Embodiments described herein relate generally to a memory card and a method for manufacturing the same.
As one of semiconductor packages, a type is known, in which semiconductor chips with different functions are enclosed in one package (SiP (system in package)).
In general, according to one embodiment, a memory card is disclosed. The memory card includes a substrate; a memory provided on the substrate; a controller provided on the substrate; and a first interconnect provided on the substrate. A distance between an edge of the substrate and the first interconnect is greater than or equal to 0.4 mm. The memory card further includes a resin covering the memory, the controller and the interconnect. The resin includes a first region and a second region, the amount of carbide in the first region is larger than the amount of carbide in the second region.
In general, according to one embodiment, a method for manufacturing a memory card is disclosed. The method includes forming a resin on a substrate; and dividing the resin and the substrate into a plurality of resins and a plurality of substrates, respectively, by using laser irradiation and blade. The plurality of resins and the plurality of substrates includes a first resin and a first substrate, respectively, a distance between an edge of the first substrate and first area is greater than or equal to 0.4 mm.
Various embodiments will be described hereinafter with reference to the accompanying drawings. In the drawings, the same portions are denoted by the same reference numbers. The overlapping descriptions are provided as necessary.
Memory card 1 of the present embodiment is used as a memory card conforming to the SD™ standard (SD™ card). Memory card 1 comprises a case 2 and a semiconductor storage device 10 of SiP (System in Package) structure accommodated in the case 2. Semiconductor storage device 10 includes an interconnect substrate, semiconductor chips with different functions formed on the interconnect substrate, and a resin layer which seals the semiconductor chips.
As shown in
The semiconductor storage device 10 further comprises a molding resin 14 which seals the interconnect substrate 11, the NAND flash memory 12 and the controller 13. In the present embodiment, molding resin 14 includes molten silica. The concentration of molten silica is, for example, 75 to 95% by weight.
An example of a method for manufacturing the semiconductor storage device of the memory card of the present embodiment will be described with reference to a flowchart in
The above-described memory, the controller and interconnect substrate 11′ including lead wires are formed in each of a plurality of interconnect substrate regions 20 on insulating substrate 21 (step S1). A material of substrate 21 is, for example, a glass epoxy resin.
The resin layer is formed on substrate 21 to seal the memories, the controllers and the lead wires on interconnect substrate regions 20 (step S2).
The resin layer and substrate 21 are processed by means of cutting by laser irradiation (laser processing) and cutting by blade (blade processing), and thereby divided into a plurality of resin layers and a plurality of interconnect substrates, respectively (step S3). Such a method of forming the plurality of interconnect substrates at the same time has higher manufacturing efficiency than a method of individually forming the plurality of interconnect substrates.
When the interconnect substrate 11′ of
Of the contour defining the external form of the interconnect substrate 11, the portion cut by laser processing includes a line 32a (first line) perpendicular to the longitudinal direction of the interconnect substrate 11, curved line 32b connected to the line 32a, and a line 32c parallel with the longitudinal direction of the interconnect substrate 11 and connected to the second line 32b. The portion cut by laser processing further includes a line 32d inclined approximately 45° toward the longitudinal direction of the interconnect substrate 11. The inclination of the line 32d is not limited to 45°.
In the present embodiment, the resin layer and the substrate are divided into the plurality of resin layers and the plurality of substrates in step S3 such that a distance D between the lead wire and a line perpendicular to the longitudinal direction of the lead wire (a first line (corresponding to line 32a in
The distance D between line 32a and lead 31 is greater than or equal to 0.4 mm. This is because, the intensive study by the inventors revealed that a short circuit (occurrence of a leakage current) between adjacent leads 31 (for example, leads 31a and 31b in
The molding resin 14 is irradiated with a laser light and heated at the time of the laser processing. Since molding resin 14 includes silica (SiO2) and carbon (C), a compound of silicon and carbon is formed by the above heating, and carbide (SiC) is thereby generated in molding resin 14. If the carbide is generated between adjacent leads 31 (for example, leads 31a and 31b in
At the time of the laser processing, an upper surface of molding resin 14 is first irradiated with a laser light 40 as shown in
In the case of
When the distance D is constant, there is a possibility that the energy density of the laser light influences on the carbonization of molding resin 14.
Furthermore, when the distance D and the energy density are constant, there is a possibility that the number of cuts (the number of irradiations) by the laser light influences on the carbonization of molding resin 14.
Therefore, an occurrence rate of the leakage current (leakage occurrence rate) is evaluated by varying the number of cuts, the energy intensity per cut, and the distance D as parameters. The distance D can be measured by using X-ray. Moreover, for convenience of the measurement, the laser irradiation is performed by using a laser equipment configured to perform irradiation by selecting either a laser light having a first wavelength (1064 nm) or a laser light having a second wavelength (532 nm). A laser equipment configured to perform irradiation by selecting an arbitrary one of three or more laser lights having different wavelengths may also be used.
Seven samples (first sample group) in
Seven samples (second sample group) in
Seven samples (third sample group) in
Seven samples (fourth sample group) in
From
Here, a tolerance of lead wire 31 is typically ±0.05 mm, a tolerance of the laser machining is typically ±0.07 mm, and a square root of a sum of squares of the tolerances squared (square root of a sum of squares of the respective tolerances) (0.052 +0.072)½ is approximately 0.39, hence the distance D is set greater than or equal to 0.4 mm.
According to an inspection of the memory device of the embodiment (D ≧0.4 mm), the leakage current flowing between adjacent leads 31 is not detected. Furthermore, according to a component analysis of molding resin layer 14 of semiconductor storage device 10 of the embodiment, carbide is detected on interconnect substrate 11 where the distance D <0.4 mm, but is not detected on interconnect substrate 11 where the distance D ≧0.4 mm. That is, the carbide which causes the leakage current by short-circuiting between adjacent leads 31 is not detected. As shown in
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
This application claims the benefit of U.S. Provisional Application No. 62/008,970, filed Jun. 6, 2014, the entire contents of which are incorporated herein by reference.
Number | Date | Country | |
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62008970 | Jun 2014 | US |