JPS59220932A - Preheater of molding resin for semiconductor element - Google Patents

Abstract

PURPOSE:To perform uniform preheating regardless of shape and size of the molding resin by performing induction heating by use of microwave while carrying the molding resin into a path of a waveguide. CONSTITUTION:The preheater is composed of a microwave generator 10 and an input-side waveguide 11A and an output-side waveguide 11B which are connected to said generator 10. The waveguide 11B is provided with a positioning device 12 including an introducing hole 18 for carrying a tablet 21 into the waveguide and positioning it in the predetermined position. The position of the introducing hole 18 is so determined that the center of a distribution of the electric field formed in the waveguide 11B becomes in accordance with the center of the tablet 21. Namely, the heating temperature of the center of the tablet 21 can be raised to be higher than that of the peripheral portion and accordingly a delay of rise of the internal temperature can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a preheating device for mold resin in a resin sealing device used for manufacturing semiconductor devices such as CPUs and microprocessors.

[Technical background of the invention and its problems]

As shown in FIG. 1, the semiconductor resin sealing device is a device that seals with resin to protect the lead frame/semiconductor pellet (not shown) mounted on the lead frame.
Generally, multiple elements are sealed with resin at the same time.

As shown in FIG. 2, the semiconductor resin encapsulation device basically consists of an upper mold (mold) 3 and a lower mold (mold) 4 paired therewith.
4, a lead frame loader j that enters and exits between the upper mold 3 and the lower mold ≠ to load and unload the lead frame, and a pot t (see Fig. 3) that is also provided in the lower mold ≠. It consists of a tablet loader 7 into which a tablet (sealing resin molded into a cylindrical shape or the like) is inserted.

FIG. 3 is a plan view of the lower mold, in which a resin injection hole A is provided between the cavity t of the MNC compound i and the upper mold 3 and the adjacent cavities. Although not shown, the upper die 3 is also provided with a cavity corresponding to the cavity t of the lower die≠. Note that ``ri'' is a gate for guiding the resin in a fluid state from the pot t to the cavity t.

Next, the operation will be explained. First, the upper mold 3 rises, and a lead frame loader is placed between the upper mold 3 and the lower mold ≠! enters and carries the lead frame l into the lower mold≠.

Next up, the lead frame loader! After the tablet is pulled in, the tablet loader 7 carries in the tablet and drops the pot inside. At this time, the lower mold 1 is heated to a temperature (1IO"c) at which the tablet can be melted into a fluid state.

Next, after the tablet die 7'' is retracted, the upper die 3 is lowered and is mated with the lower die.As a result, the mating surfaces of the upper die 3 and the lower die are exposed to the mutual cavities 6, A cavity having a shape corresponding to the resin part λ in Fig. 1 is formed.Next, the plunger provided in the barrel 7 rises to push up the fluid resin, and the fluid resin enters the cavity through the gater. Inject. When the injection is completed, the resin is thermosetting and hardens in a short time. Next, the upper mold 3 is raised,
The resin-sealed semiconductor device is taken out in the manner shown in FIG. 1, and the sealing process is completed. Incidentally, the cavities are separated in a subsequent step, but the description thereof will be omitted since it is not related to the present invention.

In the above-mentioned semiconductor resin sealing apparatus, after the tablet is placed in the pot 6, it takes several seconds to several seconds for the tablet to reach the melt molding temperature (170° C./min.0° C.) from room temperature. This time varies depending on the size of the tablet.

In order to shorten the molding cycle time from the standpoint of improving productivity, it is necessary to shorten the time required for the resin to thermoset. For this purpose, a method is generally adopted in which the amount of curing accelerator in the resin is increased to increase the curing speed. However, increasing the amount of this curing accelerator is not preferred because it reduces the moisture resistance of the product.

On the other hand, preheating the resin tablet within the mold inevitably requires a certain amount of time. If preheating is insufficient, molding time becomes longer and wire flow occurs. This is particularly problematic when molding large devices such as microprocessors. Furthermore, although increasing the heating temperature makes it possible to shorten the heating time, it leads to instability of the molding conditions and causes non-filling.

As described above, placing a tablet without preheating into a pot of a mold and preheating it has a large effect on molding time and product quality, and causes various problems.

Therefore, it is possible to solve the above-mentioned problem by shortening the molding cycle time by preheating the tablet to a semi-molten state before putting it into the container.

As a preheating device, it is possible to use, for example, heating using high frequency (J70 MHz) (IA so-called high frequency heating), but especially when applying to small tablets used in multi-pot metal shops, it is necessary to There is a problem that uniform preheating cannot be achieved unless the heating electrodes are small and close together.

[Purpose of the invention]

Therefore, the present invention enables easy and uniform preheating regardless of the form of the molding resin (i.e., tablet or powder) and regardless of the size of the tablet. It is an object of the present invention to provide a preheating device suitable for automation, which enables easy molding of semiconductor elements and shortens molding time of semiconductor elements.

[Summary of the invention]

In order to achieve the above object, a preheating device according to the present invention is a device for preheating mold resin before filling a molding die with the mold resin in a resin sealing device for a semiconductor element, A microwave generation source, a waveguide and a waveguide circuit connected to the microwave generation source, and means for positioning the molded resin in alignment with the electric field center i caused by the microwave in the waveguide. It is characterized by having the following.

[Embodiments of the invention]

The present invention will be described below based on illustrated embodiments.

First example FIG. f shows the basic configuration of the preheating device according to the present invention.

This preheating device uses a microwave (e.g. 24'OMHz
), and waveguides //A and //B connected to this microwave generator 10.
It consists of a positioning device /J for carrying the tablet into the waveguide //B.

Magneto Sun is used as the microwave generator io. For example, a rectangular waveguide can be used for the waveguide //B, and specific examples of internal dimensions are shown below! It is shown in the figure. FIGS. 3(a) and 3(b) show examples prepared according to the size of the tablet. A circuit regulator 13 is interposed in the transmission path of the waveguides //A and //B in order to block the influence of reflected waves on the oscillated waves and prevent losses. This circulator 13 is a three-opening junction type, with an input opening connected to the microwave generator 10 via an input waveguide //A, and one output opening connected to the microwave generator 10 via a directional coupler/4t. The output waveguide is brought in.// BK is connected.

In addition, the other output aperture is a waveguide/
/C is connected to i. A non-reflection terminator /S is provided at the tip of this waveguide //C. J is a heat radiation fin. The directional coupler/g is provided with a human power detector/A and a reflected power detector/7, which are used to adjust the radiation power to the tablet.

As shown in FIG. 2, the output waveguide 11B is provided with a positioning means 2J including an introduction hole is' for carrying the tablet 2/ into the waveguide and positioning it at a predetermined position. ing. The position of the introduction hole /g is set so that the center of the electric field distribution E formed inside the waveguide //B matches the center of the tablet 21. That is, by aligning the center of the electric field E with the center of the tablet 2,
A temperature difference occurs between the heating temperature at the center and the heating temperature at the outer periphery.As a result, the delay in internal temperature rise, which was a conventional problem, can be eliminated, and the outer periphery maintains a semi-solid state. Because it can be used as a mold, there is no deformation, and it is easy to handle when transporting it into a pot of a mold.

In order to carry the tablet 2/ into the introduction hole ls, a groove is provided at the opening of the introduction hole 1 to prevent microwaves from leaking to the outside and to guide the tablet 2. has been done. A cylindrical holder 0 made of a heat-resistant non-metallic material such as Teflon (trade name) is provided in the introduction hole 11. And this holder,
By providing an opening/closing device such as a shaver 3 in the opening at the lower end of the tablet 20, the tablet 2 can be inserted into the opening at the upper end of the holder J, and by opening the shampooer after preheating, the preheated tablet collet can be removed. can be automatically introduced into the popper l of the mold l, and the steps of supplying and preheating the tablets 2 can be automated. )It indicates a plunger.

Figure 7 shows the relationship between the preheating time (5ec) and the tablet center temperature ("C") using the radiated power of the preheating device as a parameter.The microwave zero frequency is 24'
j OMHz % The size of the tablet is l Buddha in diameter,
Weight 3. It is from l#. What can be learned from Figure 7 is that heating can be done in an extremely short time and with low power consumption.
Therefore, it is possible to shorten the molding cycle time,
Furthermore, by appropriately selecting the power supply and adjusting the preheating time, it is possible to obtain the desired temperature rise characteristics. The tip of B is a reflective termination, but reflection at the termination may cause the internal electric field of the waveguide//B and the reflected radio wave to interfere with each other, causing disturbance in the electric field distribution, so a non-reflection termination is used. It is preferable to do so, and an example of this case is shown in Fig.

In the example shown in Figure 1, there is a non-reflection terminator n at the tip of the waveguide //B.
is set up and crowded. As the non-reflection terminator a, a commonly known material such as polyiron or ferrite may be used.By doing so, uniform preheating becomes possible.

1st example above 3rd example. In the second example, a case has been described in which one tablet 21 is preheated, but from the viewpoint of productivity, it is desirable to preheat a plurality of tablets 21 at the same time. An example of such a case is shown in Fig. 0. Fig. 0 shows an example of a non-reflection termination, in which a plurality of positioning means 2J are provided.

Next, other examples are shown in FIGS. io (a) and (b). 10th
In Figures (a) and (b), the length point is aligned at 5 to be the maximum point of each electric field distribution, and the introduction hole /g, ! A plurality of tablets can be preheated at the same time by providing a positioning means consisting of a holder 2.0. FIG. 7(b) shows an example in which the tapered surface of a straight bond is tapered for the same purpose.

Modification: By making each waveguide //A, //C a flexible waveguide, the introduction hole IT can be easily moved to the pot of any mold, increasing flexibility in design. can be ensured. Further, in the above example, a tablet was used as the mold resin, but a powder mold resin can also be used by inserting a holder into the introduction hole IT of the waveguide //B.

〔Effect of the invention〕

As described above, according to the present invention, the mold resin is introduced into the waveguide and dielectrically heated by microwaves, so that the mold resin can be uniformly preheated regardless of its shape and size. ! In addition, by positioning the molded resin to match the center of the electric field in the molded resin waveguide, the delay in temperature rise inside the molded resin can be eliminated, and the internal temperature of the molded resin is high and Since the temperature can be lowered to a certain extent, deformation of the mold resin can be prevented, making it easier to transport the mold resin, and as a result, automation of the molding operation is possible.

Furthermore, since preheating can be performed using microwaves, the molding time can be shortened, and molding defects of the resin can be prevented.

[Brief explanation of drawings]

Figure 1 is a plan view showing an example of resin-sealing a semiconductor pellet on a lead frame, Figure 2 is an elevational view showing the basic configuration of a conventional semiconductor resin sealing device, and Figure 3 is a bottom view of the lower mold. A plan view showing an example; Fig. 5 is a schematic diagram showing the configuration of a preheating device according to the present invention; Figs. 7 is an explanatory diagram showing the relationship between preheating time and tablet center temperature in the preheating device according to the present invention; FIG. 1 is a schematic diagram showing another embodiment of the present invention; FIG. The figure is a cross-sectional view showing the configuration of the positioning means when preheating multiple tablets at the same time.
FIG. 3A is an explanatory diagram showing an example of a stepped waveguide, and FIG. 2B is an example of a tapered waveguide. l...Leet frame co...solidified mold resin 3...upper mold≠...lower mold 6...pot 10...microwave generator //A, //B, l/C ...Waveguide Ig...Introduction hole 20...Holder 2/...Tablet n...Non-reflection terminator J...Positioning means Applicant's representative Kiyoshi Inomata Figure 1, Figure 2 Figure 3 Figure 4 Figure 1 - (a) (b)

Claims (1)

[Scope of Claims] l An apparatus for resin encapsulation of semiconductor elements, which preheats the molding resin before filling the molding die with the molding resin, the apparatus comprising: a microwave generation source; and the microwave generation source. A preheating device for a semiconductor device molding device 〇λ, characterized by comprising a waveguide connected to the waveguide, and a means for positioning the molding resin in line with the center of the electric field caused by microwaves in the waveguide. A preheating device for a semiconductor device molding device according to claim 1, wherein the tip of the waveguide is formed with a non-reflective end so that the propagating microwave is not reflected. In the device according to claim 2, the waveguide is formed into a tapered seam shape with one or both of the opposing tube walls having a tapered surface that slopes toward the tip. Features: Preheating device for mold resin for semiconductor devices. In the device according to claim 2 of the patent, the waveguide is characterized in that one or both of a pair of opposing tube walls are formed into a tapered shape, with one or both of the walls being sequentially inclined in a stepped manner. A preheating device for mold resin for semiconductor devices. An apparatus for preheating mold resin for semiconductor elements, characterized in that the mold resin is formed into a tablet shape. 6. A preheating device for molding resin for semiconductor elements, which is the device according to claim 5, wherein the tablet is a small tablet. 2. A device for preheating mold resin for semiconductor devices according to claim 1, 2, 3, or 1, wherein the mold resin is formed in powder form. and Claims 1, 2, 3, 5, 5, or 7, wherein the mold resin positioning means is formed within a waveguide. 1. A preheating device for a molding resin for a semiconductor device, characterized in that the device is arranged to correspond to each of a plurality of electric field centers.