(12) United States Patent
`Benisek et al.
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 6,850,414 B2
`Feb. 1, 2005
`
`US006850414B2
`
`(54) ELECTRONIC PRINTED CIRCUIT BOARD
`HAVING A PLURALITY OF IDENTICALLY
`DESIGNED, HOUSING-ENCAPSULATED
`SEMICONDUCTOR MEMORIES
`
`(75) Inventors: Martin Benisek, Miinchen (DE);
`Martin Schober, Grobenzell (DE)
`
`(73) Assignee: In?neon Technologies AG, Munich
`(DE)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 374 days.
`
`( * ) Notice:
`
`(21) Appl. No.: 10/187,763
`(22) Filed:
`Jul. 2, 2002
`(65)
`Prior Publication Data
`
`US 2003/0002262 A1 Jan. 2, 2003
`Foreign Application Priority Data
`
`(30)
`
`Jul. 2, 2001
`
`(DE) ....................................... .. 101 31 939
`
`(51) Int. Cl.7 .......................... .. H05K 1/00; H05K 1/18;
`H05K 1/16; H05K 7/02; H05K 7/06
`(52) US. Cl. ...................... .. 361/748; 361/760; 174/260
`(58) Field of Search ............................... .. 361/728—730,
`361/735, 736—737, 748, 749, 760, 763,
`767, 768, 807, 808, 785, 788, 790, 791,
`803; 257/693, 684, 679, 678; 711/301;
`714/773; 365/51—52, 63; 174/250, 253,
`255—256, 260
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`4,656,605 A * 4/1987 Clayton ..................... .. 365/52
`5,572,457 A * 11/1996 Michael ..................... .. 365/52
`
`6,208,546 B1 * 3/2001 Ikeda . . . . . . . . . . . . .
`
`. . . . .. 365/51
`
`6,222,739 B1 * 4/2001 Bhakta et al. ............ .. 361/790
`
`6,492,714 B1 * 12/2002 Kasatani ................... .. 257/678
`6,725,414 B2 * 4/2004 Seyyedy
`714/773
`6,784,526 B1 * 8/2004 MeZaWa ................... .. 257/679
`
`OTHER PUBLICATIONS
`
`Internal Publication: “PC SDRAM Serial Presence Detect
`(SPD) Speci?cation”, Intel, Revision 1.2B, Nov., 1999, pp.
`1—30.
`Internal Publication: “PC SDRAM Registered DIMM
`Design Support Document”, Intel, Revision 1.2, Oct., 1998,
`pp. 1—61.
`Internal Publication: “133 MHZ PC SDRAM 64—Bit Non—
`ECC/Parity 144 Pin Unbuffered SO—DIMM Speci?cation”,
`Intel, Revision 1.0C, Aug., 2000, pp. 1—30.
`Internal Publication: “Platinenlayout Nr. ASE0015 im Ger
`ber—Format” [Mounting Plate—Layout No. ASE0015 in Ger
`ber—Format], IBM, picture 1.
`
`* cited by examiner
`
`Primary Examiner—Phuong T. Vu
`(74) Attorney, Agent, or Firm—Laurence A. Greenberg;
`Werner H. Stemer; Ralph E. Locher
`(57)
`ABSTRACT
`
`An electronic printed circuit board has a memory module
`and a contact strip for insertion into another electronic unit.
`The memory module has at least nine identically designed
`housing-encapsulated integrated semiconductor memories
`con?gured on the printed circuit board. The longer dimen
`sion of the housing of one of the semiconductor memories,
`Which is connected as an error correction chip, is oriented
`perpendicular to the contact strip. The longer dimension of
`the housings of the other semiconductor memories are
`oriented parallel to the contact strip. The different orienta
`tion of the semiconductor memories makes it possible to
`reduce the height of the printed circuit board While enabling
`the rectangular housings to keep the same physical form.
`
`8 Claims, 3 Drawing Sheets
`
`50
`
`58
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`
`U.S. PatentU.S. Patent
`
`
`
`Feb. 1,2005Feb. 1,2005
`
`
`
`Sheet 2 of3Sheet 2 of3
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`
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`US 6,850,414 B2US 6,850,414 B2
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`E5E5
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`3
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`U.S. PatentU.S. Patent
`
`
`
`Feb. 1,2005Feb. 1,2005
`
`
`
`Sheet 3 of3Sheet 3 of3
`
`
`
`US 6,850,414 B2US 6,850,414 B2
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`4
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`US 6,850,414 B2
`
`1
`ELECTRONIC PRINTED CIRCUIT BOARD
`HAVING A PLURALITY OF IDENTICALLY
`DESIGNED, HOUSING-ENCAPSULATED
`SEMICONDUCTOR MEMORIES
`
`BACKGROUND OF THE INVENTION
`
`Field of the Invention
`The invention relates to an electronic printed circuit
`board, Which has a memory module and a contact strip that
`can be inserted into another electronic unit. The memory
`module has at least nine identically designed integrated
`semiconductor memories encapsulated in identically
`designed rectangular housings. The housings are each indi
`vidually connected to the printed circuit board. One of the
`semiconductor memories is connected as an error correction
`chip on the printed circuit board and the rectangular housing
`of that memory is arranged on the printed circuit board in a
`manner such that the longer dimension is oriented perpen
`dicular to the contact strip.
`Printed circuit boards of this type are inserted into moth
`erboards of personal computers or netWork computers and
`serve as the main memory, for example. In netWork
`computers, the printed circuit boards are inserted into
`compartment-type elements having a small height, for Which
`reason the printed circuit boards themselves should also
`have only a small height (the dimension perpendicular to the
`contact strip). Therefore, compared With their Width, Which
`is essentially determined by the length of the contact strip,
`insertable printed circuit boards are not very high so that the
`compartment-type elements can be made very ?at.
`The height of a printed circuit board essentially depends
`on the dimensions of the largest components arranged on the
`printed circuit board. The largest components that are
`arranged on a printed circuit board are generally housings
`for semiconductor chips containing integrated circuits. The
`connections of the semiconductor chips are connected by the
`housing to corresponding contacts on the printed circuit
`board that are signi?cantly larger than the chip connections.
`The housings themselves are also much larger than the
`integrated circuits and thus concomitantly determine the
`minimum height of the printed circuit board. In the case of
`printed circuit boards Which carry memory modules, the
`largest housings are those for semiconductor memories, for
`example, for SDRAMS (synchronous dynamic random
`access memories). The housings therefore have a rectangu
`lar form and are alWays arranged on the printed circuit board
`vertically, ie they are oriented With their longer dimension
`perpendicular to the contact strip.
`The reason for this arrangement is that one of the semi
`conductor memories is used as an error correction chip in
`order to perform error checking on data that Will be stored
`in the rest of the semiconductor memories or that Will be
`read from the memories. The error correction chip is
`arranged approximately in the center of the contact strip, is
`arranged above the contact strip, and is arranged vertically,
`ie with the longer dimension of its housing at right angles
`to the contact strip, because of prescribed lengths of the
`conductor tracks Which connect the error correction chip to
`the contact strip.
`The rest of the semiconductor memories are arranged on
`both sides of the error correction chip and also on the front
`and rear sides of the printed circuit board in the same
`orientation as the error correction chip, so that all of the
`identically designed semiconductor memories are lined up
`along the contact strip in a conventional arrangement. The
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`contact strip has electrical contacts on the front side and also
`on the rear side of the printed circuit board. Equally, the
`housing-encapsulated semiconductor memories are present
`both on the front side and on the rear side of the printed
`circuit board. Only a single error correction chip is provided
`and is situated, for example, on the front side of the printed
`circuit board.
`In addition to further semiconductor chips that are encap
`sulated in smaller housings than the memory chips and that
`are arranged in proximity to the center of the contact strip,
`the printed circuit board has further, still smaller
`components, primarily passive components such as resistors
`and capacitors. In particular, many resistors are arranged in
`the outer regions of the contact strip. The resistors require a
`short connection to corresponding contacts of the contact
`strip.
`By contrast, the housing-encapsulated semiconductor
`memories arranged in the outer regions of the contact strip
`are arranged at a someWhat larger distance from the contact
`strip, since their leads to the contact strip are permitted to be
`longer than the leads of the passive components to the
`contact strip.
`The distance of all of the semiconductor memories from
`the contact strip is chosen in a uniform fashion, so that the
`vertically arranged memory housings concomitantly deter
`mine a certain minimum height of the printed circuit board.
`This is composed of the longer dimension of a memory
`housing, the height of resistors that are arranged betWeen the
`housings and the contact strip, the height of the contact strip
`itself, and possibly a safety clearance betWeen the contact
`strip and the components on the printed circuit board. This
`safety clearance serves, in the event of a slightly inclined
`attitude of the printed circuit board during insertion into
`motherboards, to protect the nearest components on the
`printed circuit board from mechanical damage, and is chosen
`to be as small as possible.
`In the case of this conventional arrangement, in Which the
`edges of the memory housings lined up along the contact
`strip are aligned, there is no more leeWay for a further
`reduction of the circuit board height (the height of the
`printed circuit board perpendicular to the contact strip).
`
`SUMMARY OF THE INVENTION
`
`It is accordingly an object of the invention to provide an
`electronic printed circuit board having a memory module
`and a contact strip that can be inserted into another elec
`tronic unit, in Which the printed circuit board overcomes the
`above-mentioned disadvantages of the prior art apparatus of
`this general type.
`In particular, it is an object of the invention to reduce the
`height of the printed circuit board still further While using
`the same memory housings.
`With the foregoing and other objects in vieW there is
`provided, in accordance With the invention, an electronic
`printed circuit board con?guration including: an electronic
`printed circuit board having a contact strip for insertion into
`another electronic unit; and a memory module having at
`least nine identically designed integrated semiconductor
`memories. Each one of the semiconductor memories is
`encapsulated in a rectangular housing having a shorter
`dimension and a longer dimension. The housing of each one
`of the semiconductor memories is identically designed and
`is individually connected to the printed circuit board. One of
`the semiconductor memories is connected as an error cor
`rection chip. The longer dimension of the housing of the
`error correction chip is oriented perpendicular to the contact
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`5
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`

`US 6,850,414 B2
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`3
`strip. The longer dimension of the housing of each one of the
`semiconductor memories, other than the error correction
`chip, is oriented parallel With the contact strip.
`The object of the invention is achieved by virtue of the
`fact that, in the case of the printed circuit board of the
`generic type, the housings of the identically designed semi
`conductor memories, other than the error correction chip, are
`arranged on the printed circuit board in a manner such that
`they are oriented With their longer dimension parallel to the
`contact strip.
`The housings of the semiconductor memories, Which are
`identically designed, and therefore, all have the same
`dimensions, are arranged on the printed circuit board With a
`different orientation. While the semiconductor memory that
`is to be connected up as the error correction chip is still
`arranged vertically in order to comply With the speci?cations
`for the conductor track lengths of its leads, the rest of the
`identically designed semiconductor memories are arranged
`horiZontally, that is to say parallel to the contact strip. In this
`position, the longer dimension of the rectangular housings
`extend parallel to the contact strip, and each horiZontally
`oriented semiconductor memory requires a smaller circuit
`board height than in the case of a vertical orientation. The
`semiconductor memory that is used as the error correction
`chip and that concomitantly determines the height of the
`printed circuit board still requires the same space and thus
`actually, moreover, the original circuit board height.
`HoWever, this semiconductor memory, and this is some
`thing that is exploited according to the invention, is the only
`one that can be brought still closer to the contact strip, since
`no resistors have to be arranged betWeen it and the contact
`strip. As a result, the board height is reduced by the distance
`that is taken up by the resistors that are arranged betWeen the
`memory housings and the contact strip. Although these
`resistors are present over the outer regions of the contact
`strip on the printed circuit board, the semiconductor memo
`ries that are arranged horiZontally overall lie closer to the
`contact strip, since they are narroWer horiZontally. The
`semiconductor memory used as the error correction chip can
`be brought up to the contact strip by the distance that is
`required by the resistors arranged in the outer regions of the
`contact strip.
`This results in a certain, albeit small, narroWing of the
`printed circuit board. In many cases, hoWever, this suf?ces
`to actually enable the incorporation into netWork computers.
`A preferred embodiment provides for the semiconductor
`memories to be arranged such that the housing of the error
`correction chip extends, as seen from the contact strip,
`through to a greater distance from the contact strip than the
`housings of the other identically designed semiconductor
`memories. In this case, the horiZontally oriented semicon
`ductor memories are brought so close to the resistors at the
`contact strip that they do not require the printed circuit board
`to have a larger height than that required by the error
`correction chip that is brought up to the contact strip. This
`exploits the maximum space saving that can be obtained by
`using the invention.
`Accordingly, in a preferred embodiment, the printed cir
`cuit board has a height that is perpendicular to the contact
`strip and that is composed of the sum of the longer dimen
`sion of a rectangular housing, the length of a contact of the
`contact strip and a safety clearance betWeen the error cor
`rection chip and the contact strip of less than 2 mm.
`Accordingly, the error correction chip is brought up to the
`contact strip in a manner that leaves a slight safety clearance.
`The safety clearance serves for, in the event that the printed
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`circuit board is placed in an inclined position during the
`insertion or WithdraWal from a motherboard, for example,
`avoiding damage to the housing of the error correction chip
`(or further modules arranged in the same proximity to the
`contact strip). It goes Without saying that the safety clear
`ance can be reduced to the amount that is still just required.
`The printed circuit board preferably has a height of 1 to
`1.2 inches perpendicular to the contact strip. The height of
`a printed circuit board is the length of the edge of the printed
`circuit board—considered from the direction of the printed
`circuit board area—Which extends perpendicularly to the
`contact strip. By contrast, the length of the edge parallel to
`Which the contact strip runs is called the board Width. The
`board height is generally quite smaller than the board Width.
`The dimension of the printed circuit board perpendicular to
`its surface is referred to, not as the height of the printed
`circuit board, but rather as the printed circuit board thick
`ness.
`The housings of the identically designed semiconductor
`memories are preferably TSOP housings (thin small outline
`packages). These are standardiZed housings of predeter
`mined dimensions (thin small outline package). Using the
`present invention, the height of the printed circuit board can
`be further reduced even When these housings continue to be
`used.
`In a further preferred embodiment, the memory module
`has nine identically designed semiconductor memories. This
`embodiment alloWs high utiliZation of the printed circuit
`board area in the case of a symmetrical arrangement When
`tWo identically designed semiconductor memories are con
`?gured on each side of the error correction chip on both the
`front side and also on the rear side of the printed circuit
`board.
`In a preferred embodiment, the printed circuit board is
`con?gured according to the standard of the PC 133 SDRAM
`registered DIMM design speci?cation, raW card A or raW
`card F. This standard relates to the type of interconnection of
`the individual components of the memory module and the
`individual contacts of the contact strip. This standard de?nes
`length speci?cations of about 800 conductor tracks that are
`laid on the printed circuit board, except for permissible
`length tolerances. This standard furthermore contains speci
`?cations concerning the thickness of conductor tracks, con
`cerning the approximate course of conductor tracks and also
`the time WindoWs for the temporal sequence of signal
`transmissions. The raW cards A and F, special standard
`groups Within the PC 133 SDRAM registered DIMM design
`speci?cation, are de?ned for printed circuit boards that
`already have a very small height anyWay. Using the present
`invention, even printed circuit boards that are con?gured
`according to these standard groups can be narroWed further.
`Finally, the printed circuit board has a Width of 5.25
`inches. This board Width has gained acceptance in the case
`of memory module boards.
`Other features Which are considered as characteristic for
`the invention are set forth in the appended claims.
`Although the invention is illustrated and described herein
`as embodied in an electronic printed circuit board having a
`plurality of identically designed, housing-encapsulated
`semiconductor memories, it is nevertheless not intended to
`be limited to the details shoWn, since various modi?cations
`and structural changes may be made therein Without depart
`ing from the spirit of the invention and Within the scope and
`range of equivalents of the claims.
`The construction and method of operation of the
`invention, hoWever, together With additional objects and
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`US 6,850,414 B2
`
`5
`advantages thereof Will be best understood from the folloW
`ing description of speci?c embodiments When read in con
`nection With the accompanying draWings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1A shoWs the front side of a conventional printed
`circuit board;
`FIG. 1B shoWs the rear side of the conventional printed
`circuit board;
`FIG. 2 shoWs the front side of an inventive printed circuit
`board; and
`FIG. 3 shoWs the rear side of the printed circuit board
`shoWn in FIG. 2.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`Referring noW to the ?gures of the draWing in detail and
`?rst, particularly, to FIG. 1A thereof, there is shoWn a plan
`vieW of the front side 11 of a conventional printed circuit
`board 1 having, at its loWer edge, a contact strip 2 inter
`rupted by tWo indentations 14. If the printed circuit board is
`rotated about a vertical aXis extending through the right
`hand indentation 14, then the rear side 12 of the printed
`circuit board becomes visible. The rear side is illustrated in
`FIG. 1B. The front side 11 and the rear side 12 overlap in a
`mirror-inverted fashion, so that the left-hand half of the front
`side 11 corresponds to the right-hand half of the rear side 12.
`The printed circuit board 1 has a number of memory chips
`4 on both printed circuit board areas 11, 12 and also has a
`further identically designed chip, Which is used as an error
`correction chip 5. Furthermore, further semiconductor mod
`ules are present, for eXample tWo register chips 9, With
`Which memory addresses in the memory chips 4 are ampli
`?ed synchronously, and a clock synchroniZation chip
`6—also called PLL (phase locked loop)—for matching the
`memory module to an external clock frequency. Each of
`these semiconductor modules is encapsulated in a housing
`that connects the connections of the semiconductor module
`to signi?cantly larger contacts of the printed circuit board.
`The dimensions of the housings are standardiZed, in Which
`case, of all the semiconductor modules 4, 5, 6 arranged on
`the printed circuit board, the memory modules 4, 5 have the
`largest housings. For this reason, the siZe of their housings
`is determinative of the required height of the printed circuit
`board. In FIG. 1, the housings for the respective semicon
`ductor modules 4, 5, 6 are designated by the reference
`symbols of the semiconductor modules themselves, since
`the housings determine their space requirement on the
`printed circuit board.
`On the conventional printed circuit board 1 illustrated in
`FIG. 1, all of the semiconductor memories 4 are arranged on
`the printed circuit board vertically, i.e. such that the longer
`dimension of their rectangular housings is oriented perpen
`dicular to the eXtent of the contact strip 2. The semiconduc
`tor memories arc thus lined up parallel to one another on the
`front side and the rear side of the printed circuit board along
`the eXtent of the contact strip 2. In this arrangement, the
`smaller edges of the housings of the semiconductor memo
`ries 4 and 5 are aligned, ie all the memory modules 4, 5 are
`arranged in a line. They are all situated at the same distance
`from the contact strip 2. This distance is predetermined by
`the Width of the resistors 8 that are arranged in betWeen the
`contact strip 2 and the memory modules 4, 5 and by the
`mechanically dictated or thermally dictated safety clear
`ances on both sides of the resistors 8. In each case, tWo of
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`these resistors 8 must be arranged betWeen one semicon
`ductor memory 4 and the contact strip 2, because the upper
`limit for the length of the leads of the resistors from the
`contact strip 2 permits no other arrangement.
`The contact strip 2, the resistors 8, the larger dimension of
`the housings of the semiconductor memories 4, 5 and also
`certain safety clearances betWeen these together produce the
`required board height of this conventionally con?gured
`printed circuit board.
`FIG. 2 shoWs the front side 11 of an inventive printed
`circuit board. FIG. 3 shoWs the rear side 12 of the printed
`circuit board and diagrammatically shoWs, an electronic unit
`3, for eXample a motherboard, into Which the contact strip 2
`of the printed circuit board 1 can be inserted.
`FIGS. 2 and 3 shoW the front side 11 and the rear side 12
`of a printed circuit board 1 con?gured according to the
`invention. The identically designed semiconductor memo
`ries are designated by 4a, 4b and their likeWise identically
`designed housings are designated by 5a, 5b.
`On the printed circuit board that is populated according to
`the invention, as shoWn by FIGS. 2 and 3, the housings 5a
`of those semiconductor memories 4a Which are not con
`nected up as the error correction chip are arranged horiZon
`tally on the printed circuit board 1, ie the respective longer
`dimension L of the rectangular housings 5a runs parallel to
`the eXtent of the contact strip 2. Only the housing 5b of the
`error correction chip 4b is arranged vertically and takes up
`the same printed circuit board height as on a conventional
`printed circuit board. HoWever, the housing of the error
`correction chip is brought up to the contact strip 2 as close
`as possible. This is possible because, betWeen the error
`correction chip or its housing 5b and the contact strip 2, there
`is no need to arrange any passive components. In particular,
`there is no need for any resistors 8, as in the case of all of
`the other identically designed semiconductor memories 4a
`that are con?gured horiZontally. By contrast, these semicon
`ductor memories 4a take up for themselves a signi?cantly
`smaller printed circuit board height than When in the vertical
`orientation, so that the actual printed circuit board height is
`determined only by the error correction chip 4b that is
`brought up to the contact strip 2.
`As a result, the height of the printed circuit board can be
`reduced from a value H1 to a smaller value H2 composed of
`the longer dimension L of the identically-designed housings
`5b, the length K of the contacts of the contact strip 2 (in the
`direction of the double arroW to L), and a safety clearance
`S betWeen the contacts of the contact strip and the resistors
`8. This reduction of the printed circuit board height enables
`incorporation into even ?atter elements of eg netWork
`computers.
`The printed circuit board illustrated in FIGS. 2 and 3 is
`populated in such a Way that it can be connected up in
`accordance With the raW card Aor raW card F of the standard
`“PC 133 SDRAM registered DIMM design speci?cation”
`(133 MHZ; dual inline memory module). It has a height of
`betWeen 1 and 1.2 inches betWeen the loWer edge, at Which
`the contact strip 2 is situated, and the upper edge.
`The remainder of the components illustrated and their
`functions correspond to the prior art. The memory modules
`4a, 4b are SDRAMs (synchronous dynamic random access
`memory modules). They are encapsulated in TSOP housings
`(thin small outline package) 5a, 5b.
`The clock synchroniZation chip 6 (PLL; phase locked
`loop) ensures that, after a feW clock cycles of the clock
`signal that is output from the electronic unit 3 via the contact
`strip 2 to the memory modules of the printed circuit board
`1, the latter can operate synchronously With the mother
`board.
`
`7
`
`

`

`US 6,850,414 B2
`
`7
`Data that is transported to the semiconductor memory
`modules 4a always contain check data. The error correction
`chip, namely memory module, 4b checks the correctness of
`the data before the data are passed on.
`AWide variety of methods are knoWn according to Which
`the error correction chip, namely memory module, 4b can
`operate. An eXample that shall be mentioned here is the ECC
`method (error correcting code), in Which a check bit is added
`to eight bits of data to be communicated.
`FIG. 2 furthermore shoWs tWo register chips 9, With
`Which the memory addresses in the memory chips 4 are
`ampli?ed synchronously.
`All of the components situated on the printed circuit board
`are connected to one another and to the contact strip by
`conductor tracks. At the present time, printed circuit boards
`usually have siX different conductor track planes lying one
`above the other in Which the conductor tracks are arranged.
`The course of the conductor tracks is con?gured according
`to a suitable raW card of the above standard. The conductor
`tracks are not illustrated in the ?gures since their speci?c
`course is not essential With regard to the present invention.
`We claim:
`1. An electronic printed circuit board con?guration, com
`prising:
`an electronic printed circuit board having a contact strip
`for insertion into another electronic unit; and
`a memory module having at least nine identically
`designed integrated semiconductor memories;
`each one of said semiconductor memories being encap
`sulated in a rectangular housing having a shorter
`dimension and a longer dimension;
`said housing of each one of said semiconductor memories
`being identically designed and being individually con
`nected to said printed circuit board;
`one of said semiconductor memories being connected as
`an error correction chip;
`said longer dimension of said housing of said error
`correction chip being oriented perpendicular to said
`contact strip; and
`
`10
`
`15
`
`25
`
`35
`
`8
`said longer dimension of said housing of each one of said
`semiconductor memories, other than said error correc
`tion chip, being oriented parallel With said contact strip.
`2. The printed circuit board according to claim 1, Wherein:
`said housing of said error correction chip eXtends a
`greater distance aWay from said contact strip than said
`housing of each one of said semiconductor memories,
`other than said error correction chip.
`3. The printed circuit board according to claim 1, Wherein:
`said contact strip has a contact With a length;
`said printed circuit board has a height extending perpen
`dicular to said contact strip; and
`said height of said printed circuit board is equal to a sum
`of said longer dimension of said housing of said error
`correction chip, said length of said contact of said
`contact strip and a safety clearance betWeen said error
`correction chip and said contact strip of less than 2 mm.
`4. The printed circuit board according to claim 1, Wherein:
`said printed circuit board has a height of 1 to 1.2 inches
`perpendicular to said contact strip.
`5. The printed circuit board according to claim 1, Wherein:
`said housing of each one of said semiconductor memories
`is a TSOP housing.
`6. The printed circuit board according to claim 1, Wherein:
`said at least nine semiconductor memories de?ne eXactly
`nine semiconductor memories.
`7. The printed circuit board according to claim 1, Wherein:
`said printed circuit board is con?gured according to a
`speci?cation selected from a group consisting of a raW
`card A of a PC 133 SDRAM registered DIMM design
`speci?cation and a raW card F of the PC 133 SDRAM
`registered DIMM design speci?cation.
`8. The printed circuit board according to claim 1, Wherein:
`said printed circuit board has a Width of 5.25 inches.
`
`8
`
`