CN100575560C

CN100575560C - Splicing ear

Info

Publication number: CN100575560C
Application number: CN200510081322A
Authority: CN
Inventors: 铃木雅史; 立石圭一郎; 小笠弘之
Original assignee: Omron Corp
Current assignee: Omron Corp
Priority date: 2004-08-04
Filing date: 2005-06-24
Publication date: 2009-12-30
Anticipated expiration: 2025-06-24
Also published as: JP2006049083A; KR20060048542A; KR100722072B1; CN1733979A; JP4320623B2

Abstract

A kind of splicing ear prevents the generation of short circuit and the increase of contact resistance effectively in the part of giving mechanically compress stress, and is good at the wetting quality of the part soldering alloy of tape welding tin.This splicing ear has the plating layer structure in the part that is endowed mechanically compress stress, this plating layer structure be on mother metal, have pure-nickel-layer, nickel-Sn intermetallic compound layer successively, by mixolimnion and stannic oxide layer that nickel-Sn intermetallic compound and pure tin constitute, the part of the nickel-Sn intermetallic compound in the mixolimnion contacts with stannic oxide layer.

Description

Splicing ear

Technical field

The present invention relates to constitute the terminal of junctor, particularly relate to having and be used for being electrically connected and give the splicing ear of the part of mechanically compress stress with other parts such as flexible substrates.

Background technology

The terminal that constitutes junctor is implemented the plating processing usually on whole.Handle as plating, from improving the viewpoint of erosion resistance and sliding, after forming the tin layer on the nickel dam, reflux (reflow) handles (for example patent documentation 1 and patent documentation 2) as can be known.

But, in the existing splicing ear that obtains by above-mentioned technology, exist to produce whisker (palpus) and contact with adjacent splicing ear, cause problem of short-circuit.In addition, also there is wetting quality reduction to the soldering alloy of splicing ear, or the problem of the contact resistance of terminal increase.

Patent documentation 1: the spy opens flat 6-73593 communique

Patent documentation 2: the spy opens the 2001-59197 communique

Summary of the invention

The present invention develops in view of the above problems, and its purpose is to provide a kind of splicing ear, prevents the generation of short circuit and the increase of contact resistance effectively in the part of giving mechanically compress stress, and is good to the wetting quality of soldering alloy in the part of tape welding tin.

Splicing ear of the present invention, has the plating layer structure in the part of giving mechanically compress stress, this plating layer structure has pure-nickel-layer, nickel-Sn intermetallic compound layer successively, is made of nickel-Sn intermetallic compound and pure tin on mother metal mixolimnion and stannic oxide layer, wherein, the part of the nickel-Sn intermetallic compound in the mixolimnion contacts with stannic oxide layer.

Though the mechanism that existing splicing ear is produced whisker is detail knowledge not, considers to have the explanation based on following mechanism.As shown in Figure 5, after forming tin layer 52 on the nickel dam 51 of mother metal 50, carry out reflow treatment, then between nickel dam 51 and tin layer 52, generate nickel-Sn intermetallic compound 53, form stannic oxide layer 54 on the surface.At this moment, when the more weak and reflow treatment of treatment condition is insufficient, there is the tin layer 52 that does not contain nickel-Sn intermetallic compound.When in a single day such tin layer is endowed mechanically compress stress 55 because of easy deformation, then the internal stress in this tin layer increases.When internal pressure increases, cause move (transfer) of tin atom, the crystalline state of the tin layer that forms during plating is destroyed, tin layer instabilityization.Then, in the process that shifts to steady state, recrystallize, the result forms whisker 56 or extrudes part (ヨリ) 57.

On the other hand, consider when the reflow treatment condition is strong that promote the generation of nickel-Sn intermetallic compound, the tin layer is transformed into nickel-Sn intermetallic compound layer, therefore, this nickel-Sn intermetallic compound causes the wetting quality of scolding tin to reduce, and contact resistance increases.

Splicing ear of the present invention is owing to the generation of restraining whisker (palpus) in the part of giving mechanically compress stress, so can prevent the generation of short circuit effectively.In addition, the contact resistance of giving the part of mechanically compress stress reduces effectively.And splicing ear of the present invention is good to the wetting quality of soldering alloy in the part of tape welding tin.

Description of drawings

Fig. 1 is the mode sectional drawing of the plating layer structure of having of the splicing ear of the present invention part of giving mechanically compress stress;

Fig. 2 is used to illustrate that splicing ear of the present invention prevents the mode sectional drawing of the mechanism of generations such as whisker;

Fig. 3 is the sketch chart of one of splicing ear of the present invention example;

Fig. 4 is the summary section that is used to illustrate the use form of splicing ear of the present invention;

Fig. 5 is used to illustrate that existing splicing ear produces the mode sectional drawing of the mechanism of whisker etc.

Embodiment

Splicing ear of the present invention has plating layer structure A shown below in the part of giving mechanically compress stress.

As shown in Figure 1, plating layer structure A is characterised in that, the Ni-Sn layer 3 that on mother metal 1, has the nickel dam 2 that constitutes by pure nickel successively, constitutes by nickel-Sn intermetallic compound 6, by mixolimnion 4 and stannic oxide layer 5 that nickel-Sn intermetallic compound 6 and pure tin 7 constitute, the part of the nickel-Sn intermetallic compound 6 in the mixolimnion 4 contacts with stannic oxide layer 5.That is, after forming pure-nickel-layer and pure stannum layer successively, by moderately carrying out reflow treatment, the nickel-Sn intermetallic compound that generates between pure-nickel-layer and pure stannum layer (simply being called " Ni-Sn ") growth arrives stannic oxide layer until its part.Therefore, there is not the tin layer that the pure tin by not nickeliferous-Sn intermetallic compound constitutes in plating layer structure A.

In this manual, pure tin uses with the tin difference that constitutes nickel-Sn intermetallic compound, and the meaning is meant the tin (monomer) that does not constitute this intermetallic compound, and the present invention does not get rid of pure tin and contains impurity such as copper, magnesium, phosphorus.

In addition, pure nickel uses with the nickel difference that constitutes nickel-Sn intermetallic compound too, and the meaning is meant the nickel (monomer) that does not constitute intermetallic compound, and the present invention does not get rid of pure nickel and contains impurity such as copper, magnesium, phosphorus.

In the present invention, constitute above-mentioned plating layer structure A, even, also can prevent through the long-time and whisker that produces or extrude part (ヨリ) while continue to give mechanically compress stress and switch on by the part of giving mechanically compress stress that makes splicing ear.In detail, as shown in Figure 2,, be present in the mixolimnion 4 and the nickel that contacts with stannic oxide layer 5-Sn intermetallic compound 6a also can bear this stress, work as support column even continue to give mechanically compress stress 9 to plating structure A (8).Therefore, in the pure tin part 7 of mixolimnion 4, internal pressure does not increase, and pure tin part 7 does not have instabilityization yet.Its result can suppress to recrystallize, and prevents whisker effectively or extrudes the partly generation of (ヨリ).

As long as the ratio that exists of the nickel-Sn intermetallic compound 6a that contacts with the stannic oxide layer 5 of mixolimnion 4 can prevent the generation of whisker etc. effectively by making this nickel-Sn intermetallic compound 6a supporting external stress, limit especially.For example, and the pure tin (Sn) on the mixolimnion surface after peeling off stannic oxide layer 5 and the occupied area ratio of nickel-Sn intermetallic compound (Ni-Sn) (Sn: Ni-Sn) preferred 99: 1～20: 80, preferred especially 80: 20～50: 50.

The occupied area ratio can be measured by following method.But, be not to utilize this method to measure, as long as can measure the occupied area ratio of the Sn and the Ni-Sn on mixolimnion surface, also can utilize any method to measure.

Specimen surface (stannic oxide layer surface) is carried out the mensuration and the argon ion etching (the about 1nm of etch depth) of Auger electron optical spectroscopy repeatedly, the appearance of layer (be present in stannic oxide layer under layer) that precognition contact with stannic oxide layer.The appearance of the layer that contacts with stannic oxide layer can be by the Auger electron optical spectroscopy the depth direction distribution and the tin spectrographic chemical deviation state of oxygen reflect.Then, by reflection contact with stannic oxide layer layer the determination data of Auger electron optical spectroscopy of appearance obtain the atomic ratio of Sn and Ni-Sn, the occupied area ratio of formation Sn and Ni-Sn.

In addition, from more effectively preventing generations such as whisker and keep the viewpoint of electrical specification that the amount of the pure tin in the mixolimnion 4 is 20～80%, preferred especially 40～60 weight %.

The amount of pure tin can be measured by the following method.But, be not to utilize this method to measure, as long as can measure the amount of the pure tin of mixolimnion, also can utilize any method to measure.

Identical with the measuring method of occupied area ratio, carry out the mensuration and the argon ion etching (the about 1nm of etch depth) of Auger electron optical spectroscopy repeatedly, precognition appearance of mixolimnion and finishing of mixolimnion.The appearance of mixolimnion can reflect by the tin in the layer that contacts with stannic oxide layer and the atomic ratio of nickel.Because tin and nickle atom ratio in nickel-Sn intermetallic compound are 3: 2, thus this atomic ratio height of the ratio of tin, and, can predict the existence of mixolimnion because nickel exists.In addition, finishing of mixolimnion can reach 3: 2 and reflect by the atomic ratio of tin and nickel.Secondly, obtain the amount of pure tin in the full determination data of the Auger electron optical spectroscopy from mixolimnion as mean value.

The thickness of nickel dam 2, Ni-Sn layer 3, mixolimnion 4 and stannic oxide layer 5 is so long as the surface of mixolimnion 4 has above-mentioned occupied area ratio (Sn: Ni-Sn), then be not particularly limited, but usually, preferably has thickness shown below from suppressing whisker and keeping the viewpoint of excellent electric characteristics.

Nickel dam: 1～5 μ m, preferred especially 2～3 μ m;

Ni-Sn layer: 0.5～2 μ m, preferred especially 0.5～1 μ m;

Mixolimnion: 0.1～2 μ m, preferred especially 0.3～1.0 μ m;

Stannic oxide layer: 0.001～0.05 μ m, preferred especially 0.001～0.015 μ m.

As the formation method of above-mentioned such plating layer structure A, after forming nickel dam and tin layer on the mother metal 1 successively, carry out the reflow treatment (heating and melting processing) of appropriateness.When the reflow treatment condition is more weak, as mentioned above, there is the tin layer of not nickeliferous-Sn intermetallic compound.That is nickel-the Sn intermetallic compound that between nickel dam and tin layer, the generates arrival stannic oxide layer of can not growing.Therefore, nickel-Sn intermetallic compound can not work as support column, and owing to internal stress makes tin layer instabilityization, the result forms whisker or extrudes part (ヨリ).On the other hand, when the reflow treatment condition was strong, the interface of the stannic oxide layer 5 in excessive easily generation of nickel-Sn intermetallic compound and the mixolimnion 4 only was made of nickel-Sn intermetallic compound, and contact resistance increases.

The formation method of nickel dam is not particularly limited, as long as adopt for example electroplate liquid composition and 40～55 ℃ and the 20～40A/dm of single nickel salt 300～380g/l, nickelous chloride 40～50g/l, boric acid 45～50g/l and additive (containing negatively charged ion is the additive of interfacial agent) 20～40ml/l ²Condition get final product.The thickness of nickel dam is generally 1～4 μ m, preferred 2～3 μ m.

The formation method of tin layer also is not particularly limited, as long as adopt electroplate liquid composition and 40～60 ℃ and the 20～40A/dm of for example sour 70～140ml/l, tin 160～600ml/l and additive (containing nonionic is the additive of interfacial agent) 20～80ml/l ²Condition get final product.The thickness of tin layer is generally 1～4 μ m, preferred 2～3 μ m.

Reflow treatment is undertaken by the established nickel dam of heating and melting-Xi layer.As long as type of heating can be realized being not particularly limited the plating structure stipulated, adopt the hot blast type of heating usually.The hot blast type of heating is the mode that realizes heating by the hot blast that blows attached specified temperature with the pressure of regulation and time.By the hot blast type of heating, easily only the part of giving mechanically compress stress of splicing ear is carried out reflow treatment, and then can more strictly control treatment condition, can more easily form above-mentioned plating layer structure A, be ideal therefore.As other type of heating, known have by in the stove of specified temperature, placing the specified time realize the stove internal heating mode that heats, but, can not only carry out reflow treatment to the part of giving mechanically compress stress of splicing ear according to this mode.And then owing to can not strictly control treatment condition, so be difficult to form above-mentioned plating layer structure A.

The reflow treatment condition that is used to form plating layer structure A exists with ... the thickness of tin layer, type of heating, splicing ear shape, material etc., therefore, can not decide without exception.

For example, the thickness of tin layer is about 2 μ m, is adopting air quantity 0.8m ³During the hot blast type of heating of/min, preferred hot blast temperature is 340～440 ℃, particularly 380～400 ℃, and the treatment time is 2～3 seconds.

In addition, for example, the thickness of tin layer is about 4 μ m, is adopting air quantity 0.8m ³During the hot blast type of heating of/min, preferred hot blast temperature is 380～400 ℃, and the treatment time is 2～3 seconds.

After carrying out reflow treatment, carry out aftertreatment usually.Aftertreatment for example also can be cooled off by naturally cooling as long as realize cooling.

As mother metal, also can use any metallic substance that in the past used as the mother metal of splicing ear, for example alloy of copper, copper and tin, iron, phosphorus etc. etc.

On mother metal, at first form nickel dam usually, carry out electrolytic degreasing processing and acid activity then and handle.

Splicing ear of the present invention also has other plating layer structure B in the part of tape welding tin.Plating layer structure B is not particularly limited as long as the surface is made of pure stannum layer, but from splicing ear have the viewpoint of the operation simplification that the part of above-mentioned plating layer structure A handles simultaneously, preferably on mother metal, have pure-nickel-layer and pure stannum layer successively.Mother metal is identical with above-mentioned mother metal.

Desirable plating layer structure B does not so carry out reflow treatment and aftertreatment, in addition, can utilize the method identical with the formation method of plating layer structure A to form.The thickness of nickel dam is generally 1～4 μ m, preferred especially 2～3 μ m.The thickness of tin layer is generally 1～4 μ m, preferred especially 2～3 μ m.

The preferred Sn3Ag0.5Cu of soldering alloy that when splicing ear of the present invention is welded on the connection substrate, uses.

Part outside the part of giving mechanically compress stress of splicing ear of the present invention and the part of tape welding tin can have the plating layer of any structure, or also can not have plating layer.From etch-proof viewpoint, preferably on mother metal, only has pure-nickel-layer.Mother metal is and above-mentioned mother metal identical materials.

Nickel dam can utilize the identical method of the nickel dam when forming plating layer structure A to form.The thickness of nickel dam is generally 1～4 μ m, preferred especially 2～3 μ m.

Splicing ear of the present invention has shape for example shown in Figure 3.In splicing ear shown in Figure 3 10, Reference numeral 11 is the parts of giving mechanically compress stress, has above-mentioned plating layer structure A.In Fig. 3, Reference numeral 12 is parts of tape welding tin, has above-mentioned plating layer structure B.In addition, carry out plating easily from splicing ear 10 and handle, and the viewpoint that obtains effect of the present invention more reliably sets out, usually as shown in Figure 3, handle so that whole X zone has plating layer structure A, whole Y zone has plating layer structure B.

Splicing ear 10 shown in Figure 3 uses under form for example shown in Figure 4.In detail, splicing ear 10 is fixed on the connection substrate 16 by soldering alloy 15 well in the part 12 of tape welding tin.On the other hand, in terminal 10, insert other parts be used for being electrically connected (for example flexible substrate 17 etc.) with this terminal.Then, by further insertion slide block 18, part 11 is situated between and is endowed mechanically compress stress by flexible substrate 17 grades, thereby realizes the electrical connection of part 11 and flexible substrate 17 etc.

Embodiment

Embodiment 1

Copper mother metal (the about 4mm of total length (L of Fig. 3)) with shape shown in Figure 3 is carried out processing shown below successively, obtain splicing ear.

Electrolytic degreasing is handled

Whole of mother metal was flooded drying 10 seconds in the alkaline cleaner of concentration 5%.

Acid activity is handled

Whole of mother metal after the electrolytic degreasing processing was flooded drying 10 seconds in the aqueous sulfuric acid of concentration 5%.

Nickel Plating Treatment

Whole condition with table 1 of mother metal after the acid activity processing carried out Nickel Plating Treatment (nickel layer thickness: 2 μ m).

Zinc-plated processing

Mother metal two ends after the Nickel Plating Treatment (being X zone and the Y zone of Fig. 3 in detail) carried out zinc-plated processing (zinc-plated thickness: 2 μ m) with the condition of table 1 successively.

Table 1

Operation	Electroplate liquid is formed	Temperature	Current density
Operation	Electroplate liquid is formed	Temperature	Current density	Nickel Plating Treatment	Single nickel salt: 300～380g/l nickelous chloride: 40～50g/l boric acid: 45～50g/l additive (containing negatively charged ion is the additive of interfacial agent): 20～40ml/l	50℃	34A/dm ²
Zinc-plated processing	Acid: 75ml/l tin: 400ml/l additive (containing nonionic is the additive of interfacial agent): 60ml/l	50℃	31A/dm ²	Nickel Plating Treatment		50℃	34A/dm ²

Reflow treatment

Reflow treatment is carried out with the condition of table 2 in X zone (texture map 3) to the mother metal after the zinc-plated processing.

Table 2

Operation	Embodiment/comparative example	Treatment condition
Operation	Embodiment/comparative example	Treatment condition	Reflow treatment	Embodiment 1	Hot blast type of heating air quantity: 0.8m ³/ min temperature: 340～360 ℃ of times: 2～3 seconds

Aftertreatment

Whole of mother metal after the reflow treatment was flooded drying 5 seconds in the soluble oil of concentration 10%.

Embodiment 2 and embodiment 3, comparative example 1 and 2

Except that the condition that the reflow treatment condition is changed in the table 3 record, utilize the method identical to obtain splicing ear with embodiment 1.

Table 3

Evaluation of physical property

The plating layer structure in the X zone (with reference to Fig. 3) in the splicing ear that analysis obtains.

The occupied area ratio

Occupied area ratio (the Sn: Ni-Sn) on the surface that mensuration stripper surface stannic oxide layer obtains.

The pure tin amount

Measure surface oxidation tin layer just down layer the pure tin amount.

Layer structure and thickness

Utilize sweep type Auger electron optical spectroscopy (NEC society system) to measure the thickness of (analyze and convert) layer structure and each layer.That is, carry out the mensuration and the argon ion etching (the about 1nm of etch depth) of Auger electron optical spectroscopy repeatedly, check layer structure and thickness based on determination data.Since on each adjacent layer based on the having or not or the boundary of each layers of grasp such as the ratio of constituting atom and variation thereof of intrinsic atom, so can obtain the thickness of layer structure and each layer.

These result is summed up in table 4 expression.

Table 4

As can be known from these results, in embodiment 1～3, has mixolimnion.

In comparative example 1, between mixolimnion and stannic oxide layer, there is pure stannum layer as can be known.

In comparative example 2, there is not mixolimnion as can be known, and has the Ni-Sn layer just down at stannic oxide layer.

Performance evaluation

Give the partial short circuit of mechanically compress stress

Check FPC being assembled with on the junctor of splicing ear, at room temperature place 500 hours after, utilize electron microscope to confirm whisker.Represent metewand below.

Zero: the whisker total length is 0 μ m (not producing whisker fully);

△: the whisker total length is less than or equal to 30 μ m (no problem in the practicality);

*: the whisker total length surpasses 30 μ m.

Give the contact resistance of the part of mechanically compress stress

Check FPC being assembled with on the junctor of splicing ear, measure with four-terminal method by the circuit element tester.Represent metewand below.

Zero: contact resistance is less than or equal to 21m Ω;

△: contact resistance is less than or equal to 40m Ω (no problem in the practicality);

*: contact resistance surpasses 40m Ω.

The junctor that will be assembled with the splicing ear of 50 pins with following conditions is installed on the printed-wiring board (PWB), confirms whether to form fillet (Off イレ Star ト).(mounting condition, scolding tin kind: Sn3Ag0.5Cu, mask thicknesses: 0.12,235 ℃ of thermal spikes are installed.)

Embodiment and comparative example all have good wetting quality, can confirm rounded shapes on whole pins.

Zero: on whole pins, confirm fillet;

*: do not form fillet.

Claims

1, a kind of splicing ear, it has the plating layer structure in the part that is endowed mechanically compress stress, this plating layer structure is mixolimnion and the stannic oxide layer that has pure-nickel-layer, nickel-Sn intermetallic compound layer successively on mother metal, be made of nickel-Sn intermetallic compound and pure tin, it is characterized in that the part of the nickel-Sn intermetallic compound in the mixolimnion contacts with stannic oxide layer.

2, splicing ear as claimed in claim 1 is characterized in that, the pure tin (Sn) on the mixolimnion surface in the interface of mixolimnion and stannic oxide layer and the occupied area ratio of nickel-Sn intermetallic compound (Ni-Sn) (Sn: Ni-Sn) be 99: 1～20: 80.

3, splicing ear as claimed in claim 1 or 2 is characterized in that, the amount of the pure tin of mixolimnion is 20～80 weight %.

4, splicing ear as claimed in claim 1 or 2 is characterized in that, splicing ear also has the plating layer structure that there is pure stannum layer on the surface in the part of tape welding tin.

5, splicing ear as claimed in claim 3 is characterized in that, splicing ear also has the plating layer structure that there is pure stannum layer on the surface in the part of tape welding tin.