US 7,095,104 B2 · Overlap stacking of center bus bonded memory chips for double density and method of manufacturing the same

Abstract

An approach to DRAM memory chip packaging leveraging the chip center position for wire bond pads to minimize time-of-flight and impedance effects resulting from stacking in a BGA application. A top layer of a dual device stack of center bus chips is stacked with an offset in a single direction with respect to a bottom layer of the dual device stack. The top layer of chips may be wire bonded to the opposite side of the module substrate. The center bus may be made to traverse to the substrate between two memory devices on the lower layer. To assemble the offset stacking devices into a high density module, devices are placed sequentially on a module substrate such that approximately one half of the protruding lower memory device is used as a support for the overhanging upper memory device chip of the next device stack.

Claims15

Dependent claims

A high density memory card comprising:

a module card on which there are assembled a plurality of dual device stacks each having a center bus wire, said plurality of dual device stacks including:
a first lower layer memory device attached to a substrate, said substrate having a plurality of wire bond pads adjacent to an aperture in said substrate center for connection to said center bus wire;
and
a first upper layer memory device stacked on top of, seated, and bonded directly to, said first lower layer memory device such that said first upper layer memory device is offset over said first lower layer memory device exposing said center bus wire of said first upper layer memory device to some of said plurality of wire bond pads at an edge of said first lower layer memory device;
said center bus wire of said upper layer memory device connected to said wire bond pads of said substrate around said edge of said first lower layer memory device.

2 more elements

Dependencies are inferred from the claim text.

Overlap stacking of center bus bonded memory chips for double density and method of manufacturing the same

Life of this patent

Overlap stacking of center bus bonded memory chips for double density and method of manufacturing the same

Life of this patent

Abstract

Claims15