Transfer-moulding method for overmoulding an electronic component and moulding device for performing the transfer-moulding method
Patent Information
- Application Number
- EP2023735257
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-06-30
- Filing Date
- 2023-06-22
- Publication Date
- 2025-05-07
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] Transfer molding process for overmolding an electronic component, molding device for carrying out the transfer molding process
[0003] The invention relates to a transfer molding process for overmolding an electronic component. Plastic pellets are used for overmolding the electronic component. These pellets are preheated by a high-frequency preheater before being arranged in the transfer molding device. The invention also relates to a molding device for carrying out the transfer molding process.
[0004] It is known that electronic components are overmolded, at least in sections, with a plastic. A problem with these known methods is that the amount of plastic to be overmolded varies greatly depending on the component to be overmolded. If only a small amount of plastic is required, cold plastic pellets are placed in the transfer molding device and heated there to the appropriate temperature. The softened plastic is then transported into a potting chamber of the transfer molding device using a movable stamp. The disadvantages here are the sometimes uneven heating of the pellets in the transfer molding device and the longer residence time of the pellets in the transfer molding device in order to warm them up or heat them accordingly. In particular, the longer residence time in the transfer molding device can lead to higher manufacturing costs.For larger plastic quantities, 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, a "sacrificial dummy" must be created to remove the pre-plasticized plastic material from an ejection zone. In other words, this increases material consumption and wear, which can result in additional costs. One object of the invention is to provide a transfer molding process and a molding device for implementing the transfer molding process, in which manufacturing costs are reduced.
[0005] This problem is solved by the subject matter of the independent patent claims. Preferred developments of the invention are the subject matter of the dependent patent claims, the following description, and the drawings. Each feature can represent an aspect of the invention, both individually and in combination, unless explicitly stated otherwise in the description.
[0006] In a first aspect, the invention provides a transfer molding method for overmolding an electronic component, comprising the steps:
[0007] - Providing a tube having at least one opening;
[0008] - Filling the pipe through the opening with pellets made of a plastic material;
[0009] - Preheating the pellets arranged in the tube using a high-frequency preheater;
[0010] - Removing the preheated pellets from the tube;
[0011] - Inserting the preheated pellets into a transfer molding device containing an electronic component;
[0012] - Displacement of a stamp arranged in the transfer molding device so that the plastic material of the pellets surrounds the electronic component at least in sections and / or partially.
[0013] In other words, according to a first aspect of the invention, a transfer molding method is provided for overmolding an electronic component. The electronic component is preferably, but not limited to, 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. It is also conceivable that the electronic component is preferably an inverter for a traction drive, a control device for a motor vehicle and / or a control device for a battery, in particular a battery management system. The electronic component preferably has a printed circuit board with electronic components arranged thereon.
[0014] In a first step, a tube is provided that has at least one opening. The at least one opening is preferably formed on a distal end face and / or an end face of the tube. Typically, the tube has an opening at each distal end. The tube can be, but is not limited to, a hollow cylindrical shape. In other words, the tube can also be referred to as a container.
[0015] In a second step, pellets of a plastic material are filled into the tube through the at least one opening. Typically, after the pellets have been arranged, the at least one opening is closed, preferably with a lid element, so that the pellets are enclosed in the tube. By using pellets, the required amount of plastic material for overmolding the electronic component can be arranged in the tube. This allows the material requirement to be precisely adjusted, thereby reducing material costs.
[0016] In a third step, the pellets arranged in the tube are preheated using a high-frequency preheater. In other words, the pellets arranged in the tube are heated by the high-frequency preheater within the tube to a temperature such that the pellets transition from a solid state to a viscoelastic state. This preferably occurs at a pellet temperature of greater than 50°C and less than 100°C, in particular at greater than 60°C and less than 90°C, including the limits. In the viscoelastic state, the pellets have a soft consistency and are deformable. By preheating the pellets, the residence time of the pellets within the transfer molding device can be reduced, so that the manufacturing process of the transfer molding method can be accelerated. This can reduce manufacturing costs.Using the high-frequency preheater, the pellets can be preheated to the appropriate temperature in a simple and cost-effective manner by induction, which can also have a positive effect on production costs.
[0017] After preheating the pellets, they are removed from the tube in a fourth step. This preferably occurs through at least one opening. If one opening is closed with a lid, this is removed beforehand to remove the pellets from the opening. It is conceivable that, with two openings spaced apart from each other, the preheated pellets are pressed out through at least one opening.
[0018] In a fifth step, the preheated pellets are inserted into a transfer molding device containing an electronic component. In other words, the preheated pellets are fed into the transfer molding device.
[0019] Subsequently, in a sixth step, a die arranged in the transfer molding device is displaced so that the plastic material of the pellets at least partially and / or partially surrounds the electronic component. By displacing the die, the plastic material of the pellets is pressed into a cavity containing the electronic component, so that the plastic material at least partially encloses the electronic component. Pre-plasticizing the pellets can reduce wear on the transfer molding device, which can increase its longevity and reduce manufacturing costs.
[0020] In this way, a transfer molding process for overmolding an electronic component is provided in which manufacturing costs can be reduced because the required amount of plastic for overmolding can be precisely adjusted thanks 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 preheater. Likewise, wear on the transfer molding device can be reduced, which can have a beneficial effect on the longevity of the transfer molding device. With the increased longevity, manufacturing costs can also be reduced. It is conceivable that the tube is fixed within the high-frequency preheater during the preheating period of the pellets, or that it is inserted loosely into the high-frequency preheater.Alternatively, the tube can be mounted rotatably in the high-frequency preheater and rotated and / or turned around the longitudinal axis of the tube at least temporarily during the pellet preheating period. This allows for uniform preheating of the pellets.
[0021] An advantageous development of the invention is that a temperature is measured within the high-frequency preheater 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, this can preferably be used to determine the temperature of the pellets. Alternatively or additionally, the temperature of the pellets can be measured directly. The degree of preheating of the pellets or the viscoelasticity of the pellets can be determined from the measured temperature.
[0022] Advantageously, the pellet preheating is carried out until a predefined temperature is reached. Consequently, the pellet preheating phase is terminated when a predefined limit temperature or a predefined temperature threshold is reached. This allows the duration of the preheating phase to be precisely monitored to ensure consistent pellet preheating for different transfer molding processes.
[0023] In principle, any suitable thermometer can be used to determine the pellet temperature. An advantageous development of the invention involves measuring the pellet temperature using an infrared thermometer. It is conceivable that the tube and / or the lid are transparent, at least in sections, and that the temperature of the pellets is measured through the transparent area in the lid and / or tube using the infrared thermometer.
[0024] An advantageous development of the invention is that the temperature of the pellets is continuously measured during the preheating phase. This allows the preheating phase to be terminated promptly when a temperature threshold is reached, which can have a beneficial effect on production time and thus also on production costs.
[0025] Alternatively and / or in addition to monitoring the preheating phase of the pellets via the pellet temperature, an advantageous further development of the invention is that the preheating time of the pellets depends on
[0026] - a filling quantity of pellets,
[0027] - a maximum diameter of the pellets,
[0028] - a thermal material property of the pellets and
[0029] - a frequency of the high-frequency preheater.
[0030] In other words, the various parameters from previously determined tests can be used to determine a pellet preheating duration, allowing these parameters to be used in addition to and / or as an alternative to pellet temperature monitoring. The preheating duration is preferably extended if the pellet fill volume and / or pellet diameter are increased. The thermal properties of the pellets, such as the viscosity properties of the plastic material used, as well as the selected frequency of the high-frequency preheater, can also influence the preheating duration.
[0031] The pellets are merely preheated in the high-frequency preheating device so that they are softened and preferably have a viscoelastic consistency. This consistency is generally not sufficient for the electronic component to be overmolded using the preheated plastic without any cavities and / or defects. An advantageous development of the invention therefore provides that the transfer molding device and / or a stamping head of the stamp is heated. The temperature of the transfer molding device and / or the stamping head is above a temperature of the preheated pellets. The transfer molding device and / or the stamping head preferably has a temperature of greater than 120°C, preferably greater than 140°C, and most preferably greater than 160°C, at a contact surface comprising the pellets, the limits being included. The preheated pellets can thus be further softened orbe liquefied in order to overmold or flow around the electronic component, at least in sections.
[0032] In this context, a preferred embodiment of the invention is that the heating of the transfer molding device and / or the stamp head takes place before and / or during the stamp displacement step. Accordingly, it can be provided that before the preheated pellets are arranged in the transfer molding device, these and / or the stamp head are preheated to a minimum temperature. This has the advantage that the transfer molding process can be accelerated. Alternatively and / or additionally, it can be provided that the transfer molding device and / or the stamp head are heated during the stamp displacement. This allows even the pellets located further outwards, i.e. those pellets with the greatest distance to the electronic component, to be brought to the appropriate temperature for encapsulating the electronic component.
[0033] In a second aspect, the invention relates to a molding device for overmolding an electronic component and for carrying out the transfer molding method according to the invention, comprising a high-frequency preheating device and a transfer molding apparatus.
[0034] The tube is preferably made of a material with non-polar properties. Particularly preferred, but not limited to, the material of the tube comprises a plastic, in particular a polyethylene (PE). It is conceivable for the tube to be made entirely of plastic. It is conceivable for a tube comprising a plastic to be made of a metal and have a plastic coating.
[0035] The tube may have fiber reinforcement, in particular glass fiber reinforcement and / or carbon fiber reinforcement. Through such tubes, heat from the inductive field generated by the electrodes of the high-frequency preheater can penetrate into the interior of the tube to preheat the pellets.
[0036] An advantageous development of the invention provides that the pellets have a maximum diameter and / or a maximum cross-section that is 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 size of the pellets, the accuracy of the required plastic quantity can be adjusted. Smaller pellets also have the advantage that they can be preheated quickly. Pellets with a maximum diameter and / or maximum cross-section between 8 mm and 50 mm have proven particularly advantageous.
[0037] The pellets are made of plastic and / or comprise a plastic material. It is conceivable that the plastic and / or the plastic material comprises a filler. Preferably, the filler has electrically insulating properties. In other words, the filler is electrically non-conductive or has negligible electrical conductivity. The filler is preferably, but not limited to, a glass-based filler, in particular a silicate glass. The filler preferably has a grain size between 5 pm and 300 pm, more preferably between 8 pm and 200 pm, and most preferably between 10 pm and 100 pm, the limits being inclusive. A filler content of greater than 50 mass% and less than 90 mass% is advantageous, more preferably greater than 60 mass% and less than 90 mass%, and most preferably greater than 70 mass% and less than 90 mass%, the limits being inclusive.The higher the filler content of the pellets, the more important it is to pre-plasticize them, particularly to ensure sufficient and homogeneous pre-plasticization of the pellets using a high-frequency preheater. This softens the plastic material surrounding the filler, allowing the softened pellets to be moved in the transfer molding device with reduced ram pressure. Pre-plasticizing the pellets, particularly those containing filler, can significantly reduce wear on the transfer molding device. Otherwise, the high filler content would limit processing of the pellets, and the abrasiveness of the filler would cause excessive wear on the transfer molding device. Furthermore, pre-plasticizing can increase the flow path length of the softened pellets, allowing larger areas to be molded over.Furthermore, the cycle time of a transfer molding process can be reduced because pre-plasticizing reduces the flow resistance of the plastic material, thus requiring only a reduced amount of additional heating of the pellets in the transfer molding device. The heat already introduced during pre-plasticizing can also initiate cross-linking within the plastic material, which can have a beneficial effect on the cycle time.
[0038] The filler in the plastic material acts like reinforcement. In other words, this allows for an overmolding that is particularly rigid and dimensionally stable. This can be advantageous if the electronic component is only overmolding on one side or the plastic material is only applied to one side. Furthermore, the overmolding formed with the filler can have a reduced thickness, which can have a beneficial effect on weight and dimensions.
[0039] Particularly advantageously, the pellets and / or the plastic material are made of or comprise an epoxy-based thermoset material. Such a material exhibits increased thermal stability for applications up to, preferably, 200°C. Likewise, increased media impermeability for corrosive media can be provided. Furthermore, the material is dimensionally stable within the application area. Furthermore, the epoxy-based thermoset material of the pellets can provide an electrically insulating coating, which can also exhibit high electrical breakdown power.
[0040] Finally, an advantageous development of the invention is that the high-frequency preheating device comprises at least two roller electrodes arranged at a distance from one another, with at least one roller electrode being designed to rotate about its longitudinal axis, and the tube being placed on the roller electrodes. In this way, the tube can be rotated during the pellet preheating phase, so that the pellets are evenly heated and thus softened.
[0041] It should be noted that all features described above and below with respect to one aspect of the present invention equally apply to any other aspect of the present invention. In particular, all features of the transfer molding process can also be features of the molding device. This also applies vice versa.
[0042] Further features and advantages of the present invention emerge from the dependent claims and the following exemplary embodiment. The exemplary embodiment is not restrictive, but rather should be understood as an example. It is intended to enable those skilled in the art to implement the invention. The applicant reserves the right to make individual and / or several of the features disclosed in the exemplary embodiment the subject of patent claims or to incorporate such features into existing patent claims. The exemplary embodiment is explained in more detail with reference to drawings.
[0043] In these show:
[0044] Fig. 1 shows a transfer molding process and a molding device according to a preferred embodiment of the invention. Fig. 1 shows a transfer molding process TMV with a molding device EM for overmolding an electronic component EB. In the present 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.
[0045] In a first step 100, a tube RO is provided that has at least one opening OE. The at least one opening OE is formed on a distal end face and / or on a distal end of the tube RO. Typically, the tube RO has an opening OE at each distal end of the tube RO.
[0046] In a second step 110, PE pellets made of a plastic material are filled into the tube RO via the at least one opening OE. The plastic material preferably comprises a filler. The filler is particularly preferably a silicate glass. A fill level of the plastic is preferably greater than 70 mass % and less than 85 mass %. Typically, after the PE pellets have been arranged in the tube RO, the at least one opening OE is closed, preferably via a cover element, so that the PE pellets are enclosed in the tube RO. By using PE pellets, the exact required amount of plastic material for overmolding the electronic component EB can be arranged in the tube RO. Thus, the material requirement can be precisely coordinated, which can reduce material costs. In the present exemplary embodiment, but not limited thereto, 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 both directions. The plastic material of the PE pellets is an epoxy-based thermoset material or comprises an epoxy-based thermoset material. The plastic material comprises a filler, which in the present exemplary embodiment is a glass-based filler. The filler has a filler content of 70% to 90% by mass. In a third step 120, 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 mounted so as to be 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 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 arranged 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, which generates heat. This heat heats the PE pellets arranged in the tube. By heating the PE pellets, the plastic material changes from a solid state to a viscoelastic state. In this case, this occurs 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, so that the transfer molding process can be accelerated and production costs can be reduced.
[0047] After preheating the PE pellets, they are removed from the tube RO in a fourth step 130. This occurs through at least one opening OE. If one opening OE is closed with a cover element, this is removed beforehand to remove the PE pellets from the opening OE. It is conceivable that, with two spaced-apart openings OE, the preheated PE pellets are pressed out through at least one opening OE.
[0048] In a fifth step 140, the preheated PE pellets are inserted into a transfer molding device TM containing an electronic component EB. The transfer molding device TM comprises at least a first mold half EWH and a second mold half ZWH that can be placed on the first mold half EWH. The two mold halves EWH and ZWH form a cavity KA in which the electronic component EB is arranged. In other words, the preheated PE pellets are fed to the transfer molding device TM.
[0049] Subsequently, in a sixth step 150, a stamp ST arranged in the transfer molding device TM is displaced so that the plastic material of the pellets PE penetrates into the cavity KA and surrounds the electronic component EB at least in sections and / or partially.
[0050] It can be provided that the transfer molding device TM and / or a stamping head STK of the stamping device ST is heated. The temperature of the transfer molding device TM and / or the stamping head SK is above a temperature of the preheated PE pellets. Preferably, the transfer molding device TM and / or the stamping head SK has a temperature between 160°C and 185°C at a contact surface comprising the PE pellets, the limits being included. Thus, the preheated PE pellets can be further softened or liquefied in order to overmold or flow around the electronic component EB, at least in sections.
[0051] Advantageously, the heating of the transfer molding device TM and / or the stamping head STK takes place before and / or during the displacement step of the stamping ST. This has the advantage of accelerating the transfer molding process, thereby reducing manufacturing costs.
Claims
Patent claims 1. Transfer molding process (TMV) for overmolding an electronic component (EB), comprising the steps: - Providing a tube (RO) having at least one opening (OE); - filling the pipe (RO) via the opening (OE) with pellets (PE) made of a plastic material; - preheating the pellets (PE) arranged in the tube (RO) using a high-frequency preheater (HVG); - Removal of the preheated pellets (PE) from the pipe (RO); - Inserting the preheated pellets (PE) into a transfer molding device (TM) containing an electronic component (EB); - Displacement of a stamp (ST) arranged in the transfer molding device (TM) so that the plastic material of the pellets (PE) surrounds the electronic component (EB) at least in sections and / or partially.
2. Transfer molding process according to claim 1, characterized in that a temperature of the pellets (PE) is measured within the high-frequency preheating device (HVG) during the preheating of the pellets (PE).
3. Transfer molding process according to claim 2, characterized in 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 in 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 one of the preceding claims, characterized in that a 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 method according to one of the preceding claims, characterized in that the transfer molding device (TM) and / or a stamp head of the stamp (ST) is heated.
7. Transfer molding method according to claim 6, characterized in that the heating of the transfer molding device (TM) and / or the stamp head takes place before and / or during the displacement step of the stamp (ST).
8. Transfer molding process according to one of the preceding claims, characterized in that pellets (PE) made of a plastic material are used, which pellets contain a filler.
9. Transfer molding process according to claim 8, characterized in that a glass-based filler is used for the pellets (PE).
10. Transfer molding process according to claim 8 or 9, characterized in that pellets (PE) with a filler are used, wherein a filler content of the filler is greater than 50 mass% and less than 90 mass%, the limits being included.
11. Molding device for overmolding an electronic component (EB) for carrying out a transfer molding process (TMV) according to one of the preceding claims, comprising - a high frequency preheater (HVG) and - a transfer molding device (TM).
12. Molding device according to claim 11, characterized in that the tube (RO) comprises a plastic and / or is formed from a plastic.
13. Molding device according to claim 11 or 12, characterized in that the pellets (PE) have a maximum diameter and / or a maximum cross section which is greater than 5 mm and less than 100 mm, including the boundaries.
14. Molding device according to one of claims 11 to 13, characterized in that the pellets (PE) are formed from an epoxy-based thermosetting material or comprise an epoxy-based thermosetting material.
15. Molding device according to one of claims 11 to 14, characterized in that the plastic material of the pellets (PE) comprises a filler.
16. Molding device according to claim 15, characterized in that the filler is a glass-based filler.
17. Molding device according to claim 15 or 16, characterized in that a filling degree of the filler is greater than 50 mass% and less than 90 mass%, the limits being included.
18. Molding device according to one of claims 11 to 17, characterized in that the high-frequency preheating device (HVG) has at least two roller electrodes (RE) arranged at a distance from one another, 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).