WO2010066410A1

WO2010066410A1 - Method and mold for producing an electronic component having a plastic insert molded carrier

Info

Publication number: WO2010066410A1
Application number: PCT/EP2009/008787
Authority: WO
Inventors: Georg Mascha; Steffen Irtenkauf; Achim Haertel; Juergen Berger
Original assignee: Trw Automotive Gmbh
Priority date: 2008-12-11
Filing date: 2009-12-09
Publication date: 2010-06-17
Also published as: DE102008061617A1

Abstract

A method for producing a component having a plastic insert molded carrier comprises the following steps: a carrier (104) is inserted into a receptacle (14) of a mold, fixation elements (18) provided in the mold are moved into a predetermined position, so that the carrier (104) is in contact with the fixation elements (18), the mold is closed, molten plastic is introduced into the mold at a first predetermined pressure, the fixation elements (18) are retracted at a predetermined fill level of the receptacle (14) and the space in the receptacle (14) released by the fixation elements (18) is filled with molten plastic.

Description

Method and tool for producing an electronic component with a plastic-coated carrier

The invention relates to a method for producing an electronic component with a plastic-coated carrier.

Many electronic devices contain components with a carrier, such as a stamped grid or a circuit board, which is equipped with various electronic components. To protect these components from environmental influences, the carriers can be completely enclosed in plastic housings. Various techniques are currently being used.

It is known, for example, to introduce the carrier, equipped with all electronic components, into a prefabricated housing and to cast it in the housing with a synthetic resin which melts at low temperature. It is also known to weld a carrier into a housing. However, these types of fabrication are expensive because they require many steps of manufacture, and in particular the use of a separate housing. It has also been proposed to overmould the carrier directly with a plastic material, but with the problem of complete enclosure of the carrier.

The object of the invention is to simplify the production of a component with a plastic-coated carrier.

According to the invention, a method with the following steps is provided for this purpose. A carrier is inserted into a receptacle of a tool. Fixing elements provided in the tool are moved to a predetermined position, so that the carrier is in contact with the fixing elements. The tool is closed. Liquid plastic is injected at a first predetermined pressure Tool introduced. At a predetermined degree of filling of the recording, the fixing elements are withdrawn. The space released by the fixing elements in the receptacle is filled with liquid plastic. The carrier is surrounded in this process directly and completely by liquid plastic and also fixed by this plastic compound. A separate housing is no longer required.

Under a carrier are here both punched grid and boards understood, each already equipped with all the proposed electronic components. Before filling the tool with liquid plastic, the carrier is held by the fixing in the receptacle so that it can be surrounded on all sides by liquid plastic, of course, except for the space occupied by the fixing. The carrier does not touch the inner wall of the recording. It is irrelevant at what time before filling the fixing are driven into the receptacle. Preferably, first the fixing elements are moved to their predetermined position and then the carrier is placed in the receptacle so that it is in its final position before the tool is closed. However, a different approach is also conceivable, in particular when fixing elements are provided in a multi-part tool in several tool parts, which are each movable.

The already beginning plasticization of the injected plastic has proven to be sufficient to keep the carrier in its predetermined position when the fixing elements are withdrawn at the predetermined degree of filling of the receptacle. This makes it possible to completely surround the carrier with plastic.

For filling the space released by the fixing elements in the receptacle, a second predetermined pressure, which is lower than the first one, is preferably used. The filling of the receptacle advantageously takes place up to the predetermined degree of filling with normal injection pressure, while the conventional holding pressure phase is utilized in order to fill the space released by the fixing elements. The retraction of the fixing is therefore preferably at the beginning or during the holding pressure phase. At this time, sufficient plasticization has already occurred to hold the carrier without its fixing elements at its predetermined carrier position in the receptacle. The degree of filling of the recording, in which the fixing elements are withdrawn, for example, is about 95%.

The fixing elements can advantageously be moved hydraulically, as is also known from conventional slides or core pullers in injection molding tools. Another drive for the movement of the fixing is of course also conceivable.

Preferably, the space released by the fixing elements is filled so that the component, when leaving the tool, has no opening extending from the outside to the support. The plastic casing produced during encapsulation thus surrounds the carrier part completely in the area where the fixing elements had reached the carrier in order to fix it.

In particular, no openings remain, which must be subsequently closed in a further process step. In this way, the carrier can be tightly enclosed in plastic, so that it is protected from environmental influences. Before closing the tool, the carrier can be provided with contact pins. It is also possible to insert the contact pins separately in the tool and to connect before or during the injection molding process by pressure with the wearer.

Prior to closing the tool, one or more slides and / or core pullers may be inserted into the tool to define a plug receptacle. In this way it is possible to create an arbitrarily coded plug receptacle at the same time during the wrapping of the carrier.

The contact pins in the finished component preferably protrude into the plug receptacle and permit electrical contacting of the carrier or the electronic components arranged on it.

The component is, for example, a sensor, such as an acceleration sensor or crash sensor, as may be provided in a vehicle. The procedure However, it is also suitable for any other carrier with electronic components arranged thereon.

The electronic components may preferably comprise one or more A-SICs, as well as various other components, including sensor elements. The invention also relates to a tool for producing an electronic component with a plastic-coated carrier, with two tool parts, in which a receptacle for the carrier is formed in the assembled state, and at least one movably arranged fixing element, which in a fixing position up to a carrier position in the Inner of the receptacle protrudes, and is arranged in a retracted position so that there is a distance between the fixing element and the carrier position.

The "carrier position" here is to be understood as meaning the position and the space occupied by a carrier inserted into the receptacle, wherein, as in the previously described method, the carrier is already equipped with all the electronic components required for the component.

In such a tool, a carrier can be overmolded with plastic in such a way that it is completely sealed off from the environment to the outside.

Preferably, the fixing element is designed in the form of a pin. However, other forms of fixation elements can also be used.

It is advantageous if at least one fixing element is arranged in each tool part in order to be able to achieve a more accurate positioning and fixing of the support.

In a particularly preferred embodiment, the fixing elements lie opposite one another in the respective tool parts, so that a particularly uniform loading of the carrier takes place during its fixing.

In each tool part a plurality of fixing elements may be provided. For example, it is possible to provide three fixing elements in each of the tool parts, which then preferably each face the three fixing elements of the other tool part. At the front end of the fixing element, a structure is preferably formed, which can engage in a complementary structure on the carrier in order to securely fix the carrier during the injection phase.

The tool is preferably designed so that the receptacle between the carrier and an inner wall of the receptacle can be completely filled with liquid plastic when the fixing element is in the retracted position. This means that the fixing element can preferably be pulled back so far that it is substantially flat in the surrounding inner wall of the

Recording passes. In this way, no reworking of the finished component is required.

Further features and advantages of the invention will become apparent from the following description of an embodiment in conjunction with the accompanying drawings. In these show:

- Figures 1 and 2 is a schematic partially sectioned view of a tool according to the invention for carrying out the method according to the invention, wherein in Figure 1, a first tool part and in Figure 2, a second tool part of the tool is shown;

- Figure 3 is an enlarged detail of Figure 2; and

- Figure 4 shows a component which can be produced in a tool according to the invention according to a method of the invention.

FIGS. 1 to 3 show a tool for producing an electronic component with a plastic-encased carrier, wherein FIG. 1 shows a first, here upper tool part 10 and in FIG. 2 a second, here lower tool part 12. FIG. 4 shows an example of a component 100 with a plastic-encapsulated component

Carrier, as can be produced in the tool shown with the method described below, in this case, the component 100 is a sensor with a plastic sheath 102 and a carrier 104 embedded in the plastic sheath 102. The carrier 104 comprises in this case a punched grid and one or more ASIC chips mounted thereon and other electronic components and sensor components, such as resistors. All necessary electronic see components are arranged directly on the stamped grid or directly connected to this (not shown here). Two contact pins 106 are fixedly connected to the carrier 104 and are from this. They provide the electrical contact for the components on the support 104. The plastic covering 102 simultaneously forms the outer surface of the component. The plastic sheath 102 also encloses a connector receptacle 108 into which the contact pins 106 protrude. Between the plug receptacle 108 and the region in which the support 104 is arranged, the plastic covering 102 is formed such that it tightly encloses the contact pins 106. The plug receptacle 108 has a predetermined coding to ensure that only the correct, associated plug and this can only be inserted in the correct position.

The carrier 104 is enveloped on all sides by the plastic material of the plastic sheath 102 and sealed off from the environment. For fixing the component 100 e.g. On a vehicle body, a fastening nut 110 is provided, which is provided on the plug receptacle 108 opposite axial end of the sensor. The fastening nut 110 is embedded in the plastic sheath 102.

Instead of a sensor, it is also possible to produce any other components with a plastic-coated carrier in the method described below and in the tool described below.

The tool has two tool parts 10, 12, which can be assembled and separated from each other and forms an injection mold, which can be used for a conventional plastic injection molding process. The tool parts 10 and 12 form in the assembled state

Cavity in the form of a receptacle 14, wherein in the upper tool part 10, the upper half of the receptacle 14 and in the lower tool part 12, the lower half of the receptacle 14 is formed.

In the receptacle 14, a carrier 104 is inserted in the open state of the tool, in this case in the lower tool part 12th

The carrier 104 in this example is a printed circuit board equipped with electronic components. Of course, as in the example above, 100, a punched grid equipped with ASICs, for example, or another suitable carrier with suitable electronic components can be used. The carrier has for example a dimension of about 25 x 22 mm.

The carrier 104 is held at a distance from the inner walls 16 of the receptacle 14 in the receptacle 14, namely, by a plurality of fixing elements 18, here in pin form, are provided in two tool parts 10, 12, which initially protrude into the receptacle 14.

Each of the fixing elements 18 has an end 20 which engages in a complementary structure 22 on the carrier 104. In the example shown, the end 20 is formed by a, with a shoulder offset from the rest of the fixing element 18, tapered tip, while the structure 22 is realized by a through opening in the carrier 104. The tip has a smaller diameter than the opening, while the fixing element 18 at the shoulder has a larger diameter than the opening. As a result, the carrier 104 rests on the shoulder of the fixing element 18 of the lower tool part 10 and is determined and fixed in its vertical position, while it is determined and fixed in its horizontal position by the ends 20 of the respective fixing element 18.

The fixing elements 18 are arranged to be movable and are moved linearly by means of a hydraulic system (not shown). In a first, advanced position, the ends 20 protrude a bit into the receptacle 14. In a second, retracted position, the fixing elements 18 are retracted so far that their ends 20 terminate at least substantially flush with the inner wall 16 of the receptacle 14.

The fixing elements 18 of the lower tool part 12 are moved into the receptacle 14 before the insertion of the carrier 104 and the carrier 104 is then placed on the fixing elements 18 such that the ends 20 engage in the structures 22. In this way, a predetermined carrier position of the carrier 104 is fixed. The fixing elements 18 at this time form the only contact points of the carrier 104, so that the carrier 104 has no contact with the inner walls 16 of the receptacle 14.

On the carrier 104 two electrical contact pins 106 are attached in this example, before the carrier 104 is inserted into the receptacle 14. Alternatively, the connection between the carrier 104 and the contact pins 106 could also occur shortly before the injection molding, for example during insertion into the receptacle 14 or only during the injection molding process.

The contact pins 106 protrude into a region of the tool that later defines a connector receptacle 108. To make this connector receptacle 108, a slider 24 is provided, which is pushed in a known manner on the contact pins 106 to keep the space for the connector receptacle 108 free.

The slider 24 is designed such that it predetermines a predetermined connector coding in order to prevent reverse polarity of a connector which is intended to contact the contact pins 106.

In the receptacle 14, the fastening nut 110 is also inserted at a designated location, so that it is also simultaneously embedded in the plastic sheath 102 during the injection molding process.

Subsequently, the tool is closed by the upper tool part 10 is placed on the lower tool part 12.

The fixing elements 18 in the upper tool part 10 are either already extended to their first, advanced position or are extended after placing the tool part 10 so that they also come into contact with the carrier 104. In the embodiment shown here, the fixing elements 18 are in the upper

Tool part 10 identical to those formed in the lower tool part 12.

In the present case, three fixing elements 18 are provided in each tool part, which are exactly opposite each other when the tool is closed, so that the carrier 104 is held without transverse loads. In the next process step, liquid plastic is injected at a predetermined first pressure in the tool. The injection takes place here with the usual injection pressure, which builds up a conventional injection molding machine. During the injection phase, a large part of the intended plastic material is introduced into the receptacle 14. At a predetermined degree of filling of the receptacle 14, here about 95%, the ends

Injection phase, and the holding pressure phase is initiated, as is known from conventional plastic injection molding processes. This is the pressure on a is reduced to a predetermined second value, which in this example corresponds to the conventionally used value for the reprint. However, this second pressure during the emphasis phase is still high enough to squeeze more material into the receptacle 14. At the beginning of the holding pressure phase or at a predetermined time during the holding pressure phase, the fixing elements 18 are retracted to their second position so that they lose their contact with the carrier 104 and a gap between the carrier 104 and the wall of the receptacle 14 or The ends 20 of the fixing elements 18 is free. The plastic mass in the receptacle 14, which surrounds the carrier 104, is already solidified at this time to the extent that the position of the carrier 104 is no longer changed when the fixing elements 18 are retracted. However, part of the mass is still flowable enough so that the volumes released by the fixing elements 18 fill up substantially or completely with liquid plastic.

In this way, a plastic sheath 102 is formed, which completely surrounds the carrier 104 on all sides. In particular, no openings remain which extend from the outer surface of the plastic envelope 102 inwardly to the carrier 104. Also in the areas where originally the fixing elements 18 have attacked the carrier 104, the plastic sheath 102 is completely closed after completion of the process.

When the holding pressure phase has ended, the slide 24 is retracted after connection to the required cooling time when the tool is opened, and then the finished component is removed. In only a single step, both the complete embedding of the carrier 104 in the plastic sheath 102, which completely surrounds the carrier 104, as well as the formation of the plug receptacle 108.

Claims

claims

1. A method for producing a component with a plastic-coated carrier, comprising the following steps: a) a carrier (104) is inserted into a receptacle (14) of a tool, b) provided in the tool fixing elements (18) are moved to a predetermined position such that the carrier (104) is in contact with the fixing elements (18), c) the tool is closed, d) liquid plastic is introduced into the device at a first predetermined pressure

Introduced tool, e) at a predetermined degree of filling of the receptacle (14), the fixing elements (18) are withdrawn and f) of the fixing elements (18) released space in the receptacle (14) is filled with liquid plastic.

2. The method according to claim 1, characterized in that the filling of the fixing elements (18) released space in the receptacle (14) takes place at a second predetermined pressure and the second predetermined pressure is lower than the first.

3. The method according to any one of the preceding claims, characterized in that the retraction of the fixing elements (18) takes place at the beginning or during a Nachdruckphase.

4. The method according to any one of the preceding claims, characterized in that the degree of filling of the receptacle (14), in which the fixing elements (18) are withdrawn, is about 95%.

5. The method according to any one of the preceding claims, characterized in that the fixing elements (18) are moved hydraulically.

6. The method according to any one of the preceding claims, characterized in that the space released by the fixing elements (18) is filled so that the component when leaving the tool has no opening which extends from the outside to the support (104) enough.

7. The method according to any one of the preceding claims, characterized in that the carrier (104) is provided prior to insertion into the tool with contact pins (106).

8. The method according to any one of the preceding claims, characterized in that before closing the tool, one or more slides (24) and / or core pulls are introduced to define a connector receptacle (108).

9. The method according to claims 7 and 8, characterized in that the contact pins (106) protrude into the connector receptacle (108).

10. The method according to any one of the preceding claims, characterized in that the component (100) is a sensor.

11. Tool for producing a component with a plastic-coated carrier, with two tool parts (10, 12), in which in the assembled state, a receptacle (14) for the carrier (104) is formed, and at least one movably arranged fixing element (18), in a fixing position up to a support position projects into the interior of the receptacle (14), and in a retracted position is arranged so that a distance between see the fixing element (18) and the support position consists.

12. Tool according to claim 11, characterized in that the fixing element (18) is designed in the form of a pin.

13. Tool according to one of claims 11 and 12, characterized in that in each tool part (10, 12) at least one fixing element (18) is arranged.

14. Tool according to claim 13, characterized in that the fixing elements (18) in the respective tool parts (10, 12) are arranged opposite one another.

15. Tool according to one of claims 11 to 14, characterized in that in each tool part (10, 12) a plurality of fixing elements (18) are provided.

16. Tool according to one of claims 11 to 14, characterized in that at the front end of the fixing element (18), a structure is formed, which can engage in a complementary structure on the carrier (104).

17. Tool according to one of claims 11 to 16, characterized in that the tool is formed so that the receptacle (14) between the support (104) and an inner wall (16) of the receptacle (14) are completely filled with liquid plastic can when the fixing member (18) is in the retracted position.