Method and Mould for Encapsulating Electronic Components Mounted on a Carrier

Abstract

The invention relates to a method for encapsulating electronic components mounted on a carrier, including the steps of: placing the carrier with electronic components in a mould, introducing a liquid encapsulating material into the at least one mould cavity, wherein the pressure on an upper side remote from the carrier of at least one calibration component mounted on the carrier is measured by at least one pressure sensor located in the contact surface of a mould part. The invention also relates to a mould for encapsulating electronic components mounted on a carrier with such a method.

Claims

1. A method for encapsulating electronic components mounted on a carrier, comprising the steps of: A) placing the carrier with electronic components in a mould, such that the carrier with electronic components lies between a contact surface of a first mould part and a contact surface of a second mould part, B) moving the mould parts toward each other and then holding the mould parts in a closed position under the influence of a closing force, wherein the contact surface of at least one of the mould parts encloses together with the carrier at least one mould cavity which wholly encloses the electronic components, C) introducing a liquid encapsulating material into the at least one mould cavity, D) allowing the encapsulating material around the electronic components to cure, and E) moving the mould parts apart and taking the carrier with encapsulated electronic components from the mould, wherein the pressure on an upper side remote from the carrier of at least one component mounted on the carrier is measured during at least one of the steps B) to D) by at least one pressure sensor located in the contact surface of one of the mould parts at the position of said upper side of the at least one component, wherein at least one component, a pressure exerted on which is measured, is a reference or calibration component.

2. The method according to claim 1, wherein at least one reference or calibration component is formed by a solid component mounted on the carrier.

3. The method according to claim 1, wherein upper side of the at least one calibration component protrudes above the upper side of the electronic components which is remote from the carrier.

4. The method according to claim 3, wherein at least one pressure sensor located in the contact surface of one of the mould parts at the position of the upper side of a calibration component also lies partially to the side of the calibration component.

5. The method according to claim 3, wherein the closing force of the mould parts is controlled during at least one of the steps B) to D) subject to the pressure on the upper side of the at least one calibration component measured by the at least one pressure sensor.

6. The method according to claim 5, wherein the closing force of the mould parts during step D) is chosen such that the final pressure on the upper side of the at least one calibration component measured by the at least one pressure sensor is greater, and preferably 1.5 to 2.5 times greater, than an isotropic pressure prevailing in the encapsulating material.

7. The method according to claim 6, wherein the pressure on the upper side of a plurality of calibration components is measured during at least one of the steps B) to D) by means of a plurality of pressure sensors distributed over the contact surface of one of the mould parts.

8. The method according to claim 7, wherein the pressure on at least one calibration component mounted centrally on the carrier is measured by a first pressure sensor arranged centrally in the contact surface, and that the pressure on a calibration component mounted laterally on the carrier is measured by a second pressure sensor arranged laterally in the contact surface at the position of a venting provision.

9. The method according to claim 7, wherein a difference in detected pressures between the plurality of pressure sensors is compensated by a redistribution of the closing force over the mould parts.

10. The method according to claim 9, wherein the distance between the contact surfaces of the mould parts in the mould cavity are adjusted during step B) such that the pressure on the upper side of the at least one calibration component measured by the at least one pressure sensor takes on a value matching a predetermined closing force of the mould parts.

11. The method according to claim 9, wherein after step A) a foil material is arranged between the carrier with the electronic components and the contact surface of the mould part in which the at least one pressure sensor is located.

12. The method according to claim 9, wherein the introduction of a liquid encapsulating material into the mould cavity as according to step C) is done by displacing the encapsulating material in liquid form to the mould cavity by means of exerting a pressure on the encapsulating material using a plunger.

13. The method according to claim 9, wherein the measurement values detected by at least one pressure sensor or the differences in detected measurement values between multiple pressure sensors are stored.

14. A mould for encapsulating electronic components mounted on a carrier with a method according to claim 9, comprising at least two mould parts movable relative to each other and each provided with a contact surface, wherein recessed into the contact surface of at least one of the mould parts is at least one mould cavity configured to wholly enclose the electronic components together with the carrier in a closed position of the mould parts, wherein provided in a part of the contact surface of at least one of the mould parts located at the mould cavity is at least one pressure sensor, configured to register a pressure prevailing at the contact surface at the position of the pressure sensor, which pressure sensor has a pressure-sensitive sensor surface.

15. The mould according to claim 14, wherein the pressure-sensitive sensor surface of the pressure sensor lies in the same plane as the contact surface of the mould.

16. The mould according to claim 14, wherein at least one of the mould parts is provided with a plurality of pressure sensors distributed over the part of the contact surface, located at the mould cavity, of said at least one mould part.

17. The mould according to claim 16, wherein at least one of the pressure sensors is arranged centrally in the part of the contact surface of one of the mould parts located at the mould cavity, and one of the pressure sensors is arranged laterally at the position of a venting provision in the part of the contact surface of said mould part located at the mould cavity.

18. The mould according to claim 16, wherein the mould comprises a drive system for exerting a closing force on the mould parts in closed position of the mould parts, which drive system comprises at least two individually controllable actuators configured to change the distribution of the closing force exerted on the mould parts by the drive system.

19. The mould according to claim 18, wherein the drive system is configured to control the at least two individually controllable actuators on the basis of the pressure registered by the plurality of pressure sensors.

20. The mould according to claim 15, wherein the mould comprises an adjusting mechanism for adjusting a distance between the contact surfaces of the respective mould parts which is present in the at least one mould cavity in a closed position of the mould parts.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The invention will be further elucidated on the basis of the non-limitative exemplary embodiments shown in the following figures. Corresponding elements are designated in the figures with corresponding reference numerals. In the figures:

[0030] FIG. 1 shows a schematic side view of a part of the encapsulating process with a mould according to the present invention;

[0031] FIG. 2 shows a schematic side view of an encapsulating device with arranged therein an alternative embodiment variant of a mould during the encapsulating process according to the present invention;

[0032] FIG. 3 shows a schematic side view of an encapsulating device with arranged therein a second alternative embodiment variant of a mould during the encapsulating process according to the present invention;

[0033] FIG. 4 shows a schematic side view of a third alternative embodiment variant of a mould during the encapsulating process according to the present invention, and

[0034] FIG. 5 shows a schematic side view of a fourth alternative embodiment variant of a mould during the encapsulating process according to the present invention.

DESCRIPTION OF THE INVENTION

[0035] FIG. 1 shows a side view of a part of an upper mould part 1 for encapsulating electronic components 3 mounted on a carrier 2, wherein a calibration component 9 is arranged on the carrier 2 between the electronic components 3. Electronic components 3 are mounted on carrier 2 with interposing of solder beads 4, which mounting makes the assembly of electronic components 3, solder beads 4 and carrier 2 vulnerable to great or too great a pressure; too great a pressure may deform solder beads 4, which poses a danger of short-circuiting of and/or damage to the carrier 2 and/or the electronic component 3. If too low a pressure is however exerted on electronic components 3, the underside of electronic components 3 can become contaminated with encapsulating material which is not desired there. For the purpose of detecting the closing pressure a calibration component 9, the function of which will be elucidated below, is arranged between the electronic components 3 shown here.

[0036] On the underside carrier 2 is supported by a part of a lower mould part 5. The shown segment of the upper mould part 1 is lined on the contact surface 6 facing toward the electronic component 3 with a foil material 7, for instance to prevent contamination of the upper mould part, to obtain a good seal, to simplify releasing of encapsulated electronic components, and so on. In upper mould part 1 a pressure sensor 8 is arranged in the contact surface 6. This pressure sensor 8 is positioned in the contact side 6 such that it is able to detect the pressure at the position of calibration component 9. This makes it possible to measure the pressure exerted with upper mould part 1 on calibration component 9 and thereby better control the quality of the encapsulating process than was possible according to the prior art.

[0037] FIG. 2 shows a schematic side view of an encapsulating device 10 with upper side 11 in which is received a wedge 13 which is displaceable by a drive 12 and whereby the pressure exerted by an upper mould part 14 on a carrier 15 with electronic components 16 (only one of which is shown here) can be controlled. A number of calibration components 21 are also placed on the carrier 15. This figure also clearly shows that recessed into the contact surface 17 of upper mould part 14 is a mould cavity 18 whereby the electronic components 16 and calibration components 21 placed on carrier 15 are wholly enclosed. Carrier 15 supports on the underside on a lower mould part 19. In the contact surface 17 of the upper mould part two pressure sensors 20 are placed at two locations in the mould cavity 18—at the position of calibration components 21—this in a manner such that the contact side of pressure sensors 20 lies in one plane with the contact surface 17 of upper mould part 14.

[0038] FIG. 3 shows an alternative embodiment variant of an encapsulating device 25 wherein similar components of encapsulating device 25 and the encapsulating device 10 as shown in FIG. 2 are designated with the same reference numerals. Other than the encapsulating device 10 as shown in FIG. 2, three pressure sensors 30 are now arranged in the upper mould part 14. These pressure sensors 30 are connected by means of connections 31 to an intelligent control 32. This intelligent control 32 can then operate the drive 12 subject to the measurement data obtained with pressure sensors 30, such that the pressure exerted on the calibration components 21 remains within a desired range and the upper side of electronic components 16 remains free of encapsulating material.

[0039] FIG. 4 shows a side view of a part of an upper mould part 40 which has some similarity to the view of FIG. 1. This is a mould part 40 for encapsulating two shown electronic components 42 mounted on a carrier 41. Electronic components 42 are mounted on carrier 41 with interposing of solder beads 43. Between the electronic components 42 a calibration component 50 is arranged on the carrier. Carrier 41 is supported on the underside by a lower mould part 44. The upper mould part 40 is here shown more fully than in FIG. 1, this making it visible that a mould cavity 45 is bounded by clamping edges 46 whereby the upper mould part 40 seals onto carrier 41 with interposing of a foil layer 47. The foil layer 47 also covers the side 48 of mould cavity 45 facing toward the electronic components 42.

[0040] Arranged in mould cavity 45 is a pressure sensor 49 which is arranged such that it projects from the side 48 of mould cavity 45 facing toward the calibration component 50. The projecting part of pressure sensor 49 is likewise shielded by foil layer 47. This makes it possible to cover the, in this FIG. 2, electronic components 42 with encapsulating material (overmoulding), while the closing pressure of mould parts 40, 44 is measured using calibration component 50.

[0041] FIG. 5 shows a side view of a part of an upper mould part 60 for encapsulating an electronic component 62 mounted on a carrier 61, wherein a calibration component 63 is arranged on the carrier 61 adjacently of the electronic component 62. The shown segment of the upper mould part 60 is lined on the contact surface facing toward electronic components 62 with a foil material 65. The electronic component 62 is mounted on carrier 61 with interposing of solder beads 64. All this largely corresponds to the embodiment as shown in FIG. 1. For the purpose of detecting the closing pressure on electronic component 62 a calibration component 63, whereby a pressure sensor 66 arranged in the contact surface of upper mould part 60 can be activated, is also arranged on carrier 61. This pressure sensor 66 is here positioned such that it is able to detect the pressure at the position of calibration component 63, but also in the free space 67 adjacently of calibration component 63. This makes it possible to measure the pressure exerted on calibration component 63, but also the pressure of the encapsulating material which is introduced into the free space 67; pressure sensor 66 thus has a dual functionality.