Metal fusion bonding – Process – Preplacing solid filler
Reexamination Certificate
1999-06-16
2001-08-14
Dunn, Tom (Department: 1725)
Metal fusion bonding
Process
Preplacing solid filler
C228S180100, C228S214000
Reexamination Certificate
active
06273327
ABSTRACT:
TECHNICAL FIELD
The present invention relates to electronic circuit board manufacturing and, more particularly, to an apparatus and method for depositing solder material onto a circuit board.
BACKGROUND OF THE INVENTION
Most electronic devices or modules include both through-hole components and surface mounted components attached to a printed circuit board. The components typically are attached to the circuit board by solder or an electrically conductive adhesive. Soldering may occur manually or by other techniques, including reflow soldering and wave soldering.
When manufacturing large quantities of electronic circuits, solder material usually is applied to electrically conductive pads of the circuit board during one or more solder paste printing process steps. The printing process occurs by applying the solder paste through an appropriately configured stencil or mask. The stencil is configured to have apertures formed through the stencil at locations corresponding to the conductive pads of the circuit board where solder is to be deposited. The stencil is positioned over the circuit board and the solder paste is applied to the circuit board in a known manner.
For example, U.S. Pat. No. 4,739,919 discloses a mask for shielding surface mounted components during a wave-soldering process. In this way, surface mounted components are protected while the leads of selected through-hole circuit components may be soldered to the circuit board.
U.S. Pat. No. 5,593,080 to Teshimi et al. discloses a mask of varying thickness for depositing varying amounts of solder onto differently sized pads of a circuit board.
U.S. Pat. No. 5,617,990 to Thompson, Sr., discloses a shield for use in a wave-soldering process. The shield has solder flow openings formed through the shield for applying solder to the circuit board. Recesses also are formed in the shield to cover and protect selected electronic components during the soldering process.
SUMMARY OF THE INVENTION
The present invention is directed to a stencil for applying solder material to a circuit board carrying a through-hole component and to which a surface mount component is to be mounted. The stencil comprises a plate having a first surface and a second surface. The second surface of the plate is engageable to a surface of the circuit board having a plurality of electrically conductive pads. At least one first aperture is formed between the first to the second surfaces of the plate. The plate has a first thickness adjacent the first aperture for depositing a first amount of solder material within the first aperture around part of a component lead that extends from the through-hole component into the first aperture. At least one second aperture also is formed between the first to the second surfaces of the plate. The plate has a second thickness, which is less than the first thickness, adjacent the second aperture for depositing a second amount of solder material within the second aperture at a desired surface mount pad location on the circuit board. The stencil thus enables predetermined amounts of solder material to be deposited around the component lead of the through-hole component and at the desired surface mount pad location.
REFERENCES:
patent: 4919970 (1990-04-01), Hoebener et al.
patent: 5189261 (1993-02-01), Alexander et al.
patent: 5615477 (1997-04-01), Sweitzer
patent: 5668699 (1997-09-01), Bell et al.
patent: 5922496 (1999-07-01), Dalal et al.
patent: 5930601 (1999-07-01), Cannizzro et al.
patent: 5941444 (1999-08-01), Sadler et al.
patent: 5953589 (1999-09-01), Shim et al.
Murray, Jr. Neil Gordon
Wright Geoffrey A.
Cooke Colleen P.
Dunn Tom
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Inc.
LandOfFree
Apparatus and method for depositing solder material onto a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for depositing solder material onto a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for depositing solder material onto a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2456269