Daughter-card retention system
A circuit board fastening system consists of a two-piece assembly including an electrically conductive circuit board retainer for surface mounting and a flexible clip for retaining a daughter-card to the retainer. The clip is preferably made of a flexible polymer so that a band portion in the middle of the clip can be comfortably folded 180 degrees at a u-shaped bend. During assembly, an arrow-shaped barb at one end of the clip is inserted into a retain bore thereby resiliently securing the daughter-card to a retainer flange upon which the card is seated. At the opposite end of the clip, a notched aperture in the clip is affixed around a groove in the retainer flange. The resilience of the barb provides a residual clamping effect to the daughter-card that is tightly sandwiched between a broad planar portion of the clip and a top surface of the retainer flange.
1. A fastening system for a circuit board, comprising:
a circuit board having a hole for receiving a fastener;
a retainer having top and bottom ends with a bore extending along a central longitudinal axis, said retainer having a shank received in the circuit board hole;
a flange on the retainer, said flange having a planar top surface perpendicular to the axis;
a groove in the flange extending around its peripheral surface;
a neck portion of the retainer extending upwardly from the flange top surface to the top end of the retainer;
an elastomeric clip having means for affixation to the retainer groove at a tail end thereof and having means for receipt and attachment to the retainer bore at an opposite attachment end of the clip; and
an electronic component tightly sandwiched between the clip attachment end and the top surface of the retainer flange.
2. The fastening system of claim 1 wherein the clip has a u-shaped bend such that said clip ends extend in the same direction and parallel to one another.
3. The fastening system of claim 1 wherein the means for affixation to the retainer at the tail end is an aperture with portions of an inner wall that engage the retainer groove.
4. The fastening system if claim 3 wherein the inner wall of the clip tail end aperture has notches.
5. The fastening system of claim 1 wherein the attachment means of the clip which is received in the retainer bore is an arrow-shaped barb with a reverse-angle tapered backend portion.
6. The fastening system of claim 5 wherein the retainer bore is stepped, having a collar perpendicular to the axis and extending between top and bottom portions of the bore of different diameters.
7. The fastening system of claim 6 wherein the backend portion of the barb engages the bore collar.
8. The fastening systems of claim 7 wherein the backend portion of the barb has a smooth uninterrupted linear surface.
9. The fastening system of claim 5 wherein the arrow-shaped barb extends orthogonally from a broad planar surface at the attachment end of the clip that extends to the lateral edges of the clip from a base of the arrow-shaped barb.
10. The fastening system of claim 1 constructed and arranged such that a residual clamp force is applied to the electronic component against the retainer flange top surface.
11. The fastening system of claim 1 further having a finger tab extending distally from the attachment end of the clip.
12. The fastening systems of claim 1 wherein the circuit board is a motherboard and the electronic component is a daughter-card.
13. The fastening system of claim 1 wherein the retainer is electrically conductive such that said electronic component electrically connected to the circuit board.
14. The fastening system of claim 1 wherein the clip is a unitary part of a molded plastic composition.
15. The fastening system of claim 1 wherein the clip has a flexible band portion at it midsection.