Electronic package having active means to maintain its operating temperature constant

{
  "publication_number": "US5491610A",
  "country": "US",
  "kind": "A",
  "title": "Electronic package having active means to maintain its operating temperature constant",
  "abstract": "An electronic package having an active cooling system for maintaining a semiconductor chip at approximately a constant temperature by monitoring the present temperature of the chip and varying the air flow over a heat sink in thermal contact with the chip in response to the temperature. In addition, the temperature difference between the semiconductor chip module and a printed circuit board is also monitored to maintain that difference at a preset value. The air flow is varied by a variable speed fan or a variable direction baffle.",
  "claims": [
    "1. An apparatus for actively cooling a semiconductor chip module comprising: a semiconductor chip module secured to a printed circuit board; a heat sink thermally secured to said module; variable air flow means for directing air flow over said heat sink; means for monitoring the temperature difference between the module and the printed current board; and control means for connecting the means for monitoring the temperature difference between the module and the printed circuit board and the variable air flow means to regulate the air flow to maintain the temperature difference at a preset value.",
    "2. The apparatus of claim 1 wherein said variable air flow means is a variable speed fan.",
    "3. The apparatus of claim 1 wherein said variable air flow means is a variable direction baffle and a fan.",
    "4. The apparatus of claim 1 wherein said means for monitoring the temperature difference between the module and the printed circuit board module is a separate temperature sensor in thermal contact with each of said module and board.",
    "5. The apparatus of claim 1 wherein said means for monitoring the temperature difference between the module and the printed circuit board including a temperature sensor in thermal contact with said board and means for sensing the supply current to a semiconductor chip attached to said module.",
    "6. The apparatus of claim 1 further including means for monitoring the temperature of a semiconductor chip mounted in said module and wherein said control means also regulates the air flow to maintain the chip temperature at a substantially constant temperature.",
    "7. A method for actively cooling a semiconductor chip module comprising the steps of: monitoring the temperature difference between a semiconductor chip module and a printed circuit board on which the module is mounted; and varying the air flow over a heat sink in thermal contact with said module in response to said temperature difference to maintain said temperature difference at a preset value.",
    "8. The method of claim 7 wherein the step of varying the air flow over a heat sink includes varying the speed of a variable speed fan.",
    "9. The method of claim 7 wherein the step of varying the air flow over a heat sink includes varying the direction of a baffle position between the heat sink and a fan.",
    "10. The method of claim 7 further including the step of monitoring the present temperature of a chip attached to said module and varying the air flow over the heat sink to maintain the temperature of the chip at a substantially constant temperature."
  ],
  "description_excerpt": "1. Field of the Invention\n\nThe present invention relates to a semiconductor package cooling and more particularly to an apparatus and method for providing a variable rate of cooling locally in the package to maintain a constant operating temperature.\n\n2. Description of the Prior Art\n\nMost high power CMOS logic chips planned for future computers are expected to operate under one or more power management schemes. In these schemes, portions of the on-chip circuits can be turned off when they are not needed or the clock rate can be reduced when the processing speed is not required. The overall power dissipation of the chip is thereby decreased and these reductions can occur in a cyclic fashion with time periods on the order of hundreds of seconds. Since the cooling rate of the packages is generally constant, this means that the chip temperature can fluctuate corresponding to the chip power cycles. The temperature excursions of this kind will generate thermal fatigue damage in the packaging materials especially the printed circuit board interconnections.\n\nSemiconductor package cooling systems are well known in the art. Variable speed fans controlled by a temperature sensor are disclosed in U.S. Pat. Nos. 5,121,291, 5,102,040, 4,817,865 and 4,664,542, as well as in research disclosures RD 31094 dated 2/90 and RID 26947 dated 9/86, and IBM Technical Disclosure Bulletins Vol. 32 No. 10A dated 3/90 and Vol. 26 No. 4 dated 9/83.\n\nU.S. Pat. No. 5,121,291 discloses a cooling system with exhaust and intake fans, the speeds of which are controlled by the temperatures in the system. U.S. Pat. No.",
  "cpc": [
    "G06F 1/206",
    "H10W 40/43",
    "Y02D 10/00"
  ],
  "ipc": [
    "G06F 1/20",
    "H05K 7/20",
    "H10W 40/43"
  ],
  "assignees": [
    "International Business Machines Corp"
  ],
  "inventors": [
    "Lawrence S.-W. Mok",
    "Sampath Purushothaman",
    "Bahgat G. Sammakia",
    "Janusz S. Wilczynski",
    "Tien Y. Wu"
  ],
  "filing_date": "1994-09-09",
  "publication_date": "1996-02-13",
  "grant_date": "1996-02-13",
  "priority_date": "1994-09-09",
  "application_number": "US-30380494-A",
  "family_id": "23173778",
  "cited_by_count": 131,
  "citations": [
    "JPS58129524A",
    "US5285347A",
    "JPH04130697A",
    "JPH04130698A",
    "JPH0899821A"
  ]
}