Transfer molding method for overmolding electronic components and molding device for implementing the method
The plastic particles are preheated through a high-frequency preheater, and the problems of uneven heating and long residence time in the prior art are solved, and the effects of reducing manufacturing costs and improving the durability of the transfer molding device are achieved.
Patent Information
- Application Number
- CN202380050525.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-06-30
- Filing Date
- 2023-06-22
- Publication Date
- 2025-02-14
AI Technical Summary
In the prior art, when the electronic components are coated and injection molded, the heating of the plastic particles is uneven and the residence time is too long, resulting in high manufacturing costs and increased material consumption.
The plastic particles are preheated with a high-frequency preheater so that they are in a viscoelastic state, reducing residence time in the transfer molding device, and reducing material costs by precisely adjusting the amount of plastic.
Preheating plastic particles through high-frequency preheaters reduces wear and material consumption of the transfer molding device, reduces manufacturing costs, and improves the durability of the transfer molding device.
Smart Images
Figure CN119451801A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a transfer molding method for overmolding electronic components, wherein plastic granules are used for overmolding the electronic components, and the plastic granules are preheated by means of a high-frequency preheater before being arranged in a transfer molding device. The subject matter of the invention is also a molding device for carrying out the transfer molding method. Background Art
[0002] It is known that electronic components are at least partially overmolded by means of plastic. The problem in the known method 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 needed, cold plastic particles are fed into the transfer molding device and heated there to the corresponding temperature, so that the softened plastic is conveyed to the casting cavity of the transfer molding device by means of a movable die in the interface. Disadvantages here are that particles are sometimes heated unevenly in the transfer molding device and there is a longer particle residence time in the transfer molding device, so as to heat the particles accordingly or make the particles heat up. In particular, a longer residence time in the transfer molding device can lead to higher manufacturing costs. In the case of a large amount of plastic, the plastic is pre-plasticized in the extruder. Due to the abrasive additives in the plastic material, the wear in the extruder increases. In addition, "consumable blanks" can be produced according to the situation of exceeding the residence time, which removes the pre-plasticized plastic material from the discharge zone. In other words, material consumption and material wear are therefore increased, which may lead to additional costs. Summary of the invention
[0003] The object of the present invention is to provide a transfer molding method and a molding device for carrying out the transfer molding method, wherein the production costs are reduced.
[0004] This object is achieved by the subject matter of the independent claim. Preferred improvements of the invention are the subject matter of the dependent claims, the following description and the drawings. Each feature may represent an aspect of the invention both individually and in combination, unless the contrary is clearly evident from the description.
[0005] In a first aspect, according to the present invention, there is provided a transfer molding method for overmolding an electronic component, the transfer molding method comprising the following steps:
[0006] - providing a tube having at least one opening;
[0007] - filling the tube through the opening with granules of plastic material;
[0008] - Preheating the particles arranged in the tube by means of a high frequency preheater;
[0009] - removing the preheated particles from the tube;
[0010] - placing the preheated granules into a transfer molding device with an electronic component;
[0011] A die arranged in a transfer molding device is moved such that the granulated plastic material at least partially and / or zone-wise surrounds the electronic component.
[0012] In other words, according to a first aspect of the present invention, a transfer molding method for overmolding an electronic component is provided. 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 component can be protected from corrosive media, such as oil.
[0013] It is also conceivable that the electronic component is preferably a converter / 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 an electronic module arranged thereon.
[0014] In the first step, a tube having at least one opening is provided. The at least one opening is preferably configured on the distal end face and / or end side of the tube. Typically, the tube has an opening at the respective distal ends. The tube can be configured as a hollow cylinder, but is not limited thereto. In other words, the tube can also be referred to as a container.
[0015] In a second step, particles of plastic material are filled into the tube through at least one opening. Usually, after the particles have been arranged, at least one opening is closed, preferably via a cover element, so that the particles are enclosed in the tube. By using particles, the required amount of plastic material for overmolding the electronic component can be arranged in the tube. Thus, the material requirements can be precisely adjusted / coordinated, whereby the material costs can be reduced.
[0016] In the third step, the particles arranged in the tube are preheated by means of a high-frequency preheater. In other words, the particles arranged in the tube are heated to a certain temperature inside the tube by the high-frequency preheater, so that the particles are transformed from a solid state to a viscoelastic state. This is preferably carried out at a particle temperature greater than 50°C and less than 100°C, in particular at a particle temperature greater than 60°C and less than 90°C, wherein the boundary values are included. In the viscoelastic state, the particles have a soft consistency or the particles are deformable. By preheating the particles, the residence time of the particles in the transfer molding device can be reduced, thereby accelerating the manufacturing process of the transfer molding method. Therefore, the manufacturing costs can be reduced. By means of a high-frequency preheater, the particles can be preheated to the corresponding temperature by induction in a simple and inexpensive manner, which can also have a favorable effect on the manufacturing costs.
[0017] After the granules have been preheated, they are removed from the tube in a fourth step. This is preferably done via at least one opening. If one opening is closed by a cover, the cover is removed beforehand in order to remove the granules from the opening. It is conceivable that the preheated granules are pressed out through at least one opening if the two openings are spaced apart from one another.
[0018] In a fifth step, the preheated particles are placed in a transfer molding device with the electronic component. In other words, the preheated particles are fed to the transfer molding device.
[0019] Subsequently, in a sixth step, the die arranged in the transfer molding device is moved so that the plastic material of the granules at least partially and / or partly surrounds the electronic component. By moving the die, the plastic material of the granules is pressed into the cavity with the electronic component, so that the plastic material at least partially wraps the electronic component. The wear of the transfer molding device can be reduced by pre-plasticizing the granules, which can increase the service life of the transfer molding device and reduce manufacturing costs.
[0020] In this way, a transfer molding method for overmolding electronic components is provided, wherein the production costs can be reduced, since the amount of plastic required for overmolding can be precisely adjusted based on the particles and the residence time of the particles in the transfer molding device can be reduced by preheating the particles in a high-frequency preheater. The wear of the transfer molding device can also be reduced, which can have a positive effect on the durability of the transfer molding device. Furthermore, the production costs can be reduced by the increased durability.
[0021] It is conceivable that the tube is fixed inside the high-frequency preheater or is loosely inserted into the high-frequency preheater during the preheating period of the particles. Alternatively, it can be provided that the tube is rotatably supported in the high-frequency preheater and is rotated and / or rotated at least temporarily around the longitudinal axis of the tube during the preheating period of the particles. In this way, uniform preheating of the particles can be achieved.
[0022] An advantageous development of the invention is that the temperature is measured within the high-frequency preheater during the preheating duration or preheating phase of the particles. Preferably, the surface temperature of the tube and / or the temperature of the particles is measured. If the surface temperature of the tube is measured, then preferably the temperature of the particles can be inferred. It is conceivable that the temperature of the particles is measured directly, alternatively or additionally. The measured temperature can be used to determine the degree of preheating of the particles or the viscoelasticity of the particles.
[0023] Advantageously, provision is made for the granules to be preheated until a predetermined temperature of the granules is reached. Thus, the preheating phase of the granules ends when a predetermined limit temperature or a predetermined temperature threshold is reached. In this way, the duration of the preheating phase can be precisely monitored to ensure uniform preheating of the granules for different transfer molding methods.
[0024] In principle, any suitable thermometer can be used to determine the particle temperature. An advantageous development of the invention is to measure the temperature of the particles by means of an infrared thermometer. It is conceivable that the tube and / or the cover are at least partially transparent and that the temperature of the particles is measured by means of an infrared thermometer through the transparent area in the cover and / or the tube.
[0025] An advantageous refinement of the invention is to measure the temperature of the particles continuously during the preheating phase of the particles. Thus, when a temperature threshold is reached, the preheating phase can be ended immediately, which can have a favorable effect on the manufacturing time and therefore also on the manufacturing costs.
[0026] As an alternative and / or in addition to monitoring the preheating phase of the particles by means of the particle temperature, an advantageous development of the invention provides that the preheating duration of the particles is dependent on the following parameters:
[0027] - the filling amount of the particles,
[0028] - the maximum diameter of the particles,
[0029] - the material thermal properties of the particles, and
[0030] -Frequency of the high frequency preheater.
[0031] In other words, the duration for preheating the granules can be determined by various parameters from previously determined experiments, so that these parameters can be used as a supplement and / or alternative to monitoring the granule temperature. When the filling amount of the granules increases and / or the diameter of the granules increases, the duration of preheating is preferably extended. Likewise, the material thermal properties of the granules, for example the viscosity properties of the plastic material of the granules, and the selected frequency of the high-frequency preheater also influence the duration of preheating.
[0032] These particles are only preheated in the high-frequency preheater so that they soften and preferably have a viscoelastic consistency. This consistency is usually not sufficient to allow electronic components to be overmolded without shrinkage holes and / or defects by means of the preheated plastic. Therefore, an advantageous improvement of the present invention provides that the transfer molding device and / or the die head of the die are heated. The temperature of the transfer molding device and / or the die head is higher than the temperature of the preheated particles. Preferably, the transfer molding device and / or the die head have a temperature of more than 120° C., preferably more than 140° C., particularly preferably more than 160° C. on the contact surface with the particles, wherein the boundary value is included. Therefore, the preheated particles can be further softened or liquefied in order to at least partially overmold the electronic components or flow around the electronic components.
[0033] In this case, a preferred embodiment of the present invention is that the transfer molding device and / or the die head are heated before and / or during the step of moving the die. It can therefore be provided that the transfer molding device and / or the die head are preheated to a minimum temperature before the preheated particles are arranged in the transfer molding device. This has the advantage that the transfer molding process can be accelerated. Alternatively and / or in addition, it can be provided that the heating of the transfer molding device and / or the die head is achieved during the movement of the die. Therefore, the particles located further out, i.e. the particles that are at the greatest distance from the electronic component, can also be adjusted to the corresponding temperature for the overmolding of the electronic component.
[0034] In a second aspect, the invention relates to a molding device for overmolding electronic components and for carrying out the transfer molding method according to the invention, the molding device having a high-frequency preheater and a transfer molding device.
[0035] The tube is preferably made of a material with non-polar properties. Particularly preferably, but not limited to, the material of the tube has plastic, in particular polyethylene (PE). It is conceivable that the tube is completely made of plastic.
[0036] It is conceivable that the tube comprising plastic is preferably made of metal and has a plastic coating.
[0037] The tube can have a fiber-reinforced structure, in particular a glass-fiber-reinforced structure and / or a carbon-fiber-reinforced structure. Through such a tube, the heat of the induction field generated by the electrodes of the high-frequency preheater can penetrate into the interior of the tube so that the particles are preheated.
[0038] An advantageous development of the invention provides that the granules have a maximum diameter and / or a maximum cross-sectional area which is greater than 5 mm and less than 100 mm, in particular greater than 25 mm and less than 70 mm, wherein the limit values are included. Depending on the size of the granules, the precision of the required amount of plastic can be adjusted. Smaller granules also have the advantage that the granules can be preheated quickly. Granules having a maximum diameter and / or a maximum cross-sectional area of between 8 mm and 50 mm have proven to be particularly advantageous.
[0039] The particles are made of plastic and / or have a plastic material. It is conceivable that the plastic and / or the plastic material have a filler. Preferably, the filler has electrical insulating properties. In other words, the filler is 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 particle size between 5 μm and 300 μm, particularly preferably between 8 μm and 200 μm, and particularly preferably between 10 μm and 100 μm, wherein the boundary values are included. The filling degree of the filler is advantageously greater than 50% by mass and less than 90% by mass, particularly preferably greater than 60% by mass and less than 90% by mass, particularly preferably greater than 70% by mass and less than 90% by mass, wherein the boundary values are included. The higher the filling degree of the filler of the particles, the more important it is to pre-plasticize the particles, in particular to pre-plasticize them sufficiently and uniformly, by means of a high-frequency preheater, so that the plastic material surrounding the filler is softened and the softened particles can be moved in the transfer molding device with a reduced compression molding pressure. By pre-plasticizing the particles, in particular the particles with fillers, the wear of the transfer molding device can be significantly reduced, since otherwise the high filler content restricts the processing of the particles and the abrasiveness of the fillers causes excessive wear of the transfer molding device. In addition, the flow length of the softened particles can be increased by pre-plasticizing, so that larger areas can be overmolded. In addition, the cycle time of the transfer molding process can be reduced, since the flow resistance of the plastic material is reduced by pre-plasticizing and thus the additional heating of the particles in the transfer molding device can also be reduced. Due to the heat already introduced within the scope of pre-plasticization, crosslinking can also start within the plastic material, which can have a favorable effect on the cycle time.
[0040] The filler in the plastic material acts like a reinforcement. In other words, a particularly rigid and dimensionally stable overmolding can be achieved in this way. This can be advantageous if the electronic component is overmolded only from one side or the plastic material is applied only on one side. In addition, the overmolding formed with the filler can have a reduced thickness, which can have a favorable effect on weight and size.
[0041] It is particularly advantageous if the particles and / or the plastic material are made of or comprise an epoxy-based thermosetting material. Such materials have an increased thermal stability for an application range of up to preferably 200° C. An increased media tightness for aggressive media can also be provided. Furthermore, the material is dimensionally stable within the application range. Furthermore, an electrically insulating encapsulation can be provided with the epoxy-based thermosetting material of the particles, which can also have a high electrical breakdown resistance.
[0042] Finally, an advantageous development of the invention is that the high-frequency preheater has at least two roller electrodes arranged at a distance from one another, wherein at least one roller electrode is designed to be rotatable about its longitudinal axis, and the tube rests on the roller electrode. In this way, during the preheating phase of the particles, the tube can be rotated so that the particles are heated uniformly and thus softened.
[0043] It should be noted that all features described above and below with respect to one aspect of the present invention are also applicable to any other aspect of the present invention. In particular, all features of the transfer molding method may also be features of the molding apparatus. Conversely, all features of the molding apparatus may also be features of the transfer molding method.
[0044] Other features and advantages of the present invention are derived from the dependent claims and the following embodiments. The embodiments should not be understood as limiting, but rather as exemplary. A person skilled in the art should be able to implement the present invention. The applicant reserves the right to include single and / or multiple features disclosed in the embodiments as the subject of the claims, or to include such features in existing claims. The embodiments are described in detail according to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0045] The figure shows:
[0046] Figure 1 A transfer molding method and a molding apparatus according to a preferred embodiment of the present invention are shown. DETAILED DESCRIPTION
[0047] exist Figure 1 1 shows a transfer molding method TMV for overmolding an electronic component EB by means of a molding device EM. The electronic component EB is a transmission control unit for a motor vehicle in this embodiment. By overmolding the electronic component EB, the electrical and / or electronic component EB can be protected from corrosive media, such as oil.
[0048] In a first step 100, a tube RO having at least one opening OE is provided. The at least one opening OE is formed on the distal end face and / or the distal end of the tube RO. Typically, the tube RO has an opening OE at the respective distal end of the tube RO.
[0049] In a second step 110, particles PE of a plastic material are filled into the tube RO through at least one opening OE. Preferably, the plastic material has a filler. The filler is particularly preferably silicate glass. The filling degree of the plastic is preferably greater than 70% by mass and less than 85% by mass. Usually, after the particles PE are arranged in the tube RO, at least one opening OE is preferably closed by a cover element so that the particles PE are enclosed in the tube RO. By using particles PE, the exact required amount of plastic material for encapsulating the electronic component EB can be arranged in the tube RO. Therefore, the material requirements can be accurately adjusted, thereby reducing material costs. In the present embodiment, the diameter of the particles PE is 9.8 mm, but it is not limited to this. Preferably, only particles with a diameter of 9.8 mm are used. However, it can also be provided that particles with different diameters are used, wherein the deviation is a maximum of 10% in both directions. The plastic material of the particles PE is an epoxy-based thermosetting material or has an epoxy-based thermosetting material. The plastic material has a filler, which is a glass-based filler in the present embodiment. The filler has a filling degree of 70% to 90% by mass.
[0050] In the third step 120, the particles PE arranged in the tube RO are preheated by means of a high-frequency preheater HVG. The high-frequency preheater HVG has two lower rolling electrodes RE. At least one rolling electrode RE is supported in a manner that can rotate and / or swivel around its longitudinal axis. It is conceivable that the two lower rolling electrodes RE are configured to be rotatable or rotatable. The tube RO filled with particles PE is arranged on the lower rolling electrode 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 rolling electrode RE. An induction field is generated between the upper electrode EL and the lower rolling electrode RE, thereby generating heat. The particles PE arranged in the tube are heated by this heat. By heating the particles PE, the plastic material is transformed from a solid state to a viscoelastic state. Currently, this is achieved when the temperature of the particles is between 70°C and 85°C. By preheating the particles, the residence time of the particles PE in the transfer molding device TM can be reduced, so that the transfer molding manufacturing process can be accelerated, thereby reducing the manufacturing cost.
[0051] After the particles PE have been preheated, they are removed from the tube RO in a fourth step 130. This is done via at least one opening OE. If an opening OE is closed by a cover element, the cover element is removed beforehand in order to remove the particles PE from the opening OE.
[0052] It is conceivable that the preheated particles PE are pressed out through at least one opening OE, with two openings OE spaced apart from one another.
[0053] In a fifth step 140, the preheated granules PE are placed in a transfer molding device TM with an electronic component EB. The transfer molding device TM has at least one 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, ZWH form a cavity KA in which the electronic component EB is arranged. In other words, the preheated granules PE are fed to the transfer molding device TM.
[0054] Subsequently, in a sixth step 150 , the stamp ST arranged in the transfer molding device TM is moved such that the plastic material of the granules PE enters the cavity KA and at least partially and / or partly surrounds the electronic component EB.
[0055] It can be provided that the transfer molding device TM and / or the die head STK of the die ST are heated. In this case, the temperature of the transfer molding device TM and / or the die head SK is higher than the temperature of the preheated particles PE. Preferably, the transfer molding device TM and / or the die head SK has a temperature of between 160° C. and 185° C. on the contact surface with the particles PE, wherein the limit values are included. The preheated particles PE can thus further soften or liquefy in order to at least partially overmold the electronic component EB or flow around the electronic component.
[0056] Advantageously, provision is made for the transfer molding device TM and / or the die head STK to be heated before and / or during the step of moving the die ST. This has the advantage that the transfer molding process can be accelerated, thereby reducing the production costs.
Claims
1. A transfer molding method (TMV) for overmolding an electronic component (EB), the transfer molding method comprising the following steps: - providing a tube (RO) having at least one opening (OE); - filling the tube (RO) with granules of plastic material (PE) through the opening (OE); - preheating of the particles (PE) arranged in the tubes (RO) by means of a high-frequency preheater (HVG); - removing the preheated particles (PE) from the tube (RO); - placing the preheated granules (PE) into a transfer molding device (TM) with an electronic component (EB); A stamp (ST) arranged in a transfer molding device (TM) is moved such that the plastic material of the granules (PE) at least partially and / or partly surrounds the electronic component (EB).
2. The transfer molding method according to claim 1, characterized in that During the preheating of the particles (PE), the temperature of the particles (PE) is measured inside the high-frequency preheater (HVG).
3. The transfer molding method according to claim 2, characterized in that The temperature of the granules (PE) was measured by an infrared thermometer.
4. The transfer molding method according to claim 2 or 3, characterized in that: The particles (PE) are preheated until a predetermined temperature of the particles (PE) is reached.
5. Transfer molding method according to any one of the preceding claims, characterized in that The duration of the preheating of the pellets depends on the following parameters: - Filling amount of granules (PE), - maximum diameter and / or cross-sectional area of the particles (PE), - Material thermal properties of the pellets (PE), and - Frequency of the high frequency preheater (HVG).
6. Transfer molding method according to any one of the preceding claims, characterized in that The transfer molding device (TM) and / or the die head of the stamping mold (ST) are heated.
7. The transfer molding method according to claim 6, characterized in that The transfer moulding device (TM) and / or the die head are heated before and / or during the step of moving the mould (ST).
8. Transfer molding method according to any one of the preceding claims, characterized in that Granules of plastic material (PE) are used, the granules having fillers.
9. The transfer molding method according to claim 8, characterized in that Glass-based fillers were used for the particles (PE).
10. The transfer molding method according to claim 8 or 9, characterized in that: Particles (PE) with fillers are used, wherein the filling degree of the filler is greater than 50% by weight and less than 90% by weight, wherein the limit values are included.
11. A molding device for overmolding electronic components (EB) for carrying out a transfer molding method (TMV) according to any one of the preceding claims, the molding device comprising: - High Frequency Heater (HVG); and - Transfer Molding Device (TM).
12. The molding device according to claim 11, characterized in that: The tube (RO) comprises plastic and / or consists of plastic.
13. The molding device according to claim 11 or 12, characterized in that: The particles (PE) have a maximum diameter and / or a maximum cross-sectional area, the maximum diameter being greater than 5 mm and less than 100 mm, wherein the limit values are included.
14. The molding device according to any one of claims 11 to 13, characterized in that: The particles (PE) are made of or comprise epoxy-based thermosetting material.
15. The molding device according to any one of claims 11 to 14, characterized in that The plastic material of the granules (PE) has fillers.
16. The molding device according to claim 15, characterized in that: The filler is a glass-based filler.
17. The molding device according to claim 15 or 16, characterized in that: The filling degree of the filler is greater than 50% by mass and less than 90% by mass, the limit values being included.
18. The molding device according to any one of claims 11 to 17, characterized in that The high-frequency preheater (HVG) has at least two rolling electrodes (RE) arranged at a distance from one another, wherein at least one rolling electrode (RE) on which the tube (RO) rests is designed to be rotatable about its longitudinal axis.