Transfer molding process for overmolding an electronic component, molding device for carrying out the transfer molding process

Abstract

Transfer molding process (TMV) for overmolding an electronic component (EC), comprising the following steps: - Providing a pipe (RO) that has at least one opening (OE); - Filling the pipe (RO) through the opening (OE) with pellets (PE) made of a plastic material; - Preheating of the pellets (PE) arranged in the pipe (RO) via a high-frequency preheating device (HVG); - Removal of the preheated pellets (PE) from the pipe (RO); - Inserting the preheated pellets (PE) into a transfer mold device (TM) containing an electronic component (EB); - Relocation of a punch (ST) arranged in the transfer mold device (TM) so that the plastic material of the pellets (PE) surrounds the electronic component (EB) at least sectionally and / or partially.

Description

[0001] The invention relates to a transfer molding process for overmolding an electronic component, wherein plastic pellets are used for overmolding the electronic component, which are preheated by means of a high-frequency preheating device before being arranged in the transfer molding apparatus. The invention also relates to a molding device for carrying out the transfer molding process.

[0002] It is known that electronic components are at least partially overmolded with plastic. A problem with known methods is that the amount of plastic to be overmolded varies considerably depending on the component. If only a small amount of plastic is required, cold plastic pellets are placed in the transfer mold and heated to the appropriate temperature. A movable plunger then transfers the softened plastic into a casting chamber of the transfer mold. A disadvantage of this method is the sometimes uneven heating of the pellets in the transfer mold and the longer residence time required for them to heat up. The longer residence time in the transfer mold, in particular, can lead to higher manufacturing costs.For larger quantities of plastic, the plastic is pre-plasticized in an extruder. Due to the abrasive additives in the plastic material, wear in the extruder is increased. Furthermore, depending on the residence time being exceeded, a "sacrificial dummy" must be created to remove the pre-plasticized plastic material from a discharge zone. In other words, material consumption and wear are increased, which can lead to additional costs.

[0003] A transfer molding device is disclosed in JP H03-26 518 A.

[0004] JP H04-8 517 A shows a heating procedure for a plate made of a plastic material for sealing a semiconductor component.

[0005] From DE 1 839 639 U a device for automatic injection molding of hardenable molding compounds is known.

[0006] US Patent 4,601,866 A describes a method for manufacturing tablets.

[0007] One object of the invention is to provide a transfer molding process and a molding device for carrying out the transfer molding process in which the manufacturing costs are reduced.

[0008] The problem is solved by the subject matter of the independent patent claims. Preferred embodiments of the invention are the subject matter of the dependent patent claims, the following description, and the drawings.

[0009] In a first aspect, the invention provides a transfer molding process for overmolding an electronic component, comprising the steps: - Providing a pipe that has at least one opening; - Filling the pipe through the opening with pellets made of a plastic material; - Preheating the pellets arranged in the pipe via a high-frequency preheating device; - Removal of the preheated pellets from the pipe; - Inserting the preheated pellets into a transfer mold device containing an electronic component; - Relocation of a punch arranged in the transfer mold device so that the plastic material of the pellets surrounds the electronic component at least sectionally and / or partially.

[0010] In other words, according to a first aspect of the invention, a transfer molding process for overmolding an electronic component is provided. The electronic component is preferably a transmission control unit for a motor vehicle. By overmolding the electronic component, the electrical and / or electronic components can be protected from corrosive media, such as oil.

[0011] In a first step, a tube is provided that has at least one opening. This opening is preferably located on a distal end face and / or an end face of the tube. Typically, the tube has one opening at each distal end.

[0012] In a second step, pellets made of a plastic material are filled into the tube through at least one opening. After the pellets have been arranged, the opening is usually closed, preferably with a lid, so that the pellets are enclosed within the tube. By using pellets, the required amount of plastic material for overmolding the electronic component can be precisely measured and placed within the tube. This allows for precise control of the material requirements, thereby reducing material costs.

[0013] In a third step, the pellets arranged in the tube are preheated using a high-frequency preheater. In other words, the pellets are heated within the tube by the high-frequency preheater to a temperature such that they transition from a solid to a viscoelastic state. This preferably occurs at a pellet temperature greater than 50°C and less than 100°C, particularly greater than 60°C and less than 90°C, including the limits of this range. In the viscoelastic state, the pellets have a soft consistency and are deformable. Preheating the pellets reduces their residence time in the transfer mold, thus accelerating the transfer molding process.

[0014] This allows for a reduction in production costs. The high-frequency preheating unit enables the pellets to be preheated to the required temperature simply and cost-effectively through induction, which can also have a positive impact on production costs.

[0015] After preheating the pellets, they are removed from the tube in a fourth step. This is preferably done through at least one opening. If one of the openings is closed with a lid, the lid is removed beforehand to allow the pellets to be extracted. It is also conceivable that, with two spaced-apart openings, the preheated pellets could be pushed out through at least one of them.

[0016] In a fifth step, the preheated pellets are placed into a transfer molding device containing an electronic component. In other words, the preheated pellets are fed into the transfer molding device.

[0017] In a sixth step, a punch located in the transfer mold is repositioned so that the plastic pellets at least partially and / or completely surround the electronic component. This repositioning of the punch forces the plastic pellets into a cavity containing the electronic component, thus encasing it at least partially.

[0018] In this way, a transfer molding process for overmolding an electronic component is provided, which can reduce manufacturing costs because the required amount of plastic for overmolding can be precisely adjusted due to the pellets, and the residence time of the pellets in the transfer molding device can be reduced by preheating the pellets in the high-frequency preheating device.

[0019] It is conceivable that the pipe is fixed within the high-frequency preheater during the pellet preheating period or loosely inserted into the high-frequency preheater. Alternatively, the pipe could be mounted on a rotating bearing within the high-frequency preheater and rotated around its longitudinal axis, at least intermittently, during the pellet preheating period. This would ensure uniform preheating of the pellets.

[0020] An advantageous embodiment of the invention lies in the fact that a temperature is measured within the high-frequency preheating device during the preheating period or preheating phase of the pellets. Preferably, a surface temperature of the tube and / or a temperature of the pellets is measured. If a surface temperature of the tube is measured, the temperature of the pellets can preferably be inferred from this. It is conceivable that, alternatively or additionally, the temperature of the pellets is measured directly. The degree of preheating of the pellets or the viscoelasticity of the pellets can be determined from the measured temperature.

[0021] The system advantageously allows the pellets to be preheated until a predefined temperature is reached. Consequently, the preheating phase ends when a predefined limit temperature or threshold is reached. This allows for precise monitoring of the preheating duration, ensuring consistent pellet preheating for different transfer mold processes.

[0022] In principle, any suitable thermometer can be used to determine the pellet temperature. An advantageous embodiment of the invention lies in measuring the pellet temperature using an infrared thermometer. It is conceivable that the tube and / or the lid are at least partially transparent, and that the pellet temperature is measured through the transparent area in the lid and / or the tube using the infrared thermometer.

[0023] An advantageous further development of the invention lies in the fact that the temperature of the pellets is continuously measured during the pellet preheating phase. Thus, the preheating phase can be terminated promptly upon reaching a temperature threshold, which can have a beneficial effect on production time and therefore also on production costs.

[0024] Alternatively and / or in addition to monitoring the preheating phase of the pellets via the pellet temperature, an advantageous further development of the invention lies in the fact that a preheating duration of the pellets depends on - a filling quantity of pellets, - a maximum pellet diameter, - a thermal material property of the pellets and - a frequency of the high-frequency preheating device.

[0025] In other words, the various parameters from previously determined tests can be used to determine the preheating time for the pellets, allowing these parameters to be used in addition to and / or as an alternative to pellet temperature monitoring. The preheating time is preferably extended when the pellet quantity is increased and / or the pellet diameter is enlarged. Similarly, the thermal material properties of the pellets, such as the viscosity of the pellet material, as well as the selected frequency of the high-frequency preheater, can influence the preheating time.

[0026] The pellets are only preheated in the high-frequency preheating device so that they are softened and preferably have a viscoelastic consistency. This consistency is generally insufficient to allow the electronic component to be overmolded with the preheated plastic without voids and / or defects. An advantageous embodiment of the invention therefore provides that the transfer mold device and / or a punch head of the punch is heated. The temperature of the transfer mold device and / or the punch head is higher than the temperature of the preheated pellets. Preferably, the transfer mold device and / or the punch head has a temperature greater than 120°C, preferably greater than 140°C, and most preferably greater than 160°C, including the limits. Thus, the preheated pellets can be further softened or...must be liquefied in order to overmold or flow around the electronic component, at least in sections.

[0027] In this context, a preferred embodiment of the invention lies in the fact that the heating of the transfer mold device and / or the punch head takes place before and / or during the punch repositioning step. Accordingly, it can be provided that the preheated pellets and / or the punch head are preheated to a minimum temperature before being arranged in the transfer mold device. This has the advantage that the transfer molding process can be accelerated. Alternatively and / or additionally, it can be provided that the transfer mold device and / or the punch head are heated during the punch repositioning. This allows even the pellets located further out, i.e., those pellets furthest from the electronic component, to be brought to the appropriate temperature for overmolding the electronic component.

[0028] In a second aspect, the invention relates to a molding device for overmolding an electronic component and for carrying out the transfer molding process according to the invention, comprising a high-frequency preheating device and a transfer molding device.

[0029] In this context, it is advantageous for the pipe to be made of or comprised of a plastic. A pipe made of plastic may preferably be made of metal and have a plastic coating. The pipe may have fiber reinforcement, in particular glass fiber reinforcement and / or carbon fiber reinforcement. Heat from the inductive field generated by the electrodes of the high-frequency preheating device can penetrate such pipes to preheat the pellets.

[0030] An advantageous embodiment of the invention provides that the pellets have a maximum diameter and / or a maximum cross-section greater than 5 mm and less than 100 mm, in particular greater than 25 mm and less than 70 mm, including the limits. Depending on the pellet size, the accuracy of the required amount of plastic can be adjusted. Smaller pellets also have the advantage of being quicker to preheat. Pellets with a maximum diameter and / or maximum cross-section between 8 mm and 50 mm have proven particularly advantageous.

[0031] The pellets are made of plastic. Particularly advantageous are pellets made of an epoxy-based thermoset material. Such a material exhibits increased thermal stability for applications up to, preferably, 200°C. It also provides enhanced media tightness for corrosive media. Furthermore, the material is dimensionally stable within its operating range. In addition, the epoxy-based thermoset material can provide an electrically insulating coating for the pellets, which can also exhibit high dielectric strength.

[0032] Finally, an advantageous further development of the invention consists in the fact that the high-frequency preheating device has at least two roller electrodes arranged at a distance from each other, wherein at least one roller electrode is designed to rotate about its longitudinal axis, and the tube is placed on the roller electrodes. In this way, the tube can be rotated during the preheating phase of the pellets, so that the pellets are heated uniformly and thus softened.

[0033] It should be noted that all features described above and below with respect to one aspect of the present invention apply equally to every other aspect of the present invention. In particular, all features of the transfer molding process can also be features of the molding device. The reverse is also true.

[0034] Further features and advantages of the present invention will become apparent from the dependent claims and the following exemplary embodiment. The exemplary embodiment is explained in more detail with reference to the drawings.

[0035] These show: Fig. 1 a transfer molding process and a molding device, according to a preferred embodiment of the invention.

[0036] In Fig. Figure 1 shows a transfer molding process TMV with a mold unit ME for overmolding an electronic component EB. In this embodiment, the electronic component EB is a transmission control unit for a motor vehicle. By overmolding the electronic component EB, the electrical and / or electronic components EB can be protected from corrosive media, such as oil.

[0037] In a first step, a tube RO is provided, which has at least one opening OE. The at least one opening OE is formed on a distal end face and / or at a distal end of the tube RO. As a rule, the tube RO has one opening OE at each distal end.

[0038] In a second step 110, PE pellets made of a plastic material are filled into the tube RO through the at least one opening OE. Usually, after the PE pellets have been arranged in the tube RO, the at least one opening OE is closed, preferably by means of a cover element, so that the PE pellets are enclosed in the tube RO. By using PE pellets, the exact amount of plastic material required for overmolding the electronic component EB can be placed in the tube RO. Thus, the material requirement can be precisely controlled, thereby reducing material costs. In the present embodiment, but not limited to it, the PE pellets have a diameter of 9.8 mm. Preferably, only pellets with a diameter of 9.8 mm are used.However, it is also possible to use pellets with different diameters, with a maximum deviation of 10% in either direction. The plastic material of the pellets is PE, an epoxy-based thermoset material.

[0039] In a third step, the PE pellets arranged in the tube RO are preheated using a high-frequency preheater HVG. The high-frequency preheater HVG has two lower roller electrodes RE. At least one roller electrode RE is rotatable and / or rotatable about its longitudinal axis. It is conceivable that both lower roller electrodes RE are rotatable or rotatable. The tube RO, filled with the PE pellets, is arranged on the lower roller electrodes RE. An upper electrode EL is arranged above the tube RO. In other words, the tube RO is positioned between the upper electrode EL and the lower roller electrodes RE. An inductive field is generated between the upper electrode EL and the lower roller electrodes RE, producing heat. This heat warms the PE pellets arranged in the tube. As the PE pellets are heated, the plastic material transitions from a solid state to a viscoelastic state.This is done at a pellet temperature between 70°C and 85°C. By preheating the pellets, the residence time of the PE pellets within the transfer molding device TM can be reduced, thus accelerating the manufacturing process of the transfer molding and thereby reducing production costs.

[0040] After preheating the PE pellets, they are removed from the RO pipe in a fourth step. This is done via at least one opening OE. If one of the openings OE is closed with a cover element, this is removed beforehand to extract the PE pellets from the opening OE. It is conceivable that, with two spaced-apart openings OE, the preheated PE pellets are pushed out through at least one of them.

[0041] In a fifth step, 140, the preheated pellets PE are inserted into a transfer mold TM containing an electronic component EB. The transfer mold TM has at least one first mold half EWH and a second mold half ZWH that can be placed on top of the first mold half EWH. The two mold halves EWH and ZWH form a cavity KA in which the electronic component EB is located. In other words, the preheated pellets PE are fed into the transfer mold TM.

[0042] Subsequently, in a sixth step, a punch ST arranged in the transfer mold device TM is moved so that the plastic material of the pellets PE penetrates the cavity KA and surrounds the electronic component EB at least sectionally and / or partially.

[0043] It can be provided that the transfer mold device TM and / or a punch head STK of the punch ST is heated. The temperature of the transfer mold device TM and / or the punch head SK is above the temperature of the preheated pellets PE. Preferably, the transfer mold device TM and / or the punch head SK has a temperature between 160°C and 185°C at a contact surface containing the pellets PE, including the limits of this range. Thus, the preheated pellets PE can be further softened or liquefied in order to overmold or flow around the electronic component EB, at least in sections.

[0044] Advantageously, the heating of the transfer molding device TM and / or the punch head STK takes place before and / or during the transfer step of the punch ST. This has the advantage of accelerating the transfer molding process, thereby reducing manufacturing costs. Reference symbol list EB Electronic Component EL electrode EWH First Tool Half HVG high-frequency preheater KA cavity ME Molding Equipment OE opening PE Pellet RE roller electrode RO pipe ST stamp STK stamp head TM Transfermold device TMV Transfermold process ZWH Second tool half

Claims

[1] Transfer molding process (TMV) for overmolding an electronic component (EC), comprising the steps: - Providing a pipe (RO) that has at least one opening (OE); - Filling the pipe (RO) through the opening (OE) with pellets (PE) made of a plastic material; - Preheating of the pellets (PE) arranged in the pipe (RO) via a high-frequency preheating device (HVG); - Removal of the preheated pellets (PE) from the pipe (RO); - Inserting the preheated pellets (PE) into a transfer mold device (TM) containing an electronic component (EB); - Relocation of a punch (ST) arranged in the transfer mold device (TM) so that the plastic material of the pellets (PE) surrounds the electronic component (EB) at least sectionally and / or partially. [2] Transfer molding process according to claim 1, characterized by, that within the high-frequency preheating device (HVG) a temperature of the pellets (PE) is measured during the preheating of the pellets (PE). [3] Transfermold process according to claim 2, characterized by that the temperature of the pellets (PE) is measured using an infrared thermometer. [4] Transfer molding process according to one of claims 2 or 3, characterized by , that the preheating of the pellets (PE) is carried out until a predefined temperature of the pellets (PE) is reached. [5] Transfer molding process according to any of the preceding claims, characterized by that the preheating time of the pellets depends on - a filling quantity of pellets (PE), - a maximum diameter and / or cross-section of the pellets (PE), - a thermal material property of the pellets (PE) and - a frequency of the high-frequency preheater (HVG). [6] Transfer molding process according to any of the preceding claims, characterized by , that the transfer mold device (TM) and / or a punch head of the punch (ST) is heated. [7] Transfermold process according to claim 6, characterized by , that the heating of the transfer mold device (TM) and / or the punch head takes place before and / or during the transfer step of the punch (ST). [8] Molding device for overmolding an electronic component (EC) for carrying out a transfer molding process (TMV) according to one of the preceding claims, comprising - a high-frequency preheater (HVG) and - a transfer mold device (TM). [9] Molding device according to claim 8, characterized by that the pipe (RO) is made of plastic and / or is formed from plastic. [10] Molding device according to claim 8 or 9, characterized by, that the pellets (PE) have a maximum diameter and / or a maximum cross-section that is greater than 5 mm and less than 100 mm, including the limits. [11] Molding device according to any one of claims 8 to 10, characterized by that the pellets (PE) are made from an epoxy-based thermoset material. [12] Molding device according to any one of claims 8 to 11, characterized by , that the high-frequency preheating device (HFD) has at least two roller electrodes (RE) arranged apart from each other, wherein at least one roller electrode (RE) is designed to be rotatable about its longitudinal axis, and the tube (RO) is placed on the roller electrodes (RE).

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