Patent ID: 12218444

DETAILED DESCRIPTIONS

Printed circuit board assemblies (PCBAs) are a fundamental component used in nearly all electronics. PCBAs provide electrical connections and mechanical support to electronic components and are generally made of copper layers laminated onto, through, and/or between one or more non-conductive substrate layers. The copper layers are etched with traces, planes, and other features to create electrical connections for the electronic components.

Depending on the circuit complexity and performance requirements, multiple copper layers (e.g., copper clad laminates or CCL's) may be utilized in a singular PCBA. For example, one copper layer may be used to provide an electrical ground, another copper layer may be used to provide an electrical power, and yet another copper layer may be used to provide a de-coupling plane to meet noise and electromagnetic compatibility (EMC) requirements, for example. Press-fit pin connections are often driven through the non-conductive substrate layers to connect power or ground across multiple conductive copper layers within a PCBA and/or connect electronic components on opposing sides of the substrate layer(s).

Some new PCBA designs utilize fewer, but larger contact pins (e.g., power pins) in place of a greater number of smaller contact pins. With larger contact pin sizes (e.g., contact pins in excess of 6 mm in diameter), press-fit pin connections become more difficult to achieve with repeatable reliability in electrical connection without damaging surrounding features in a PCBA. The press-fitting assembly fixtures, contact pins, and methods described herein are capable of repeatable reliability and avoid intermittent (open connections) and tailing (short connections) failures.

FIG.1illustrates an elevation sectional view of an example printed circuit board assembly (PCBA)100including a pair of power pins102,104pressed in using an assembly fixture (not shown, see e.g., assembly fixtures254,354ofFIGS.2and3, respectively) according to the presently disclosed technology. The PCBA100includes an insulating substrate106(e.g., a woven fiberglass cloth with an epoxy resin binder) with a network of conductive layers (e.g., conductive layers128,130,132,134), vias (e.g., vias110,112,114), traces (e.g., traces116,118) and other conductive paths or areas thereon and therethrough. Further, thru-holes136,138are formed in the PCBA100and copper clad (e.g., copper cladding140) for power and/or ground connections. The power pins102,104are press-fit through the copper-clad thru-holes136,138, respectively, and are used to connect power across the conductive layers128,130,132,134of the PCBA100.

The PCBA100further includes a variety of electronic components (e.g., electronic components120,122,124) soldered to the network of conductive paths on a first side of the substrate106and other electronic components (e.g., electronic component126) attached to a second side of the substrate106to create a functional electrical network interconnecting the electronic components on both sides of the substrate106, within the substrate106, as well as through the substrate106.

In various implementations, the electronic components120,122,124,126or other electronic components (not shown) may include capacitors, resistors, microprocessors, storage devices, etc. The PCBA100may be single-sided (e.g., having one layer forming the conductive network), double-sided (e.g., having two conductive layers forming the conductive network) or multi-layer (e.g., having inner and outer conductive layers forming the conductive network, as shown inFIG.1). Various implementations described herein may be implemented on single-sided, double-sided, or multi-layer PCBAs.

In various implementations, a far greater number and complexity of conductive traces, vias, copper-clad thru-holes, and other conductive paths, as well as electronic components, are included in the PCBA100as compared to that shown inFIG.1. Further, PCBAs as referred to herein are defined as any insulating substrate with a network of conductive paths formed thereon, therein, and/or therethrough. In various implementations, the substrate106may include ceramics, fiberglass, plastics (e.g., flexible polymers), or any combination thereof. The conductive paths or areas are generally made of copper alloys (also referred to as simply copper herein).

Detail A illustrates the power pin102press-fit in an axial direction148through the copper-clad thru-hole136. In order to adequately electrically connect the power pin102to the copper cladding140and one or more of the conductive layers128,130,132,134, without substantially damaging the copper cladding140and/or the conductive layers128,130,132,134, the copper-clad thru-hole136is carefully sized to be slightly smaller in diameter than the power pin102. In an example implementation, the copper-clad thru-hole136is 6.0 mm in diameter, with a +/−0.05 mm tolerance, while the power pin102is 6.085 mm in diameter with a +/−0.025 mm tolerance. In this implementation, the interference between the power pin102and the copper-clad thru-hole136is held to 0.15 mm-0.16 mm for adequate performance (e.g., 0.16 mm is calculated according to a 6.11 mm diameter power pin102and a 5.95 mm diameter copper-clad thru-hole136).

This power pin/thru-hole sizing permits some deformation of the copper cladding140as the power pin102is press-fit to ensure conductive contact, but not so much deformation of the copper cladding140so as to damage the copper cladding140(e.g., cause greater than a 33% loss of copper cladding140thickness post press-fitting) and/or the adjacent conductive layers128,130,132,134. In one implementation, deformation142of the adjacent conductive layers128,130,132,134is limited to up to 0.05 mm (or less than 1% of the power pin diameter) vertically of the conductive layers128,130,132,134in the area of the power pin102for adequate performance.

The power pins102,104may each include self-centering bottom chamfers144,146that serve to center the power pins102,104in their thru-holes136,138as press-fitting the power pins102,104into the thru-holes136,138, all respectively, is begun. The chamfers144,146are at a steep angle (e.g., less than 30 degrees, or approximately 20 degrees, referencing the axial direction148, to minimize damage to the copper cladding140if the power pins102,104are initially slightly off-center with reference to the copper-clad thru-holes136,138, respectively. The power pins102,104may each also include top flanges150,152, respectively, that rest against the conductive layer134(or the surrounding substrate106) when the power pins102,104are fully seated within their respective thru-holes136,138.

In various implementations, press fitting the power pin104into the copper clad thru-hole138, or other press-fit pins into other conductive holes in the PCBA100may be similar to that described above with specific reference to power pin102and copper-clad thru-hole136. In other implementations, one or both of the power pins102,104may be ground pins or pins capable of carrying another electrical connection that is not explicitly power or ground (e.g., a signal). In still further implementations, while two power pins102,104are illustrated inFIG.1, the presently disclosed technology may utilize only one or more than two power pins press-fit to the PCBA100.

FIG.2illustrates a perspective view of an assembly fixture254according to the presently disclosed technology used to press-fit contact pins in a PCBA200. Only a small part of the PCBA200is illustrated inFIG.2for clarity. Further, electronic components (see e.g., electronic components120,122,124ofFIG.1) and a network of conductive layers (see e.g., conductive layers128,130,132,134ofFIG.1), vias (see e.g., vias110,112,114ofFIG.1), traces (see e.g., traces116,118ofFIG.1), and other conductive paths or areas thereon and therethrough are omitted fromFIG.2as well for clarity. Various features of the PCBA200may be as described above with reference to PCBA100.

The assembly fixture254includes a top jig256and a bottom jig258arranged on opposing sides of the PCBA200. The top jig256and the bottom jig258are aligned such that pin apertures260,262in a top housing264of the top jig256are axially aligned with corresponding guide pins (not shown see e.g., guide pins376,378ofFIG.3) in a bottom housing266of the bottom jig258.

The pin apertures260,262in the top housing264are sized for a slip fit with contact pins (not shown, see e.g., contact pins302,304ofFIG.3) to-be press fit into the PCBA200. The bottom jig258is aligned with the top jig256such that the guide pins extend out of the bottom housing266, through the PCBA200, into the pin apertures260,262of the top housing264, and meeting the contact pins. The contact pins are press-fit into the PCBA, as illustrated by arrows248,249, with the assembly fixture254maintaining axial alignment of contact pins as they are pressed into the PCBA200in a direction parallel with the opposing forces illustrated by the arrows248,248and normal to the PCBA200.

In various example implementations, the press-fitting force applied to the assembly fixture254may range from 320N-850N (or be approximately 650N) to fully seat the contact pins to the PCBA200. The press-fitting force varies both inside and outside of the range provided above based on PCBA stack up layers, associated materials, final PTH hole copper plate thickness, and PCBA/power pin manufacturing tolerances, as examples. The top jig256and the bottom jig258may each be made of a structurally stiff material (e.g., a metal alloy, such as steel or aluminum alloy) capable of withstanding forces applied to press-fit the contact pins into the PCBA200without substantial deflection. Further the assembly fixture254may be placed in a press (not shown) to apply the compressive forces illustrated by the arrows248,248.

In various implementations, the contact pins may be power (or power-supplying) pins, ground pins, or pins capable of carrying another electrical connection that is not explicitly power or ground (e.g., a signal). Further, while two pin apertures260,262that accommodate two contact pins simultaneously are illustrated inFIG.2, the presently disclosed technology may be scaled to include an assembly fixture254that simultaneously accommodates only one or more than two contact pins to be press-fit to the PCBA200. Assembly fixtures, such as the assembly fixture254ofFIG.2, that accommodate two or more contact pins simultaneously are referred to herein as having sets of duplicated features for each of the contact pins.

FIG.3illustrates a perspective sectional view of an assembly fixture354according to the presently disclosed technology used to press-fit contact pins302,304in a PCBA300. Only a small part of the PCBA300is illustrated inFIG.3for clarity. Further, electronic components (see e.g., electronic components120,122,124ofFIG.1) and a network of conductive layers (see e.g., conductive layers128,130,132,134ofFIG.1), vias (see e.g., vias110,112,114ifFIG.1), traces (see e.g., traces116,118ofFIG.1), and other conductive paths or areas thereon and therethrough are omitted fromFIG.3as well for clarity. Various features of the PCBA300may be as described above with reference to PCBA100.

The assembly fixture354includes a top jig356and a bottom jig358arranged on opposing sides of the PCBA300. The bottom jig358includes a bottom housing366with a pair of guide apertures368,370extending through the bottom housing366and guide seats372,374which are a stepped portion of the guide apertures368,370, respectively. Guide pins376,378are slip fit with the guide apertures368,370, respectively, and extend out of one end of the bottom housing366with pin heads380,382resting against the guide seats372,374, respectively.

Guide plugs384,386are screwed into the guide apertures368,370, respectively, thereby sealing an opposing end of the bottom housing366. Guide springs388,390are oriented between the guide pins376,378and the guide plugs384,386, respectively. The guide springs388,390bias the pin heads380,382against the guide seats372,374. The top jig356and the bottom jig358are aligned such that pin apertures360,362in atop housing364of the top jig356are axially aligned with the guide pins376,378in the bottom housing366of the bottom jig358.

The pin apertures360,362in the top housing364are sized for a slip fit with the contact pins302,304to-be press fit into the PCBA300. The contact pins302,304are loaded into a PCBA-facing side of the top jig356with pin flanges392,394resting against the top housing364. The bottom jig358is aligned with the top jig356such that the guide pins376,378extend out of the bottom housing366, through the PCBA300, into the pin apertures360,362of the top housing364, and meeting the contact pins302,304, respectively. The guide pins376,378extend into apertures in the bottom of the contact pins302,304, which forces the contact pins302,304in axial alignment with the guide pins376,378. The contact pins302,304are press-fit into the PCBA300, as illustrated by arrows348,349, with the assembly fixture354maintaining axial alignment of the contact pins302,304as they are pressed into the PCBA300in a direction parallel with the opposing forces illustrated by the arrows348,348and normal to the PCBA300.

In various example implementations, the press-fitting force applied to the assembly fixture354may range from 320N-850N (or be approximately 650N) to fully seat the contact pins302,304to the PCBA300. The press-fitting force varies both inside and outside of the range provided above based on PCBA stack up layers, associated materials, final PTH hole copper plate thickness, and PCBA/power pin manufacturing tolerances, as examples. Various components of the assembly fixture354, including but not limited to the top jig356, the bottom jig358, and the guide pins376,378, may each be made of a structurally stiff material (e.g., a metal alloy, such as steel or aluminum alloy) capable of withstanding forces applied to press-fit the contact pins302,304into the PCBA300without substantial deflection. Further the assembly fixture354may be placed in a press (not shown) to apply the compressive forces illustrated by the arrows348,348.

In various implementations, the contact pins302,304may be power (or power-supplying) pins, ground pins, or pins capable of carrying another electrical connection that is not explicitly power or ground (e.g., a signal). Further, while two pin apertures360,362that accommodate two contact pins302,304simultaneously are illustrated inFIG.3, the presently disclosed technology may be scaled to include an assembly fixture354that simultaneously accommodates only one or more than two contact pins302,304to be press-fit to the PCBA300. Assembly fixtures, such as the assembly fixture354ofFIG.3, that accommodate two or more contact pins simultaneously are referred to herein as having sets of duplicated features for each of the contact pins.

FIG.4illustrates an elevation/partial sectional view of a power pin402with a steep chamfer444to be press-fit using an assembly fixture (not shown, see e.g., assembly fixtures254,354ofFIGS.2and3, respectively) according to the presently disclosed technology. The power pin402is made of a conductive material (e.g., copper, stainless steel, aluminum, or other alloys) with a generally cylindrical shape. The power pin402is further generally radially symmetric about axis448, which is generally aligned with the axial direction discussed elsewhere herein. Other implementations of the power pin402may have features or shapes differing from that shown and described with reference toFIG.4.

The power pin402is made up of several distinct sections405,410,415,420. A connection section405serves as an electrical connector (not shown) to a wire or other lead providing power from a power supply (also not shown) to the power pin402. The connection section405includes a recess496to seat the electrical connector. A body section410serves as a conductive stanchion projecting away from a PCBA (not shown, see e.g., PCBA100ofFIG.1) once the power pin402is press fit to the PCBA. In some implementations, the connection section405and a top end of the body section410functionally serves as the electrical connector.

A pin flange section415contains pin flange492, which serves as a mechanical limit to press-fitting the power pin402to the PCBA as the pin flange492comes in contact with the PCBA once the power pin402is fully pressed into the PCBA. An insertion section420is the part of the power pin402that is seated within a copper clad thru-hole (not shown, see e.g., thru-holes136,138ofFIG.1) in the PCBA. The insertion section420has a slightly larger diameter than the copper clad thru-hole, as described above with reference to the power pin102and the corresponding copper clad thru-hole136ofFIG.1to ensure good conductive contact, but without damaging the copper-clad thru-hole or various conductive layers of the PCBA.

In various implementations, the insertion section420includes the chamfer444, which is oriented at a steep angle (e.g., less than 30 degrees, or approximately 20 degrees, as illustrated) referencing the axial direction, illustrated by axis448. The steep angle minimizes damage to the copper cladding within a thru-hole if the power pin402is initially slightly off-center with reference to the copper-clad thru-hole to which it is to be press-fit. In other implementations, the chamfer444is omitted.

In some implementations, the insertion section420further includes exterior surface finishing498(e.g., knurling, ribbing, texturing, and the like) to facilitate electrical contact with the copper-clad thru-hole and locking of the power pin402within the copper-clad thru-hole. In other implementations, the power pin402may be a ground pin or a pin capable of carrying another electrical connection that is not explicitly power or ground (e.g., a signal).

FIG.5illustrates example operations500for press-fitting contact pins into a PCBA. A first providing operation505provides a planar substrate forming a mechanical base for the PCBA. In various implementations the PCBA substrate includes ceramics, fiberglass, plastics, or any combination thereof. Further, the PCBA substrate may be an FR-1 through FR-6 material, a G-10 or G-11 material, a CEM-1 through CEM-5 material, PTFE, PTFE composite, RF-35, aluminum or other metal core board (i.e., insulated metal substrate), alumina, polyimide foil, and polyimide-fluoropolymer composite foil.

The planar substrate includes one or more PCBA thru-holes, each of which intended for press-fitting one of the contact pins. The PCBA thru-holes may each be copper-clad to aid in conductive contact with the contact pins, post press-fitting. The pairings of PCBA thru-holes and contact pins may range from one pairing to as many pairings as practical in a PCBA substrate.

A second providing operation510provides a bottom jig including a bottom housing with guide apertures and guide seats for each guide aperture. A guide pin is slip fit within each guide aperture and extends out of one end of the bottom housing with a pin head resting against the guide seat. A guide plug is placed in each guide aperture, effectively sealing an opposing end of the bottom housing. A guide spring is oriented between each pairing of a guide pin and a guide plug. The guide springs bias the pin heads against the guide seats.

An insertion operation515inserts the guide pins through the thru-holes in the PCBA thereby placing and aligning the bottom jig on a bottom side of the PCBA. A third providing operation520provides a top jig including a top housing with pin apertures that correspond to each of the guide pins in the bottom jig. The pin apertures are sized for a slip fit with contact pins to-be press fit into the PCBA. A loading operation525loads the top jig with the contact pins, one in each of the pin apertures. Flanges on the contact pins rest against a PCBA-facing side of the top jig when the contact pins are loaded in the top jig.

An alignment operation530axially aligns the top jig to the bottom jig using the guide pins extending out of the bottom housing, through the PCBA, into the pin apertures of the top housing, and meeting the contact pins loaded in the top jig. A press-fitting operation535press fits the contact pins into the PCBA by compressing the PCBA between the bottom jig and the top jig. In various implementations, the press-fitting operation535is accomplished by loading the bottom jig, PCBA, contact pins to-be press fit, and the top jig (collectively, the assembly fixture) into a press that applies sufficient compressive force to press-fit the contact pins into their corresponding thru-holes in the PCBA.

The operations making up the embodiments of the invention described herein are referred to variously as operations, steps, objects, or modules. The operations may be performed in any order, adding or omitting operations as desired, unless explicitly claimed otherwise or a specific order is inherently necessitated by the claim language.

An implementation of the presently disclosed technology includes an assembly fixture for a printed circuit board assembly (PCBA) comprising a bottom jig and a top jig. The bottom jig includes a bottom housing with a guide aperture and a guide seat; a guide pin slip fit with the guide aperture and extending out of one end of the bottom housing with a pin head resting against the guide seat; a guide plug in the guide aperture sealing an opposing end of the bottom housing; and a guide spring oriented between the guide pin and the guide plug, the guide spring to bias the pin head against the guide seat. The top jig includes a top housing with a pin aperture, the pin aperture sized for a slip fit with a contact pin to-be press fit into the PCBA, the bottom jig to be aligned with the top jig such that the guide pin extends out of the bottom housing, through the PCBA, into the pin aperture of the top housing, and meeting the contact pin, the contact pin to be press-fit into the PCBA with the assembly fixture maintaining axial alignment.

In some implementations, the bottom jig includes two or more sets of guide apertures, guide seats, guide pins, pin heads, guide plugs, and guide springs; and the top jig includes two or more sets of pin apertures, wherein each guide pin extends out of the bottom housing, through the PCBA, into a corresponding pin aperture of the top housing, and meeting a corresponding contact pin, each of the contact pins to be press-fit into the PCBA with the assembly fixture maintaining axial alignment.

In some implementations, the contact pin includes a contact pin flange resting against an exterior surface of the top housing facing the PCBA.

In some implementations, the contact pin is fully press-fit into the PCBA when the contact pin flange rests against the PCBA.

In some implementations, the contact pin is a power-supplying pin for the PCBA.

In some implementations, interference between the contact pin and the copper-clad aperture in the PCBA that the contact pin is to be press-fit into is 0.15 mm-0.16 mm.

An implementation of the presently disclosed technology includes a method of press-fitting pins into a printed circuit board assembly (PCBA). The method comprises providing a bottom jig including: a bottom housing with a guide aperture and a guide seat; a guide pin slip fit with the guide aperture and extending out of one end of the bottom housing with a pin head resting against the guide seat; a guide plug in the guide aperture sealing an opposing end of the bottom housing; a guide spring oriented between the guide pin and the guide plug, the guide spring to bias the pin head against the guide seat. The method further comprises inserting the guide pin through an thru-hole in the PCBA, loading a top jig with a contact pin, the top jig including a top housing with a pin aperture, the pin aperture sized for a slip fit with the contact pin to-be press fit into the PCBA, axially aligning the top jig to the bottom jig using the guide pin extending out of the bottom housing, through the PCBA, into the pin aperture of the top housing, and meeting the contact pin; and press fitting the contact pin into the PCBA by compressing the PCBA between the bottom jig and the top jig.

In some implementations, the bottom jig includes two or more sets of guide apertures, guide seats, guide pins, pin heads, guide plugs, and guide springs; the top jig includes two or more sets of pin apertures, each of the pin apertures sized for a slip fit with a contact pin to-be press fit into the PCBA; the insertion operation includes inserting each of the guide pins through a thru-hole in the PCBA; the loading operation includes loading the top jig with each of the contact pins; the aligning operation includes axially aligning the top jig to the bottom jig using each of the guide pins extending out of the bottom housing, through the PCBA, into the pin apertures of the top housing, and meeting the contact pins; and the press fitting operation includes press fitting the contact pins into the PCBA by compressing the PCBA between the bottom jig and the top jig.

In some implementations, the contact pin includes a contact pin flange, and following the loading operation, the contact pin flange rests against an exterior surface of the top housing facing the PCBA.

In some implementations, following the press-fitting operation, the contact pin is fully press-fit into the PCBA when the contact pin flange rests against the PCBA.

In some implementations, the thru-hole in the PCBA is copper clad.

In some implementations, interference between the contact pin and the copper-clad aperture in the PCBA prior to the press-fitting operation is 0.15 mm-0.16 mm.

An implementation of the presently disclosed technology includes an assembly fixture comprising a bottom jig, a printed circuit board assembly (PCBA) including a thru-hole; a power pin to be press-fit into thru-hole in the PCBA; and a top jig. The bottom jig includes a bottom housing with a guide aperture and a guide seat; a guide pin slip fit with the guide aperture and extending out of one end of the bottom housing with a pin head resting against the guide seat; a guide plug in the guide aperture sealing an opposing end of the bottom housing; and a guide spring oriented between the guide pin and the guide plug, the guide spring to bias the pin head against the guide seat. The top jig includes a top housing with a pin aperture, the pin aperture sized for a slip fit with the contact pin, the bottom jig to be aligned with the top jig such that the guide pin extends out of the bottom housing, through the PCBA, into the pin aperture of the top housing, and meeting the power pin, the power pin to be press-fit into the PCBA with the assembly fixture maintaining axial alignment.

In some implementations, the bottom jig includes two or more sets of guide apertures, guide seats, guide pins, pin heads, guide plugs, and guide springs; and the top jig includes two or more sets of pin apertures, wherein each guide pin extends out of the bottom housing, through the PCBA, into a corresponding pin aperture of the top housing, and meeting a corresponding power pin, each of the power pins to be press-fit into the PCBA with the assembly fixture maintaining axial alignment.

In some implementations, the power pin includes a power pin flange resting against an exterior surface of the top housing facing the PCBA.

In some implementations, the power pin is fully press-fit into the PCBA when the power pin flange rests against the PCBA.

In some implementations, the thru-hole in the PCBA is copper clad.

In some implementations, interference between the power pin and the copper-clad aperture in the PCBA that the power pin is to be press-fit into is 0.15 mm-0.16 mm.

In some implementations, the power pin includes a less than 30-degree chamfer on an insertion section of the power pin.

In some implementations, the power pin includes surface finishing on an insertion section of the power pin to facilitate electrical contact with the thru-hole in the PCBA.

The above specification, examples, and data provide a complete description of the structure and use of exemplary embodiments of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended. Furthermore, structural features of the different embodiments may be combined in yet another embodiment without departing from the recited claims.