Surface mount component height control

• US 5,726,861 A
• Filed: 01/03/1995
• Issued: 03/10/1998
• Est. Priority Date: 01/03/1995
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Ostrem, Fred E.
• Primary Examiner(s): SPARKS, DONALD ALAN
• Application Number:
  US08/367,967
• Time in Patent Office: 1,162 Days
• Field of Search: 174/261, 174/260, 174/263, 228/180.21, 228/180.22, 257/778, 257/712, 257/779, 257/723, 257/724, 257/725, 361/760, 361/772, 361/767, 361/768, 361/773, 361/774, 361/777, 361/779, 361/782, 361/783, 361/771, 439/68, 439/71, 439/83, 437/209, 437/71
• US Class Current: 361/767
• CPC Class Codes: H05K 2201/09781 Dummy conductors, i.e. not used for normal transport of current; Dummy electrodes of components
• CPC Class Codes: H05K 2201/10636 Leadless chip, e.g. chip capacitor or resistor
• CPC Class Codes: H05K 2201/10727 Leadless chip carrier [LCC], e.g. chip-modules for cards
• CPC Class Codes: H05K 2203/306 Lifting the component during or after mounting; Increasing the gap between component and PCB
• CPC Class Codes: H05K 3/3442 having edge contacts, e.g. leadless chip capacitors, chip carriers
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A method and structure for controlling solder height of a surface mount device on a substrate uses electrical connection pads (105, 105'"'"') disposed onto a substrate (101). A height control pad (111) is also disposed onto the substrate (101) positioned apart from the electrical connection pads (105, 105'"'"'). Solder fillets (107, 107'"'"', 113) are disposed onto both the electrical connection pads (105, 105'"'"') and the height control pad (111). A component (103) having an electrical termination portion (109, 109'"'"') in contact with the solder fillets (107, 107'"'"') associated with the electrical connection pads (105, 105 '"'"') and a body portion (115) in contact with the solder fillet (113) associated with the height control pad (111). The resulting structure (100 has a height relationship (119) between the surface mount component (103) and the substrate (101) controlled principally by a quantity of solder in the electrically conductive solder fillet (113) is disposed onto the height control copper pad (111) and a geometry of the copper pads (105) and (105'"'"') and the height control copper pad (111).

Claims

1. A circuit assembly comprising a surface mount device on a substrate, the assembly comprising:

a pair of electrical connection pads disposed onto a first surface of the substrate;

a solderable height control pad disposed onto the first surface of the substrate positioned between the two electrical connection pads;

solder fillets soldered onto each of the two electrical connection pads and the height control pad; and

a component having two opposing ends with an electrical termination portion located at each of the two ends, and a non-solderable body portion, wherein the two electrical termination portions extend from a surface on each of the two opposing ends to a surface on a bottom portion of the component, and wherein each of the surfaces of the two electrical termination portions are bonded to the solder fillet associated with a corresponding one of the pair of electrical connection pads, and the non-solderable body portion is resting on the solder fillet associated with the height control pad.

2. A circuit assembly in accordance with claim 1 wherein the component has a center of gravity and wherein the height control pad is positioned at the center of gravity of the component.

3. A circuit assembly in accordance with claim 1 wherein the height control pad is electrically isolated from the pair of electrical connection pads.