 formed in the mould surface. The apparatus is characterised by the provision of sealing members 30, 33, slidably mounted on mould parts 1, 2 such that, on closure of the mould, they can by brought together in the direction of mould closure (Figs 12, 13 not shown) to seal the region of the mould cavities, resin supply pot and resin supply path against the ingress of air while still providing a path (38, Fig 12 not shown) between the enclosed area of the mould and vacuum line 39. <IMAGE>

Description

TITLE OF THE INVENTION A Method of Molding Resin Sealing of Semiconductor Device and Apparatus Thereof BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an improvement of a method of molding resin to seal electronic parts such as ICs, LSIs, diodes, capacitors and so forth, for example, and particularly to preventing formation of void inside or outside of a molded resin sealing body (a mold package) of electronic parts.

Description of the Background Art The transfer mold method has been conventionally introduced as a method of molding resin to seal electronic parts. This method is usually performed as described below using a mold for resin molding of the first conventional example as shown in Figs. 1 and 2, for example.

A stationary upper mold 51 and a movable lower mold 52 are heated to a predetermined resin molding temperature by a heater64 in advance and also the upper and lower molds 51 and 52 are opened as shown in Fig. 1.

Next, a lead frame 62 on which an electronic part 63 is attached is fittingly set to a predetermined position in a concave portion 61 for setting provided in a molding surface of lower mold 52, and also resin tablet 67 is supplied into a pot 53.

Next, lower mold 52 is moved upwards to close the upper and lower molds 51 and 52 as shown in Fig. 2. At this time, the electronic part 63 and the lead frame around it are fittingly set inside upper and lower cavities 55 and 56 oppositely formed in both of the molding surfaces, and the resin tablet 67 inside the pot 53 is heated to gradually melt.

Next, the resin tablet 67 inside the pot 53 is pressurized by a plunger 54. Then, the melted resin material is injected into both of the cavities 55 and 56 through a resin path 57 provided between the pot 53 and the upper mold cavity 55. Then, the electronic part 63 and the lead frame 62 therearound are sealed in the resin sealing body molded corresponding to the shape of both of the cavities 55, 56. Accordingly, after a time required for hardening of the melted resin material has passed, the hardened molded resin body, and the lead frame 62 and the hardened resin inside the resin path are respectively separated from the molds by ejector pins 65 simultaneously with opening the upper and lower molds.

Air exists inside a space formed between both of the molding surfaces when the upper and lower molds 51 and 52 are closed1 that is, a space of molds including the pot 53, the resin path 57 and the upper and lower cavities 55 and 56. Accordingly, it has a problem in molding resin that voids or defective portions are formed inside or on the surface of a molded resin body because the remaining air mixes into the melt resin material. Accordingly it is configured so that the remaining air can be naturally pushed out through the air vent 58 utilizing the effects of transmitting, ejecting and filling the melt resin material inside the pot 53 through resin path 57 into the upper and lower cavities 55 and 56 by communicating the above-mentioned mold space (cavity 55) portion to outside of the mold by an appropriate air vent 58.

As described above, the air existing in pot 53, resin path 57 and both of the cavities 55 and 56 can be naturally pushed out from air vent 58. Actually, however, especially the formation of inner voids in molded resin bodies and the like can not be effectively prevented.

Accordingly, the problems of damaging the humidity resistance and appearance of products have not been completely solved in practice.

In order to avoid formation of voids inside molded resin bodies, the following improved approaches are possibilities. For example, by applying predetermined resin pressure to a melted resin material injected to fill the both cavities 55 and 56, the bubbles which mixed into the melted resin material are compressed to a neglectable degree for implementing condition under which inner voids are not apparently formed. In this method, however, although the advantage of effects can be realized to some extent, there are problems that apparatus, mechanisms and the like with high lasting quality are necessary for applying high resin pressure and furthermore that the work is risky.

The air existing in pot 53, resin path 57 and both cavities 55 and 56 is forced to be exhausted outside, to prevent the air from contaminating the melted resin material. This method is excellent in that the air does not easily mix into the melted resin material since the air existing in the pot, the resin path and both cavities is exhausted outside. As compared to the conventional method of naturally exhausting the air outside, the formation of inner voids in molded resin bodies can be prevented more effectively. However, despite that the formation of inner voids can be effectively avoided, the forced exhaustion method is not actually applied or practiced as a method of molding resin sealing of electronic parts. Also, even if attempting to apply or practice the method, the effects as described above can not be obtained actually.

Also, when the seal molding of electronic parts with resin is not surely performed, or when the condition of contact between the molded resin body and the lead frame of the electronic parts is insufficient, the humidity resistance of products is also degraded similarly to the above-described case where voids are formed in molded resin bodies. Furthermore, for example, in the working process of bending an outer lead provided to protrude from a molded resin body, cracks may be produced in the molded resin body due to the bending work force applied to a base portion of the outer lead, or the portion might be broken.

Accordingly, because of disadvantages such as ones mentioned above, it has a serious problem that the high quality and high reliability strongly demanded for this kind of products can not be obtained.

Next, a second conventional example of a method of molding resin sealing of electronic parts according to the transfer mold method and apparatus thereof will be described referring to Figs. 3 and 4.

The conventional apparatus shown in Figs. 3 and 4 introduces the multiplunger type system and is configured as described below (refer to U.S. Pat. No. 4,793,785).

That is, the apparatus includes a stationary mold 1 and a movable mold 2 disposed below and opposed to the mold 1. These molds 1 and 2 include bases 3 and 4, respectively, which are provided with heating means 5 and 6 such as oil heaters, electric heaters or the like.

The stationary mold base 3 and the movable mold base 4 are respectively provided with a stationary chase block 7 and a movable chase block 8 movably fitted therein by a mortise joint.

The movable chase block 8 has a plurality of pots 9 each of which is provided with a pair of right and left lower cavities 10 in the vicinity thereof. Means (not shown) for heating the lower cavity 10 is provided in the vicinity of the cavity 10. Disposed below the chase block 8 are a lower ejector plate 12 having ejector pins 12a for ejecting resin bodies molded in the lower cavities 10, and a plunger holder 13 supporting thereon plungers 13a for applying a pressure to the resin material supplied to the pots 9. The ejector pins 12a are fittingly inserted in bores 14 extending through the chase block 8 and communicating with the lower cavities 10. Each plunger 13a is inserted through bores 15, 16 formed in the movable mold base 4 and the ejector plate 12, respectively, and fitted in the pot 9. The tenon 8a of the chase block 8 has at least one vertical screw hole (not shown). When the tenon 8a is fitted in the mortise 4a to install the chase block 8 in the base 4, the screw hole is in resistor with a vertical bolt hole 18 formed in the base.

Accordingly, the block 8 can be properly fixed in position to the base 4 by screwing a positioning bolt 19 into the screw hole 17 through the belt hole 18.

The stationary chase block 7 has a pair of right and left upper cavities opposed to each pair of lower cavities 10, 10. The heating means (not shown) is provided in the vicinity of the upper cavities. Disposed above the chase block 7 are an upper ejector plate 22 having ejector pins 22a, a support pin 22b for the plate 22, and a spring 23 for depressing the plate 22 through the pin 22b. The ejector pins are fittingly inserted through vertical bores 25 formed in the block 7 and communicating with the upper cavities 20 or culls (not shown) opposed to the pots 9.

The ejector plate 22 is depressed by the force of the spring 23 when the molds are opened, whereby the resin bodies molded in the upper cavities, the culls and gates (not shown) through which the cavities communicate with the culls are forced out therefrom.

At this time, the lower ejector plate 12 is pushed up by the ejector bar 12b which is fixed at a portion 12c located on the outer side of the movable mold 2, whereby the molded resin bodies in the lower cavities 10 are ejected. However, when the movable mold 2 is risen into clamping contact with the stationary mold 1 at the plane of their parting line P.L., upper and lower return pins (not shown) opposed to and mounted on the upper and lower ejector plates 22, 12 retract the plates 22, 12 upward and downward, respectively.

The stationary cavity block 7 and the stationary mold base 3 have a tenon 7a and a mortise 3a which are the same as the tenon 8a and the mortise 4a of the movable chase block 8 and the movable mold block 4. Further provided is fixing means comprising a screw hole, a bolt hole and a bolt and identical with the above-mentioned means for fixing the movable chase block 8 to the movable mold base 3.

The movable chase block 8 is fittable into or removable from the base a, for example, together with the lower ejector plate 12 when the plungers 13a are in downwardly moved position.

The stationary chase block 7 is fittable into or removable from the base 3, for example, together with the upper ejector plate 22 after the support pin 22b is removed from the plate 22.

The operation of sealing electronic parts with resin according to the conventional apparatus is almost the same as that of the above-described first conventional example.

Inside and outside of the cavity described above usually communicate with each other through an appropriate air vent and the air inside the cavity is naturally pushed out through the air vent through the effect of the resin injection and filling when injecting to fill both of the cavities with the melted resin material.

The electronic part and the lead frame around it are encapsulated inside the resin body molded corresponding to the shape of the both cavities. After the resin hardens, the lower mold is moved downwards to open the upper and lower molds, and almost simultaneously, the molded resin body and the lead frame inside both cavities and the hardened resin inside the resin path are released by a releasing mechanism, respectively.

As described in the description about the first conventional example, the remaining air existing in the pot, the resin path and both cavities is naturally exhausted outside through the air vent. Using this means for naturally exhausting the remaining air, however, there is a problem that the formation of voids in molded resin bodies can not be effectively prevented because the exhausting action is not sure, and so forth.

In order to solve the problem of the formation of voids in molded resin bodies, for example, it is a possibility to exhaust the remaining air existing in a pot, a resin path and both cavities by force using an exhausting effect of a vacuum source.

However, although this exhaust forcing means is excellent in that the above-mentioned remaining air inside the space of the mold structure is not easily mixed into the melt resin material, it is not actually put into practice because of the following technical problems.

That is to say, upper and lower molds of a mold for resin mold are opened and closed every time the resin is molded, and for introducing the above-stated exhausting forcing means, it is necessary to seal at least the pot, the resin path, and cavity portion from outside air when clamping both molds and exhaust the remaining air and moisture within the area.

As the above-mentioned outside air excluding means, for example, the followings are possibilities; 0 rings are provided on molding surfaces of both molds, which are depressed when closing the molds to exclude the outside air from the area defined thereby, or fitting concave and convex portions are oppositely provided on molding surfaces of both molds, which are fit to each other when closing the molds, and 0 rings provided on fitting surfaces of the concave and convex portions are depressed to exclude the outside air from the area set thereby.

However, when providing outside air excluding means such as 0 rings and fitting concave and convex portions and so forth on molding surfaces of both molds, closing of both molds and the action of excluding the outside air by the outside air excluding means are performed almost simultaneously. Accordingly, for example even when an abnormality occurs, for example when a lead frame supplied to mold surfaces is not set at a predetermined position or state due to some reasons, the mold closing action and the outside excluding action are performed almost simultaneously, resulting in a problem that the molding surfaces of both molds, the lead frame and the outside air excluding means itself are damaged.

Also, if attempting to fix the outside air excluding means on molding surfaces of both molds or the like, a problem is caused that attaching and replacing works of chase blocks to both of the molds are troublesome.

Furthermore, in ones of the type in which chase blocks are often replaced for the demand of production of many kinds and small amounts, there is a problem that the total productivity is reduced because the chase block replacing work takes time, and the like.

When supplying a resin tablet into a pot and melting the resin tablet by heating means and pressurizing means, for the purpose of aiding the thermally melting effect, the resin tablet is pre-heated before supplying the resin tablet into the pot.

Since a melted resin layer is formed on a surface of the pre-heated resin tablet, however, when supplying the same into the pot and applying the heating action by the means for heating the molds, large amounts of air and moisture included inside the resin tablet can not be extracted outside because it is prevented by the abovementioned melted resin layer. Accordingly, the large amounts of air and moisture mixes into the melted resin material to enter the cavities to be formed as voids on a surface portion and an inside portion of a molded resin body, which is a problem.

When excluding the area of the pot, the resin path and the cavity portion from the outside and exhausting the remaining air and moisture inside that area by the exhausting effect by a vacuum source when both molds are completely closed, the remaining air and moisture are exhausted outside through an air vent formed of fine gaps provided between molding surfaces of both molds. That is, this is because it is extremely difficult that the air and moisture go out from the contact surface of both molds, since surfaces of both molds are connected closely and strongly because of the demand in resin molding of preventing occurrence of resin flash on the both mold surfaces.

Accordingly, when both molds are completely closed, even if applying the above-described exhausting effect by a vacuum source, the efficiency of exhausting the remaining air and moisture existing between molding surfaces of both molds is inferior, resulting in a problem that a vacuum condition can not be actually implemented inside the above-stated area.

SUMMARY OF THE INVENTION It is a first object of the present invention to introduce the above-described method of forcing out air and further improve the same to provide a method of molding resin sealing of an electronic part capable of efficiently and surely preventing formation of voids and defective portions inside and a surface portion of a molded resin body by completely preventing air from mixing into melted resin material which is heated and melted inside a pot by efficiently and surely exhausting air and moisture not only inside the pot, a resin path and both cavities but also included in the resin material (a resin tablet).

It is a second object of the present invention to provide a method of molding resin sealing of an electronic part capable of efficiently and surely molding sealing of an electronic part with resin and capable of obtaining a product having high quality and high reliability by attempting to enhance the closeness between a molded resin body and a lead frame of an electronic part.

It is a third object of the present invention to simplify the total procedure and structure of means for forcing out the remaining air and moisture within an outside air excluded area to enhance the workability and operability.

It is a fourth object of the present invention to provide a method of molding resin sealing of an electronic part capable of preventing contamination of remaining air and moisture into a melted resin material by efficiently and surely exhausting the remaining air and moisture outside.

It is a fifth object of the present invention to provide a method of molding resin sealing of an electronic part capable of preventing contamination of air and moisture into a melted resin material by efficiently and surely exhausting outside the air and moisture inside a resin tablet which is supplied into a pot.

It is a sixth object of the present invention to simplify the structure of the above-mentioned means for forcing the remaining air to outside to enhance the workability and operability, and to provide an apparatus for molding resin sealing of an electronic part capable of simply and surely performing attaching and detaching works of both chase blocks on a stationary side and a movable side for both of the stationary and movable molds.

The method of molding resin sealing of an electronic part of the present invention which achieves the first and second objects relates to a method of molding to seal an electronic part with resin on a lead frame fittingly set inside a cavity by supplying a resin material into a pot of a mold for molding resin including a stationary mold and a movable mold and heating to melt the resin material, and also by injecting the melted resin material into the cavities through the resin path of the mold. Now, the feature of the method will be described. A hermetical area is set so that at least the pot, the resin path and the cavity portion of the mold is in a hermetical state.

Also, the air inside the hermetical area is exhausted outside to set a vacuum state inside the hermetical area and the resin material (resin tablet) supplied into the pot is heated to be expanded for providing permeability inside and outside the resin material, thereby implementing condition under which the air and moisture closed inside the resin material can easily go out of the same when the resin material is expanded. Furthermore, by implementing a vacuum state in the hermetical area under such a condition, the air and moisture inside the resin material are surely absorbed and exhausted outside the hermetical area.

By the molding method, the air inside a pot, a resin path for transferring melted resin material and cavities for resin molding in a mold for resin molding, and air and moisture included in a resin material (resin tablet) can be forced out. Also, it prevents contamination of air into a melted resin material which is heated and melted inside a pot. Accordingly, the formation of voids and defective portions inside and on a surface of a molded resin body can be prevented.

Furthermore, sealing molding of an electronic part with resin can be surely performed and also the closeness between the molded resin body and a lead frame of an electronic part is enhanced. Accordingly, the two can be surely integrated and its moisture resistance is enhanced.

A method of molding resin to seal an electronic part according to the present invention which achieves the third and fifth objects relates to a method of molding resin to seal an electronic part set in a cavity in which an upper mold and a lower mold are oppositely provided, a resin tablet is supplied into a pot provided in the upper mold, the resin tablet is melt by heating means and pressurizing means, and the melted resin material is injected into the cavity between the upper and lower molds through a resin path. This method includes a step of excluding the outer air from an outer side periphery of at least a pot, a resin path and a cavity portion in the above-described upper and lower molds, a resin tablet expanding step of heating and expanding in the pot the resin tablet supplied into the lower pot, an intermediate mold clamping step of the both molds of closing the molds with a required gap maintained between molding surfaces of the molds under the outside air excluded condition by the outside air excluding step, a completely closing step of both molds for connecting molding surfaces of both molds in the outside air excluded state by the outside air excluding step, and a forced exhaust step of forcing out remaining air and moisture between molding surfaces of both molds in the mold intermediate mold clamping step and the complete mold clamping step. The resin tablet is expanded upwards inside the pot by the resin tablet expanding step to push out the air and moisture included inside the resin tablet to a portion between surfaces of both molds and also the air and moisture are forced out by the above-stated forced exhaust step.

According to the method, when the upper and lower molds are clamped intermediately and when the molds are completely clamped, by sliding both outside air excluding members so that both of the outside air excluding members fit together, an outside air excluded space portion can be easily formed surrounding an outer side periphery of at least a pot, a resin path and a cavity portion in both molds.

Accordingly, when the both molds are clamped intermediately, by driving a vacuum source connected to communicate with the outside air excluded air portion, the forced exhaustion step can be performed for exhausting efficiently and surely the air and moisture remaining in the outside air excluded space portion through a vacuum path to the outside.

Also, since the resin tablet supplied into the lower mold pot is heated on its bottom portion and peripheral face and the top portion of the pot is open, the resin tablet expands upwards from its upper face portion side in the pot to implement a permeable state between inside and outside.

Accordingly, the air and moisture included in the resin tablet sequentially go out to a portion between molding surfaces of both molds from the upper surface side of the expanded resin tablet. Accordingly, the air and moisture can also be forced to be exhausted outside by the forced exhaustion step.

Also, since the air and moisture remaining in the outside air excluded space portion and the air and moisture included inside the resin tablet can be exhausted outside by the forced exhaustion step, contamination of the air and moisture into a melted resin material can be prevented efficiently and surely.

Another method of molding resin to seal an electronic part of the present invention which achieves the third and fifth objects relates to, in another aspect, a method of molding resin to seal an electronic part according to the multi plunger method for molding resin to seal an electronic part set in a cavity, in which an upper mold and a lower mold are oppositely provided, resin tablets are supplied into a plurality of pots provided in the lower mold, the resin tablets are melted by heating means and pressurizing means, and the melted resin materials are injected into cavities between the upper and lower molds through a resin path. This method includes a step of excluding outside air between both molds for excluding outside air from at least the outer side periphery of the pot, the resin path and the cavity portion in the abovementioned both of the upper and lower molds, a step of completely clamping both of the molds for connecting surfaces of both of the molds in the outside air excluded state by the outside air excluding step, a resin tablet expanding step for heating and expanding in the pots the resin tablet supplied into the lower mold pot, and a forced exhaustion step for forcing air and moisture remaining in the completely clamping step between molding surfaces of both of the molds outside through a air path provided between the surfaces of both molds. By the above-described resin tablet expanding step, the resin tablet is expanded upwards in the pot with permeability between inside and outside thereof and air and moisture included inside the resin tablet are put out between molding surfaces of both of the molds, and the air and moisture are forced outside by the above-described forced exhaustion step.

Also, in a preferred embodiment, a method of molding resin to seal an electronic part according to the present invention, the above, described resin tablet expanding step includes a step of heating a bottom portion and a peripheral surface of a resin tablet to expand the resin tablet from its top surface side upwards in the pot.

Also, it includes a step of performing the abovementioned forced exhaustion step while performing the step of heating and expanding the resin tablet in the pot, or performing the process of heating and melting the resin tablet.

An apparatus for molding resin seal of an electronic part of the present invention which achieves the sixth object includes a mold for molding resin having a stationary mold and a movable mold oppositely provided, in which a pair of outside air excluding members are slidably fitted to the stationary mold and the movable mold covering outer side peripheries of the stationary mold and the movable mold at least at the position of a pot to be supplying with a resin material, a resin path and a cavity portion for resin molding. The pair of outside air excluding members are arranged fittably to each other when the stationary mold and the movable mold are clamped together. Each fitting face between the stationary mold and the movable mold and the pair of outside air excluding members and the fitting face between the pair of outside air excluding members are provided with a sealing member interposed therebetween. Furthermore, when the pair of outside air excluding members fit each other, the outside air excluded space portion set between the stationary mold and the movable mold and a vacuum source side communicate with each other through a vacuum path.

An apparatus for molding resin to seal an electronic part of the present invention which achieves the sixth object, in another aspect, includes a mold for molding resin having a stationary mold and a movable mold oppositely provided and a pair of chase blocks detachably and fittingly attached to the stationary mold and the movable mold, in which a pair of outside air excluding members covering an outer side periphery of the stationary mold and the movable mold at least at a portion of a pot for supply of a resin material, a resin path and a cavity portion for molding resin are respectively fitted slidably to the stationary mold and the movable mold. Both of the pair of outside air excluding members are arranged fittably each other when the stationary mold and the movable mold are clamped together and arranged retractably to a position at which they do not intercept the attaching and detaching work when attaching and detaching the chase blocks to and from the stationary mold and the movable mold. A seal member is interposed between each fitting face respectively between the stationary mold and the movable mold and the pair of outside air excluding members, and the fitting face between the pair of outside air excluding members, and furthermore, the outside air excluded space portion set between the stationary mold and the movable mold and a vacuum source side are communicated with each other thorough a vacuum path when the pair of outside air excluding members fit together.

By the structure of the present invention, when clamping the stationary mold and the movable mold, a pair of outside air excluding members (33.30) are slided to mutuary fit for covering an outer periphery of at least a pot, a resin path and cavities to easily form an outer air excluded space portion (38).

Accordingly, by operating a vacuum source (40) communicating with the outside air excluded space portion (38), the remaining air inside the outside air excluded space portion (38) is efficiently and certainly exhausted outside through a vacuum path (39).

Also, by performing resin seal molding of an electronic part under this condition, contamination of the remaining air inside the outside air excluded space portion (38) into a melted resin material can be prevented. Furthermore, even when the air inside the resin material goes out into the outside air excluded space portion (38) in the process of heating and melting resin material (17), the air can be prevented from mixing into the melted resin material.

Furthermore, the mutual fitting effect of both of the pair of out accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a partial broken longitudinal section illustrating an opened state of a main portion of an apparatus for molding resin to seal an electronic part by the transfer mold method of the first conventional example.

Fig. 2 is a partial broken longitudinal section illustrating a clamped state of the main portion of the apparatus shown in Fig. 1.

Fig. 3 is a partial exploded perspective view illustrating the entirety of a resin sealing molding apparatus of an electronic part by the transfer mold method of a second conventional example.

Fig. 4 is a partial broken longitudinal side section when the apparatus shown in Fig. 3 is in a mold clamped state.

Fig. 5 is a sectional view illustrating a state in which molds are opened, of a main portion of an apparatus for molding resin to seal an electronic part in a first embodiment of the present invention.

Fig. 6 is a sectional view illustrating a mold clamped state of a main portion of the apparatus shown in Fig. 5.

Fig. 7 is a partial broken bottom view illustrating a molding surface of an upper mold of the apparatus shown in Fig. 5.

Fig. 8 is a partial broken plan view illustrating a molding surface of a lower mold corresponding to the molding surface of the upper mold shown in Fig. 7.

Fig. 9 is a partial broken bottom view illustrating an example of structure different from that in Fig. 7, of the molding surface of the upper mold.

Fig. 10 is a partial exploded perspective view illustrating the entirety of an apparatus for molding resin to seal an electronic part in a second embodiment of the present invention.

Fig. 11 is a partial broken longitudinal section illustrating a mold opened state of a main portion of the apparatus shown in Fig. 10.

Fig. 12 is a partial broken longitudinal sectional view illustrating an intermediate mold clamped state of a main portion of the apparatus shown in Fig. 10.

Fig. 13 is a partial broken longitudinal view illustrating a complete mold clamped state of a main portion of the apparatus shown in Fig. 10.

Fig. 1 is a diagram for describing releasing of a molded resin body from the mold when the molds are opened after molding resin of a main portion of the apparatus shown in Fig. 10.

Fig. 15 is a partial broken enlarged section of a fitting portion of a pair of'outside air excluding members of the apparatus shown in Fig. 10.

Fig. 16 is a partial broken enlarged section illustrating another example of a shape of a fitting portion of the pair of outside air excluding members.

Fig. 17 is a partial broken enlarged section illustrating the vicinity of a pot in the intermediate mold clamped state of the apparatus shown in Fig. 10.

Fig. 18 is a partial broken enlarged section illustrating the vicinity of a pot in the complete mold clamped state when the apparatus shown in Fig. 10 is of the multiplunger system.

Fig. 19 is a partial broken longitudinal section illustrating a main portion in the complete mold clamped state in the case where the apparatus shown in Fig. 10 has no air vent.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to Figs. 5 through 9, an embodiment of a method of molding resin to seal an electronic part corresponding to the above-described first conventional example will be described below as a first embodiment of the present invention.

In Figs. 5 and 6, a main portion of a mold apparatus for resin seal molding for practicing a method of molding resin to seal electronic parts according to the first embodiment of the present invention is shown, respectively. The same reference numerals are assigned to common elements to those in the above-described first conventional example.

The mold apparatus for molding resin encapsulation includes an upper mold (a stationary mold) 51 on the stationary side, a lower mold (a movable mold) 52 on the movable side provided opposing to the upper mold 51, a required number of pots 53 provided on the lower mold 52 side, a plunger 54 for pressurizing a resin material each fitted to each of the pots 53, and a required plurality of upper cavities 55 and lower cavities 56 oppositely provided on molding surfaces of the upper and lower molds, which has structure of the multiplunger system in which each pot 53 and one or a plurality of cavity or cavities (in the figure, the upper cavity 55) each provided at a predetermined position in the vicinity thereof are communicated through a resin path 57 each of which is short and of the same length or of substantially equal length.

The above-described lower mold 52 is, for example, reciprocatable up and downwards by an appropriate mold opening and closing mechanism (not shown) which is electrically driven or uses fluid pressure such as oil pressure or the like as a driving source.

An upper end portion of each plunger 54 described above is always fittingly put into each pot and its lower end portion is freely and fittingly supported by a plunger holder (not shown). The plunger holder is, for example, provided for reciprocating up and downwards by an up and down reciprocating driving mechanism (not shown) which is electrically driven or uses fluid pressure such as oil pressure or the like as a driving source. By reciprocating the plunger holder up and downwards, each of the plungers 5 can be reciprocated upwards and downwards.

Furthermore, each plunger 54 is provided to be supplied with elastic pressure in the upward direction by an elastic means such as a spring or the like provided inside the plunger holder or an appropriate pressing mechanism (not shown) by the fluid pressure or the like.

Air vents 58 communicating with respective upper mold cavities 55 are formed on the above-described upper mold surface. These air vents 58 communicate with a common air path 59 having an air vent function (refer to Fig. 7) and the air path 59 communicates with a vacuum source provided outside (not shown).

At a part of a mold face (in the figure, the lower mold surface) which is an outer periphery of the air path 59 when the upper and lower molds 51, 52 are clamped each other, an appropriate seal member 60 having heat resistance, wearing resistance and required elasticity (refer to Fig. 8) is provided.

Accordingly, when both of the molds are clamped together, at least the pot 53, the resin path 57 and both of the cavities 55, 56 are brought into a hermetical state, and an area surrounded by the seal member 60 is set as a hermetical area. Accordingly, by operating the vacuum source, the air inside the hermetical area can be forced out to set a vacuum state in the hermetical area.

A structure may be introduced in which the air path 59 is connected to each pot 53 or each resin path 57 as shown by the chain line in Fig. 9, or the air path 59 shown by the solid line and that shown by the chain line in Fig. 9 can be provided together.

Furthermore, the above-mentioned seal member 60 may be provided at an appropriate portion such as a fitting surface or a connecting surface and the like when the upper and lower molds are clamped together, as needed.

The numeral 61 in the figure denotes a concave portion for fittingly setting a lead frame 62 therein provided on the lower mold surface, the numeral 63 denotes an electronic part attached on the lead frame 62, and the numeral 64 denotes a heater for heating the upper and lower molds, respectively.

The numeral 65 denotes each ejector pin in a mold releasing mechanism (not shown). The ejector pins are so adapted that the tip surfaces retract to inner bottom faces of cavities 55 and 56 and resin path 57, respectively, when the molds are clamped together as shown in Fig. 6. On the other hand, when the molds are opened as shown in Fig. 5, respective tip surfaces can advance to respectively push out molded resin bodies (and a lead frame) within both cavities and hardened resin in the resin path.

The numeral 66 denotes a groove for setting a seal member 60 formed on the upper mold surface.

A method of molding resin to seal an electronic part according to the present invention implemented using the above-described mold apparatus will be described.

Similarly to the conventional case, stationary upper mold 51 and movable lower mold 52 are heated in advance toa predetermined resin molding temperature (for example, about 1750C) by a heater 64.

Next, the lower mold 52 is moved downwards by the mold opening and closing mechanism to open the upper and lower molds 51, 52 (refer to Fig. 5).

Next, a lead frame 62 having an electronic part 63 attached thereon is supplied and set to a predetermined position of a concave portion 61 provided on a mold surface of lower mold 52.

Next, the lower mold 52 is moved upwards by the mold opening and closing mechanism to close the upper and lower molds 51, 52 (refer to Fig. 6).

At this time, each pot 53 and resin path 57 and both of the upper and lower cavities 55, 56 are brought into a hermetical state by seal member 60 provided around the outer periphery of air path 59. The area surrounded by the seal member 60 is set as a hermetical area. The electronic part 63 and the lead frame around the same are fitted inside both cavities 55, 56 oppositely provided on both of the mold surfaces, and resin tablet 67 in each pot 53 is heated to sequentially melt. Furthermore, under such a condition, driving the vacuum source, the air within the hermetical area is forced outside to implement a vacuum state within the hermetical area. An intermediate vacuum state of approximately 1-10-3 Torr is enough as the vacuum state, but it may be set to obtain a higher vacuum state than that, and the set conditions and the like can be appropriately and arbitrarily set by adjusting the vacuum source, for example.

The above-mentioned resin tablet 67 usually includes air and moisture in the atmosphere in the step of molding the resin tablet for solidifying resin powder, or after the molding. Accordingly, the resin tablet 67 supplied into pot 53 thermally expands because of heating by the mold.

The method of the present invention is characterized in that, utilizing the thermal expanding effect of resin tablet 67, air and moisture included inside are absorbed and exhausted by force out of the hermetical area and the resin tablet 67 is heated and pressurized to be completely melted after that or while it is absorbed and exhausted out of the hermetical area.

That is to say, in the step of heating and melting resin tablet 67 in pot 53, by operating a vacuum source, not only air and moisture in the pot 53, resin path 57 for transferring the melted resin material and both cavities 55, 56 for resin molding within the hermetical area, but also air and moisture inside the resin tablet 67 which were absorbed and forced by the vacuum effect when resin tablet 67 which were expands can also be absorbed and forced out of the hermetical area.

Furthermore, with air and moisture removed from the pot 35, the resin path 57 and both of the cavities 55, 56 and resin tablet 67, the resin tablet 67 can be heated and pressurized to be completely melted.

Next, pressurizing the resin tablet 67 in the pot 58 with plunger 54 to inject melted resin material into both cavities 55, 56 through resin path 57 provided between the pot 53 and the upper mold cavity 55, electronic part 63 and lead frame 62 around it is encapsulated in a molded resin body which is molded corresponding to the shape of both cavities. Accordingly, after the time required for hardening the melted resin material has passed, both of the upper and lower molds are opened and the hardened resin body and lead frame 62, and the hardened resin inside the resin path are released by ejector pins 65 in a simultaneous manner, respectively.

As described above, since not only air and moisture inside pot 53, resin path 57 and both cavities 55, 56 in the hermetical area but also air and moisture inside resin tablet 67 can be efficiently and surely forced out of the hermetical area, contamination of air and moisture into the melted resin material can be completely prevented.

That is, the resin tablet 67 can be heated and melted with the air and moisture being removed, so that void and a defective portion are not formed inside the molded resin body of the electronic part molded in the above-described respective steps and the surface thereof.

Also, as described above, in addition to set a vacuum state inside the hermetical area, the air and moisture inside resin tablet 67 can be exhausted by force out of the hermetical area to completely prevent contamination of the air and moisture into the melted resin material, so that molding to seal the electronic part with resin can be efficiently and surely performed and also the melted resin material and lead frame 62 can be adhered to each other strongly.

Furthermore, the melted resin material and lead frame 62 are in a complete adhered state without an air layer, void and the like interposed on the contacting surface of the two. Accordingly, also in the step of bending process of an outer lead provided to protrude from the molded resin body, the problems, that is, occurrence of cracks in the molded resin body due to the bending process force applied to a base portion of the outer lead, and formation of defective portions, for example, can be solved in advance.

The present invention is not limited to the embodiment described above, but can be introduced within the range not departing from the gist of the present invention with arbitrary and appropriate modification and selection as needed.

For example, air and moisture inside the resin material may be absorbed and exhausted out of the hermetical area after heating and expanding the resin material (resin tablet) supplied into the pot, and the resin material may be pressurized to be completely melted thereafter.

Also, the air and moisture inside the resin material may be absorbed and exhausted out of the hermetical range while heating and expanding the resin material (resin tablet) supplied into the pot, and the resin material may be pressurized to be completely melted after that.

Also, there is no problem in performing a pre-heating step for preliminarily heating to thermally expand the resin material before supplying the resin material (resin tablet) into a pot, and also preforming a resin pressurizing step for immediately pressurizing the resin material to be melted while heating the resin material after supplied into the pot.

Furthermore, without the pre-heating step for the resin material (resin tablet) outside the pot, the preheating step may be performed inside the pot by taking a required time with the resin material at ordinary temperature being set in the pot.

Also, a small resin tablet (mini tablet) of approximately 7g or lighter may be used as a resin material, for example.

Especially, when using the above-described apparatus for resin seal molding of the multiplunger type, this kind of small resin tablet can be introduced to enhance the heating efficiency and also to reduce the total time for molding. In this case, the above described pre-heating step of the resin material (resin tablet) can be set inside or outside the pot arbitrarily.

The method of the present embodiment has an effect of providing a method of molding resin to seal an electronic part which can efficiently and surely prevent formation of voids and defective portions inside a molded resin body of an electronic part and on a surface thereof. Such an effect was obtained just from experimentations over a long time period. Also, by the method of the embodiment, the above-described method of forcing air outside can be effectively and efficiently practiced as a method of molding resin to seal an electronic part.

Also, according to the method of the embodiment, resin can be molded to seal an electronic part efficiently and surely, and also the closeness between a molded resin body of an electronic part and a lead frame can be enhanced.

Accordingly, integration of the molded resin body and the lead frame and enhancement of moisture resistance of products can be surely attempted, so that it has an effect of providing a method of molding resin to seal an electronic part which can produce products having high quality and high reliability.

Next, as a second embodiment of the present invention, an embodiment of a method and an apparatus for molding resin to seal an electronic part corresponding to the second conventional example will be described referring to Figs. 10 through 19.

In Fig. 10, the structure of an apparatus for molding resin to seal an electronic part is schematically shown, in Figs. 11 through 14, a main portion of a mold in the apparatus is schematically shown, and the main portion of the mold is shown enlarged in Figs. 15 through 18.

In this apparatus, an upper mold 1 (stationary mold) provided on an upper stationary plate and a lower mold 2 (movable mold) provided on a lower movable plate are oppositely provided.

Also, heating means 5, 6 such as heaters are respectively provided on a mold base 3 on the stationary side (upper side) and a mold base 4 on the movable side (lower mold side). Also, a stationary side chase block 7 is detachably attached to stationary side mold base 3 by fitting means of a dovetail groove 3a and a dovetail portion 7a, or the like.

Also, a movable side chase block 8 is detachably attached to movable side mold base 4 by fitting means of a dovetail groove 4a, a dovetail portion 8a or the like.

Also, the chase blocks (7, 8) fitted into the mold bases (3, 4) are provided to fit at predetermined positions through appropriate blocks 7b, 8b fixed at its front and back sides.

Although the case where both of the front and back ends of both of the chase blocks (7, 8) are fixed to blocks (7b, 8b) has been illustrated in Fig. 10, it is also possible to omit either one of the blocks (7b, 8b), e.g., the back side blocks of the device and form portions corresponding to the blocks on the one side and both mold bases (3, 4) integrally.

Furthermore, an appropriate seal member (not shown) may be interposed between the both chase blocks (7, 8) and both stationary blocks (7b, 8b).

Also, a required plurality of resin material supply pots 9 are provided in movable side chase block 8, and a required plurality of resin molding cavities 10 are provided at predetermined positions near the respective pots 9.

Dedicated heating means 11 such as a heater is provided in the movable side chase block 8.

A lower portion ejector plate 12 having an ejector pin 12a for releasing a resin body molded inside cavity 10, and a plunger holder 13 having a plunger 13a (pressurizing means) for pressuring each resin tablet 17 supplied into each pot 9 are respectively provided at positions below the movable side chase block 8.

An upper end of each of the ejector pins 12a is fit into a pin hole 14 communicating with each cavity 10.

An upper end of each of the plungers 13a is fit in each pot 9 through insert holes 15, 16 provided in movable side mold base 4 and ejector plate 12.

The plunger holder 13 is provided detachably to a rail member 13b provided at a lower portion of the movable side mold base 4.

Appropriate seal members (not shown) may be interposed between a fit space portion of lower portion ejector plate 12 provided in the movable side mold base 4 and outside, and between the fit space portion of the plunger holder 13 and outside.

Cavities 20 corresponding to positions and the number of cavities 10 of the movable side chase block are respectively provided in stationary side chase block 7.

A dedicated heating means 21 such as a heater is provided in the stationary side chase block 7.

An upper portion ejector plate 22 having ejector pins 22a for releasing resin bodies molded in cavities 20 and a pin 22b for supporting the upper ejector plate, and an elastic member 23 such as a spring for pushing down the upper ejector plate 22 through the supporting pin 22b are respectively provided above the chase block 7.

Also, a lower end of each of the ejector pins 22a is fitted into a pin hole 24 communicating with each cavity 20 and a pin hole 24a communicating with a cull portion 25 provided opposing to the position of each pot 9.

The ejector plate 22 is pushed down by the elasticity of elastic member 23 when both molds (1, 2) are opened as shown in Figs. 11 and 14, and molded resin body 18 which hardened within the cavities 20 and a resin path portion (in the figure, cull portion 25 and a gate portion 26) having a required length provided between the pots 9 and the cavities 20 can be released from the mold downwards (refer to Fig. 14).

When the molds (1, 2) are opened, the lower portion ejector plate 12 is pushed up by an ejector bar 12b and each ejector pin 12a releases molded resin body 18 in each cavity 10 upwards (refer to Fig. 14). When the molds are completely clamped together, upper and lower return pins (not shown) oppositely provided in the upper and lower ejector plates (22, 12) make both of the ejector plates retract upwards and downwards (refer to Fig. 13).

In the above-described movable side mold base 4, an outside air excluding member 30 of cylindrical shape, rectangular shape or the like is fitted covering at least the outer periphery of each pot 9 and each cavity 10 in the molding surfaces of lower mold 2, which is provided slidably in the direction of opening and closing the molds through a required driving mechanism 31. Furthermore, an appropriate seal member 32 is provided at a fitting surface of the movable side mold base 4 and the outside air excluding member 30.

An outside air excluding member 33 of cylindrical shape, rectangular shape or the like is fitted in the stationary side mold base 3 covering the outer periphery of at least each resin path (cull portion 25 and gate portion 26) and each cavity 20 in the mold surface of upper mold 3, which is provided slidably in the direction of opening and closing molds through a required driving mechanism 34. Furthermore, an appropriate seal member 35 is provided on the fit surface of the stationary side mold base 3 and the outside air excluding member 33.

At the time of intermediate mold clamping (refer to Fig. 12) and at the time of complete mold clamping (refer to Fig. 13) of both molds (1, 2), moving ahead both of the outside air excluding members (30, 33) in the mold clamping direction by the driving mechanisms (31, 34), tip portions of both of the outside air excluding members (30, 33) fit together.

In Fig. 13, the case is illustrated where an upper end of outer air excluding member 30 fitted to movable side mold base t is moved upwards to the vicinity of the mold surface of lower mold 2 and the outside air excluding member 33 fitted to stationary side mold base 3 is fitted to the peripheral surface at outer air excluding member 30 of the movable side mold base 4.

An appropriate seal member 36 is provided at the fitting face of both of the outside air excluding members (30, 33). Furthermore, appropriate seal members 37 are provided between both mold bases (3, 4) and both chase blocks (7, 8), chase blocks (7, 8) and each of ejector pins (22a, 12a), and between the movable side chase block 8 and pot 9 and plunger 13a.

Accordingly, at the time of intermediate mold clamping and at the time of complete mold clamping of both molds (1, 2) shown in Figs. 12 and 13, by fitting together tip portions of both outside air excluding members (30, 33), between molding surfaces of both molds (1, 2), a space 38 is formed from which outside air is excluded by both outside air shielding members (30, 33) and each of the seal members (32, 35, 36, 37).

A portion between both mold (1, 2) surfaces is in a state in which outside air is substantially excluded by both of the seal members (35, 36), so that the interposing provision of each seal member 37 is not necessarily required.

In place of the provision of the respective seal members 37, or when omitting the same, as described above, an appropriate seal member is preferably provided between both chase blocks (7, 8) and both stationary blocks (7b, 8b).

Furthermore, an appropriate seal member 37a and a seal cover 37b may be provided between space portion 2a of lower mold 2 provided for fitting plunger holder 13 and outside to introduce the structure for attempting to exclude outside air from the space portion 2a (refer to Fig. 10).

One end of vacuum path 39 such as a vacuum pipe is connected to the outside air excluding space portion 38 formed when both of the outside air excluding members (30, 33) are fitted together, and the other end of the vacuum path 39 is connected to an appropriate vacuum source 40 side such as a vacuum pump and the like.

The fitting planes of both of the outside air excluding members (33, 30) can be sectional vertical planes 41 in the vertical direction as shown in Fig. 11 15, or it can be a tapered plane 42 as shown in Fig. 16.

That is to say, it is sufficient that it can exclude flow of air and moisture between the two by seal member 36 interposed at the fitting plane of the two.

Accordingly, when vacuum source 40 is operated at the time of intermediate mold clamping of both molds (1, 2) as shown in Fig. 12, remaining air and moisture in the outside air excluded space portion 38 including the pot 9 the resin path (25, 26) and cavity (10, 20) portion are absorbed and exhausted to be forced outside to implement a vacuum state in the entirety of the outside air excluded space portion 38.

If vacuum source 40 is operated at the time of complete mold clamping of both molds (1, 2) shown in Fig.

13, air and moisture inside the pot 9, the resin path (25, 26), the cavity (10, 20) portion are forced out through a certain air vent 43 provided at least one of the molding surfaces of both molds (in the figure, the molding surface of the upper mold), which also implements a vacuum state in the entirety of the outside air excluded space portion 38.

The vacuum state is set more certainly inside the outside air excluded space portion 38 by continuously performing the forced exhaustion action at the intermediate mold clamping and the forced exhaustion action at the complete mold clamping.

In Fig. 18, a mold in an apparatus for molding resin to seal an electronic part by the multiplunger system in which a plurality of pots are provided in its lower mold is shown, which is in the completely clamped state. In the figure, the case is illustrated in which a desired air path 44 for communicating pot 9, the resin path (25, 26) to outside (outside air excluded space portion 38) is provided between molding planes in both molds (1, 2).

As required, by providing a valve pin for opening and closing the path at a desired portion of the air path 44, the structure may be introduced for preventing melted resin material from invading into the path when molding resin, for example.

As described above, if a desired air path 44 is provided for communicating the pot and the resin path to outside between the molding planes of both molds, the air can be forced outside of the outside air excluded space portion 38 in the complete mold clamping state.

At this time, the entirety of the outside air excluded space portion 38 including the pot, the resin path, the cavity portion can be brought into a vacuum state.

Accordingly, for example, it enables to exclude outside air at the outer periphery of the pot, the resin path and the cavity portion, and to immediately and completely clamping both molds and force the air and moisture between the molding planes under this condition, so that, in this case, there are advantages such as that the intermediate mold clamping of both molds can be omitted, the total molding time can be reduced, or the like.

The above-mentioned both of the outside air excluding members (30, 33) are provided so that they retract to a position at which they do not intercept detaching and attaching/exchanging works of the both chase blocks (7, 8) for both of mold bases (3, 4) through both of the driving mechanisms (31, 34).

Accordingly, since the opening and closing operations of both molds (1, 2) can be performed with both of outside air excluding members (30, 33) moved ahead to the advanced position shown in Figs. 12 and 13, respectively, it is not necessarily required to retract both of the outside air excluding members (30, 33) in every molding cycle the fitting space portion of both of the ejector plates (12, 22) through a desired vacuum path 39a (refer to Fig.

14).

Although structure of the type in which both chase blocks (7, 8) are frequently detached and attached is shown in the above-described figures of the embodiments, it can be similarly applicable to an apparatus for molding resin to seal an electronic part having the structure of a normal type.

As the above-described driving mechanisms (31, 34) for outside air excluding members (33, 30), for example, any of mechanical driving mechanisms such as an appropriate rack and pinion mechanism, electric driving mechanisms such as an electric motor, and fluid driving mechanisms such as of hydraulic and pneumatic can be introduced, but in view of molding resin to seal an electronic part, it is preferred to introduce the abovedescribed electrical driving mechanism or the pneumatic driving mechanism and the like.

A method of molding resin to seal an electronic part 27a attached to a lead frame 27 using the above-described apparatus for resin seal molding will be described below.

First, lead frame 27 is supplied to be set at a predetermined position of a concave portion 29 provided in a molding plane of a lower mold by an appropriate supply/retrieve mechanism 28 and a resin tablet 17 is supplied into each pot 9 (refer to Fig. 11).

Next, lower mold 2 is raised by a lower portion movable plate, and intermediate mold clamping is performed with a desired gap S being maintained between molding planes of upper and lower molds (1, 2) (refer to Figs. 12 and 17).

Next, in the intermediate mold clamping state, both of the outside air excluding members (30, 33) are slided to fit both of the outside air excluding members together to form an outside air excluded space portion 38 surrounding an outer periphery of at least pots 9, resin path (25, 26) and a cavity (10, 20) portion in both of the molds (refer to Figs. 12 and 17).

Next, in this intermediate mold clamping state, vacuum source 40 connected to the outside air excluded space portion 38 is operated to force out the remaining air and moisture inside the outside air excluded space portion through vacuum path 39. Accordingly, at this time, the entirety of the outside air excluded space portion 38 including the pots 9, the resin path (25, 26) and the cavity (10, 20) portion is set into a vacuum state.

Next, lower mold 2 is further raised to implement complete mold clamping in which molding planes of both molds (1, 2) are abutted each other (refer to Fig. 13).

Also, in this complete mold clamping state, the forced exhaustion action inside the outside air excluded space portion 38 is maintained by vacuum source 40.

Since resin tablets 17 in pots 9 are sequentially melted by heating means (5, 6, 11, 21), the melted resin material can be injected into both cavities (10, 20) through resin path (25, 26) by pressurizing the resin tablets 17 with plunger 13a to encapsulate electronic part 27a set in the cavity in molded resin body 18.

The above-described molded resin body 18 can be released between both molds (1, 2) by the upper and lower ejector plates (22, 12) (refer to Fig. 14).

Resin tablet 17 supplied into pot 9 is subjected to heating and expanding effect by heating means (5, 6, 11, 21) inside the pot 9 of which top is opened.

That is, the resin tablet 17 is heated at its bottom portion and peripheral portion, so that it expands upwards from its upper surface side inside pot 9 to be brought into a permeable state between its inside and outside.

Accordingly, air and moisture closed inside resin tablet 17 can easily escape outside.

Also when the molds are completely clamped together, since the forced exhaustion effect inside outside air excluded space portion 38 is maintained by vacuum source 40, air and moisture inside the resin tablet is forced to be absorbed and exhausted outside through the air vent 43 and outside air excluded space portion 38.

Thus, the air and moisture remaining in outside air excluded space portion 38 and the air and moisture included inside resin tablet 17 can be forced out to efficiently and surely prevent contamination of the air and moisture into the melted resin material.

The present invention is not limited to the embodiments described above, but can be introduced within the range of the gist of the present invention arbitrarily with appropriate modification and selection as needed.

According to the present embodiment, when the upper and lower molds 1, 2 are intermediately clamped and when they are completely clamped, the air and moisture remaining inside outside air excluded space portion 38 in both molds 1, 2 and the air and moisture included inside resin tablet 17 can be surely and efficiently exhausted outside, so that contaminations of the air and moisture into the melted resin material can be prevented.

Accordingly, it has an effect of providing a method and an apparatus for molding resin to seal an electronic part which can prevent the formation of voids and defective portions due to the above-mentioned remaining air and moisture inside the molded resin body 18 and on the surfaces thereof.

Also, it has an excellent effect that this kind of products having high quality and high reliability can be molded.

The present embodiment also has an excellent and practical effect that the total procedure and structure of means for exhausting remaining air and moisture inside the outside air excluded area 38 to outside by force can be simplified to enhance the workability and operability.

In the second embodiment, until completion of molding resin to seal an electronic part, the intermediate mold clamping step (refer to Fig. 12) and the complete mold clamping step (refer to Fig. 13) of the upper mold 1 and the lower mold 2 are performed. In each of the mold clamping steps, the remaining air and moisture in the outside air excluded space portion are absorbed and exhausted by vacuum source 40 to remove effectively air and moisture included in resin tablet 17. Also when the molds are clamped together completely, a desired air vent 43 is provided between molding surface of the upper moldl and the lower mold 2.

However, it is not limited to such a structure, and such a method can be introduced that it proceeds from the mold opened state shown in Fig. 11 to the complete mold clamping state shown in Fig. 19 without the intermediate mold clamping state. In this case, in the complete mold clamping state, it is also a possibility to introduce such structures in which the volume of air vent 43 as shown in Fig. 13 is extremely small, or air vent 43 is not formed at all. Fig. 19 shows a complete mold clamping state in which air vent 43 is not formed. In such a case, during there is a gap between the molding surface immediately before the complete mold clamping state in which molding surface c upper mod 1 and lower mold 2 are in close contact, it is neces ary to sufficiently absorb and exhaust air and moisture included resin tablet 17 by vacuum source 40.

Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.

Claims (2)

1. An apparatus for molding resin to seal an electronic part, comprising: a stationary mold (1) and a movable mold (2) oppositely provided to each other; a pair of chase blocks (7, 8) which are detachably fitted to the stationary mold (1) and the movable mold (2), respectively, in which main portions for resin seal molding are mounted as blocks; a pair of outside air excluding members (30, 33) provided for covering an outer side periphery of said stationary mold (1) and said movable mold (2) at a position where a pot (9) for resin material supply provided at least either one of said stationary mold (1) and said movable mold (2), a resin path (25, 26) and a cavity (10, 20) for resin molding, and provided slidably along the outer side periphery; seal members (32, 35, 36) provided at respective fitting surfaces of said stationary mold (1) and said movable mold (2) and said pair of outside air excluding members (30, 33) and a fitting surface of the pair of outside air excluding members (30, 33); and a vacuum path (39) for communicating an outside air excluded space portion (38) set between said stationary mold (1) and said movable mold (2) and a vacuum source (40) when said pair of outside air excluding members (30, 33) are fitted together; wherein said pair of outside air excluding members (30, 33) are respectively provided fittably when said stationary mold (1) and'said movable mold (2) are clamped together and provided retractably to a position at which they do not intercept attaching/detaching work when said chase block (7, 8) are attached/detached to and from said stationary mold (1) and said movable mold (2).

2. The apparatus for molding resin to seal an electronic part according to claim 1, where each of said pair of outside air excluding members (30, 33) is slidably fitted to an outer periphery of each of stationary side mold base (3) and a movable side mold base (") to which each of said stationary mold (1) and said movable mold (2) is attached.