FR3088484A1 - ELECTRONIC MODULE WITH PROTECTION AGAINST ENERGY PARTICLES - Google Patents

Description

FIELD OF THE INVENTION

The invention relates to the field of electronic modules intended to operate in environments with aggressive radiation and more particularly those intended to operate exposed to energetic particles.

BACKGROUND OF THE INVENTION

An electronic module conventionally comprises an insulating substrate on which is attached an electronic component connected by a printed link on the surface of the substrate to a plurality of external communication connectors. Commercial components withstand radiation doses of up to one hundred Grays in general, while components intended to operate in a space or military environment may have doses to withstand several dozen times these values. Note that space can require uniforms of up to three thousand Grays, military components up to ten thousand Grays.

For operation in an aggressive radio environment, the component is enclosed inside an airtight tungsten case. The connection with the external communication connectors is then ensured using a chain of glass or ceramic beads which convey optical or electrical signals through a wall of the housing. Such a connection constitutes a break in the protection of the electronic component. The electronic module then receives an additional external cover. This configuration does not allow mounting in CMS (Component

Surface Mounted) - that is, in which the legs of the component do not cross the substrate. Thus, the known electronic modules cannot be assembled by standard methods and must be assembled by manual soldering. These modules are therefore expensive to implement and the additional box increases their size.

OBJECT OF THE INVENTION

The object of the invention is to reduce the costs of manufacturing and implementing an electronic module intended to operate in an environment exposed to aggressive radiation.

SUMMARY OF THE INVENTION

For this purpose, an electronic module is provided comprising a housing connected to a substrate and at least one electronic component disposed inside the housing. The electronic module comprises at least one external connector opening out of the housing and at least one internal connection extending in the substrate for connecting the external connector to the electronic component. According to the invention, the housing defines at least one baffle in which extends at least a portion of the internal connection, the housing having a thickness and the housing material having an atomic mass such that the housing provides protection of the component against energetic particles.

An electronic module is thus obtained in which the internal connections to the external connectors do not require drilling the protective box. Such an electronic module allows mounting in CMS according to standard methods, inexpensive and reliable.

Advantageously, the housing provides protection of the component on four steradian feet.

The elements making up the case are particularly compact when the case comprises a material having an atomic mass greater than 100.

The compactness of the module can also be improved when the housing comprises at least one element extending substantially parallel to a main plane of the electronic component.

The number of elements constituting the housing is reduced when the housing comprises at least one element extending in a direction substantially orthogonal to a main plane of the electronic component.

Protection against energetic particles is particularly effective when the baffle comprises at least a first obstacle and a second obstacle, a length of overlap of the first obstacle by the second obstacle considered along an axis of the first or of the second obstacle being greater than 10 microns.

The costs of implementing the module of the invention are reduced when the external connector comprises a ball and 1 ¹ connection interface is of the BGA type, or when the external connector comprises a column and the connection interface is of the CGA type , or when the external connector comprises a patch and the connection interface is of LGA type, or in which the external connector comprises a brazed pad and the connection interface is of QFN type, or in which the external connector comprises a frame conductor and the link interface is of the “gull wing” type. Indeed, these different arrangements make it possible to implement standardized assembly procedures.

Satisfactory levels of electrical insulation are obtained when the substrate comprises a material of the epoxy resin and / or polymer liquid crystal or polyetheretherketone type.

Routing of internal links is facilitated when the internal link includes a housing portion.

Other characteristics and advantages of the invention will emerge on reading the following description of particular non-limiting embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will be made to the appended drawings, in which:

- Figure 1 is a schematic sectional view of an electronic module according to a first embodiment of the invention;

- Figure 2 is a schematic exploded perspective view of the electronic module of Figure 1 seen at a first angle;

Figure 3 is a schematic exploded perspective view of the electronic module of Figure 1 seen from a second angle;

- Figure 4 is a schematic sectional view of an electronic module according to a second embodiment of the invention;

- Figure 5 is a schematic sectional view of an electronic module according to a third embodiment of the invention;

- Figure 6 is a schematic sectional view of an electronic module according to a fourth embodiment of the invention;

- Figure 7 is a schematic exploded perspective view of the electronic module of Figure 6 before implementation of the substrate.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, the electronic module according to the invention, generally designated 100, comprises a silver casing 1 composed of a first parallelepipedal element 2 of casing 1 and a second parallelepipedic element 3 of casing 1 connected to a substrate 20 , here in epoxy resin. The substrate 20 comprises a first portion 21 of substrate 20 and a second portion 22 of substrate 20 which define a parallelepiped. The second portion 22 of substrate 20 extends around the first element 2 of housing 1.

A microprocessor 30 extending in a first plane PI is disposed inside the housing 1. A first copper wire 40 connects a port 31 of the microprocessor 30 to a first metallic connection ball 50.1 carried by the substrate 20 and which opens out outside the housing 1. A second copper wire 41 connects a port 32 of the microprocessor 30 to the second housing element 3 1. A third copper wire 42 connects the second housing element 3 to a second metallic ball 50.2 of connection carried by the substrate 20 and which opens out of the housing 1. The substrate 20 also includes a third ball 50.3 and a fourth ball 50.4 respectively connected to the microprocessor 30 by a fourth copper wire 43 and a fifth copper wire 44 .

The first ball 50.1, second ball 50.2, third ball 50.3 and fourth ball 50.4 form part of a matrix of balls 50 of BGA type which extends on a lower face 23 of the second portion 22 of substrate 20.

As more particularly visible in FIG. 2, the first element 2 of housing 1 comprises a first rectangular plate 4 of thickness e4 equal to two hundred microns whose length L4 is greater than a length L30 of the microprocessor 30. The width 14 of the first plate 4 is greater than a width 130 of the microprocessor 30

A first peripheral wall 5 of equal thickness e5

two hundred microns stretches, according to a direction orthogonal to PI plan, projecting of the face lower 4.1 of the first plate 4 who made facing

microprocessor 30 over a first distance 15. The end 5.1 of the first wall 5 penetrates over a first distance d5.1 into the upper face 24 of the first portion 21 of substrate 20. The second element 3 of housing 1 comprises a second rectangular plate 6 of thickness e6 equal to two hundred microns whose length L6 is greater than a length L30 of the microprocessor 30 and less than the length L4 of the first rectangular plague 4. The width 16 of the second plate 6 is greater than a width 130 of the microprocessor 30 and less than the width 16 of the second plate 6. A second peripheral wall 7 of thickness e7 equal to two hundred microns extends projecting from the upper face 6.1 of the second plate 6 over a second distance 17. The second wall 7 enters the substrate 20 through the underside 23 of the second portion 22 of the substrate 20

The end 7.1 of the second wall 7 extends, in a direction orthogonal to the plane PI, at a second distance d7.1 from the upper face 24. The second distance d7.1 is here ten microns less than the first distance d5 .1. Thus, a length 18 of the covering 8 of the first wall 5 by the second wall 7 considered along the direction in which the first wall 5 extends is equal to ten microns.

The combination of the differences between the respective lengths L4 and L6 of the first element 2 of housing 1 and of the second element 3 of housing 1, of the widths 14 and 16 respectively of the first element 2 of housing 1 and of the second element 3 of housing 1 as well as the length 18 of the overlap 8 creates a first chicane 10, a second chicane 11, a third chicane 12 and a fourth chicane 13. The first chicane 10 is composed of a first side 5.10 of the first wall 5 of the first element 2 of housing 1 which extends opposite a first side 7.10 of the second wall 7 of the second element 3 of housing 1 with an overlap 8. The second baffle 11 is composed of a second side 5.11 of the first wall 5 of the first element 2 of housing 1 which extends opposite a second side 7.11 of the second wall 7 second element 3 of housing 1 with an overlap 8. The third baffle 12 is composed of a third side 5.12 of the first wall 5 of the first element 2 of housing 1 which s stretches out against a third me side 7.12 of the second wall 7 of the second element 3 of housing 1 with an overlap 8. The fourth baffle 13 is composed of a third side 5.12 of the first wall 5 of the first element 2 of housing 1 which extends opposite a third side 7.12 of the second wall 7 of the second element 3 of the housing 1 with an overlap 8.

Within the meaning of the present application, a baffle is an arrangement of at least a first obstacle and a second obstacle separated by a non-zero distance and which obstructs the natural path of a body or a wave in motion by imposing a zigzag course.

As more particularly visible in FIG. 1, the wire 40 extends in the first baffle 10, in the space 10 which separates the first side 5.10 of the first element 2 of housing 1 and the first side 7.10 of the second element 3 of housing 1 .

An electronic module 100 is thus obtained, the housing 1 of which protects microprocessor 30 out of 15 four n steradians against energetic particles.

The protection offered by the case 1 with a thickness equal to two hundred microns as described makes it possible to protect the microprocessor 30 from a radiation level of up to three thousand Grays. Obviously, the thickness and the material of the housing can be adjusted to provide higher or lower protection of the microprocessor 30 against energetic particles.

The electronic module 100 of the invention is manufactured by pre-manufacturing the first element 2 of housing 1, the second element 3 of housing 1, the first portion 21 of substrate 20 and the second portion 22 of substrate 20. A spacer 25 made of epoxy can be inserted between the upper face 24 of the second portion 22 of substrate 20 and the second element 3 of housing 1. These various components can be assembled together by gluing.

The second element 3 of housing 1 is mounted in a first groove 26 of the second portion 22 of substrate 20. The first, second and third wires 40, 41 and 42 have been previously engaged in dedicated paths of the second portion 22 of substrate 20 and connected to balls 50.1 and 50.2. The microprocessor 30 is then welded to the second wire 41. The first wire 40 is engaged in an internal path of the spacer 25 then connected to the microprocessor 30 before being put in place to cover the microprocessor 30. The first element 2 of housing 1 is then placed in a second groove 27 for receiving the second portion 22 of substrate 20. Finally the first portion 21 of substrate 20 is placed on the first element 2 of housing 1. Compaction is carried out to ensure bonding components of the electronic module 100.

Elements identical or analogous to those previously described will bear a reference numeral identical to these in the description which follows of the second, third and fourth embodiments of the invention.

According to a second embodiment shown in FIG. 4, the electronic module 100 does not have a first portion 21 of substrate 20 and the microprocessor 30 is buried in the second portion 22 of substrate 20. In this second embodiment, the first element 2 housing 1 is in direct contact with the upper face 24 of the second portion 22 of substrate 20.

Such a module can in particular be obtained by injection of an epoxy resin 28 forming the substrate 20 around an electronic component previously wired and connected or by known techniques of burial of chips in printed circuits.

According to a third embodiment represented in FIG. 5, the microprocessor 30 rests directly on the second element 3 of housing 1 which has no second wall 7 and which rests on the upper face 24 of the second portion 22 of substrate 20. The second element 3 of housing 1 has here a thickness e3 of two hundred microns considered in a direction substantially orthogonal to the plane PI. The housing 1 is here composed of a third substantially parallelepipedal element 60 which extends in a direction substantially orthogonal to the plane PI in a third groove 29 and provides an overlap 8 with the wall 5 to form a third baffle 12. The first element 2 of housing 1 comprises a third wall 61 whose length 161 is such that the third wall 61 extends partially opposite the flank 3.1 of the second element 3 of housing 1 to form a first baffle 10. As visible in FIG. 5, a fourth wall 80 in aluminum is attached by brazing to the first element. The fourth wall 80 extends parallel to the third wall 61 and has a thickness of one hundred microns. The fourth wall 80 makes it possible to avoid the formation of secondary electrons after the passage of an energetic particle through the third wall 61.

According to a fourth embodiment shown in Figure 6, the housing 1 comprises a fourth element

62, a fifth element 63, a sixth element 64 and a seventh item 65, all in money drowned in the substrate 20. The sections of fourth element 62, fifth item 63, sixth item 64 and seventh item 65 > understand fit portions of T and of portions projecting whose 1 layout around of

microprocessor 30 provides protection against energetic particles over an area of four n steradians, in particular by creating a first baffle 10 (bottom right according to the representation in FIG. 6) comprising a portion of the fourth element 62 and of the fifth element 63. A second baffle 11 (top left according to the representation of FIG. 6) is created by a portion of the fifth element 63 and the seventh element 65. A third baffle 12 (bottom left according to the representation of FIG. 6) is created by a portion of the sixth element 64 and of the seventh element 65. A fourth baffle 13 (bottom in the middle according to the representation of FIG. 6) is created by a portion of the fourth element 62 and of the sixth element 64.

As visible in FIG. 7, the electronic module 100 according to the fourth embodiment of the invention is produced by placing the fourth element 62, the fifth element 63, the sixth element 64 and the seventh element 65 around the microprocessor 30 in a mold 70. A first wall 66 in silver and a second wall 67 in silver close the front and rear faces (according to the representation of FIG. 7) of the housing 1. The first wire 40, second wire 41, third wire 42, fourth wire 43 and fifth wire 44 connecting the microprocessor 30 to the first ball 50.1, the second ball 50.2, the third ball 50.3 and the fourth ball 50.4 have been previously routed in the first chicane 10, second chicane 11, third chicane 12 and fourth baffle 13. An epoxy resin 28 is then poured and hardened in the mold 7 0 to bond the fourth element 62, fifth element 63, sixth element 64 seventh element 65, the microprocessor 30, the first era wall 66, the second wall 67 and the first wire 40, second wire 41, third wire 42, fourth wire 43 and fifth wire 44 together as well as the matrix of balls 50. The hardened resin 28 constitutes the substrate 20.

As can be seen in FIGS. 6 and 7, the fourth element 62 comprises a portion 62.1 for anchoring in the substrate 20. The portion 62.1 for anchoring here has a T section. A portion 63.1 for anchoring the fifth element 63, the section is also in T, has the upper part 63.2 of its section which extends near the microprocessor 30, in a direction substantially parallel to the plane PI. Such a configuration allows the fifth element 63 to capture and remove, more efficiently than the resin 28, the calories generated by the microprocessor 30. In fact, the part 63.2 captures the calories generated by the microprocessor 30 and transmits it, by conduction, to a part 63.3 located on one side of the case 1 which is in contact with the outside environment. In general, the housing elements 1 incorporated in the substrate 20 also contribute to heat dissipation of the calories generated by the microprocessor 30 and to its protection for electromagnetic compatibility (EMC).

Of course, the invention is not limited to the embodiments described but encompasses any variant coming within the scope of the invention as defined by the claims.

In particular,

- although here all the elements constituting the case are made of silver, the invention also applies to a case made of other types of material having an atomic mass greater than 100 such as, for example, tantalum or tungsten . Only the portions of the elements which contribute to protection against radiation may be made of such material, the other portions of the elements may be made of another material;

- Although here the substrate is made of epoxy resin, the invention also applies to other types of substrates which may comprise a material of the liquid crystal polymer or polyetheretherketone type. The substrate can be isotropic, continuous anisotropic or discontinuous;

- Although here the first portion of substrate is in one piece, the invention also applies to a first portion of substrate constituted by an assembly of several portions;

- although here the processor is connected to the balls by copper wires, the invention also applies to other types of internal connections such as for example electrical conductors in silver, or with low conductive ink, or further optical fiber optic links;

- although here the processor is connected to metal connection balls to form a connection interface of BGA matrix type (Ball Grid Array), the invention also applies to other types of external connectors such as by example of columns forming a bonding interface of the CGA column matrix type (Column Grid Array), pads forming a bonding interface of the LGA matrix matrix type (Land Grid Array), external connectors comprising a brazed pad forming a interface QFN (Quad Flat No Lead) type link, or a module comprising a lead frame and the link interface is of the Gull Wing type.

- Although here the link interface of the module comprises four balls, the invention also applies to a link interface comprising a different number of external connectors such as a single connector, two, three or more than four;

- although here the processor is connected to metallic connection balls by copper wires, the invention also applies to other types of internal connections such as for example silver electrical conductors, or based on conductive ink, or optical fiber optic links;

- although here, the module includes a microprocessor, the invention also applies to other types of electronic components, such as for example an assembly of circuits, diodes, transistors, processors, logistics doors or an FPGA;

- although here the second metal ball is connected to the processor via a connection to the second element, the invention also applies to other types of internal connection comprising an element of the housing such as for example a copper wire connecting a ball metallic to the first housing element;

- although here the first wall projects from a rectangular plate in a direction orthogonal to the plane Pi comprising the microprocessor, the invention also applies to other geometries for the housing elements, such as for example portions of spheres, polygons, walls extending at any angles projecting from bases which can assume any varied shape;

- Although here the module comprises four baffles, the invention also applies to a module comprising at least one baffle such as a module comprising a single baffle, two, three or more than four;

- although here the case provides protection of the component against energetic particles on four n steradians, the invention also applies to other levels of protection, such as for example protection greater than 3.86 steradians;

although here the module is manufactured by stacking of glued elements or by resin injection on previously placed elements, the invention applies to other embodiments of the module such as for example three-dimensional machining of a substrate poured around the component to place the housing elements there;

although here the first wall and the second wall achieve mutual overlap in a direction orthogonal to the plane PI, the invention also applies to a baffle whose mutual overlap of the first obstacle and the second obstacle is considered along an axis of the first or second obstacle and is greater than ten microns. The invention also applies to other covering values of between ten and one hundred microns;

- although here the case is composed of elements whose thickness is equal to two hundred microns for protection against radiation levels of up to three thousand Grays, the invention also applies to elements of housings of different thicknesses, such as for example a thickness greater than two hundred microns or less than two hundred microns, the level of radiation against which the component is protected varies with the increase or decrease in thickness of the elements of the housing;

although here the fourth wall is made of aluminum and a thickness of one hundred microns, the invention also applies to other types of protection against the formation of secondary electrons such as for example a fourth wall made of a material of atomic mass less than thirty such as boron or beryllium. The invention also applies to other values of the thickness of the fourth wall, for example a thickness greater than one micron. Such a fourth wall can extend in three directions of space;

- Although here the fourth wall is attached by brazing to the first element, the invention also applies to other means for connecting the fourth wall to the first or the second cover element.

Claims (12)

1. Electronic module (100) comprising: - a metal case (1) connected to a substrate (20); - at least one electronic component (30) disposed inside the housing (1); the electronic module (100) comprising at least one external connector (50.1, 50.2, 50.3, 50.4) opening out of the housing (1) and at least one internal connection (40, 41, 42, 43, 44) s' extending into the substrate (20) for connecting the external connector (50.1, 50.2, 50.3, 50.4) to the electronic component (30); - the housing (1) defining at least one baffle (10, 11, 12, 13, 14) in which extends at least a portion of the internal connection (40, 41, 42, 43, 44), the housing ( 1) having a thickness and the material of the housing (1) having an atomic mass such that the housing (1) provides protection of the electronic component (30) against energetic particles. 2. Electronic module (100) according to claim 1, wherein the housing (1) provides protection of the electronic component (30) on four sterad pi 3. Electronic module (100) according to claim 1, wherein the housing (1) comprises a material having an atomic mass greater than 100. 4. Electronic module (100) according to any one of the preceding claims, wherein the housing (1) comprises at least one substantially parallel to the electronic component (30). element (63.2) extending a main plane (PI) of the 5. Electronic module (100) according to any one of the preceding claims, in which the housing (1) comprises at least one element extending in a direction substantially orthogonal to a main plane (PI) of the electronic component (30). 6. Electronic module (100) according to any one of the preceding claims, in which the baffle (10, 11, 12, 13, 14) comprises at least a first obstacle (5) and a second obstacle (7), a length overlap of the first obstacle (5) by the second obstacle (7) considered along an axis of the first obstacle (5) or the second obstacle (7) being greater than ten microns. 7. Electronic module (100) according to any one of the preceding claims in which the external connector (50.1, 50.2, 50.3, 50.4) comprises a ball (50.1, 50.2, 50.3, 50.4) and the connection interface is of the type BGA. 8. Electronic module (100) according to any one of claims 1 to 6, in which the external connector comprises a column and the connection interface is of the CGA type. 9. Electronic module (100) according to any one of claims 1 to 6, in which the external connector comprises a patch and the connection interface is of the LGA type. 10. Electronic module (100) according to any one of claims 1 to 6, in which the external connector comprises a brazed pad and the connection interface is of the QFN type. 11. Electronic module (100) according to any one of claims 1 to 6, in which the external connector comprises a conductive frame and the connection interface is of the “gull wing” type. 11. Electronic module (100) according to any one of the preceding claims, in which the substrate (20) comprises a material of epoxy resin type and / or of liquid crystal polymer and / or of polyetheretherketone. 12. Electronic module (100) according to any one of the preceding claims, in which the internal link (40, 41, 42, 43, 44) comprises a portion (22) of housing (1).