DE10213879C1 - Electronic component has semiconductor chips fitted into respective recesses in surface of electronic circuit board - Google Patents

Abstract

The electronic component has an electronic circuit board (10) and at least one semiconductor chip (20) provided with an integrated circuit (21), fitting into a recess (15) provided in the surface of the electronic circuit board. The width and length of the recess corresponds to the size of the base surface of the semiconductor chip, with side elements for gripping the inserted semiconductor chip in the correct position for mechanical and electrical connection with the electronic circuit board.

Description

The invention relates to an electronic component with an electronic circuit board and at least one semiconductor chip which has an integrated semiconductor circuit which is electrically connected to the circuit board,

• - The circuit board has a recess, the tie fe is smaller than the thickness of the circuit board and its lateral dimensions of the base of the semiconductor chip correspond, and
• - The semiconductor chip unhoused at least up to one Part of its thickness embedded in the recess and thereby is attached directly to the circuit board.

Memory modules and other electronic components, the multiple Semiconductor chips essentially consist of one electronic printed circuit board (PCB), on of the semiconductor chips on one or both sides are ordered. The circuit board contains one or more PCB layers on which are printed or otherwise manufactured conductor tracks are arranged, which on the Printed circuit board arranged semiconductor chips with each other and with the plug connector of the electronic circuit board connect. Memory modules are for example from WO 00/14788 A2, WO 01/65595 A2, US 2002/20898 A1 and US 2002/01872 A1 known. For electrically connecting one of the on one side of the semiconductor chip arranged integrated semiconductor circuit with the circuit board, the semiconductor chip in one Bordered chip housing, the first contact ends with contact areas of the semiconductor integrated circuit who connected by bonding, for example. The one from the semiconductor chip and the The existing semiconductor device is then replaced with a second Contact ends of the chip housing placed on the circuit board and electrically connected to it, for example by bonding Soldering or by other methods.  

The chip housing for the electrical connection of a semiconductor Chips with an electronic circuit board are standardized. To the electrical connection with appropriate contacts on the Printed circuit board come in various processes such as bonding (COB; Chip on board), soldering of packaged chips, ball grid array Contact connections etc. are used.

The constraint to progressive miniaturization leads to one Downsizing of all structures, for example the conductor rail NEN on the circuit board and corresponding contact connections se. Furthermore, printed circuit boards now consist of six superimposed layers that ver are bound. Finally, through optimized interconnect further miniaturization has been achieved.

In order to count the number of semiconductors in an electronic component terchips, the one circuit board per existing circuit board can increase the surface area, the circuit board can Have recess whose depth is less than the thickness the PCB and its lateral dimensions the reason correspond to the area of the semiconductor chip. The semiconductor chip can then be unhoused at least up to a part of its thickness recessed in the recess and thus directly on the PCB are attached.

With this design, the use of chip housings for the electrical connection of semiconductor chips with a Lei waived plate. Instead, it becomes a side Fixation of the placed on the circuit board, not yet electrically connected semiconductor chips to enable a Recess made in the circuit board in which the half conductor chip can be inserted.

A printed circuit board as in WO 00/14788 A1 or WO 01/65595 A2 has a recess same lateral dimensions as the semiconductor chip, so that the semiconductor chip embedded in this recess  laterally fixed and unerringly electrically connected that can; the functionality of the entire electronic Component remains guaranteed. The recess is not so deep as the circuit board thickness, so that the semiconductor chip rests on the bottom surface of the recess and in the side Direction through the side walls of the recess in position is fixed on the base of the circuit board.

With an electronic one constructed in the above construction Component there is the problem that in the recess of the Printed circuit board embedded semiconductor chips hardly out again the recess can be removed if after the electri contacting the embedded semiconductor chip with the Printed circuit board an electrical functional test of the semiconductor chips fails and an exchange of the semiconductor chips required. Because there in the above Design the lateral dimensions of the recess in the Printed circuit board just the side dimensions of the recessed its semiconductor chips correspond to a lateral alignment Enabling the chip contacts is the semiconductor chip no more accessible from the side than from his on the ground the recess arranged front. An afterthought Detaching the semiconductor chip is therefore difficult.

It is the object of the present invention to provide an electronic To provide cal component, in which one in the recess the semiconductor chip embedded in the retrofit Lich can be removed again, especially without the circuit board to destroy their recess.

This object is achieved in that the Recess in the printed circuit board lateral extensions to the Grei fen of the embedded semiconductor chip.

The fact that the recess of the circuit board is lateral Runner for gripping an embedded semiconductor chip point, a removal of an already inserted, elec  tric and mechanically connected semiconductor chips easier tert.

It is preferably provided that the semiconductor chip in the Recess of the circuit board is arranged so that the integrated semiconductor circuit of the circuit board is facing and that of the integrated semiconductor circuit overlying rear side of the semiconductor chip from the conductor plate is turned away. The semiconductor chip is turned upside down, that is, with the side of the semiconductor integrated circuit arranged down towards the circuit board so that the integrated semiconductor circuit within the Lei terplatte is located. In this position it can also be elec be connected to the circuit board.

For this purpose, it is preferably provided that the circuit board over with electrical contacts in the bottom surface of the recess the semiconductor circuit of the semiconductor chip electrically ver is bound. In this embodiment, the printed circuit board a large number of contacts in the bottom surface of their recess that protrude slightly higher than the floor surface and their arrangement within the floor surface as a mirror image the arrangement of contact areas of the integrated semiconductors circuit on the surface of the semiconductor chip corresponds. Becomes the semiconductor chip is inserted upside down into the recess, see above the contact surfaces of the semiconductor circuit come with the Contacts at the bottom of the recess and can un be contacted indirectly, the side walls of the off take a lateral guide of the semiconductor chip to the elec effect trical contact. The so let in and elek tric as well as mechanically connected to the circuit board Semiconductor chip is well fixed in its position. In particular in the case of electrical contacts in the form of a ball grid array an additional mechanical attachment can be made by additional additional contacts or contact areas on the edge of the ground area of the recess or the semiconductor chip is reached the. Because the electrical connection between the contacts and  The contact areas can be a bond connection a defective semiconductor chip can also be subsequently removed NEN, since the bond connection increases without excessive temperature hung can be solved.

Finally, it is preferably provided that the off Acceptance embedded semiconductor chip with one from an Ab covering layer formed protective layer is covered. This protection layer covers the semiconductor chip and the surrounding chip Part of the circuit board and closes thin gaps between the side walls of the recess and the side edges of the Semiconductor chips, which makes the semiconductor integrated circuit is shielded from external influences. A masking compound at for example from a cooled or hardened state highly thermally conductive material can be easier and cheaper ter be applied to the circuit board as a chip housing, initially with the contact surfaces of the semiconductor chips and then with corresponding contact connections of the PCB must be connected. For the protective layer can a masking compound can be selected, which is characterized by light Temperature increase can be removed to a defective or defective semiconductor chip subsequently removed NEN.

The semiconductor chip is preferably a semiconductor memory chip, the electronic component preferably a memory mo dul. Memory modules have several, for example eight or sixteen semiconductor chips (or including nine or eighteen Lich error correction chips), the number on one PCB to be arranged semiconductor chips through the conductors plate area and traditionally also by the size of the ge standardized chip housing is limited. Since with the invention trained electronic component, for example Spei no chip housing are required and therefore pro Semiconductor chip only has a much smaller footprint PCB is needed as for a chip package, one can  Larger number of memory chips on the circuit board be classified. Memory modules in particular benefit from this.

The extensions can preferably be in the form of channels or differently formed resolutions to the side of the outline of the half conductor chips can be provided in the circuit board around the one grab the left chip from the side and lift it off.

The electronic component according to the invention can be manufactured be prepared by placing a circuit board with a recess the depth of which is less than the thickness of the lei terplatte and their lateral dimensions of the base of the Semiconductor chips correspond, and by the semiconductor chip un housed at least up to a part of its thickness in the Aus admission is admitted. The recess allows a full permanent or - with only shallow deepening - partial on leave the semiconductor chip in the circuit board and allows a lateral fixation during the time of the electri connecting the semiconductor chip to the circuit board and up to this point of time.

This technology makes it possible to use semiconductor chips with very small contact areas with a printed circuit board to connect electrically, so the need of Chipge houses is eliminated. This can make semiconductor chips essential higher number and density arranged on the circuit board become.

Electrical contacts can be made in the bottom surface of the recess be provided, the location of the location of contact surfaces of the semiconductor integrated circuit corresponds, and the semi-conductor terchip can be in an orientation where the integrated Semiconductor circuit of the semiconductor chip of the circuit board is turned into the recess in the circuit board become.  

The semiconductor integrated circuit can be electrically connected to the PCB is connected by the contacts in the out take on the contact surfaces of the integrated semiconductors circuit can be bonded. Here is during the Einlas sens of the semiconductor chip in the recess using the slightly preheated bond contacts simultaneously the electrical Connection closed.

The recess in the printed circuit board can be made by milling or Stamping of printed circuit board layers can be produced. This can be milled individually or in part or punched out before at least one circuit board layer that serves as the bottom for the recess with this milled or punched layers is connected.

Milling and punching allow dimensionally accurate dimensions Nation of the lateral dimensions of the recess correspond chend the base of the semiconductor chips to be admitted. It is preferably provided that the recess is dimensioned so is niert that their lateral dimensions by a maximum of 50th Percent of the width of a contact area of the semiconductor chip and are no more than 10 µm larger than the base area of the semiconductor chip.

In addition, the recess can be so deep that the half lead terchip at least 25 percent of its thickness in the recess can be let in. At the inlet depth is a ge white distance between the bottom surface of the recess and vorzuse the surface of the semiconductor integrated circuit hen, in which the bond contacts find space.

Finally, on the circuit board in the area with the Semiconductor chip covered recess a protective layer a masking compound can be applied. The protective layer serves for additional mechanical stabilization, for shielding of the semiconductor integrated circuit with respect to the environment rivers and / or for faster heat dissipation.  

The invention is described below with reference to FIGS. 1 to 5 be. Show it:

Fig. 1 is an electronic circuit board according to the invention with recesses formed and a semiconductor chip,

Fig. 2, a method for introducing a semiconductor chip into a recess of the circuit board,

Fig. 3 is a circuit board having sixteen embedded in corresponding recesses in the semiconductor chip,

Fig. 4 shows the finished electronic component and

Fig. 5 shows a cross section through a circuit board for Ver illustration of the manufacture and dimensioning tion of a recess according to the invention.

Fig. 1 shows an electronic circuit board 10 , whose outer dimensions represent the floor plan G, on which as many semiconductor chips 20 as possible should be arranged and mechanically and electrically connected to the circuit board. A semi-conductor chip 20 is exemplarily shown below the printed circuit board 10 . According to the invention, the circuit board 10 for each semiconductor chip 20 has a recess 15 in the Lei terplattenoberfläche on. The base area of a recess 15 corresponds to the base area g of a memory chip 20 , so that it can be inserted into the recess 15 . In addition Lich 15 dashed electrical contacts 11 are arranged in the bottom surface of each recess, which are used for elec trical connection of the contact surfaces 22 of the semiconductor chip 20 with the circuit board 10 . The semiconductor chip 20 shown in FIG. 1 is placed upside down, ie with the side of its integrated semiconductor circuit and its contact surfaces 22 in the direction of the circuit board surface 10 , and is laterally fixed by the side walls of the recess 15 until the electrical connections, are preferably produced by bonding.

The process of inserting the semiconductor chip 20 into a recess 15 is shown in cross section in FIG. 2. The semiconductor chip, initially shown individually, has an integrated semiconductor circuit 21 on its upper side, which has a multiplicity of contact areas 22 . The semiconductor chip is turned upside down and lowered over the recess 15 of the circuit board 10 so that the contacts 11 on the bottom of the recess 15 and the contact surfaces 22 come to lie when the semiconductor chip 20 is inserted into the recess 15 . In the embedded state, the semiconductor chip 20 protrudes, if at all, only with a part of its thickness beyond the upper surface of the printed circuit board 10 ; the underside of the semiconductor chip is protected and electrically connected to the printed circuit board above the bottom surface of the recess 15 . As an alternative to FIG. 2, the semiconductor chip can also be inserted with the integrated semiconductor circuit 21 upward into the recess 15 , in which case the recess also fixes the semiconductor chip laterally in order to reliably establish bond connections between the chip and the printed circuit board on the upper side ,

Fig. 3 shows the circuit board 10 with a total of sixteen already embedded in corresponding recesses semiconductor chips 20 , preferably memory chips such as DRAMs (dynamic random access memory). Their integrated circuits, which are now at the bottom, are electrically connected to the printed circuit board 10 and therefore also to one another and to the contact strip 18 of the printed circuit board. Since no chip housings are used in this technology, the semiconductor chips 20 can be packed much more densely on the printed circuit board 10 .

The electronic component shown in Fig. 3, in particular memory module is already functional as such. For better handling, better shielding from environmental influences and better heat dissipation, a protective layer 30 made of a highly thermally conductive covering compound can additionally be applied to the printed circuit board and the semiconductor chips, as shown in FIG. 4. The masking compound can be removed from the storage module 40 in regions before, preferably by slight heating, in order to subsequently remove a defective semiconductor chip.

The semiconductor chip to be removed must be locally warmed slightly to loosen the bond connections formed above the bottom of the recess. In addition, the semiconductor chip 20 to be removed must be able to be gripped in order to pull it out of the recess. For this purpose, as shown in Fig. 3 Darge, four extensions or extensions 17 are provided in each recess 15 , which are formed in the form of channels of the same depth as the recess and were manufactured simultaneously with the recess, for example by punching or milling individual or several layers of printed circuit boards. With the help of the extensions 17 , the underside of the semiconductor chips 20 with the semiconductor circuit 21 is accessible at individual points; the semiconductor chip 20 can be removed.

Fig. 5 shows in cross-section a circuit board 10 with two recesses 15. The production of the depression is shown in the area of the right depression 15 . It can be seen that the circuit board from six individual circuit board layers 1 , 2 ,. , ., 6 , of which the two uppermost 1, 2 were already machined with a punch 7 or a milling cutter 8 before being joined to the lower layers in order to form the recess 15 . During punching or milling who 15 adapted to the lateral dimensions of the recess at the base of the semiconductor chip 20 to be admitted that it fits with a minimum lateral clearance into the off recess.

As shown in Fig. 5 left, the lateral dimen- sions S of the recess 15 are slightly larger than the base area g of the semiconductor chip 20 , and the depth T of the Ausneh tion can be chosen so large that the semiconductor chip of thickness d completely or also only partially sinks into the recess, with a certain margin for the bond connections to be formed. The relationships between the lateral and vertical dimensions are not to scale.

In the method according to the invention, chip housings such as TSOPs are unnecessary, which significantly enlarge the base area of the printed circuit board per semiconductor chip. Instead of packaged semiconductor terchips, so-called components, unpackaged semiconductor terchips can be mechanically connected directly to the circuit board and then electrically connected in a targeted manner. In particular, a bond method can also be used with downward-facing integrated semiconductor circuit 21 of a semiconductor chip 20 , which allows subsequent replacement of defective chips without excessive temperature increases. The more purposeful connection of the contacts 22 above the bottom surface of the recess 15 with contact surfaces (pads) of about 70 × 70 μm today is made possible by the small tolerance of the lateral dimension of the recess. As a result, a high storage density can be achieved with cost-effective mass production analogous to the BOC process (Bord On Chip) or the MOST process. Mobile devices such as cell phones are particularly suitable as applications for particularly high packing densities.

When bonding, pressure and temperature are set per se as in conventional bonding processes, so that when the semiconductor chips are lowered onto the head, a bond is produced directly. In this way, standard module boards such as DIMMs or SO-DIMMs (small outline dual inline memory modules) can be used, whose glass fiber epoxy layers are milled or punched to a depth of one third of the chip thickness (approx. 200 µm). The contacts at the bottom of the recesses 15 can preferably be gold-plated and can be seen with an additional drop of a gold alloy as the bonding material. If the temperature and pressure are optimized for the bonding process, the mechanical and electrical connection to the printed circuit board is simultaneously established when a semiconductor chip is pressed into the recess or depression.

The recesses serve as "landing pads" for the half lead terchips and enable their lateral guidance during bonding. Because of the omitted chip housing, the package density of the memory chips on the printed circuit board on a var ches be increased.  

LIST OF REFERENCE NUMBERS

1

.

2

,. , .,

6

PCB layers

7

punching tool

8th

milling tool

10

circuit board

11

Contact

15

recess

17

lateral extension of the recess

20

Semiconductor chip

21

integrated semiconductor circuit

22

contact area

30

Protective layer made of a covering compound

40

electronic component, in particular memory module

Claims (6)

1. Electronic component ( 40 ) with an electronic circuit board ( 10 ) and at least one semiconductor chip ( 20 ) which has an integrated semiconductor circuit ( 21 ) which is electrically connected to the circuit board ( 10 ),
wherein the circuit board (10) has a recess (15), whose depth (T) is smaller than the thickness (D) of the circuit board (10) and its lateral dimensions (S) of the base surface (g) of the semiconductor chip (20) correspond, and
wherein the semiconductor chip ( 20 ) unhoused at least up to a part of its thickness (d) in the recess ( 15 ) and thereby directly attached to the circuit board ( 10 ) be fastened,
characterized in that
the recess ( 15 ) in the circuit board ( 10 ) has lateral runners ( 17 ) for gripping the embedded semiconductor chip ( 20 ). 2. The electronic component according to claim 1, characterized in that the semiconductor chip (20) plate in said recess (50) of the conductor (10) oriented, in that the semiconductor integrated circuit (21) facing the printed circuit board (10) and the the integrated semiconductor circuit ( 21 ) opposite the back of the semiconductor chip ( 20 ) facing away from the printed circuit board ( 10 ). 3. Electronic component according to claim 2, characterized in that the circuit board ( 10 ) via electrical contacts ( 11 ) in the bottom surface (B) of the recess ( 15 ) with the semiconductor circuit device ( 21 ) of the semiconductor chip ( 20 ) is electrically connected. 4. Electronic component according to one of claims 1 to 3, characterized in that the semiconductor chip ( 20 ) let into the recess ( 15 ) is covered with a protective layer ( 30 ) formed from a covering compound. 5. Electronic component according to one of claims 1 to 4, characterized in that the semiconductor chip ( 20 ) is a semiconductor memory chip and the electronic component is a memory module ( 40 ). 6. Electronic component according to one of claims 1 to 5, characterized in that the extensions ( 17 ) in the form of channels are provided laterally from the outline of the semiconductor chip ( 20 ) in the printed circuit board ( 10 ).