Electronic device comprising surface-mount device type dipoles, and corresponding assembly method

Abstract

A base substrate has a thickness between two faces. The base substrate includes at least one hole extending in a thickness of the base substrate perpendicular to one of the two faces. At least one dipole of a surface-mount device type is housed in the at least one hole of the base substrate.

Claims

1. A method, comprising: forming a hole extending in a thickness of a base substrate; inserting at least one dipole of a surface-mount device type in the hole; wherein said at least one dipole of the surface-mount device type includes electrical terminations; mounting an integrated circuit chip including an electrical chip connection element on a front face of the base substrate; and securing the at least one dipole of the surface-mount device type within the hole using a volume of conductive adhesive; wherein said volume of conductive adhesive physically contacts both said at least one electrical termination of the at least one dipole of the surface-mount device type and the electrical chip connection element of the integrated circuit chip.

2. The method of claim 1, wherein forming said hole comprises forming the hole to extend completely through the thickness of the base substrate.

3. The method of claim 2, further comprising: providing an electrical contact on a back face of the base substrate; and using a further volume of conductive adhesive to secure the at least one dipole of the surface-mount device type within the hole and form an electrical connection between another electrical termination of the at least one dipole of the surface-mount device type and the electrical contact on the back face of the base substrate.

4. The method of claim 3, further comprising forming a solder mask layer on the back face of the base substrate.

5. The method of claim 4, wherein said solder mask layer covers the hole.

6. The method of claim 1, further comprising: providing an electrical contact on the front face of the base substrate; and wherein mounting the integrated circuit comprises connecting another electrical chip connection element to the electrical contact on the front face of the base substrate.

7. The method of claim 1, wherein the base substrate is one of a printed circuit board or a ball array housing board.

8. The method of claim 1, wherein the electrical chip connection element of the integrated circuit chip is one of a pillar or a connection ball.

9. The method of claim 1, wherein forming the hole comprises forming the hole with a size and shape conforming to a cylindrical shape of the at least one dipole of the surface-mount device type.

10. The method of claim 1, further comprising forming a solder mask layer on the front face of the base substrate.

11. A method, comprising: forming a hole extending in a thickness of a base substrate; inserting at least one dipole of a surface-mount device type in the hole; wherein said at least one dipole of the surface-mount device type includes electrical terminations; securing the at least one dipole of the surface-mount device type within the hole using a volume of conductive adhesive; forming a solder mask layer on a front face of the base substrate; wherein said solder mask layer completely covers the hole; mounting an integrated circuit chip to the solder mask at the front face of the base substrate; wherein said volume of conductive adhesive forms at least part of an electrical connection between at least one electrical termination of the at least one dipole of the surface-mount device type and the integrated circuit chip.

12. The method of claim 1, wherein the at least one dipole of the surface-mount device type comprises two or more dipoles of the surface-mount device type inserted in the hole.

13. A method, comprising: forming a hole extending in a thickness of a base substrate; inserting a first dipole of a surface-mount device type in the hole; placing a volume of conductive adhesive within the hole; inserting a second dipole of a surface-mount device type in the hole; wherein the volume of conductive adhesive electrically connects adjacent electrical terminations of the first and second dipoles of the surface-mount device type within the hole; securing one or more of the first and second dipoles of the surface-mount device type within the hole using a further volume of conductive adhesive; and mounting an integrated circuit chip on a front face of the base substrate; wherein said further volume of conductive adhesive forms at least part of an electrical connection between said one or more of the first and second dipoles of the surface-mount device type and the integrated circuit chip.

14. The method of claim 13, wherein said adjacent electrical terminations of the first and second dipoles of the surface-mount device type are opposite polarity electrical terminations.

15. The method of claim 13, wherein a further part of the electrical connection between at least one electrical termination of the one or more of the first and second dipoles of the surface-mount device type and the integrated circuit chip comprises a bonding wire, the method further comprising mounting the bonding wire at the integrated circuit chip.

16. The method of claim 13, wherein a further part of the electrical connection between at least one electrical termination of the one or more of the first and second dipoles of the surface-mount device type and the integrated circuit chip comprises a connection element associated with the integrated circuit chip.

17. The method of claim 16, wherein said connection element is a connection pillar, the step of mounting the integrated circuit chip on the front face of the base substrate including placing the connection pillar in contact with the volume of conductive adhesive.

18. The method of claim 16, wherein said connection element is a connection ball, the step of mounting the integrated circuit chip on the front face of the base substrate including placing the connection ball in contact with the volume of conductive adhesive.

19. The method of claim 13, wherein forming said hole comprises forming the hole to extend completely through the thickness of the base substrate.

20. The method of claim 19, further comprising: providing an electrical contact on a back face of the base substrate; and using an additional volume of conductive adhesive to secure said one or more of the first and second dipoles of the surface-mount device type within the hole and form an electrical connection between another electrical termination of the one or more of the first and second dipoles of the surface-mount device type and the electrical contact on the back face of the base substrate.

21. The method of claim 13, wherein forming the hole comprises forming the hole with a size and shape conforming to a cylindrical shape of the at least one dipole of the surface-mount device type.

22. The method of claim 11, wherein forming said hole comprises forming the hole to extend completely through the thickness of the base substrate.

23. The method of claim 22, further comprising: providing an electrical contact on a back face of the base substrate; and using a further volume of conductive adhesive to secure the at least one dipole of the surface-mount device type within the hole and form an electrical connection between another electrical termination of the at least one dipole of the surface-mount device type and the electrical contact on the back face of the base substrate.

24. The method of claim 11, wherein forming the hole comprises forming the hole with a size and shape conforming to a cylindrical shape of the at least one dipole of the surface-mount device type.

25. The method of claim 11, further comprising: providing an electrical contact on the front face of the base substrate; forming an opening in the solder mask layer at said electrical contact; and electrically connecting an electrical chip connection element of the integrated circuit chip through the opening in the solder mask layer to the electrical contact.

26. The method of claim 25, wherein the electrical chip connection element is one of a pillar or a connection ball.

27. The method of claim 11, wherein the base substrate is one of a printed circuit board or a ball array housing board.

28. The method of claim 11, wherein a further part of the electrical connection between at least one electrical termination of the at least one dipole of the surface-mount device type and the integrated circuit chip comprises a bonding wire, the method further comprising mounting the bonding wire at the integrated circuit chip.

29. The method of claim 11, wherein a further part of the electrical connection between at least one electrical termination of the at least one dipole of the surface-mount device type and the integrated circuit chip comprises a connection element associated with the integrated circuit chip.

30. The method of claim 29, wherein said connection element is a connection pillar, the step of mounting the integrated circuit chip on the front face of the base substrate including placing the connection pillar in contact with the volume of conductive adhesive.

31. The method of claim 29, wherein said connection element is a connection ball, the step of mounting the integrated circuit chip on the front face of the base substrate including placing the connection ball in contact with the volume of conductive adhesive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and features of the invention will emerge on studying the detailed description of embodiments and implementations, in no way restrictive, and of the appended drawings wherein:

(2) FIG. 1 illustrates an electronic device;

(3) FIGS. 2A-2C illustrate embodiments of the electronic device comprising a surface-mount device type dipole;

(4) FIG. 3 illustrates an embodiment of the electronic device comprising a surface-mount device type dipole;

(5) FIG. 4 illustrates an embodiment of the electronic device comprising a surface-mount device type dipole; and

(6) FIG. 5 illustrates an embodiment of an electronic device comprising a plurality of dipoles.

DETAILED DESCRIPTION

(7) FIG. 1 illustrates an electronic device, comprising a base substrate S-1, in the form of a board, which has a first face F1-1 and a second face F2-1. For example, the base substrate forms a BGA (Ball Grid Array) type integrated circuit housing, or according to a further alternative, a PCB (Printed Circuit Board).

(8) The board of the base substrate S-1 includes an overlay of layers which are disposed symmetrically with respect to a central core O-1 ensuring the rigidity of the base substrate. For example, a first solder mask M1-1, typically a varnish, coats a first metal level I1-1 of an interconnection grid, typically made of copper, formed on a surface of the central core O-1.

(9) Symmetrically with respect to the central core O-1, a second solder mask M2-1 coats a second metal level I2-1 of the interconnection grid, also in contact with the central core O-1.

(10) A hole T-1 traverses the thickness of the base substrate from the first face F1-1 to the second face F2-1, therefore traversing all of the layers of the substrate. The hole T-1 extends perpendicularly with respect to one of the faces F1-1, F2-1 of the base substrate S-1. The hole T-1 is, for example, obtained by drilling using a rotary drill bit, and typically of cylindrical shape.

(11) In a first example, the base substrate is included in a BGA type integrated circuit housing. In this case, the first face F1-1 is the face which includes one or more integrated circuit chips mounted on the base substrate, located inside the integrated circuit housing, and typically coated with a resin and a cap. The second face F2-1 of the base substrate is the face opposite the first face and supports external solder balls of the BGA housing. Other housing technologies than BGA type housings can obviously be envisaged.

(12) In a second example, the base substrate is a PCB printed circuit board, and the first face F1-1 of the base substrate can be the face supporting most of the components mounted on the printed circuit board. The second face of the base substrate F2-1 is the face opposite the first face and, and includes no components, or indeed a minority of components in the case where the PCB printed circuit board is of the double-sided type.

(13) A dipole D-1, of the surface-mount device type, has a first termination TER1-1 and a second termination TER2-1. The dipole is inserted entirely into the hole T-1. The terminations of the dipole D-1 are thus located between the two faces F1-1, F2-2 of the base substrate S-1. In the context of this disclosure, the term dipole or (reference D-1 for example) will be understood to mean and refer to an electrical circuit component having two electrical terminals (for example, a capacitor, a resistor, a diode, etc.).

(14) Optionally, the dipole D-1 can protrude from the hole T-1, at least one of the terminations of the dipole then protruding from one of the faces of the base substrate S-1.

(15) The dipole D-1 is electrically connected to the interconnection grid of the base substrate S-1 by volumes of conductive adhesive.

(16) Advantages and features of embodiments of first, second, third, and fourth volumes of conductive adhesive will be described hereinafter with reference to FIGS. 1 to 5.

(17) In the example in FIG. 1, a first volume of conductive adhesive C1-1 electrically connects the first metal level I1-1 and a termination TER1-1 of the dipole D-1. As in the example illustrated, the other termination TER2-1 of the dipole D-1 can be connected to another metal level I2-1. Another first volume of conductive adhesive C2-1 then electrically connects the second metal level and I2-1 and the other termination of the dipole D-1.

(18) The first volume of conductive adhesive C1-1 electrically connects the first metal level of the interconnection grid of the substrate and a termination of the dipole D-1 over a flank portion of the hole T-1. Indeed, drilling the hole T-1 has opened a side wall of the metal level, for example of cylindrical shape, delimited by the flank of the hole.

(19) Furthermore, the portion connected by the first volume of conductive adhesive C1-1 further comprises an exposed surface of the metal level I1-1. The surface of the metal level is of typically annular shape and of a diameter greater than a diameter of the hole T-1, and parallel with a face F1-1, F2-1 of the base substrate S-1. By analogy, the other first volume of adhesive can electrically connect the second metal level on metal levels I2-1 in the same way.

(20) One or more electronic chips U1-1, U2-1 can be mounted on the surface of the first face F1-1 of the base substrate S-1. As illustrated by way of example in FIG. 1, a chip can be electrically connected to the first metal level I1-1, for example by a ball (see, chip U2-1) or, a pillar or indeed a metal wire (see, chip U1-1). The electronic chips U1-1, U2-1 then form an electric circuit with the dipole D-1. The dipole D-1 can, for example, be a decoupling capacitor suitable for smoothing the power supply voltage of the electronic chips U1-1, U2-1.

(21) Moreover, any type of electronic components suitable for being mounted on a base substrate can be electrically connected to the dipole D-1.

(22) It is obvious that the dipole D-1 can be electrically connected to one or more electronic components suitable for being mounted on a base substrate, in all the embodiments described hereinafter with reference to FIGS. 2A to 5.

(23) FIG. 2A illustrates an embodiment of the electronic device comprising a surface-mount device type dipole D-2a, having a first termination TER1-2a, and a second termination TER2-2a. The dipole D-2a is housed in a hole T-2a drilled in a base substrate S-2a.

(24) The base substrate S-2a has two faces F1-2a, F2-2a, metal levels I1-2a, I2-2a, a core O-2a, and protective layers M1-2a M2-2a of the same types as the corresponding elements described previously with reference to FIG. 1, and respectively referenced F1-1, F2-1, I1-1, I2-1, O-1, TER1-1, TER2-1, M1-1, M2-1. These common elements will not be described again hereinafter.

(25) FIG. 2A illustrates an embodiment wherein an electronic chip U2-2a is disposed on the first face of the base substrate S-2a. The chip U2-2a is of the same type as the chip U2-1 described previously with reference to FIG. 1. The chip U2-2a comprises a chip connection element E1-2a. The connection element E1-2a is electrically connected to a termination TER1-2a of the dipole D-2a inserted into the hole T-2a by a second volume of conductive adhesive C1-2a.

(26) This chip connection element E1-2a can be located above the hole T-2a and aligned in the axis of the hole T-2a, the second volume of adhesive then forms a direct electric path between the electronic chip and the dipole D-2a housed in the hole. Optionally, the chip connection element is coupled with the metallic interconnection grid I1-2a, I2-2a formed in the thickness of the base substrate S-2a. The connection element E1-2a can be a pillar or a connection ball of an integrated circuit chip disposed on the BEOL interconnection part of the chip U2-2a.

(27) FIG. 2B illustrates an embodiment of the electronic device comprising a surface-mount device type dipole D-2b, having a first termination TER1-2b, and a second termination TER2-2b. The dipole D-2b is housed in a hole T-2b drilled in a base substrate S-2b.

(28) The base substrate S-2b has two faces F1-2a, F2-2a and metal levels I1-2b, I2-2b, a core O-2b and protective layers M1-2b, M2-2b of the same type as the corresponding elements described previously with reference to FIG. 1, and respectively referenced F1-1, F2-1, I1-1, I2-1, O-1, M1-1, M2-1. These elements are common and will not be described again hereinafter.

(29) In the embodiment in FIG. 2B, an external electrical connection element E2-2b disposed on the second face of the base substrate S-2b is electrically connected to the second termination TER2-2b of the dipole D-2b by a second volume of conductive adhesive C2-2b. This external electrical connection element E2-2b can be a solder ball disposed on the second face F2-2b of the base substrate S-2b, for example, in the context of an application of the electronic device in a BGA type housing, a solder ball of the ball array.

(30) FIG. 2C illustrates an embodiment of the electronic device comprising a surface-mount device type dipole D-2c, having a first termination TER1-2c, and a second termination TER2-2c. The dipole D-2c is housed in a hole T-2c drilled in a base substrate S-2c.

(31) The base substrate S-2c has two faces F1-2c, F2-2c and metal levels I1-2c, I2-2c, a core O-2c and protective layers M1-2c, M2-2c, of the same type as the corresponding elements described previously with reference to FIG. 1, and respectively referenced F1-1, F2-1, I1-1, I2-1, O-1, M1-1, M2-1. These common elements will not be described again hereinafter.

(32) Firstly, an electronic chip U2-2c is disposed on the first face of the base substrate S-2c, comprising a first connection element E1-2c electrically connected to the first termination TER1-2c of the dipole D-2c by a second volume of conductive adhesive C1-2c.

(33) Secondly, an external electrical connection element E2-2c disposed on the second face F2-2c of the base substrate S-2c is electrically connected to the second termination TER2-2c of the dipole D-2c by a second volume of conductive adhesive C2-2c. This dipole can therefore connect elements located on the opposite faces F1-2c, F2-2c of the base substrate.

(34) For example, a serial mounting can successively connect the first chip mounted on the first face F1-2c of the substrate, the dipole D-2c inserted in the hole T-2c, and a second electronic chip mounted on the second face of the substrate S-2c, particularly in the case of an application of the electronic device in a double-sided PCB.

(35) According to a further example, a serial mounting can successively connect the chip mounted on the first face F1-2c of the substrate, the dipole D-2c inserted in the hole T-2c, and a solder ball forming an external electrical connection element of the electronic device, particularly in the case of an application of the electronic device in a BGA type ball array integrated circuit housing.

(36) FIG. 3 illustrates an embodiment of the electronic device comprising a surface-mount device type dipole D-3, having a first termination TER1-3, and a second termination TER2-3. The dipole D-3 is housed in a hole T-3 drilled in a base substrate S-3.

(37) The base substrate S-3 has two faces F1-3, F2-3, a core O-3 and metal levels I1-3, I2-3 of the same type as the corresponding elements described previously with reference to FIG. 1, and respectively referenced F1-1, F2-1, O-1, I1-1, I2-1. These common elements will not be described again hereinafter.

(38) In the embodiment in FIG. 3, the two faces F1-3, F2-3 of the base substrate S-3 are each coated with a protective layer M1-3, typically a solder mask, sealing the hole T-3 containing the dipole D-3. The two terminations TER1-3, TER2-3, of the dipole are entirely contained in the hole of the substrate, thus the protective layers M1-3, M2-3 coat, and therefore mechanically and electrically protect, the first two volumes of conductive adhesive C1-3, C2-3 connecting the terminations of the dipole D-3 to the respective metal levels M2-3 of the interconnection grid of the substrate S-3.

(39) Obviously, the hole T-3 containing the dipole D-3 can be sealed by the respective protective layer M1-3, M2-3 only on the side of one or the other of the two faces F1-3, F2-3.

(40) FIG. 4 illustrates an embodiment of the electronic device comprising a surface-mount device type dipole D-4, housed in a hole T-4 drilled in a base substrate S-4.

(41) The base substrate S-4 has two faces F1-4, F2-4 and two first volumes of adhesives C1-4, C2-4, a core O-4, and two protective masks M1-4, M2-4 of the same type as the corresponding elements, described previously with reference to FIG. 1, respectively referenced F1-1, F2-1, C1-1, C2-1, O-1, M1-4, M2-4. These common elements will not be described again hereinafter.

(42) Furthermore, the example illustrated in FIG. 4 differs particularly from the example in FIG. 1 in that it comprises four metal levels forming an interconnection grid I1-4, I2-4, I3-4, I4-4, as well as two electrical insulator levels P1-4, P2-4, respectively alternating between each metal level, and symmetrically on either side of the central core O-5.

(43) The electrical insulator levels comprise for example epoxy resin type resin, and fibers, and serve as binder and electrical insulators from one metal level to another.

(44) The hole T-4 traverses this stack of metal levels alternating with the electrical insulator levels.

(45) The number of layers of a base substrate can be greater than the number of layers described herein by way of example.

(46) A first dipole D1-4 comprises a first termination TER11-4, and a second termination TER21-4. The dipole D1-4 is inserted into the hole T-4 of the base substrate.

(47) A second dipole D2-4, of the surface-mount device type, having a similar or different function from the first dipole D1-4 is also inserted into the same hole T-4. The second dipole also comprises a first termination TER11-4 and a second termination TER21-4. The two dipoles can be arranged so as to be aligned lengthwise.

(48) The two dipoles D1-4, D2-4, respectively have two terminations suitable for being inserted entirely into the base substrate S-4. If the thickness of the base substrate permits, more than two surface-mount device type dipoles can be inserted into the hole T-4.

(49) Two first volumes of conductive adhesive C1-4, C2-4 can electrically connect the first metal level I1-4 with a first termination of the first dipole D1-4, and electrically connect the fourth metal level and I4-4 with a second termination of the second dipole D2-4, in the manner described with reference to FIG. 1.

(50) The two dipoles D2-4, D3-4 can be electrically connected to one another by a fourth volume of conductive adhesive C3-4 located at the level of the second termination of the first dipole and the first termination of the second dipole. For example, the two dipoles can thus be mounted in series.

(51) Alternatively, the two terminations of the two dipoles D2-4, D3-4 can be simply in mechanical contact, therefore creating an electrical connection of the serial mounting.

(52) FIG. 5 illustrates an embodiment of an electronic device comprising a first dipole D1-5, and a second dipole D2-5, both of the surface-mount device type, respectively housed in a first hole T1-5 and a second hole T2-5, drilled in a base substrate S-5. The first dipole D1-5 has a first termination TER1A-5, and a second termination TER2A-5. The second dipole D2-5 has a first termination TER1B-5 and a second termination TER2B-5.

(53) The base substrate S-5 has two faces F1-5, F2-5 and two first volumes of adhesives CIA-5, C2B-5, a core O-5, and two protective masks M1-5, M2-5 of the same type as the corresponding elements, described previously with reference to FIG. 1, respectively referenced F1-1, F2-1, C1-1, C2-1, O-1, M1-4, M2-4. These common elements will not be described again hereinafter.

(54) Furthermore, the example illustrated in FIG. 5 differs particularly from the example in FIG. 1 in that the base substrate S-5 comprises eight metal levels forming an interconnection grid I1-5, I2-5, I3-5, I4-5, I6-5, I7-5, I8-5, I9-5, as well as six electrical insulator levels P1-5, P2-5, P3-5, P4-5, P5-5, P6-5, respectively alternating between each metal level, and symmetrically on either side of the central core O-5.

(55) The holes T1-5, T2-5 traverse this stack of metal levels alternating with the electrical insulator levels.

(56) The number of layers of a base substrate can be different from the number of layers described herein by way of example.

(57) A first volume of conductive layer C2A-5 can electrically connect a plurality of successive metal levels of the substrate, to the second termination TER2B-5 of the first dipole D1-5, housed in the first hole T1-5. This first plurality of levels electrically connected to the termination of the first dipole D1-5 is, for example, located in a zone comprised between the core of the substrate and the second face of this base substrate. The first volume of conductive adhesive C2A-5 then also mechanically connects the dipole D1-5 to all of the levels comprised in this zone, also comprising the insulator levels.

(58) Alternatively in the second hole T2-5, a first volume of adhesive C1B-5 can connect in an equivalent manner a second plurality of levels for example located in a zone comprised between the first face F1-5 of the substrate S-5 and the core O-5 of the substrate S-5, with the termination TER2A-5 of the second dipole D2-5.