Plastic article or earthenware shaping or treating: apparatus – Distinct means to feed – support or manipulate preform stock... – Opposed registering coacting female molds
Patent
1992-05-20
1994-03-29
Nguyen, Khanh
Plastic article or earthenware shaping or treating: apparatus
Distinct means to feed, support or manipulate preform stock...
Opposed registering coacting female molds
425121, 4251261, 425149, 425150, 425226, 425227, 425436RM, 425544, 425556, 425593, 4254516, 425DIG228, B29C 4502, B29C 4542, B29C 4576
Patent
active
052978974
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
For the molding of electronic components, chips, molding apparatus are used wherein a so-called leadframe supporting an electronic component, such as a chip is placed into a mold wherein the mold displays recesses for receiving the parts for molding, and in addition cavities are arranged in the mold wherein measured quantities of molding material are placed and wherein by supplying heat and exerting pressure in these cavities the molding material becomes liquid, moves via channels intended for that purpose to the parts for molding and, curing there, encapsulates the leadframe. The leadframe is subsequently removed from the molding apparatus and subjected to further processing. An apparatus of this type is known for example from Patent Abstracts of Japan, vol. 4, No. 128 (M-31)(610), Sep. 9, 1980, & JP,A, 5587517 of Jul. 2, 1980.
SUMMARY OF THE INVENTION
The object of the invention is to provide a single-strip molding apparatus which combines a simple construction with a relative high production rate.
This achieved according to the invention by providing a single-strip molding apparatus comprising a mold formed by two mold halves vertically movable relative to one another and closable onto one another, means for placing a leadframe supporting an electronic component into one of the mold halves, means for carrying molding material into cavities of the mold, means for exerting pressure and supplying heat to said cavities to liquify the molding material and channels for supplying said molding material to said recesses, means for heating the mold halves, means for cleaning the mold halves and means for removing a molded product from the mold.
By combining different processes such as cleaning, which has to take place after each molding cycle, with the removal of the molded product an optimal production rate is achieved.
From U.S. Pat. No. 3,059,305 a molding apparatus is known in which a reciprocating hopper is provided that combines the function of supplying molding material and cleaning of the mold cavity. After molding the object the molding pushes the product outwardly of the mold and cleans the mold cavity. The mold press consists of two plungers pressing the molding material in the cavity.
According to a preferred embodiment the cleaning-discharge unit performs a reciprocating movement and during the outward movement the one mold half is cleaned and during the inward movement the molded product is removed and the other mold half cleaned in one operating stroke.
An optimal production rate is achieved by setting into operation the means for placing a subsequent leadframe in a mold immediately following the inward movement of the cleaning-discharge unit.
The means for exerting pressure preferably consist of at least one plunger which is driven by means of an electromotor, a screwed rod and a nut arranged on a screwed rod. Driving has taken place to date in the usual manner with hydraulic means, which however entails various drawbacks. Hydraulic driving requires cooling and is not otherwise well compatible with the clean surroundings in which the process must take place. There has further been the drawback that there was no direct proportional relation between the exerted hydraulic pressure and/or the controlled volume flow of the hydraulic oil and the displacement speed of the plunger. The pressure-raising process was difficult to control. Using the electromechanical driving a direct relation is achieved between the action of the electromotor and the displacement speed of the plunger and/or the force to be exerted by the plunger on the molding material by converting the rotation movement of the electromotor into a linear movement of the plunger rod using the nut and the screwed rod. An electromotor moreover does not pollute the surrounding area which befits the cleanliness required of the area wherein the process takes place. In addition the energy consumption of a hydraulic plunger drive is much greater than that of an electromechanical plunger drive. With hydraulic plunger dr
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Harmsen Wilhelmus H. J.
Venrooij Johannes L. G. M.
Verwoerd Wouter B.
ASM Fico Tooling B.V.
Nguyen Khanh
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