JPH05169482A - Plunger for transfer mold apparatus - Google Patents

Abstract

PURPOSE:To enhance the strength, toughness, releasability and abrasion resistance of a plunger by forming the leading end part which comer into contact with a molten resin material of the plunger from a hard phase composed of carbide of group 4a-6a metal of the Periodic Table and a bonding phase based on Ni and Co. CONSTITUTION:The leading end part 1 of a plunger having a columnr shape brought to the violent contact with a molten resin material at the time of the sliding of the plunger is constituted of 70-80wt.% of a hard phase and the remainder of a bonding phase. The hard phase is formed from at least one of carbide, nitride, carbonate, nitride-oxide and boride of group 4a-6a metal of the Periodic Table and the bonding phase is formed from Ni-Co, Ni-Cr, Co-Cr or Ni-Mo. By this constitution, the friction and abrasion resistance to a resin is enhanced by the hard phase and the bonding phase is present at the grain boundary of the hard phase not only to make a metal dense but also to enhance releasability and abrasion/friction resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger for a transfer molding apparatus, which is optimum for sealing and molding an electronic component such as a semiconductor element with a resin.

[0002]

2. Description of the Related Art Conventionally, a plunger used in a transfer mold apparatus is disclosed in, for example, Japanese Patent Laid-Open No. 63-14402.
A base material of an iron-based alloy, a Ni-based alloy or a Co-based alloy as disclosed in Japanese Patent Laid-Open No. 3 and plated with hard chromium, or as disclosed in Japanese Patent Laid-Open No. 61-58708. A high-speed powder steel base material coated with titanium nitride or titanium carbide is used.

In these plungers, the plating layer or coating at the tip of the plunger is easily peeled off, and the tip of the plunger that comes into contact with the molten resin wears quickly.
The clearance with the inner peripheral surface of the pot that fits with this becomes large, the molten resin infiltrates into this clearance part, causing defective molding of the product, and when the resin adhering to the clearance part peels after curing, There is a problem that the tip portion, especially the edge portion of the plunger is damaged, and it is necessary to replace the plunger due to these problems, and the operating rate is reduced.

As a solution to these problems, recently, a plunger made of a sintered alloy of tungsten carbide and cobalt has been put into practical use.

[0005]

A plunger made of a sintered alloy of tungsten carbide and cobalt is different from the above-mentioned plunger having a plated layer or a coating, and is stable and has a long service life without the risk of peeling. Although it was made possible, recently, with the thinning of the package, low-viscosity resin has been used, which tends to accelerate the damage of the plunger, and The clearance between them tends to be set as small as possible so as not to hinder the sliding of the plunger from preventing resin leakage.
Therefore, even a slight damage on the surface of the plunger has a great influence on the service life, and there is a problem that the effect as before cannot be expected.

The present invention has solved the above-mentioned problems, and more specifically, it is a transfer mold made of a sintered alloy having high strength and excellent in abrasion resistance and corrosion resistance against resin. The purpose is to provide a device plunger.

[0007]

DISCLOSURE OF THE INVENTION The present inventors have paid attention to the fact that the plunger for a transfer mold apparatus has an extremely short life depending on the use conditions, and studied the cause in detail. First, It was found that the tip portion in contact with the molten resin material is discolored, and that this discoloration is caused as a result of considering not only the tribological wear of the resin but also the corrosive wear of the resin.

Secondly, a hard phase containing tungsten carbide or titanium carbonitride as a main component and Ni or Ni, Co,
A sintered alloy composed of at least two kinds of binder phases of Cr and Mo has excellent corrosion resistance and wear resistance to a resin, and has strength and toughness necessary for a plunger for a transfer molding apparatus. I got the knowledge.

The present invention has been completed based on the first and second findings.

That is, the plunger for the transfer molding apparatus of the present invention has at least a tip of the plunger which comes into contact with the molten resin material, and is a carbide, nitride, carbonate or nitrous oxide of a group 4a, 5a or 6a metal of the periodic table. , Boride and at least one of these mutual solid solutions, a hard phase of 70 to 98% by weight, and the balance of Ni or Ni, C
It consists of a binder phase containing at least two of o, Cr, and Mo as main components and unavoidable impurities.

The hard phase in the present invention is specifically, for example, TiC, ZrC, HfC, VC, NbC, TaC,
WC, Cr ₃ C ₂ , Mo ₂ C, TiN, ZrN, HfN,
VN, NbN, TaN, CrN, Ti (C, N), Ti
(C, O), Ti (N, O), Ti (C, N, O),
(W, Ti) C, (W, Ti) (C, N), (W, T
i) (C, O), (W, Ti) (N, O), (W, T
i) (C, N, O), (W, Ti, Ta) C, (W, T
i, Ta, Nb) C, (W, Ti, Ta) (C, N),
(W, Mo) C, TiB ₂ , ZrB ₂ , TaB ₂ , W ₂ B ₅
Can be mentioned.

Further, the binder phase in the present invention contains Ni as a main component or contains at least two kinds of Ni, Co, Cr and Mo as main components, specifically, Ni--C.
o, Ni-Cr, Co-Cr, Ni-Mo, Ni-Co
-Cr, Ni-Co-Mo, Ni-Co-Cr-Mo can be mentioned. These binder phases have corrosion resistance,
In the case where elements constituting the hard phase are contained in a trace amount from the manufacturing process within a range that does not extremely deteriorate wear resistance and toughness, or Fe may be contained in a few%, especially in the former case. It is preferable because it has the effect of enhancing corrosion resistance and wear resistance.

The combination of these hard and binder phases is
It is particularly preferable that the former contains carbonitride containing tungsten carbide or titanium as a main component, and the latter contains Ni and / or Co and Cr, or Ni and / or Co, Cr and Mo. Specifically, for example, WC-Ni
-Cr, WC-Co-Cr, WC-Ni-Co-Cr,
Ti (C, N) -Ni-Co-Cr, Ti (C, N)-
Ni-Co-Mo-Cr, (Ti, W) (C, N) -N
i-Co-Cr, (Ti, W, Ta) (C, N) -Ni
-Co-Cr, (Ti, W, Ta) (C, N) -Ni-
Co-Mo-Cr, (Ti, W, Ta, Nb) (C,
N) -Ni-Co-Cr, (Ti, Zr, W, Ta)
A combination of (C, N) -Ni-Cr can be mentioned.

The relationship between the hard phase and the binder phase in the present invention is such that when the hard phase is less than 70% by weight, the binder phase is relatively increased to more than 30% by weight and the wear resistance is significantly reduced. On the contrary, when the hard phase exceeds 98% by weight and increases, the binder phase becomes relatively less than 2% by weight, and the strength,
The decrease in toughness becomes remarkable. Particularly in the case of a hard phase containing tungsten carbide as a main component, it is preferably 2 to 20% by weight.
Of a binder phase of 4 to 10% by weight, more preferably 4 to 10% by weight, and in the case of a hard phase containing a carbonitride containing titanium as a main component, preferably 5 to 25% by weight of a binder phase, more preferably 10% by weight. ~ 20 wt% binder phase.

The plunger for the transfer molding apparatus has a cylindrical shape, and the resin pressing surface for pressing the molten resin material corresponding to at least the end surface portion of this cylindrical shape and the tip outer peripheral surface continuous with it, in other words, at least of the plunger. The plunger tip portion, which is a portion that is in heavy contact with the molten resin material during sliding, is manufactured by the plunger of the present invention.

Further, when at least the resin pressing surface of the cylindrical shape and the outer peripheral surface of the tip connected to the resin pressing surface have a surface roughness of 0.1 μm or less, the mold releasing property with respect to the resin and the friction and abrasion resistance are excellent and the life is long. It is preferable because it improves.

The transfer mold apparatus plunger of the present invention can be manufactured by the conventional powder metallurgy method. Specifically, it can be produced, for example, by using a starting material having a size of several μm or less, preferably a submicron, and mixing, pulverizing, molding, sintering, and then polishing finishing.

[0018]

In the transfer mold apparatus plunger of the present invention, the hard phase mainly functions to enhance the friction and wear resistance to the resin, and the binder phase exists in the hard phase grain boundary to make the sintered alloy dense. In addition, it acts to enhance the mold release property and corrosion wear resistance to resin, and enhances the strength, toughness, mold release property to resin, friction wear resistance and corrosion wear resistance by the synergistic effect of these hard phase and binder phase. Is what

[0019]

Example 1 Average particle size 4.5 μm, 1.5 μm, 0.5
μm tungsten carbide and Co having an average particle size of 1 to 3 μm,
The respective powders of Ni and Cr were used and blended as shown in Table 1.

[0020]

[Table 1] Each sample in Table 1 was wet mixed and pulverized with a ball mill, pressure-molded into a predetermined shape, lubricant volatilization treatment at 800 ° C. in nitrogen gas, and sintering at 1300 ° C. to 1460 ° C. in vacuum were carried out. Samples of Comparative Products 1 to 4 were obtained.

The products 1 to 10 of the present invention and the comparative products 1 to 4 thus obtained were subjected to a bending strength test, a corrosion test with respect to a resin and a friction wear test, and the results are shown in Table 2. Invention product 11 to 11
15 and comparative products 5 and 6 were obtained.

In the corrosion test, each sample having a size of 13 × 13 × 5 mm, which was entirely polished by using an electric furnace, was set on the mesh of SUS, and it was put on the market at the bottom of each sample for semiconductor encapsulating material. Epoxy resin is installed, and the inside of the furnace is heated to 300 ° C. to melt and vaporize the resin, and the corrosive loss (weight loss) of each sample corroded by the vaporized gas of the resin at this time is calculated. It was shown to.

[0023]

[Table 2] In the friction and wear test, a pipe-shaped test piece prepared from each sample was fixed in a cylindrical container, and the container was filled with a mixture of 40 vol% epoxy resin and the remaining crystalline silica,
The pressure of 300 kgf / cm ² and 15 m / m so that this mixture in contact with the inner peripheral surface of the above-mentioned test piece in the molten state may rub against it.
It was reciprocated at a speed of in, and the frictional thickness reduction of the inner diameter of the test piece at this time was determined and shown in Table 2. (However, it was calculated by the wear reduction = the inner diameter after the test-the inner diameter before the test.)

[0024]

Example 2 TiC, Ti having an average particle size of 0.5 to 4 μm
(C, N), TiN, WC, TaC, Mo ₂ C, Ni,
Powders of Co, Cr, and Mo were used and blended so as to have the composition components shown in Table 3. (However, only the product 14 of the present invention has a Ti (C
N) was used. )

[0025]

[Table 3] Each sample in Table 3 was produced by the same method as in Example 1 to obtain inventive products 11 to 15 and comparative products 5 and 6.

The products 11 to 15 of the present invention and the comparative products 5 and 6 thus obtained were subjected to a bending strength, a resin corrosion test and a friction wear test in the same manner as in Example 1, and the results are shown in Table 4.
It was shown to.

[0027]

[Table 4]

[0028]

[Embodiment 3] Of the samples produced in Embodiment 1 and Embodiment 2, the invention products 6, 7, 8, 10, 12, 13, 14 and comparative products 3, 4, 6 were used to form a plunger. It was produced and incorporated in a transfer mold device to carry out a practical test, and the wear reduction of the outer peripheral surface of the plunger tip at the number of shots of the resin sealing material at that time was measured and shown in Table 5.

[0029]

[Table 5] As the practical test conditions, a transfer mold device which has been practically used in the past was used, and as a sealing material, 30 vol% of an epoxy resin resin and the remaining silica-based high hardness filler were used.

The shape of the plunger is a conventionally used shape. For the products 6 and 12 of the present invention and the comparative product 3, only the tip 1 shown in FIG. A plunger was used in which the main body 3 made of steel was brazed and integrally joined. In addition, the products of the present invention 7, 8,
As for 13 and the comparative product 4, a plunger in which the entire tip portion 1 and the main body portion 3 shown in FIG. Further, for the products 10 and 14 of the present invention and the comparative product 6, only the tip portion 1 shown in FIG. 3 was made of each material, and the body portion 3 made of a die steel of a long cylinder was attached to the tip portion 1 with silver brazing. Then, the plunger which was integrally connected was used. Instead of these silver brazings, they can be integrally joined by shrink fitting or other conventional joining methods.

Further, the screw hole 5 in FIG. 2 may be manufactured by making only that part of steel and brazing or shrink fitting, or may be manufactured in the process of powder metallurgy and the whole of FIG. 2 may be integrated. it can. Furthermore, the leakage prevention groove provided at the tip is
At least one is required, but it is preferable to provide a plurality, especially two or three, because the sliding of the plunger is stable.

[0032]

EFFECT OF THE INVENTION The plunger for transfer molding apparatus according to the present invention is higher in flexural strength, releasability from resin, corrosion resistance, and resin than the comparative products conventionally used and the comparative products deviated from the present invention. The friction and wear resistance with and are excellent in a well-balanced manner, and have the effect of being 6 to 12 times as long as the life in a practical test.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a plunger in which a tip portion of a sintered alloy used in Example 3 and a steel body are integrated by brazing,

FIG. 2 is a vertical cross-sectional view of a sintered alloy-integrated plunger used in Example 3;

FIG. 3 is a longitudinal sectional view of a plunger in which the sintered alloy used in Example 3 and a base body are integrated by brazing,

FIG. 4 is a vertical cross-sectional view of a plunger in which only the screw holes 5 are made of steel and the other parts are made of a sintered alloy.

[Explanation of symbols]

 1 Tip Part 2 Resin Pressing Surface 3 Body Part 4 Brazing Material 5 and 5'Leakage Prevention Groove 6 Screw Hole 7 Steel Screw Groove

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // H01L 21/56 T 8617-4M

Claims (4)

[Claims] 1. A plunger installed in a transfer mold apparatus, wherein at least a tip end portion of the plunger which comes into contact with the molten resin material is 4a, 5a, 6a of the periodic table.
70 to 98% by weight of a hard phase composed of at least one of a carbide, a nitride, a carbonate, a nitride oxide, a boride of a group metal and their mutual solid solutions, and the balance being Ni or Ni,
A plunger for a transfer molding apparatus, which comprises a binder phase containing at least two kinds of Co, Cr, and Mo as main components and an unavoidable impurity. 2. The plunger for a transfer molding apparatus according to claim 1, wherein the hard phase is composed of carbonitride containing tungsten carbide or titanium as a main component. 3. The binder phase is Ni and / or Co and C.
The plunger for a transfer molding apparatus according to claim 1, wherein the plunger is r, or Ni and / or Co, Cr, and Mo. 4. The plunger for a transfer molding apparatus according to claim 1, wherein at least the tip portion of the plunger has a surface roughness of 0.1 μm or less.