GB1584241A

GB1584241A - Mechanical bonding of surface conductive lavers

Info

Publication number: GB1584241A
Application number: GB5630/78A
Authority: GB
Original assignee: Lomerson R B
Current assignee: Lomerson R B
Priority date: 1977-02-15
Filing date: 1978-02-13
Publication date: 1981-02-11
Also published as: IL53957A0; IT7848041A0; FR2380686B1; NL7801594A; JPS6252479B2; JPS5416670A; FR2380686A1; IT1102270B; DE2805535A1

Description

(54) MECHANiCAL BONDING OF SURFACE CONDUCTIVE LAYERS.

(71) I, ROBERT BOGARDUS LOM ERSON, a citizen of the U.S.A. of Route 9, Box 196, Fort Worth, Tarrant County, Texas, United States of America, do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates generally to electrical component mounting boards and more particularly to a method for forming an electrically conductive path through an insulating material.

There are a number of methods in the prior art for providing an electrical connection through a printed circuit board to connect the opposing sheets. The most widely used method is the plated-through hole. Plating requires numerous steps involving various chemical baths which have to be carefully adjusted to maintain the correct chemical balance. It is an object of this invention to provide a through connection without the use of chemicals.

Other techniques use eyelets or stakes which are mounted in the board. This invention does not use such devices. There is a need in the industry for a faster and less expensive method for providing a through connection. It is the object of this invention to provide such a method.

According to the present invention there is provided a method of establishing a conductive path through an insulating plate which comprises forming at least one hole through the plate, placing conductive material over each opening of the hole and in flush contact with each surface of the plate, and applying a force against at least a first of the conductive materials to drive it through the hole and into contact with a second of the conductive materials, and producing a metallurgical junction between the conductive materials at the zone of contact.

The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as further objects and advantages thereof will best be understood by reference to the following detailed description of an illustrative embodiment taken in conjunction with the accompanying drawings, in which: Figure 1 is a side view of symmetrical bonding dies, an insulating plate and conductive sheets; Figure 2 is a side view of the insulating plate of Figure 1 in which the opposing conductive sheets have been bonded; Figure 3 is a side view of a single die, base plate, insulating plate and conductive sheets; Figure 4 is a side view of the insulating plate of Figure 3 in which the opposing conductive sheets have been bonded; Figure 5 is a side view of symmetrical bonding dies, multiple insulating plates and multiple conductive sheets; and Figure 6 is a side view of the insulating plates of Figure 5 in which the multiple conductive sheets have been bonded.

Referring to Figure 1, holes 11 and 12 are formed through insulating plate 10. Conductive sheets 13 and 14 are on opposite surfaces of insulating plate 10 and cover hole 11. Conductive sheets 15 and 16 are on opposite surfaces of insulating plate 10 and cover hole 12. Die 20 has die face 31 facing hole 11 and die face 33 facing hole 12. Die 21 has die face 32 facing hole 11 and die face 34 facing hole 12.

Referring to Figure 2, conductive sheets 13 and 14 are on opposite surfaces of insulating plate 10 and are in contact within hole 11. Conductive sheets 15 and 16 are on opposing surfaces of insulating plate 10 and are in contact within hole 12.

Referring to Figures 1 and 2, holes 11 and 12 are first formed in insulating plate 10. After these holes are formed sheets of conductive material such as copper or aluminum are placed into flush contact with each side of the insulating plate and in such fashion that the holes which were previously formed are covered by the conductive plate. Dies 20 and 21 are constructed of a material such as hardened steel. Die faces such as 31 and 32 are formed in locations so that they mutually oppose each other. The insulating plate 10 with its conductive layers 13, 14, 15 and 16 is placed between the dies such that the holes which have been formed in the plates are aligned between the mutually opposing die faces. After the insulating plate with the conductive layers has been aligned between dies 20 and 21 these dies are forced together. Die face 31 contacts conductive sheet 13 and die face 32 contacts conductive sheet 14. These two conductive sheets are bent inward until they meet.

After the plates meet they are mechanically bonded to form an electrical contact. This is done by using sufficient force on dies 20 and 21 to cause a cold weld between sheets 13 and 14, by vibrating dies 20 and 21 to cause an ultrasonic bond or by heating to solder or braze a junction between sheets 13 and 14 or a fusion weld is formed between sheets 13 and 14. In a similar fashion conductive sheets 15 and 16 are bonded together by die faces 33 and 34.

The resulting bonded condition is shown in Figure 2. Sheets 13 and 14 are physically joined within hole 11 and sheets 15 and 16 are physically joined within hole 12. In the embodiment shown the opposing sheets will be bonded over the entire area of contact.

But if desired, the die faces could be so formed to punch a hole through the bonded surface leaving the sheets in contact only around the circumference of the hole.

Referring to Figure 3, holes 41 and 42 are formed in plate 40. Conductive sheets 43 and 44 are on opposite surfaces of plate 40 and cover hole 41. Conductive sheets 45 and 46 are on opposite surfaces of plate 40 and cover hole 42. Die 50 has die face 52 facing hole 41 and die face 53 facing hole 42. Plate 51 has a flat surface facing die 50.

Referring to Figure 4, conductive sheets 43 and 44 are on opposite surfaces of plate 40 but are joined together through hole 41.

Conductive sheets 45 and 46 similarly configured are joined through hole 42.

Figures 3 and 4 show a similar bonding configuration to that of Figures 1 and 2 except that there is only one die with protruding die faces. The conductive sheets are bonded together as a result of force exerted by die faces 52 and 53 against plate 51. The only difference from the previous technique is that the area of contact is in the plane of the lower sheets, 44 and 46, rather than the center of the hole.

Referring to Figure 5, insulating plates 60, 61 and 62 are maintained in alignment and holes 75 and 76 are formed through the plates. Conductive sheets 63 and 71 are on the upper surface of plate 60. Sheets 64 and 72 are between plates 60 and 61.

Sheets 65 and 73 are between plates 61 and 62. Sheets 66 and 74 are on the lower surface of plate 62. Sheets 63, 64, 65 and 66 cover hole 75. Sheets 71, 72, 73 and 74 cover hole 76. Die face 82 on die 80 is aligned over hole 75 and opposes die face 84 on die 81. Die face 83 on die 80 is aligned over hole 76 and opposes die face 85 on die 81.

Referring to Figure 6 insulating plates 60, 61 and 62 and conductive sheets 63, 64, 65, 66, 71, 72, 73 and 74 are arranged in the same fashion as in Figure 5.

Referring to both Figures 5 and 6, there is shown an embodiment of this invention wherein multiple layers of conductive sheets are electrically connected. The mechanical bonding of the multiple layers is performed in the same manner as previously described. In addition, multiple layers could be connected using only one die with die faces as is shown in Figures 3 and 4.

The primary techniques for bonding the conductive sheets, cold welding and ultrasonic welding, have been described above.

But there are other joining techniques which can be used. If the two metals to be joined are properly selected and contacted in a particular gaseous environment, a fusion weld is formed and much less force is required than that needed for cold welding. Another method consists of heating the metal sheets to near their melting points then forcing them together and forming a thermal bond. Also, conventional solder or welding techniques could be used.

Although sheets of metal have been used in the previous embodiments, it is to be understood that wires or metallic ribbons could be so joined. Also, any combination of sheets, wires and ribbons can be utilized.

While embodiments of the invention have been described in detail, modifications and alterations may occur to others upon a reading and understanding of the specification. It is intended to include all such modifications and alterations as fall within the scope of the appended claims.

WHAT WE CLAIM IS: 1. A method of establishing a conductive path through an insulating plate which comprises forming at least one hole through the plate, placing conductive material over each opening of the hole and in flush contact with each surface of the plate, and applying a force against at least a first of the conductive materials to drive it through the hole and into contact with a second of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. with each side of the insulating plate and in such fashion that the holes which were previously formed are covered by the conductive plate. Dies 20 and 21 are constructed of a material such as hardened steel. Die faces such as 31 and 32 are formed in locations so that they mutually oppose each other. The insulating plate 10 with its conductive layers 13, 14, 15 and 16 is placed between the dies such that the holes which have been formed in the plates are aligned between the mutually opposing die faces. After the insulating plate with the conductive layers has been aligned between dies 20 and 21 these dies are forced together. Die face 31 contacts conductive sheet 13 and die face 32 contacts conductive sheet 14. These two conductive sheets are bent inward until they meet. After the plates meet they are mechanically bonded to form an electrical contact. This is done by using sufficient force on dies 20 and 21 to cause a cold weld between sheets 13 and 14, by vibrating dies 20 and 21 to cause an ultrasonic bond or by heating to solder or braze a junction between sheets 13 and 14 or a fusion weld is formed between sheets 13 and 14. In a similar fashion conductive sheets 15 and 16 are bonded together by die faces 33 and 34. The resulting bonded condition is shown in Figure 2. Sheets 13 and 14 are physically joined within hole 11 and sheets 15 and 16 are physically joined within hole 12. In the embodiment shown the opposing sheets will be bonded over the entire area of contact. But if desired, the die faces could be so formed to punch a hole through the bonded surface leaving the sheets in contact only around the circumference of the hole. Referring to Figure 3, holes 41 and 42 are formed in plate 40. Conductive sheets 43 and 44 are on opposite surfaces of plate 40 and cover hole 41. Conductive sheets 45 and 46 are on opposite surfaces of plate 40 and cover hole 42. Die 50 has die face 52 facing hole 41 and die face 53 facing hole 42. Plate 51 has a flat surface facing die 50. Referring to Figure 4, conductive sheets 43 and 44 are on opposite surfaces of plate 40 but are joined together through hole 41. Conductive sheets 45 and 46 similarly configured are joined through hole 42. Figures 3 and 4 show a similar bonding configuration to that of Figures 1 and 2 except that there is only one die with protruding die faces. The conductive sheets are bonded together as a result of force exerted by die faces 52 and 53 against plate 51. The only difference from the previous technique is that the area of contact is in the plane of the lower sheets, 44 and 46, rather than the center of the hole. Referring to Figure 5, insulating plates 60, 61 and 62 are maintained in alignment and holes 75 and 76 are formed through the plates. Conductive sheets 63 and 71 are on the upper surface of plate 60. Sheets 64 and 72 are between plates 60 and 61. Sheets 65 and 73 are between plates 61 and 62. Sheets 66 and 74 are on the lower surface of plate 62. Sheets 63, 64, 65 and 66 cover hole 75. Sheets 71, 72, 73 and 74 cover hole 76. Die face 82 on die 80 is aligned over hole 75 and opposes die face 84 on die 81. Die face 83 on die 80 is aligned over hole 76 and opposes die face 85 on die 81. Referring to Figure 6 insulating plates 60, 61 and 62 and conductive sheets 63, 64, 65, 66, 71, 72, 73 and 74 are arranged in the same fashion as in Figure 5. Referring to both Figures 5 and 6, there is shown an embodiment of this invention wherein multiple layers of conductive sheets are electrically connected. The mechanical bonding of the multiple layers is performed in the same manner as previously described. In addition, multiple layers could be connected using only one die with die faces as is shown in Figures 3 and 4. The primary techniques for bonding the conductive sheets, cold welding and ultrasonic welding, have been described above. But there are other joining techniques which can be used. If the two metals to be joined are properly selected and contacted in a particular gaseous environment, a fusion weld is formed and much less force is required than that needed for cold welding. Another method consists of heating the metal sheets to near their melting points then forcing them together and forming a thermal bond. Also, conventional solder or welding techniques could be used. Although sheets of metal have been used in the previous embodiments, it is to be understood that wires or metallic ribbons could be so joined. Also, any combination of sheets, wires and ribbons can be utilized. While embodiments of the invention have been described in detail, modifications and alterations may occur to others upon a reading and understanding of the specification. It is intended to include all such modifications and alterations as fall within the scope of the appended claims. WHAT WE CLAIM IS:

1. A method of establishing a conductive path through an insulating plate which comprises forming at least one hole through the plate, placing conductive material over each opening of the hole and in flush contact with each surface of the plate, and applying a force against at least a first of the conductive materials to drive it through the hole and into contact with a second of

the conductive materials, and producing a metallurgical junction between the conductive materials at the zone of contact.

2. A method according to claim 1, further comprising applying a force against the second conductive material to drive it through the hole into contact with the first conductive material.

3. A method according to claim 1 or 2, wherein the or each force is applied to the conductive materials at the zone of contact to form a hole therethrough.

4. A method according to claim 1, 2 or 3, wherein the metallurgical junction is cold weld.

5. A method according to claim 1, 2 or 3, wherein the metallurgical junction is formed by vibrating at least that portion of the conductive materials in the zone of contact to cause the conductive materials to bond at the point of said contact.

6. A method according to claims 1, 2 or 3, wherein the metallurgical junction is a fusion weld.

7. A method of establishing a conductive path through an insulating plate, the method being substantially as herein described with reference to the accompanying drawings.

8. An insulating plate having a conductive path therethrough and produced by a method according to any of the preceding claims.