WO1992005679A1 - Procede d'enrobage de composants electriques - Google Patents

Procede d'enrobage de composants electriques Download PDF

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Publication number
WO1992005679A1
WO1992005679A1 PCT/US1990/005197 US9005197W WO9205679A1 WO 1992005679 A1 WO1992005679 A1 WO 1992005679A1 US 9005197 W US9005197 W US 9005197W WO 9205679 A1 WO9205679 A1 WO 9205679A1
Authority
WO
WIPO (PCT)
Prior art keywords
temperature
surge suppressor
recited
ramping
suppressor
Prior art date
Application number
PCT/US1990/005197
Other languages
English (en)
Inventor
Samuel B. Crout
Original Assignee
Crout Samuel B
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Crout Samuel B filed Critical Crout Samuel B
Priority to PCT/US1990/005197 priority Critical patent/WO1992005679A1/fr
Publication of WO1992005679A1 publication Critical patent/WO1992005679A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0066—Constructional details of transient suppressor
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/28—Applying non-metallic protective coatings
    • H05K3/284—Applying non-metallic protective coatings for encapsulating mounted components
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K5/00—Casings, cabinets or drawers for electric apparatus
    • H05K5/0091—Housing specially adapted for small components
    • H05K5/0095—Housing specially adapted for small components hermetically-sealed
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/11—Treatments characterised by their effect, e.g. heating, cooling, roughening
    • H05K2203/1121—Cooling, e.g. specific areas of a PCB being cooled during reflow soldering
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/13—Moulding and encapsulation; Deposition techniques; Protective layers
    • H05K2203/1305—Moulding and encapsulation
    • H05K2203/1316—Moulded encapsulation of mounted components
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/13—Moulding and encapsulation; Deposition techniques; Protective layers
    • H05K2203/1305—Moulding and encapsulation
    • H05K2203/1322—Encapsulation comprising more than one layer

Definitions

  • surge suppressors that simply protect the equipment but cannot supplement power if the line voltage drops, say, during a "brown out.”
  • surge suppressors cannot "clip", or stop, all voltage surges.
  • a surge suppressor may pass as much or more than 1000 volts on a 120 volt line. Such a surge downstream from a surge suppressor can cause severe damage.
  • surge suppressors remain the preferred means for preventing damage to electrical equipment.
  • the present invention is a method of encapsulating an electrical component, such as a surge suppressor, comprising embedding the component in resin, curing the resin, reducing the temperature of the embedded component to a temperature below zero degrees Fahrenheit, preferably below minus 40 degrees, maintaining the temperature of the embedded component at that temperature until it reaches thermal equilibrium or, preferably, for at least one hour, and then raising the temperature of the embedded component rampwise to room temperature, preferably slowly.
  • a layer of river rock is applied over the components prior to encapsulation with resin.
  • Fig. 2 is a schematic diagram of the circuitry of the circuit board shown in Fig. 1 ;
  • Fig. 3 is a schematic diagram of another preferred embodiment of circuitry for a surge suppressor according to the present invention.
  • Fig. 4 is a schematic diagram of still another preferred embodiment of circuitry for a surge suppressor according to the present invention.
  • Fig. 5 is a side cross sectional view of a surge suppressor according to a preferred embodiment of the present invention.
  • FIG. 1 which shows a circuit board for a voltage suppressor, generally indicated by the reference character 10 comprises a substrate 12 with a series of wide, metal strips.
  • the particular circuit board shown in Fig. 1 is for a 480 volt, three phase, "Y" connection.
  • a first strip 14, preferably “L” shaped, is at "ground” potential;
  • a second strip 16 is "neutral”; and
  • three additional strips 20, 22, and 24, are for three separate phases of alternating current.
  • MOVs metal oxide varistors
  • Connecting strips 14, 16. 20, 22, and 24 are several metal oxide varistors (MOVs) which are voltage clipping devices that operate like a back-biased Zener diode; that is, below a threshold voltage an MOV is an open circuit, above that voltage, it will conduct. Below the voltage threshhold, then, strips 14. 16, 20, 22, and 24 are isolated electrically from each other by nonconducting substrate 12. Above the voltage, the MOVs will direct the excess voltage of the transient along a dissipation path from one phase strip to another and then to neutral and to ground.
  • MOVs metal oxide varistors
  • MOV is rated to clip to a specified voltage within a certain period of time.
  • the choice of MOV depends on the particular application.
  • the positioning and arrangement of the MOVs with respect to each other is also very important. No two
  • MOVs should be closer than approximately one centimeter in order to preclude arcing and the incoming surge must be directed along a path to allow it to dissipate as much as possible before being grounded.
  • a first MOV 30 connects strip 20 to strip 22: a second MOV 32. spaced apart from the first, connects strips 22 and 24; a third MOV 34 connects strips 20 and 24.
  • these MOVs are all of the commonly available type designated 480L80.
  • Connecting strip 20 and neutral strip 16 is a fourth MOV 36: connecting strip 22 and neutral strip 16 is a fifth MOV 38: and connecting strip 24 and neutral strip 16 is a sixth MOV 40.
  • MOVs 36, 38, and 40 are preferably of the type customarily designated 275-40B. Each of the strips 16, 20, 22, 24 are connected through separate MOVs 42, 44, 46, and 48 to ground strip 14. MOVs 42, 44, 46, and 48 are also preferably of type 275-40B.
  • FIGs. 3 and 4 show examples of circuitry for surge suppressors for a 208 volt, three phase "Y" connection and a 120 volt, single phase plug connection, respectively. Each shows the same, basic approach as applied in the circuit of Fig. 2.
  • three MOVs 60, 62, and 64 connect a first strip 66 to a second strip 68, second strip 68 to a third strip 70, and first strip 66 to third strip 70 so that all three phases are interconnected.
  • MOVs 60, 62, and 64 are preferably of the type designated 250-40B.
  • Each phase strip is connected to a neutral strip 72; first strip 66 is connected to neutral strip 72 by an MOV 74: second strip 68 is connected to neutral strip 72 by an MOV 76: and third strip 70 is connected to neutral strip 72 by an MOV 78.
  • MOVs 74, 76, and 78 are preferably 130-20B types.
  • each strip 66, 68, 70, and 72 is connected to a ground strip 80 by MOVs 82, 84, 86, and 88, respectively, which are also 130-20Bs.
  • River rocks have a high iron content that is believed to cause them to interact in a favorable way with the magnetic and electrical fields generated when a voltage surge occurs and to help dissipate both heat and electromagnetic energy.
  • Container 122 is shaken to settle river rocks 126 between any MOVs 128 installed on circuit board 120, with the depth of river rocks 126 approximately even with the top of MOVs 128.
  • container 122 is filled to the top with liquid potting material 130, preferably resin and most preferably epoxy resin such as DC 331 or DC 356 manufactured by THERMOSET.
  • the potting material is cured to a solid polymer in accordance with the manufacturer's instructions.
  • the next step in making the surge suppressor involves chilling the potted suppressor to a temperature below zero degrees Fahrenheit, preferably holding the temperature to which the suppressor is chilled until it reaches equilibrium and also preferably through a relatively slow cool down phase, an equilibrium phase and a slow warm up phase, where the suppressor is allowed to warm to room temperature or thereabouts. More preferably, the potted surge suppressor is chilled to a temperature of approximately minus forty degrees or colder in a two hour ramp down in temperature, followed by more than one hour at that temperature, then a two hour ramp up in temperature. "Ramping" the temperature down or up means to cause a change in the temperature of the suppressor at a nearly constant rate from one end of the temperature range to the other.
  • a 120 volt suppressor with the circuit pattern described above and shown in Fig. 4 will clip a minimum voltage of about 330 volts before chilling but clip in the 160 to 180 volt range after chilling.
  • a 208 volt, three phase "Y" suppressor will have a similar improvement: clipping approximately 600 volts before chilling and approximately 280 volts after chilling.
  • a 480 volt suppressor will clip a minimum voltage in the range of 900 volts without chilling and a voltage of 590 after chilling.

Landscapes

  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

Limiteur de sustension (10) réalisé en enrobant le circuit limiteur dans une résine époxy (130), en faisant durcir la résine et en refroidissant la résine durcie jusqu'à une température égale à au moins zéro degré Fahrenheit, ou, de préférence, égale à moins quarante degrés Fahrenheit, puis en la réchauffant jusqu'à la température ambiante. Il est également préférable de placer une couche de petits cailloux de rivière (126) sur le circuit limiteur de sustension, puis d'enrober ledit circuit et les cailloux avec la résine. L'étape de refroidissement, ayant lieu de préférence en faisant passer la température du limiteur de la température ambiante à la température de refroidissement sur une période de deux heures, puis en laissant le limiteur à la température de refroidissement pendant une heure ou bien jusqu'à ce que le limiteur atteigne l'état d'équilibre, et enfin en élevant la température sur une autre période de deux heures, augmente la capacité d'écrêtage du limiteur, spécialement en association avec l'utilisation de cailloux de rivière.
PCT/US1990/005197 1990-09-13 1990-09-13 Procede d'enrobage de composants electriques WO1992005679A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US1990/005197 WO1992005679A1 (fr) 1990-09-13 1990-09-13 Procede d'enrobage de composants electriques

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1990/005197 WO1992005679A1 (fr) 1990-09-13 1990-09-13 Procede d'enrobage de composants electriques

Publications (1)

Publication Number Publication Date
WO1992005679A1 true WO1992005679A1 (fr) 1992-04-02

Family

ID=22221039

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1990/005197 WO1992005679A1 (fr) 1990-09-13 1990-09-13 Procede d'enrobage de composants electriques

Country Status (1)

Country Link
WO (1) WO1992005679A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999056292A1 (fr) * 1998-04-27 1999-11-04 Square D Company Appareil de contention et de protection pour circuits electroniques encapsules

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3070647A (en) * 1959-06-29 1962-12-25 Int Resistance Co Encapsulated electrical component
US3771091A (en) * 1972-10-31 1973-11-06 Gen Electric Potted metal oxide varistor
US4082916A (en) * 1976-12-16 1978-04-04 Westinghouse Electric Corporation Encapsulated electrical inductive apparatus
US4907119A (en) * 1986-10-28 1990-03-06 Allina Edward F Packaged electrical transient surge protection
US4914547A (en) * 1988-05-06 1990-04-03 American Shizuki Corporation Process for making capacitors

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3070647A (en) * 1959-06-29 1962-12-25 Int Resistance Co Encapsulated electrical component
US3771091A (en) * 1972-10-31 1973-11-06 Gen Electric Potted metal oxide varistor
US4082916A (en) * 1976-12-16 1978-04-04 Westinghouse Electric Corporation Encapsulated electrical inductive apparatus
US4907119A (en) * 1986-10-28 1990-03-06 Allina Edward F Packaged electrical transient surge protection
US4914547A (en) * 1988-05-06 1990-04-03 American Shizuki Corporation Process for making capacitors

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999056292A1 (fr) * 1998-04-27 1999-11-04 Square D Company Appareil de contention et de protection pour circuits electroniques encapsules

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