EMBEDDED DUAL IN-LINE MEMORY MODULE

An embedded dual in-line memory module (DIMM) is provided. The memory module includes a printed circuit board (PCB), a first memory chip set, and a second memory chip set. A plurality of memory chips of the first memory chip set is arranged and electrically connected to a first circuit layer of the PCB by flip chip. A plurality of memory chips of the second memory chip set is arranged and electrically connected to a second circuit layer of the PCB by flip chip. The respective chips are directly disposed on the PCB by flip chip. Thereby the memory module has a condition that there is no metal wire for electrical connection generated by wire bonding. This helps cost reduction at manufacturing end and improves electrical performance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 112103424 filed in Taiwan, R.O.C. on Feb. 1, 2023, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a dual in-line memory module (DIMM), especially to an embedded DIMM in which all electrical connections are formed by flip-chip during manufacturing processes.

Window Ball Grid Array (window BGA) is a type of packaging used for dynamic random access memory (DRAM), also used for manufacturing dual in-line memory module (DIMM) available now. Refer toFIG.7, a conventional DIMM2includes a printed circuit board2a,a surface2b,a wire2c,a chip package set2d,a read-only memory (ROM)2f,and a conductive contact2g.The chip package set2dconsists of a plurality of chip packages2eeach of which is produced by window BGA and composed of a carrier plate2h,a chip2i,and an opening2j.The chip2iis electrically connected to the carrier plate2hby metal wires through the opening2jwhile the metal wires are produced by wire bonding (not shown in figure). The chip package set2dis arranged and electrically connected to the wire2con the surface3bof the printed circuit board2acorrespondingly by flip chip.

Thus it is learned that the DIMM available now is produced by the following processes. First a plurality of chips is packaged into a plurality of chip packages by wire bonding (considered as the first packaging process). Then the plurality of chip packages is disposed on a printed circuit board (considered as the second packaging process). Thus the DIMM has the following shortcomings. (1) The manufacturing processes of the DIMM available now include the first and the second packaging processes. Thus electrical connection wires in structure are increased relatively and this leads to poor electrical performance. (2) The manufacturing processes include the first and the second packaging processes so that manufacturing cost at manufacturing end is increased. This doesn't meet requirement for energy reduction now. (3) The first packaging process is completed by wire bonding so that metal wires (such as gold wire) used increase material cost at manufacturing end.

Moreover, the printed circuit board and the chip package of the DIMM available now are exposed so that they are easily damaged. The long term exposure also leads to oxidation of metal materials so that service life is reduced.

SUMMARY OF THE INVENTION

Therefore, it is a primary object of the present invention to provide an embedded dual in-line memory module (DIMM) which includes a printed circuit board (PCB), a first memory chip set, and a second memory chip set. A plurality of memory chips of the first memory chip set is arranged and electrically connected to a first circuit layer on a first surface of the PCB by flip chip correspondingly. A plurality of memory chips of the second memory chip set is arranged and electrically connected to a second circuit layer on a second surface of the PCB by flip chip correspondingly. The respective memory chips of the memory module are directly disposed on the PCB by flip chip (such as wafer level chip scale package (WLCSP) on DIMM)). Thus the memory module has a condition that there is no metal wire for electrical connection generated by wire bonding. The shortcomings of the DIMM available now can be effectively improved.

In order to achieve the above object, an embedded dual in-line memory module (DIMM) according to the present invention includes a printed circuit board (PCB), a first memory chip set, and a second memory chip set. The PCB consists of a first surface, a second surface opposite to the first surface, a first circuit layer, a second circuit layer, and a conductive contact. The first circuit layer and the second circuit layer are respectively located on the first surface and the second surface. The conductive contact is used for electrical connection to a motherboard of an external electronic device. The first memory chip set is composed of a plurality of memory chips each of which is arranged and electrically connected to the first circuit layer on the first surface of the PCB by flip chip correspondingly. The second memory chip set is composed of a plurality of memory chips each of which is electrically arranged and connected to the second circuit layer on the second surface of the PCB by flip chip correspondingly. The respective memory chips on the memory module are directly disposed on the PCB by flip chip. Thus the memory module has a condition that there is no metal wire for electrical connection generated by wire bonding. A method of manufacturing the memory module includes the following steps. Step S1: providing a printed circuit board (PCB). The PCB consists of a first surface, a second surface opposite to the first surface, a first circuit layer, a second circuit layer, and a conductive contact. The first circuit layer and the second circuit layer are respectively located on the first surface and the second surface. Step S2: arranging and electrically connecting a first memory chip set to the first circuit layer on the first surface of the PCB by flip chip. The first memory chip set includes a plurality of memory chips. Step S3: arranging and electrically connecting a second chip memory chip set to the second circuit layer on the second surface of the PCB by flip chip. Thus manufacturing of a memory module is completed. The second chip memory chip set includes a plurality of memory chips.

Preferably, the memory module further includes a sealing film layer which is covering the memory module by injection molding yet the conductive contact on the PCB of the memory module is exposed.

Preferably, the sealing film layer further includes a flat first surface and a flat second surface opposite to each other. The first surface is located outside the first memory chip set while the second surface is located outside the second memory chip set.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Refer toFIG.1andFIG.2, an embedded dual in-line memory module (DIMM)1according to the present invention includes a printed circuit board (PCB)10, a first memory chip set20, and a second memory chip set30.

As shown inFIG.2, the PCB10consists of a first surface11, a second surface12opposite to the first surface11, a first circuit layer13, a second circuit layer14, and a conductive contact15. The first circuit layer13and the second circuit layer14are respectively located on the first surface11and the second surface12. The conductive contact15is used for electrical connection to a motherboard of an external electronic device such as a server, a workstation, or a personal computer, but not limited.

The first memory chip set20is composed of a plurality of memory chips21each of which is arranged and electrically connected to the first circuit layer13on the first surface11of the PCB10by flip chip correspondingly, as shown inFIG.1andFIG.2. In the embodiment shown inFIG.1, the number of the memory chips21is 8, but not limited.

The second memory chip set30is composed of a plurality of memory chips31each of which is disposed and electrically connected to the second circuit layer14on the second surface12of the PCB10by flip chip correspondingly, as shown inFIG.1andFIG.2. In the embodiment shown inFIG.1, the number of the memory chips31is 8, but not limited.

The respective memory chips21,31on the memory module1are directly disposed on the PCB10by flip chip (such as wafer level chip scale package (WLCSP) on DIMM), as shown inFIG.2. Thus the memory module1has a condition that there is no metal wire (such as gold wire) for electrical connection generated by wire bonding.

Refer toFIG.1andFIG.3-6, a method of manufacturing the memory modules1includes the following steps.Step S1: providing a printed circuit board (PCB)10, as shown inFIG.3. The PCB10consists of a first surface11, a second surface12opposite to the first surface11, a first circuit layer13, a second circuit layer14, and a conductive contact15. The first circuit layer13and the second circuit layer14are respectively located on the first surface11and the second surface12.Step S2: arranging and electrically connecting a first memory chip set20to the first circuit layer13on the first surface11of the PCB10by flip chip, as shown inFIG.3andFIG.4. The first memory chip set20includes a plurality of memory chips21, as shown inFIG.1.Step S3: arranging and electrically connecting a second chip memory chip set30to the second circuit layer14on the second surface12of the PCB10by flip chip, as shown inFIG.5andFIG.6. Thus production of a memory module1is completed. The second chip memory chip set30includes a plurality of memory chips31, as shown inFIG.1.

The respective memory chips21are welded on the first circuit layer13by at least one solder ball50, as shown inFIG.3. The respective memory chips31are welded on the second circuit layer14by at least one solder ball50, as shown inFIG.5.

Refer toFIG.2, the memory module1further includes a sealing film layer40which is covering the memory module1by injection molding yet the conductive contact15on the PCB10of the memory module1is exposed. The sealing film layer40further includes a flat first surface41and a flat second surface42opposite to each other, as shown inFIG.2. The first surface41is located outside the first memory chip set20while the second surface42is located outside the second memory chip set30, as shown inFIG.2.

Compared with the memory module (DIMM)2available now (as shown inFIG.7), the respective memory chips21,31on the present memory module1are directly disposed on the PCB10by flip chip, as shown inFIG.2. In the memory module2available now (as shown inFIG.7), a plurality of chips is packaged by wire bonding to form a plurality of chip packages (the first packaging process). Then the plurality of chip packages is packaged on the printed circuit board (the second packaging process). Therefore, the memory module1(as shown inFIG.1) according to the present invention has the following advantages.(1) The respective memory chips21,31are directly disposed on the PCB10by flip chip so that connecting circuit between electronic components is shortened and electrical performance between the electronic components is good.(2) Production of the memory module1is completed by only one packaging process so that manufacturing cost at manufacturing end is reduced.(3) The manufacturing process of the memory module1doesn't include wire bonding so that no metal wires (such as gold wires) are used at manufacturing end. This helps reduction of material cost at the manufacturing end.

Moreover, the present memory module1further includes the sealing film layer40, as shown inFIG.2. The sealing film layer40is covering the memory module1by injection molding but the conductive contact15on the PCB10of the memory module1is exposed. The shortcoming of the chip and the circuit exposed such as easily damaged or oxidized can be avoided. A yield rate and service life of products are increased and this is beneficial to improving product competitiveness in the market.