Micro soldering system for electronic components

• US 5,364,011 A
• Filed: 04/06/1994
• Issued: 11/15/1994
• Est. Priority Date: 04/05/1993
• Status: Expired due to Fees

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Ford Motor Company
• Inventors: Baker, Jay D., Mikkor, Matti, Merala, Thomas B., McMillan, Richard K. II, Green, Wells L., Stevenson, Paul E., Lemecha, Myron, Meyer, Bernard A., Salisbury, Kenneth A.
• Primary Examiner(s): Ramsey, Kenneth J.
• Application Number:
  US08/223,569
• Time in Patent Office: 223 Days
• Field of Search: 228/33, 228/219, 228/180.21, 118/50, 118/302, 427/96, 427/256
• US Class Current: 228/180.21
• CPC Class Codes: B23K 1/012 Soldering with the use of hot gas
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 3/0623 for shaped solder piece feeding, e.g. preforms, bumps, balls, pellets, droplets
• CPC Class Codes: H05K 3/3457 Solder materials or compositions; Methods of application thereof

Abstract

A micro soldering apparatus and method comprising a system (10) for attaching an electronic component (12) to a substrate (14). The system (10) comprises a soldering tool (16) including a dispensing orifice assembly (18) for pulsatingly dispensing a controlled quantity of molten solder (19) to a component (12) and substrate (14) so that the component is joined to the substrate (14) mechanically and electrically upon solidification of the molten solder (19). There is no physical contact between the dispensing orifice assembly (18) and joint. The system (10) also includes a controller for the soldering tool (16). The controller functions in response to process control parameters so that the controlled quantity of molten solder (19) is dispensed through a non-oxidizing atmosphere by a pressure pulse applied to the molten solder.

Claims

1. An micro soldering system for attaching an electronic component to a substrate, comprising:

a soldering tool including a dispensing orifice assembly for dispensing a controlled quantity of molten solder at one or more sites on the component or the substrate or both so that the component is attached to the substrate mechanically and electrically upon solidification of the molten solder without physical contact between the dispensing orifice assembly and the one or more sites; and

means for controlling the soldering tool in response to process control parameters so that the controlled quantity of molten solder is dispensed by a pressure pulse through a non-oxidizing atmosphere.

2. The micro soldering system of claim 1, further including:

a reservoir disposed in fluid communication with the dispensing orifice assembly for delivering molten solder thereto;

the dispensing orifice assembly comprising;

a hollow barrel member in communication with the reservoir, the barrel member defining an open bore therewithin;

a cap which engages an end of the barrel member, the cap being provided with an aperture which communicates with the bore;

a die sealingly received within the aperture, the die having one or more flow passages through which the molten solder may pass before alighting upon one or more sites to be soldered.

3. The micro soldering system of claim 2 wherein the die comprises silicon, the die, and the one or more flow passages being prepared by silicon micro machining procedures.

4. The micro soldering system of claim 3, wherein the die and the flow passages are provided with a cladding layer so that the molten solder is chemically isolated from the die, thereby avoiding flow obstruction by reaction products of molten solder with the die and solder contamination.

5. The micro soldering system of claim 4, wherein the cladding layer comprises a member selected from the group consisting of silicon nitride, boron nitride, and the like.

6. The micro soldering system of claim 2 wherein the die includes a downstream edge defining a chamfered portion, each flow passage extending through the chamfered portion.

7. The micro soldering system of claim 2, wherein at least one of the flow passages is provided with a triangular section along at least part of its length.

8. The micro soldering system of claim 2, wherein one or more of the flow passages is characterized by an aspect ratio defined by the relationship of its length (L) to its average diameter (D), the aspect ratio being about 100:

1.

9. The micro soldering system of claim 2, wherein each dispensing orifice assembly is provided with 64 flow passages.

10. The micro soldering system of claim 2, wherein there is a single component, and the soldering tool is provided with a number of dispensing orifice assemblies selected from the group consisting of 1, 2, 3, and 4.

11. The micro soldering system of claim 1, further including:

means for replacing the soldering tool.

12. The micro soldering system of claim 1, further including:

means for reposing the soldering tool at a parking station in readiness for deployment, the parking station providing a non-oxidizing atmosphere and temperature sufficient to sustain the solder in a fluid state.

13. The micro soldering system of claim 1, further including inerting means for providing an inert atmosphere above the reservoir to minimize oxidation of the molten solder before dispensing.

14. The micro soldering system of claim 1, further including means for altering the relative positioning between the substrate and the dispensing orifice assembly.

15. The micro soldering system of claim 1, wherein the means for controlling the soldering tool includes means for altering the relative positioning between the dispensing orifice assembly and the substrate.

16. The micro soldering system of claim 1, wherein the soldering tool includes means for delivering thermal energy to the reservoir of molten solder.

17. The micro soldering system of claim 1, further comprising:

means for retrieving components and positioning them on a substrate.

18. A method for attaching an electronic component to a substrate, comprising the steps of:

providing a soldering tool including a dispensing orifice assembly for dispensing a controlled quantity of molten solder in a pulsed manner at one or more sites on the component or the substrate or both so that the component is attached to the substrate mechanically and electrically upon solidification of the molten solder without physical contact between the dispensing orifice assembly and the one or more sites;

conveying the substrate and one or more components to be soldered thereto so that the lateral and vertical location thereof is registered in relation to the soldering tool;

purging oxygen from a region surrounding the substrate and dispensing orifice assembly, thereby establishing a non-oxidizing environment therein;

dispensing the controlled quantity of molten solder from one or more dispensing orifice assemblies, the molten solder travelling through the non-oxidizing atmosphere and striking a surface of the component or substrate or both to be joined, the molten solder wetting the surfaces thereof and forming a localized electrical and mechanical contact between the surfaces to be joined.

19. The method of claim 18, further comprising the step of:

preheating the substrate during the purging step.

20. The method of claim 19, further comprising the step of:

heating the substrate during the solder dispensing step.