CN1167115C

CN1167115C - Inverse-fastening process of miniature chip

Info

Publication number: CN1167115C
Application number: CNB021108781A
Authority: CN
Inventors: 程知群; 孙晓玮
Original assignee: Shanghai Institute of Microsystem and Information Technology of CAS
Current assignee: Shanghai Institute of Microsystem and Information Technology of CAS
Priority date: 2002-02-22
Filing date: 2002-02-22
Publication date: 2004-09-15
Anticipated expiration: 2022-02-22
Also published as: CN1367529A

Abstract

The present invention relates to inverse-fastening technology of a miniature chip the dimension of which is smaller than the hole diameter of a suction head of an inverse-fastening machine, which belongs to the technical field of microelectronics integration and encapsulation. The present invention is characterized in that (1) an adhesive in solid state under room temperature can be arranged on a carrier; the carrier can be heated until the adhesive is melted, and the heating can be stopped; the adhesive can be solidified on the surface of the carrier by natural cooling, and a thin layer of uniform thickness can be formed; (2) the back surface of a bare chip can be arranged on the carrier coating with the thin layer of the adhesive, and the carrier can be heated until the adhesive is melted; then, the carrier can be cooled to room temperature, and the chip can be stuck on the carrier by the adhesive; (3) the linkage between the bare chip and a basal plate can be completed by an inverse-fastening machine which is applied in general; (4) finally, the carrier can be heated until the adhesive is melted, the carrier can be taken off, and the linkage of a miniature chip and a circuit can be realized. For the existing inverse-fastening device, a special suction head for manufacturing miniature hole diameter for a miniature chip is not needed by the technology provided by the present invention, and the problem of miniature chip assembly is solved.

Description

A kind of micro chip back-off process

Technical field

The present invention relates to a kind of micro chip back-off technology new method, the back-off method of micro chip in a kind of multi-chip module (MCM) is provided or rather.Promptly on existing chip back-off method basis, solve a kind of process that to implement back-off because of size less than the micro chip in back-off machine suction nozzle aperture.Belong to the integrated and method for packing field of microelectronics.

Background technology

MCM occurred in the seventies in 20th century, and a kind of advanced microelectronics assemble method that the nineties, acquisition developed rapidly also is a kind of advanced interfaces method between military electronic devices and components and the machine system.People generally believe that MCM a kind ofly is applicable to the method for packing of advanced very lagre scale integrated circuit (VLSIC) (VISI) device thereby is can bring into play high integration to greatest extent at present, the premium properties of high-speed semiconductor integrated (IC), make the high-velocity electrons system, realize the effective way of complete electronic set miniaturization.

The semiconducter IC bare chip of un-encapsulated is directly installed on the multi-layer wire substrate of MCM, and this is a great development of little method for packing, also is the cause why MCM makes a name the whole world.The welding of IC bare chip (bonding) becomes an important key method in the MCM manufacturing, and it not only greatly influences volume, the weight of MCM product, and packaging efficiency, length of arrangement wire, properties of product, reliability and ratio defective product are all had very big influence.The welding of semiconducter IC bare chip (bonding) method is the research focus in current microelectronics assembling field.

At present, the chip of MCM and substrate be electrically connected three kinds of main modes: wire bond, carrier band weld (TAB) and flip chip bonding automatically.Wherein wire bond is a kind of the most general, also is the most ripe interconnecting method.It is to use hot pressing, ultrasonic or hot sonic soldering Al silk (Au silk) bonding or spot weld chip and substrate on corresponding land positions.The advantage of this method is reliable, with used chip compatibility at present, check easily and reprocess, but it is slow to weld many pins device speed, price is expensive, and assembling productivity ratio is low, and welding wire is longer, inductance is bigger, and chip testing and aging difficulty not too are fit to produce in enormous quantities.TAB connects chip and substrate by carrier band, and chip is connected by solder bump again with carrier band.Carrier band adopts polyimides and Cu material usually.TAB has good electricity, hot property and mechanical performance.TAB automation technolo degree height, before the assembling, chip can be tested and wear out in advance, is suitable for the IC chips welding of I/O pin, minuteness space.But the TAB method is more expensive than wire bond price, needs Special Equipment.Flip-chip is a kind of popular interconnecting method, is subjected to designer's welcome.This method be with IC chip placed face down on the solder bump on the substrate, salient point is aimed at corresponding welding zone figure on the chip and (perhaps solder bump is made on the chip welding zone, corresponding welding zone is aimed on solder bump on the chip and the substrate), then by reflow welding with the IC chips welding to substrate.This chip interconnect method is not because of there being the lead frame of wire bond and TAB, again owing to the welding zone that is chip directly is connected with the welding zone of substrate, so save the space, has the shortest telecommunication path, the interconnection density height, good heat dissipation, the heat that produces in the circuit can directly shed from chip back, when particularly higher or power was big in frequency, advantage was more obvious, in addition, to chip test and the aging ability wire bond that compares easy, also owing to have only a solder side, the reliability height is so be considered to optimal interconnection process.Shortcoming is chip and base plate alignment difficulty, and the visual examination of chip assembling is difficulty also, also needs special equipment, and is in addition, difficult more for the micro chip back-off.

Summary of the invention

The invention provides a kind of special back-off method, purpose is to solve inhales the present situation that the aperture, hole can not pick up chip greater than the back-off machine of bare chip physical dimension, propose a kind of micro chip back-off process, realize the welding (bonding) of chip and substrate by intermediary.Technological operation of the present invention is easy, need not increase any optional equipment, realizes easily.

The implementation procedure of the special back-off method that provides of the present invention comprises:

(1) selects to be under a kind of sheet transparent carrier and a kind of room temperature bonding agent of solid state.Get an amount of bonding agent and be placed on the carrier, carrier is heated to the bonding agent fusing, stop heating.Bonding agent solidifies behind the natural cooling, forms the uniform thin layer of a thickness at carrier surface.

(2) bare chip is placed on the carrier of bonding agent (chip back links to each other with carrier), once more carrier is heated to the bonding agent fusing, be cooled to room temperature again, bare chip just is bonded on the carrier by bonding agent.

(3) finish said process after, bare chip and the welding between substrate (bonding) that just can adopt normally used back-off machine to finish to have carrier.

(4) last, carrier is heated to the bonding agent fusing, take carrier away.Thereby realize the welding (bonding) between bare chip and substrate.

This shows that the key point of micro chip back-off process provided by the invention is:

(1) two sides of chip carrier is smooth, and physical dimension is inhaled the aperture, hole greater than the back-off machine; Carrier is preferably transparent, and the carrier of selecting the transparency is the position of being convenient to observe from the carrier back side chip.

(2) bonding agent between bare chip and carrier is required: be solid insulator under the room temperature, promptly fusing point is greater than room temperature, but fusing point can not be too high.Because temperature is too high, can influence the performance of the active device in the chip, the bonding agent that is lower than 150 ℃ with fusing point is advisable.

The present invention compares with existing method, and the advantage that has is for ready-made back-off equipment, does not need to make for micro chip specially the suction nozzle of micro-aperture.The suction nozzle manufacturing expense height of micro-aperture, difficulty are big, therefore, adopt process provided by the invention just can enlarge the back-off equipment scope of application, solve micro chip assembling difficulty, simultaneously, have also saved the optional equipment expenditure.

Description of drawings

Fig. 1 adopts process provided by the invention to make the bonding process schematic diagram of micro chip and circuit.

Among the figure:

1-wafer carrier 2-insulating adhesive

3-chip 4-mixting circuit

(a) on carrier, add insulating adhesive;

(b) back side of chip is connected with carrier by binding agent;

(c) chip is by carrier and circuit bonding;

(d) take the bonding that carrier is finished chip and circuit away.

Embodiment

With series diode chip (hereinafter to be referred as chip) and ring mixer circuit back-off being connected and composed the balanced mixer that goes in ring is example (with reference to Fig. 1).Chip is of a size of 0.3 * 0.7mm ², the back-off machine inhale the aperture, hole be the back-off machine of 1mm can't be directly with chip bonding in the ring mixer circuit.Adopt physical dimension greater than 1 * 1mm ²Thin slice (two sides is smooth), fusing point is 80 ℃ an insulator bonding agent, the back side of chip is bonding by bonding agent and thin slice.Use the back-off machine with thin slice (microarray strip) and circuit bonding then.At last, be heated to 80 ℃ and melt bonding agent, take out thin slice, thereby be easy to realize the bonding of micro chip and circuit.

Claims

1. micro chip back-off process is characterized in that:

(1) binding agent that is solid state under the room temperature is placed on the carrier, the two sides of carrier is smooth, and the physical dimension of carrier is inhaled the aperture, hole greater than the back-off machine, carrier is heated to the binding agent fusing, stop heating, natural cooling makes binding agent be set in carrier surface, forms the uniform thin layer of a thickness;

(2) the bare chip back side is placed on the carrier that scribbles the binding agent thin layer, once more carrier is heated to the binding agent fusing, be cooled to room temperature once more, chip is bonded on the carrier by binding agent;

(3) adopt the back-off machine that is suitable for usually to finish bonding between bare chip and substrate;

(4) last, carrier is heated to the binding agent fusing, take carrier away, realize the bonding of micro chip and circuit.

2. by the described micro chip back-off of claim 1 process, it is characterized in that described carrier is transparent.

3. by the described micro chip back-off of claim 1 process, it is characterized in that the binding agent fusing point that is solid state under the described room temperature is lower than 150 ℃.