CN104684249A - Printed wiring board and method of manufacturing same - Google Patents
Printed wiring board and method of manufacturing same Download PDFInfo
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- CN104684249A CN104684249A CN201410697006.9A CN201410697006A CN104684249A CN 104684249 A CN104684249 A CN 104684249A CN 201410697006 A CN201410697006 A CN 201410697006A CN 104684249 A CN104684249 A CN 104684249A
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Abstract
The invention provides a printed wiring board and a method of manufacturing the same. Local interlamination through holes can be formed in a highly efficient manner, and the local interlamination through holes and conductive layers can be electrically connected quite reliably. The printed wiring board includes a substrate having a first surface and a second surface that are opposite to each other; a first conductive layer formed on the first surface of the substrate; a second conductive layer formed on the second surface of the substrate; and local interlamination through holes penetrating the substrate and electrically connected to the first surface and the second surface. The local interlamination through holes include conductive particles. The average grain diameter of the conductive particles is greater than or equal to 0.5[mu]m and smaller than or equal to 5.0[mu]m. The draw ratio of the conductive particles is greater than or equal to 2 and smaller than or equal to 20.
Description
Technical field
The present invention relates to a kind of printing distributing board and manufacture method thereof.
Background technology
As printing distributing board, there is the flexible printing patch panel at surface and back side conductive pattern being configured in flexible base, board, use the rigidity printing distributing board of hard substrate and stacked hard substrate and flexible base, board and obtain firm-flexible printing patch panel etc.
As involved printing distributing board, there is upper formation the 1st conductive layer in face (the 1st face) of the side at base material, and the printed on both sides distributing board of upper formation the 2nd conductive layer in face (the 2nd face) of opposite side at substrate.In this printed on both sides distributing board, connect via via hole between the partial layers such as blind hole between usual 1st conductive layer and the 2nd conductive layer.
Between this partial layer, via hole such as runs through the 1st conductive layer and base material, and with the 2nd conductive layers make contact.Between partial layer as above, via hole implements plating (with reference to patent documentation 1) by the inner surface in via hole hole, or carries out after the conductive paste of filling vias hole firing (with reference to patent documentation 2, patent documentation 3) and being formed in via hole hole.
Patent documentation 1: Japanese Unexamined Patent Publication 2006-114787 publication
Patent documentation 2: Japanese Unexamined Patent Publication 2008-103548 publication
Patent documentation 3: Japanese Unexamined Patent Publication 2001-345555 publication
But, when forming via hole by plating, in plating process, if the coating formed from the bottom (surface of the 2nd conductive layer) in via hole hole touches the 1st conductive layer, then also to the 1st conductive layer supply electric power.Therefore, likely precipitating metal on the surface of the 1st conductive layer, the thickness of the 1st conductive layer increases, and is difficult to form fine rule distribution.Problem described above can prevent by forming cover layer on the surface of the 1st conductive layer.But, the surface of the 1st conductive layer is formed cover layer and makes the formation process of via hole complicated, and then cause the complicated of the manufacturing process of printing distributing board, productivity is worsened.
On the other hand, when forming via hole by conductive paste, even if do not form cover layer on the surface of the 1st conductive layer and suppress thickness to increase.But when filled conductive cream, if remain bubble in via hole hole, conductive paste, then the filling likely to the conductive paste in via hole hole is insufficient.Insufficient meeting of the filling of conductive paste described above becomes via hole and the bad reason of the 2nd conductive layers make contact, and especially less the and degree of depth of the diameter in via hole hole more easily occurs more greatly.Therefore, in order to filled conductive cream abundant to via hole hole, the froth breaking operation that the bubble remained in via hole hole, conductive paste is eliminated is needed.In order to carry out this froth breaking operation, need the equipment investment to the vacuum printer of lotion filling etc. can be carried out under vacuum conditions.In addition, when the formation process in implementing path hole, due to need repeatedly to carry out container vacuum attraction and to atmosphere opening, therefore productivity declines.
Summary of the invention
The present invention proposes in view of shortcoming as above, and its object is to provide a kind of printing distributing board and manufacture method thereof, it can form via hole between partial layer efficiently, and between partial layer, the reliability of electrical connection of via hole and conductive layer is excellent.
Printing distributing board of the present invention has: base material, and it has 1st and the 2nd respect to one another; 1st conductive layer, it is formed at the 1st of this base material; 2nd conductive layer, it is formed at the 2nd of above-mentioned base material; And via hole between partial layer, it runs through above-mentioned base material, and be electrically connected above-mentioned 1st conductive layer and above-mentioned 2nd conductive layer, between above-mentioned partial layer, via hole contains conducting particles, the average grain diameter of above-mentioned conducting particles is more than or equal to 0.5 μm and is less than or equal to 5.0 μm, and the draw ratio of above-mentioned conducting particles is more than or equal to 2 and is less than or equal to 20.
In the manufacture method of printing distributing board of the present invention, this printing distributing board has via hole between partial layer, via hole electrical connection the 1st conductive layer and the 2nd conductive layer between this partial layer, 1st conductive layer is formed at the 1st of the base material with the 1st and the 2nd respect to one another, 2nd conductive layer is formed at the 2nd the 2nd conductive layer formed of above-mentioned base material, and the manufacture method of this printing distributing board has: form the via hole operation having bottom outlet; Conductive paste containing conducting particles and adhesive is filled to this via hole operation having bottom outlet, and the operation that this conductive paste is solidified, the viscosity of above-mentioned conductive paste is more than or equal to 20Pas and is less than or equal to 95Pas, thixotropic index is more than or equal to-0.05 and is less than or equal to 0.50, the average grain diameter of above-mentioned conducting particles is more than or equal to 0.5 μm and is less than or equal to 5.0 μm, draw ratio is more than or equal to 2 and is less than or equal to 20, further, the mass ratio of above-mentioned conducting particles and above-mentioned adhesive is more than or equal to 80:20 and is less than or equal to 96:4.
The effect of invention
The present invention can provide a kind of printing distributing board and manufacture method thereof, and it can form via hole between partial layer efficiently, and between partial layer, the reliability of electrical connection of via hole and conductive layer is excellent.
Accompanying drawing explanation
Fig. 1 is the schematic cross sectional views of the important part representing printing distributing board of the first embodiment of the present invention.
Fig. 2 A is the schematic cross sectional views of the important part of the manufacture method of the printing distributing board represented for illustration of Fig. 1.
Fig. 2 B is the schematic cross sectional views of the important part of the manufacture method of the printing distributing board represented for illustration of Fig. 1.
Fig. 2 C is the schematic cross sectional views of the important part of the manufacture method of the printing distributing board represented for illustration of Fig. 1.
Fig. 2 D is the schematic cross sectional views of the important part of the manufacture method of the printing distributing board represented for illustration of Fig. 1.
Fig. 2 E is the schematic cross sectional views of the important part of the manufacture method of the printing distributing board represented for illustration of Fig. 1.
Fig. 2 F is the schematic cross sectional views of the important part of the manufacture method of the printing distributing board represented for illustration of Fig. 1.
Fig. 3 is the schematic cross sectional views of the important part representing printing distributing board of the second embodiment of the present invention.
The explanation of label
1,1A printing distributing board
2,2A base material
20,20A base material through hole
3 the 1st conductive layers
30 conductive layer through holes
4,4A the 2nd conductive layer
40A conductive layer through hole
5 the 1st cover layers
50 coverlays
51 bond layers
6 the 2nd cover layers
60 coverlays
61 bond layers
7,7A via hole is with there being bottom outlet
8,8A blind hole
80,80A flange part
81,81A main part
82,82A recess
90,91 metal films
92 conductive pastes
Embodiment
[explanations to embodiments of the present invention]
The present invention is a kind of printing distributing board, has: base material, and it has 1st and the 2nd respect to one another; 1st conductive layer, it is formed at the 1st of this base material; 2nd conductive layer, it is formed at the 2nd (with the face of the 1st opposition side) of above-mentioned base material; And via hole between partial layer, it runs through above-mentioned base material and is electrically connected above-mentioned 1st conductive layer and above-mentioned 2nd conductive layer, between above-mentioned partial layer, via hole contains conducting particles, the average grain diameter of above-mentioned conducting particles is more than or equal to 0.5 μm and is less than or equal to 5.0 μm, and the draw ratio of above-mentioned conducting particles is more than or equal to 2 and is less than or equal to 20.
In this printing distributing board, between partial layer, via hole contains conducting particles, by making the average grain diameter of this conducting particles and draw ratio in above-mentioned scope, and the conductive paste forming via hole between partial layer is when filling to via hole hole, plays suitable mobility.Thus, improve when forming via hole between partial layer by conductive paste, conductive paste is to the fillibility in via hole hole.Therefore, this printing distributing board can suppress gas bubbles left in via hole hole, conductive paste, can form via hole between partial layer without the need to carrying out froth breaking operation.That is, can not need to form via hole between partial layer under vacuum conditions.Its result, this printing distributing board can for not performing the equipment investment of froth breaking operation, in addition also without the need to repeating vacuum state and to atmosphere opening state, therefore, it is possible to improve productivity.In addition, by suppressing bubble residual to via hole hole, conductive paste, the adhesion of via hole and the 2nd conductive layer between partial layer can be improved, therefore, it is possible to make reliability of electrical connection improve.Therefore, this printing distributing board can form via hole between partial layer efficiently, and between partial layer, the reliability of electrical connection of via hole and the 1st conductive layer and the 2nd conductive layer is excellent.
Between above-mentioned partial layer, via hole can also contain adhesive.As the mass ratio of above-mentioned conducting particles and above-mentioned adhesive, be less than or equal to 96:4 preferably greater than or equal to 80:20.As mentioned above, by the mass ratio of conducting particles and adhesive is set to above-mentioned scope, and fully can guarantee the conductivity of via hole between partial layer, and the thermal coefficient of expansion of via hole between the mobility of conductive paste and partial layer can be made suitable when forming via hole between partial layer.Thereby, it is possible to the reliability of electrical connection of via hole and conductive layer between raising partial layer.
Between above-mentioned partial layer, via hole can be solidified to form by making conductive paste.As the thixotropic index of above-mentioned conductive paste, be less than or equal to 0.50 preferably greater than or equal to-0.05.As mentioned above, according to the conductive paste of thixotropic index in above-mentioned scope, can being guaranteed by (during high shear) during the applying conductive cream such as silk screen printing to conductive paste is filled to via hole hole and suitable mobility.On the other hand, after the filling of conductive paste, (when low sheraing) viscosity of appropriateness can be played, therefore, it is possible to suitably maintain the state be filled to by conductive paste in via hole hole.Therefore, it is possible to improve further when forming via hole between partial layer, conductive paste to the fillibility in via hole hole, and can suppress being mixed into of bubble, residual to via hole hole, conductive paste.Its result, can form via hole between partial layer further efficiently, and the reliability of electrical connection of via hole and conductive layer between partial layer can be made to improve further.
As the viscosity of above-mentioned conductive paste, be less than or equal to 95Pas preferably greater than or equal to 20Pas.As mentioned above, according to the conductive paste of viscosity in above-mentioned scope, to improve further when forming via hole between partial layer conductive paste to the fillibility in via hole hole.Therefore, it is possible to form via hole between partial layer efficiently further, and the reliability of electrical connection of via hole and conductive layer between partial layer can be made to improve further.
As the thermal coefficient of expansion on the thickness direction of above-mentioned base material, preferably greater than or equal to 0.1 times of the above-mentioned thermal coefficient of expansion of via hole between above-mentioned partial layer, and be less than or equal to 10 times of the above-mentioned thermal coefficient of expansion of via hole between above-mentioned partial layer.As mentioned above, by making the thermal coefficient of expansion of base material relative to the thermal coefficient of expansion of via hole between partial layer for being more than or equal to 0.1 times, and be less than or equal to 10 times, can, between partial layer when via hole and base material generation thermal expansion or thermal contraction, make the stress at the interface acting on them less.Its result, can make the reliability of electrical connection of via hole and conductive layer between partial layer improve further.
Between above-mentioned partial layer, via hole is formed by using the silk screen printing of conductive paste.As mentioned above, can expect if by conductive paste silk screen printing is formed via hole between partial layer, then make the moving direction orientation of the long axis scraper plate of the conducting particles in conductive paste by making scraper plate move.Thereby, it is possible to conducting particles contact area each other ensured comparatively large, the contact resistance of via hole and conductor between the resistance of via hole between partial layer and this partial layer can be made to reduce.Its result, can make the reliability of electrical connection of via hole and conductive layer between partial layer improve further.
Between above-mentioned partial layer, via hole can be the blind hole being formed at via hole hole with the end (via hole is with there being bottom outlet).As the above-mentioned via hole internal diameter having bottom outlet, be less than or equal to 100 μm preferably greater than or equal to 40 μm.Preferred above-mentioned via hole is more than or equal to 10 μm with there being the degree of depth of bottom outlet and being less than or equal to 100 μm.In this printing distributing board, even if having the internal diameter of bottom outlet and the degree of depth in above-mentioned scope for the via hole forming via hole between partial layer, also fully can guarantee that conductive paste is to the via hole fillibility having bottom outlet.Therefore, even if this printed wiring is when making via hole miniaturization between partial layer to distribution miniaturization, also can forms via hole between partial layer efficiently, and the reliability of electrical connection of via hole and conductive layer between partial layer can be guaranteed.
The present invention comprises the manufacture method of printing distributing board, wherein, this printing distributing board has via hole between partial layer, via hole electrical connection the 1st conductive layer and the 2nd conductive layer between this partial layer, 1st conductive layer is formed at the 1st formation of the base material with the 1st and the 2nd respect to one another, 1st conductive layer is formed at the 2nd the 2nd conductive layer formed of above-mentioned base material, and the manufacture method of this printing distributing board has: form the via hole operation having bottom outlet; Conductive paste containing conducting particles and adhesive is filled to this via hole operation having bottom outlet; And the operation that this conductive paste is solidified, the viscosity of above-mentioned conductive paste is more than or equal to 20Pas and is less than or equal to 95Pas, thixotropic index is more than or equal to-0.05 and is less than or equal to 0.50, the average grain diameter of above-mentioned conducting particles is more than or equal to 0.5 μm and is less than or equal to 5.0 μm, draw ratio is more than or equal to 2 and is less than or equal to 20, further, the mass ratio of above-mentioned conducting particles and above-mentioned adhesive is more than or equal to 80:20 and is less than or equal to 96:4.
In this manufacture method, as at via hole with there being the conductive paste of filling in bottom outlet, use the conductive paste containing conducting particles, wherein this conducting particles average grain diameter and draw ratio are in above-mentioned scope, thus residual bubble in via hole hole, conductive paste can be suppressed, do not need carry out froth breaking operation and via hole between partial layer can be formed.That is, can not need to form via hole between partial layer under vacuum conditions.Its result, this manufacture method can there is no need for the equipment investment performing froth breaking operation, in addition also without the need to repeating vacuum state and to atmosphere opening state, therefore, it is possible to form via hole between partial layer efficiently.In addition, by suppressing being mixed into of bubble, residual to via hole hole, conductive paste, and the adhesion of via hole and the 2nd conductive layer between partial layer can be improved, therefore, it is possible to provide the printing distributing board of reliability of electrical connection excellence.In addition, by making the viscosity of conductive paste and thixotropic index in above-mentioned scope, conductive paste can be made to improve further to via hole with there being the fillibility of bottom outlet.In addition, as conductive paste, the mass ratio of conducting particles and adhesive in above-mentioned scope, thus fully can guarantee the conductivity of via hole between partial layer further, and the thermal coefficient of expansion of via hole between partial layer can be made suitable.Therefore, this manufacture method can provide and can form via hole between partial layer efficiently, and the printing distributing board of the reliability of electrical connection excellence of via hole and conductive layer between partial layer.
Herein, " between partial layer via hole " is the concept comprising blind hole and buried via hole." average grain diameter " is the nominal value of median particle diameter (D50) or the manufacturer calculated according to the cumulative distribution utilizing laser diffractometry to determine." viscosity " is the value determined according to JIS-Z8803:2011.This viscosity such as can use cone plate type viscometer (" the TV22 type viscosimeter " of East Machine industry society: cone No.7), at rotating speed 1rpm (shear rate 2s
-1), measure under the condition of 25 DEG C." thermal coefficient of expansion " is according to JIS-R3251 " determination method based on the coefficient of linear expansion of the laser interferance method of low-expansion glass ": 1995 and the value determined.This thermal coefficient of expansion such as can use LASER HEAT dilatometer (" the LIX-2L type " of ULVAC science and engineering society) and measure.
In addition, " thixotropic index " is the value utilizing following formula (1) to calculate.
Thixotropic index=log (η 1/ η 2)/log (D2/D1) ... (1)
D1 (shear rate): 2s
-1(rotating speed 1rpm)
D2 (shear rate): 20s
-1(rotating speed 10rpm)
η 1: the viscosity of conductive paste during shear rate D1
η 2: the viscosity of conductive paste during shear rate D2
[detailed contents of embodiments of the present invention]
Hereinafter, with reference to the accompanying drawings of printing distributing board of the present invention and manufacture method thereof.
[the 1st execution mode]
The printing distributing board 1 of Fig. 1 as flexible double-sided printing distributing board distributing board and form.This printing distributing board 1 has: base material 2, the 1st conductive layer 3, the 2nd conductive layer 4, the 1st cover layer 5, the 2nd cover layer 6, via hole are with having bottom outlet 7 and blind hole 8.
< base material >
Base material 2 has 1st and the 2nd respect to one another, on these faces stacked 1st conductive layer 3 and the 2nd conductive layer 4.This base material 2 has insulating properties and flexibility.Base material 2 has the formation via hole base material through hole 20 having bottom outlet 7.
Resin molding can be adopted as base material 2.As this resin molding, such as, can enumerate polyimide film, PETG film etc.
As the lower limit of the average thickness of base material 2, preferably 5 μm, more preferably 10 μm.As the upper limit of the average thickness of base material 2, preferably 100 μm, more preferably 50 μm.If the average thickness of base material 2 is less than above-mentioned lower limit, then likely the intensity of base material 2 is insufficient.On the other hand, if the average thickness of base material 2 exceedes the above-mentioned upper limit, then likely can not meet the requirement of slimming, and likely damage flexibility.In addition, average thickness is defined as the mean value of the thickness determined at any ten points.For its key element except base material 2, when being called average thickness, define similarly.
As the lower limit of the thermal coefficient of expansion at thickness direction of base material 2, be preferably 0.1 times of the thermal coefficient of expansion of blind hole 8, more preferably 0.5 times.Further, as the lower limit of the thermal coefficient of expansion of base material 2, preferred 10ppm/ DEG C, more preferably 20ppm/ DEG C.As the upper limit of the above-mentioned thermal coefficient of expansion of base material 2, be preferably 10 times of the thermal coefficient of expansion of blind hole 8, more preferably 5 times.Further, as the upper limit of the thermal coefficient of expansion of base material 2, preferred 200ppm/ DEG C, more preferably 150ppm/ DEG C.If the thermal coefficient of expansion of base material 2 is less than above-mentioned lower limit, or exceed the above-mentioned upper limit, then likely base material 2 is excessive relative to the difference of the thermal coefficient of expansion of blind hole 8.Its result, when base material 2 and blind hole 8 thermal expansion or thermal contraction, the stress of the interface interaction at them can not be made fully to reduce, and the reliability of electrical connection of base material 2 and blind hole 8 likely reduces.
< the 1st conductive layer >
Base material 2 has 1st and the 2nd respect to one another, and the 1st conductive layer 3 is layered on the 1st (being positioned at the face of upper side in the base material 2 of Fig. 1) of base material 2.1st conductive layer 3 forms pattern with the plan view shape of regulation and has conductive layer through hole 30.As the material of formation the 1st conductive layer 3, the material with conductivity can be listed, such as copper, silver, aluminium, nickel, comprise the alloy of these metals being more than or equal to a kind, wherein, consider the aspect such as conductivity, durability, preferably copper.
As the lower limit of the average thickness of the 1st conductive layer 3, preferably 2 μm, more preferably 5 μm.As the upper limit of the average thickness of the 1st conductive layer 3, preferably 50 μm, more preferably 30 μm.If the average thickness of the 1st conductive layer 3 is less than above-mentioned lower limit, then conductivity is likely insufficient.On the other hand, if the average thickness of the 1st conductive layer 3 exceedes the above-mentioned upper limit, then the flexibility of printing distributing board is likely damaged.
< the 2nd conductive layer >
2nd conductive layer 4 is layered on the 2nd (being positioned at the face of lower side in the base material 2 of Fig. 1) of base material 2.2nd conductive layer 4 forms pattern with the plan view shape of regulation.As the material of formation the 2nd conductive layer 4, the material identical with the 1st conductive layer 3 can be listed.In addition, the average thickness of the 2nd conductive layer 4 is set to identical with the 1st conductive layer 3.
< the 1st cover layer >
1st cover layer 5 protects the 1st conductive layer 3, is layered in the 1st side of base material 2.1st cover layer 5 has coverlay 50 and bond layer 51.
(coverlay)
Coverlay 50 has flexibility, preferably has insulating properties.
As the principal component of coverlay 50, such as can enumerate polyimide resin, epoxy resin, phenolic resins, acrylic resin, mylar, thermoplastic polyimide resin, pet resin, fluororesin, liquid crystal polymer etc., consider thermal endurance aspect, preferred polyimide resin.In addition, this coverlay 50 also can containing other resin, weather resisting agent, antistatic agent etc. except principal component.
As the lower limit of the average thickness of coverlay 50, preferably 3 μm, more preferably 10 μm.As the upper limit of the average thickness of coverlay 50, preferably 500 μm, more preferably 150 μm.If the average thickness of coverlay 50 is less than above-mentioned lower limit, then likely insufficient to the protection of the 1st conductive layer 3.On the other hand, if the average thickness of coverlay 50 exceedes the above-mentioned upper limit, then the flexibility of printing distributing board 1 likely reduces.
(bond layer)
Bond layer 51 is laminated in coverlay 50, makes this coverlay 50 bonding with base material 2 and the 1st conductive layer 3.As this bond layer 51, the material of preferred flexibility, excellent heat resistance, such as, can enumerate polyamide, epoxy resin, butyral resin, acrylic resin etc.
As the lower limit of the thickness of bond layer 51, preferably 12.5 μm, more preferably 15 μm.As the upper limit of the average thickness of bond layer 51, preferably 75 μm, more preferably 50 μm.If the average thickness of bond layer 51 is less than above-mentioned lower limit, then likely fully can not guarantee adhesive strength.On the other hand, if the average thickness of bond layer 51 exceedes the above-mentioned upper limit, then likely damage the flexibility of printing distributing board 1.
< the 2nd cover layer >
2nd cover layer 6 protects the 2nd conductive layer 4, is layered in the 2nd side of base material 2.This cover layer 6 has coverlay 60 and bond layer 61.
Coverlay 60 and bond layer 61 are layers same with the coverlay 50 of the 1st cover layer 5 and bond layer 51.
In addition, the 1st cover layer 5 and the 2nd cover layer 6 are not limited to 2 layers of structure with coverlay and bond layer, also can be have insulating properties, and utilization heating waits and plays the monofilm of suitable cementability.
< via hole is with there being bottom outlet >
Via hole is for forming the via hole hole with the end of blind hole 8 with there being bottom outlet 7.This via hole runs through the 1st conductive layer 3 and base material 2 with there being bottom outlet 7, and overlooks (cross section) shape and be formed as circular and vertical sectional shape is formed as trapezoidal taper.Limit the via hole inner peripheral surface having bottom outlet 7 by the conductive layer through hole 30 of the 1st conductive layer 3 and the base material through hole 20 of base material 2, limit the via hole bottom surface having bottom outlet 7 by the surface (face of substrate layer 2 side) of the 2nd conductive layer 4.
As the via hole lower limit of internal diameter having bottom outlet 7, preferably 40 μm, more preferably 50 μm, preferably 60 μm further.As the via hole upper limit of internal diameter having bottom outlet 7, preferably 100 μm, more preferably 90 μm, preferably 80 μm further.If via hole is less than above-mentioned lower limit with there being the internal diameter of bottom outlet 7, then be likely difficult to form via hole with there being bottom outlet 7.On the other hand, if via hole exceedes the above-mentioned upper limit with there being the internal diameter of bottom outlet 7, then likely obstruction is caused to the graph thinning of the distribution of formation the 1st conductive layer 3 and the 2nd conductive layer 4.Herein, via hole is via hole maximum gauges had in bottom outlet 7 (diameter of upper opening) with there being the internal diameter of bottom outlet 7.
As the via hole lower limit of the degree of depth having bottom outlet 7, preferably 10 μm, more preferably 15 μm, preferably 20 μm further.As the via hole upper limit of the degree of depth having bottom outlet 7, preferably 100 μm, more preferably 75 μm, preferably 50 μm further.If via hole is less than above-mentioned lower limit with there being the degree of depth of bottom outlet 7, then be likely difficult to form via hole with there being bottom outlet 7.On the other hand, if via hole exceedes the above-mentioned upper limit with there being the degree of depth of bottom outlet 7, then likely obstruction is caused to the graph thinning of the distribution of formation the 1st conductive layer 3 and the 2nd conductive layer 4.
< blind hole >
Blind hole 8 is formed in via hole with having in bottom outlet 7, for realizing conducting of the 1st conductive layer 3 and the 2nd conductive layer 4, is equivalent to an example of via hole between partial layer.This blind hole 8 comprises flange part 80, main part 81 and recess 82, runs through the 1st conductive layer 3 and base material 2 at main part 81 place.
The surface contact of flange part 80 and the 1st conductive layer 3.The top of the outer peripheral face of main part 81 contacts with the inner surface of the conductive layer through hole 30 of the 1st conductive layer 3, and the bottom of outer peripheral face contacts with the inner surface of the base material through hole 20 of base material 2.And, the bottom surface of main part 81 and the surface contact of the 2nd conductive layer 4.As mentioned above, blind hole 8 contacts with the 1st conductive layer 3 by making the top of flange part 80 and main part 81, and time main part 81 bottom surface contact with the 2nd conductive layer 4, thus the 1st conductive layer 3 and the 2nd conductive layer 4 to be conducted.
Recess 82 pairs of blind holes 8 are given and are held yielding characteristic.This recess 82 is formed in the central portion of the upper surface of blind hole 8.
Blind hole 8, owing to having recess 82, therefore when printing distributing board 1 bends, is easy to maintain the contact condition with the 1st conductive layer 3 well.Such as, if by printing distributing board 1 with make the 1st conductive layer 3 become outside mode bend, then base material 2 is deformed into, the 1st conductive layer 3 side extend and the 2nd conductive layer 4 side shrink.Now, along with the distortion of this base material 2, both are made to be separated such power to blind hole 8 with the 1st conductive layer 3 effect.On the other hand, the blind hole 8 of printing distributing board 1 has recess 82, and therefore along with the change of base material 2, blind hole 8 is easily deformable, is easy to relax make blind hole 8 be separated such power with both the 1st conductive layers 3.Therefore, printing distributing board 1 is easy to the contact condition maintaining blind hole 8 and the 1st conductive layer 3 well.
Blind hole 8 as described later, by the conductive paste containing conducting particles and adhesive being filled to via hole with after having bottom outlet 7, heating this conductive paste and making it be solidified to form.Therefore, blind hole 8 is containing conducting particles and adhesive.
Conducting particles is for guaranteeing the conductivity of blind hole 8.As conducting particles, preferably use metallic.As this metallic, such as, can enumerate gold particle, silver particles, copper particle, nickel particles, scolding tin particle, silver-plated copper particle etc.These metallics can be used alone, and also can two or more use together.Wherein, consider conductivity aspect, be preferably used alone silver particles or silver-plated copper particle, or use silver particles and silver-plated copper particle together.
As the shape of conducting particles, such as, can enumerate tabular, flat spherical (shape by ball flattening), needle-like etc.The lower limit of the draw ratio of conducting particles is 2, is preferably 3, is more preferably 4.The upper limit of the draw ratio of conducting particles is 20, is preferably 15, is more preferably 10.Being less than or equal to the above-mentioned upper limit by making the draw ratio of conducting particles be more than or equal to above-mentioned lower limit, can giving to conductive paste the thixotropy expected.In addition, if the draw ratio of conducting particles is less than above-mentioned lower limit, then conducting particles contact area each other reduces, and the resistance of blind hole 8 likely becomes excessive.On the other hand, if the draw ratio of conducting particles exceedes the above-mentioned upper limit, then likely because conducting particles causes conducting particles uneven to the dispersiveness deterioration of adhesive, there is poor flow.
The lower limit of the average grain diameter (D50) of conducting particles is 0.5 μm, preferably 0.75 μm, is more preferably 1.0 μm.The upper limit of the average grain diameter (D50) of conducting particles is 5.0 μm, preferably 4.5 μm, is more preferably 4.0 μm.Be less than or equal to the above-mentioned upper limit by making the average grain diameter of conducting particles (D50) be more than or equal to above-mentioned lower limit, and can give to conductive paste the thixotropy expected.In addition, if the average grain diameter of conducting particles (D50) is less than above-mentioned lower limit, then conducting particles contact area each other reduces, and the resistance of blind hole 8 likely becomes excessive.On the other hand, if the average grain diameter of conducting particles (D50) exceedes the above-mentioned upper limit, then likely because conducting particles causes conducting particles uneven to the dispersiveness deterioration of adhesive, there is poor flow.In addition, as the maximum particle diameter (Dmax) of conducting particles, 14 μm are preferably less than or equal to.As mentioned above, by making the maximum particle diameter of described conducting particles (Dmax) be less than or equal to 14 μm, and particle size distribution can be suppressed to magnify, the difference of the peak diameter in particle size distribution and average grain diameter can be made to reduce.Thus, the control of blind hole 8 is easily carried out.
As the lower limit of the specific area of conducting particles, preferred 0.7m2/g, more preferably 1.0m2/g.As the upper limit of the specific area of conducting particles, preferred 3.8m2/g, more preferably 3.0m2/g.Being less than or equal to the above-mentioned upper limit by making the specific area of conducting particles be more than or equal to above-mentioned lower limit, can giving to conductive paste the thixotropy expected.In addition, if the specific area of conducting particles is less than above-mentioned lower limit, then conducting particles contact area each other diminishes, and via hole resistance likely becomes excessive.On the other hand, if the specific area of conducting particles exceedes the above-mentioned upper limit, then likely because the dispersiveness of conducting particles to adhesive worsens, and cause conducting particles uneven, poor flow occurs.
As the lower limit of the tap density of conducting particles, preferred 2.0g/cm3, more preferably 2.5g/cm3.As the upper limit of the tap density of conducting particles, preferred 4.5g/cm3, more preferably 4.0g/cm3.Being less than or equal to the above-mentioned upper limit by making the tap density of conducting particles be more than or equal to above-mentioned lower limit, can giving to conductive paste the thixotropy expected.In addition, if the tap density of conducting particles is less than above-mentioned lower limit, then conducting particles contact area each other diminishes, and the resistance of blind hole 8 likely becomes excessive.On the other hand, if the specific area of conducting particles exceedes the above-mentioned upper limit, then likely because the dispersiveness of conducting particles to adhesive worsens, and cause conducting particles uneven, poor flow occurs.
Above-mentioned adhesive is retraction volume by making conducting particles be bonded to each other, thus realizes the connection of the conducting particles in blind hole 8, meanwhile, realizes blind hole 8 with via hole with having the bonding of bottom outlet 7 or being connected.
As adhesive, such as can enumerate epoxy resin, phenolic resins, mylar, polyurethane resin, acrylic resin, melmac, polyimide resin, polyamide-imide resin etc., wherein, the aspect such as thermal endurance, thermal expansivity is considered, preferred epoxy.
As epoxy resin, such as, can enumerate the bisphenol-type epoxy resin, naphthalene type epoxy resin, phenol aldehyde type epoxy resin, biphenyl type epoxy resin, dicyclopentadiene type epoxy resin, phenoxy resin etc. using bisphenol A-type, bisphenol-f type, bisphenol S type, bisphenol-A D type etc. as skeleton.In these resins, preferred bisphenol A-type.
As the molecular weight of epoxy resin preferably greater than or equal to 45,000 and be less than or equal to 55,000.As epoxide equivalent, preferably greater than or equal to 7,500 and be less than or equal to 8,500.By the molecular weight of epoxy resin and equivalent are set to above-mentioned scope, and the thermal endurance, thermal expansivity etc. expected can be given to base material 2.
As the curing agent of epoxy resin, such as, can enumerate imidazole curing agent, acid anhydride type curing agent, amine curing agent etc., but wherein, consider term of validity aspect, preferred latent curing agent, more preferably microcapsule-type imidazole curing agent.
As the lower limit of the mass ratio of conducting particles and adhesive, preferred 80:20.The preferred 96:4 of the upper limit as this mass ratio, more preferably 93:7.Being less than or equal to the above-mentioned upper limit by making the mass ratio of conducting particles and adhesive be more than or equal to above-mentioned lower limit, the thermal coefficient of expansion of blind hole 8 can being set to desired value.In addition, if the mass ratio of conducting particles and adhesive is less than above-mentioned lower limit, then the relative step-down of the ratio of conducting particles, and the ratio of adhesive uprises relatively, and the resistance of blind hole 8 likely becomes excessive.On the other hand, if above-mentioned mass ratio exceedes the above-mentioned upper limit, then the ratio of conducting particles uprises relatively, and the relative step-down of the ratio of adhesive, conductive paste worsens to via hole with there being the fillibility of bottom outlet 7, between the 1st conductive layer 3 and the 2nd conductive layer 4, likely produce loose contact.
< advantage >
This printing distributing board 1 by making blind hole 8 containing conducting particles, and makes the average grain diameter of this conducting particles and draw ratio in specific scope, thus when utilizing conductive paste formation blind hole 8, conductive paste improves to via hole with there being the fillibility of bottom outlet 7.Therefore, this printing distributing board 1 can suppress to remain bubble at via hole with having in bottom outlet 7, conductive paste, just can form blind hole 8 without the need to carrying out froth breaking operation.Thereby, it is possible to do not need to form blind hole 8 under vacuum conditions.Its result, this printing distributing board 1 can there is no need for the equipment investment performing froth breaking operation, in addition also without the need to repeating vacuum state and to atmosphere opening state, therefore, it is possible to suppress productive deterioration.In addition, because the residual of the bubble to via hole hole 7, conductive paste is inhibited, therefore, it is possible to improve the adhesion of blind hole 8 and the 2nd conductive layer 4, so reliability of electrical connection can be made to improve.Therefore, this printing distributing board 1 can form blind hole 8 efficiently, and the reliability of electrical connection of blind hole 8 and the 1st conductive layer 3 and the 2nd conductive layer 4 is excellent.
The manufacture method > of < printing distributing board
Below, the manufacture method of printing distributing board 1 is described with reference to Fig. 2 A ~ Fig. 2 F.
The manufacture method of this printing distributing board 1 has: at the two sides laminated metal film 90 of base material 2, the operation (with reference to Fig. 2 A) of 91, to metal film 90, 91 carry out patterning and form the operation (with reference to Fig. 2 B) of the 1st conductive layer 3 and the 2nd conductive layer 4, base material 2 is formed the operation (with reference to Fig. 2 C) of base material through hole 20, conductive paste 92 is filled to the via hole operation (with reference to Fig. 2 D and Fig. 2 E) having bottom outlet 7, to the operation (with reference to Fig. 2 E) that the conductive paste 92 after filling heats, the operation (with reference to Fig. 2 F) of stacked 1st cover layer 5 and the 2nd cover layer 6.
(metal film lamination process)
As shown in Figure 2 A, metal film lamination process is the operation using being laminated to base material 2 as the metal film 90,91 of the 1st conductive layer 3 and the 2nd conductive layer 4.As method metal level 90,91 being laminated to base material 2, be not particularly limited, such as, can use: utilize the bonding method that metal forming is fitted by bonding agent; The material of coated substrate 2 and the casting of resin combination on metal foil; On the thin conductive layer (lamella) of the thickness number nm utilizing sputtering or vapour deposition method to be formed on base material 2, plating is utilized to form the sputtering/plating of metal level; Utilize the laminating etc. that metal forming is pasted by hot pressing.
(conductive layer formation process)
As shown in Figure 2 B, conductive layer formation process forms the operation of the 1st conductive layer 3 and the 2nd conductive layer 4 by carrying out patterning to metal film 90,91.The patterning of metal film 90,91 such as can utilize photoetch and carry out.Photoetch is passed through, after the formation of the surface of metal film 90,91 has the etchant resist of predetermined pattern, to process, and remove etchant resist and carry out with etching solution to the metal film 90,91 exposed from etchant resist.
In addition, when this patterning, conductive layer through hole 30 can be formed at the 1st conductive layer 3 simultaneously.As mentioned above, this conductive layer through hole 30 forms via hole with there being bottom outlet 7.
In addition, this metal film pattern also can be bonded to the method for base material 2 by after carrying out patterning to the metal film formed on the surface of release film, carry out stacked method etc. carry out the metal film after stamping-out by the patterning of metal film 90,91.
(through hole formation process)
Through hole formation process as shown in Figure 2 C, is formed to form the via hole operation of base material through hole 20 having bottom outlet 7 on base material 2.This base material through hole 20 by the position irradiating laser exposed from the conductive layer through hole 30 of the 1st conductive layer 3 to base material 2, and is formed as being communicated with conductive layer through hole 30, and the surface of the 2nd conductor layer 4 is exposed.By forming base material through hole 20 as above on base material 2, and base material through hole 20 forms via hole with there being bottom outlet 7 together with conductive layer through hole 30.
The irradiation of laser can use gas laser and carry out.As gas laser, such as, can enumerate excimer laser, CO
2laser, Ar laser, He-Ne laser etc.
In addition, after laser irradiates, preferably de-smear carried out to the inner surface of base material through hole 20 and carry out residue removal.
(conductive paste filling work procedure)
As shown in Fig. 2 D and Fig. 2 E, conductive paste filling work procedure comprises to the via hole coating of conductive paste 92 having bottom outlet 7, and the placement of conductive paste 92 after coating.
(conductive paste)
Conductive paste 92, containing conducting particles and adhesive, preferably contains curing agent and solvent.
For the conducting particles of conductive paste 92, adhesive and curing agent, due to as the conducting particles of blind hole 8, adhesive and curing agent and the content illustrated is identical, therefore omit repeat specification.
As the lower limit of the mass ratio of the conducting particles in conductive paste 92 and adhesive, preferred 80:20.As the upper limit of this mass ratio, preferred 96:4, more preferably 93:7.If the mass ratio of conducting particles and adhesive is less than above-mentioned lower limit, then the relative step-down of the ratio of conducting particles, and the ratio of adhesive uprises relatively, and via hole resistance likely becomes excessive.On the other hand, if above-mentioned mass ratio exceedes the above-mentioned upper limit, then the ratio of conducting particles uprises relatively, and the relative step-down of the ratio of adhesive, conductive paste 92 likely worsens to via hole with there being the fillibility of bottom outlet 7, between the 1st conductive layer 3 and the 2nd conductive layer 4, produce loose contact.
As the lower limit of the viscosity of this conductive paste 92, preferred 20Pas, more preferably 25Pas, further preferred 30Pas.As the upper limit of the viscosity of conductive paste 92, preferred 95Pas, more preferably 90Pas, further preferred 85Pas.If the viscosity of conductive paste 92 is less than above-mentioned lower limit, then the coating of conductive paste 92 likely worsens, and blind hole 8 likely high resistance.If the viscosity of conductive paste 92 exceedes the above-mentioned upper limit, then likely worsen to via hole with there being the fillibility of bottom outlet 7, the reliability of electrical connection of blind hole 8 reduces.
As the lower limit of the thixotropic index of conductive paste 92, preferably-0.05, more preferably-0.025, further preferably 0.As the upper limit of the thixotropic index of conductive paste 92, preferably 0.50, more preferably 0.45, further preferably 0.40.If the thixotropic index of conductive paste 92 is less than above-mentioned lower limit, or exceed the above-mentioned upper limit, then conductive paste 92 coating and likely worsen to via hole with there being the fillibility of bottom outlet 7, the reliability of electrical connection of blind hole 8 reduces.
(coating of conductive paste)
The coating of conductive paste 92 is by carrying out with having bottom outlet 7 and its periphery to apply a certain amount of conductive paste 92 at via hole.Because the thixotropic index of conductive paste 92 is in above-mentioned scope, the viscosity of the conductive paste 92 be coated with is less, therefore, it is possible to by being coated with to via hole with there being bottom outlet 7 filled conductive cream fully.
As the coating process of conductive paste, such as, silk screen printing, jet printing etc. can be enumerated, preferred silk screen printing.According to this silk screen printing, the moving direction orientation of the long axis scraper plate of the conducting particles made by making scraper plate move in conductive paste 92 can be expected.Thereby, it is possible to conducting particles contact area each other ensured comparatively large, the resistance of blind hole 8 and the contact resistance of this blind hole 8 and the 2nd conductive layer 4 can be made to reduce.Its result, can make the reliability of electrical connection of blind hole 8 and the 2nd conductive layer 4 improve further.
As to the via hole lower limit of coating weight of conductive paste having bottom outlet 7, relative to the via hole volume having bottom outlet 7, preferably 60 capacity %, more preferably 80 capacity %.As the upper limit of this coating weight, relative to the via hole volume having bottom outlet 7, preferably 100 capacity %.Being less than or equal to the above-mentioned upper limit by making above-mentioned coating weight be more than or equal to above-mentioned lower limit, fully can guaranteeing conducting of the 1st conductive layer 3 and the 2nd conductive layer 4, and blind hole 8 can be suppressed unnecessarily too to protrude from the surface of the 1st conductive layer 3.
(placement of the conductive paste after coating)
As shown in Figure 2 E, the placement of the conductive paste 92 after coating carries out with there being bottom outlet 7 to make be coated with conductive paste 92 be filled to via hole.As mentioned above, conductive paste 92 has the thixotropy of regulation.Therefore, by placing after the coating of conductive paste 92, due to compared with during coating, the shearing force acted on to conductive paste 92 diminishes, thus the viscosity of conductive paste 92 increases.Its result, by the placement of the conductive paste 92 after coating, suppresses mix bubble with having in the conductive paste 92 of filling in bottom outlet 7 and realize stabilisation at via hole, therefore, it is possible to improve fillibility.
Standing time after conductive paste printing according to the number to be printed of the viscosity of conductive paste 92, thixotropic index, conductive paste 92, via hole with having volume of bottom outlet 7 etc. and determining.The lower limit of above-mentioned printing time normally 1 minute, preferably 2 minutes, is more preferably 3 minutes.The upper limit of above-mentioned printing time normally 60 minutes, preferably 45 minutes, is more preferably 30 minutes.If above-mentioned printing time is less than above-mentioned lower limit, then conductive paste 92 to via hole with there being being filled with of bottom outlet 7 may be insufficient.On the other hand, even if above-mentioned printing time exceedes the above-mentioned upper limit, the change of fillibility is not likely seen yet.
The thixotropic index of conductive paste 92 according to formula as above (1), based on shear rate D1 (2s
-1), shear rate D1 (2s
-1) time viscosities il 1, the shear rate D2 (20s of conductive paste
-1) and shear rate D2 (20s
-1) time conductive paste 92 viscosities il 2 and calculate.And in order to improve conductive paste 92 to the via hole fillibility having bottom outlet 7, viscosity when preferably effect is less to the shearing force of conductive paste 92, namely η 1 is less.Specifically, as the lower limit of η 1, preferred 20Pas, more preferably 40Pas.As the upper limit of η 1, preferred 300Pas, more preferably 150Pas.
(heating of conductive paste)
The heating of conductive paste 92 obtains blind hole 8 to make the adhesive of conductive paste 92 solidify to carry out.
The heating of conductive paste 92 such as can be enumerated: the method etc. of the method kept in the heating furnace of high-temperature atmosphere, the method for blowing hot-air, use stamping machine pressurized, heated, wherein, considers the aspect that the conductivity of blind hole 8 is improved, the method for preferred pressurized, heated.
According to pressurized, heated, when heating, conductive paste 92 is compressed, and the density of the conducting particles in blind hole 8, contact area become large, and the contact area of conducting particles and the 1st conductive layer 3 and the 2nd conductive layer 4 diminishes.Thus, the contact resistance of blind hole 8 and the 1st conductive layer 3 and the 2nd conductive layer 4 diminishes.
The heating-up temperature of conductive paste 92 is according to the kind of conductive paste 92, and especially the kind of adhesive determines, normally 100 DEG C ~ 280 DEG C.
The heating of conductive paste 92 as above uses heat-curing resin at the adhesive as conductive paste 92, preferably carry out after pre-drying.
Predryingly to carry out to remove the solvent comprised in conductive paste 92.As mentioned above, by removing the residual solvent of conductive paste 92 before making adhesive solidification, and can preventing from producing space at via hole with having in bottom outlet 7, can contact resistance be reduced.In addition, when using thermoplastic resin as adhesive, also can by means of only the heating completing conductive paste 92 with predrying same operation.
(cover layer lamination process)
As shown in Figure 2 F, cover layer lamination process covers stacked 1st cover layer 5 of mode of the 1st conductive layer 3 and the 2nd conductive layer 4 and the operation of the 2nd cover layer 6.This cover layer lamination process such as obtains being pre-formed bond layer 51,61 on coverlay 50,60 after the 1st cover layer 5 and the 2nd cover layer 6 load in the mode covering the 1st conductive layer 3 and the 2nd conductive layer 4, being fixed on base material 2 by coverlay 50,60 and carrying out by pressurized, heated via bond layer 51,61.
In addition, as long as the condition of pressurized, heated suitably determines according to the principal component etc. of the bond layer 51,61 used in the 1st cover layer 5 and the 2nd cover layer 6.In addition, also when the heating of cover layer lamination process, the heating of conductive paste 92 can be carried out simultaneously.
< advantage >
In the manufacture method of this printing distributing board, as via hole with have in bottom outlet 7 fill conductive paste 92, by using the conductive paste containing average grain diameter and the conducting particles of draw ratio in above-mentioned scope, can suppressing to remain bubble at via hole with having in bottom outlet 7, conductive paste 92, just can form blind hole 8 without the need to froth breaking operation.Thereby, it is possible to do not need to form blind hole 8 under vacuum conditions.Its result, the manufacture method of this printing distributing board can there is no need for the equipment investment performing froth breaking operation, in addition also without the need to repeating vacuum state and to atmosphere opening state, therefore, it is possible to suppress productive deterioration.In addition, by suppressing bubble residual to via hole hole 7, conductive paste 92, the adhesion of blind hole 8 and the 2nd conductive layer 4 can be improved, therefore, it is possible to make reliability of electrical connection improve.In addition, by making the thixotropic index of conductive paste 92 and viscosity in above-mentioned scope, and conductive paste 92 can be made further to improve to via hole with there being the fillibility of bottom outlet 7.In addition, as conductive paste 92, by making the mass ratio of conducting particles and adhesive in above-mentioned scope, and fully can guarantee the conductivity of blind hole 8 further, and the thermal coefficient of expansion of blind hole 8 can be made suitable.Therefore, this manufacture method can form blind hole 8 efficiently, and can provide the printing distributing board 1 of the reliability of electrical connection excellence of blind hole 8 and the 1st conductive layer 3 and the 2nd conductive layer 4.
[the 2nd execution mode]
Below, with reference to Fig. 3, printing distributing board of the second embodiment of the present invention is described.But in figure 3, for the label that the element annotation that the printing distributing board 1 with Fig. 1 is identical is identical, omit repeat specification in the following.
The printing distributing board 1A of Fig. 3 is basic identical with the printing distributing board 1 of Fig. 1, and difference is also have via hole with there being bottom outlet 7A and blind hole 8A.
< via hole is with there being bottom outlet >
Via hole is for forming the via hole hole with the end of blind hole 8A with there being bottom outlet 7A.This via hole runs through the 2nd conductive layer 4A and base material 2A with there being bottom outlet 7A, and overlooks (cross section) shape and be formed as circular and vertical sectional shape is formed as trapezoidal taper.Limit the via hole inner peripheral surface having bottom outlet 7A by the conductive layer through hole 40A of the 2nd conductive layer 4A and the base material through hole 20A of base material 2A, limit the via hole bottom surface having bottom outlet 7A by the surface (face by substrate layer 2A side) of the 1st conductive layer 3.This via hole is with having the via hole of the internal diameter of bottom outlet 7A and the degree of depth and Fig. 1 with there being bottom outlet 7 identical.
< blind hole >
Blind hole 8A, for realizing conducting of the 1st conductive layer 3 and the 2nd conductive layer 4A, is equivalent to an example of via hole between partial layer.This blind hole 8A comprises flange part 80A, main part 81A and recess 82A, runs through the 2nd conductive layer 4A and base material 2A at main part 81A place.
Flange part 80A contacts with the surface (face of the 2nd cover layer side) of the 2nd conductive layer 4A.The top (side near flange part) of the outer peripheral face of main part 81A contacts with the inner surface of the conductive layer through hole 40A of the 2nd conductive layer 4A, and the bottom (side near bottom surface) of outer peripheral face contacts with the inner surface of the base material through hole 20A of base material 2A.Further, the bottom surface of main part 81A contacts with the surface (face of substrate layer 2A side) of the 1st conductive layer 3.As mentioned above, blind hole 8A contacts with the 2nd conductive layer 4A by making the top of flange part 80A and main part 81A (side near flange part), and the bottom surface of main part 81A is contacted with the 1st conductive layer 3, thus conducts the 1st conductive layer 3 and the 2nd conductive layer 4A.
Recess 82A gives blind hole 8A and holds yielding characteristic.This recess 82A is formed in the central portion of the upper surface (face of the 2nd cover layer side) of blind hole 8A.Recess 82A is identical due to the effect of the recess 82 of the blind hole 8 with Fig. 1, therefore when printing distributing board 1A is bent, easily maintains the contact condition with the 2nd conductive layer 4A well.Therefore, printing distributing board 1A easily maintains the contact condition of blind hole 8A and the 2nd conductive layer 4A well.
[other execution mode]
Will be understood that this time disclosed execution mode is illustrate in all respects, and be not restrictive content.Scope of the present invention is not limited to the structure of above-mentioned execution mode, and it comprises by shown in claim, and all change scope in impartial with the scope of claim.
In the above-described embodiment, as an embodiment of printing distributing board, be illustrated to have flexible printing distributing board, but scope of the present invention is not limited thereto.As this printing distributing board, also rigidity printing distributing board can be adopted.In addition, this printing distributing board also can adopt by flexible printing patch panel and rigidity printing distributing board integration and obtain firm-flexible printing patch panel, multi-ply construction laminated substrate etc.
In the above-described embodiment, the printing distributing board as via hole between partial layer with blind hole is illustrated, but this printing distributing board also can adopt buried via hole etc. as via hole between partial layer.
The forming position of blind hole, brush amount and shape are not limited to the structure illustrated in the above-described embodiment.Such as, blind hole is taper not necessarily, can be cylindric, and the cross section of horizontal direction also can be other shape outside circle.
[embodiment]
Below, in further detail the present invention is described based on embodiment.But embodiment not delimit the scope of the invention.
[embodiment 1]
Preparation does not use bonding agent and is fitted with Double-face adhesive copper base (the polyimides film thickness: 25 μm of Copper Foil on the two sides of polyimide film, copper thickness: 12 μm), etching and processing is carried out to the Copper Foil of this Double-face adhesive copper base and on two sides, forms distribution (conductive layer).In addition, establish via hole hole with the end (opening diameter 100 μm) by YAG laser open, and implement dry de-smear process.Form 1296 via hole holes.
Then, as adhesive, bisphenol A type epoxy resin 6 mass parts is dissolved in acetic acid butyl carbitol ester (BCA).Add latent curing agent 2 mass parts of imidazoles wherein, make conductive paste as conducting particles interpolation silver particles 73 mass parts and silver-plated copper particle 4 mass parts.In addition, the average grain diameter of silver particles and silver-plated copper particle and draw ratio are respectively 1.1 μm and 3.4.
Above-mentioned conductive paste is filled to by silk screen printing in all via hole holes.Conductive paste applies in the mode of hole, overlay path hole entirety, and coating diameter is set to 150 μm.Thereafter, carrying out predrying and solvent that is that remove in conductive paste by being heated to 70 DEG C, making the printing distributing board that 1296 via holes connect with daisy chain structure.
[embodiment 2 ~ embodiment 12 and comparative example 1 ~ 11]
Except be used in the physical property shown in table 1 and composition as conductive paste except, make the printing distributing board of embodiment 2 ~ embodiment 12 and comparative example 1 ~ 11 identically with embodiment 1.In addition, "-" in table 1 refers to and is not mixed in conductive paste by this composition.
[table 1]
[evaluation]
For the printing distributing board of embodiment 1 ~ 12 and comparative example 1 ~ 11, thermal expansion character and connection reliability are evaluated.The results are shown in table 2.
< thermal expansion character >
Thermal expansion character as the thermal coefficient of expansion (A) of base material and the thermal coefficient of expansion (B) of via hole ratio ((A)/(B)) and evaluate.The thermal coefficient of expansion of base material and via hole is according to JIS-R3251 " determination method based on the coefficient of linear expansion of the laser interferance method of low-expansion glass ": 1995, uses LASER HEAT dilatometer (" the LIX-2L type " of ULVAC science and engineering society) and measures.
This thermal expansion character when thermal coefficient of expansion than be more than or equal to 0.1 and be less than or equal to 10 can be judged as good.
< connection reliability >
Connection reliability as the initial resistivity value before thermal shock test and the contact resistance before and after thermal shock test rate of change (resistance change rate) and evaluate.In addition, resistance change rate utilizes following formula to calculate.
Resistance change rate (%)=100 × (resistance value-initial resistivity value after thermal shock test)/initial resistivity value
This connection reliability is less than or equal to 50 Ω in initial resistivity value, and when the absolute value of resistance change rate is less than 10%, can be judged as good.
(thermal shock test)
Thermal shock test is by repeatedly exposing printing distributing board at low ambient temperatures with some cycles and carrying out under hot environment.Specifically, by expose 15 minutes under the low temperature environment of-45 DEG C after, under the hot environment of 125 DEG C, expose 15 minutes as 1 cover operation, this cover operation repetition 1000 times.
(evaluation of contact resistance)
Contact resistance utilizes 4 terminal methods from the two ends of daisy chain and measures.In addition, can think that resistance value is the total of contact resistance of the resistance of 1296 via holes, the resistance of conductive layer and via hole and conductive layer.
[table 2]
As shown in Table 2, the printing distributing board of embodiment 1 ~ 12 is that in the scope of 0.77 ~ 6.33, thermal expansion character obtains good result at thermal coefficient of expansion ratio ((A)/(B)).
In addition, the initial resistivity value of the printing distributing board of embodiment 1 ~ 12 is 38.1 Ω to the maximum, and the maximum absolute value of resistance change rate is 6%, and connection reliability is excellent.
On the other hand, the printing distributing board of comparative example 1 ~ 11 is except comparative example 11, although thermal coefficient of expansion ratio ((A)/(B)) obtains good result, initial resistivity value is comparatively large on the whole, and the absolute value of resistance change rate has exceeded 10%.As mentioned above, the printing distributing board of comparative example 1 ~ 11 becomes the lower result of connection reliability.
According to above result, can expect, as via hole conducting particles by be more than or equal to containing average grain diameter 0.5 μm and be less than or equal to 5.0 μm, draw ratio be more than or equal to 2 and be less than or equal to 20 conducting particles, thus reliability of electrical connection improve.In addition, can deduce, be more than or equal to 20Pas by the viscosity of the conductive paste for the formation of via hole is set to and is less than or equal to 95Pas, the thixotropic index of above-mentioned conductive paste being set to and being more than or equal to-0.05 and being less than or equal to 0.50, and obtain the higher via hole of reliability of electrical connection.
Industrial applicibility
The present invention can provide a kind of printing distributing board and manufacture method thereof, and it can form via hole between partial layer efficiently, and between partial layer, the reliability of electrical connection of via hole and conductive layer is excellent.
Claims (8)
1. a printing distributing board, it has:
Base material, it has 1st and the 2nd respect to one another; 1st conductive layer, it is formed at described 1st of described base material; 2nd conductive layer, it is formed at described 2nd of described base material; And via hole between partial layer, it runs through described base material, and is electrically connected described 1st conductive layer and described 2nd conductive layer,
Between described partial layer, via hole contains conducting particles,
The average grain diameter of described conducting particles is more than or equal to 0.5 μm and is less than or equal to 5.0 μm,
The draw ratio of described conducting particles is more than or equal to 2 and is less than or equal to 20.
2. printing distributing board according to claim 1, wherein,
Between described partial layer, via hole is also containing adhesive,
The mass ratio of described conducting particles and described adhesive is more than or equal to 80:20 and is less than or equal to 96:4.
3. printing distributing board according to claim 1 and 2, wherein,
Between described partial layer, via hole is solidified to form by making conductive paste,
The thixotropic index of described conductive paste is more than or equal to-0.05 and is less than or equal to 0.50.
4. printing distributing board according to claim 3, wherein,
The viscosity of described conductive paste is more than or equal to 20Pas and is less than or equal to 95Pas.
5. printing distributing board according to any one of claim 1 to 4, wherein,
Thermal coefficient of expansion on the thickness direction of described base material is more than or equal to 0.1 times of the described thermal coefficient of expansion of via hole between described partial layer, and is less than or equal to 10 times of the described thermal coefficient of expansion of via hole between described partial layer.
6. printing distributing board according to any one of claim 1 to 5, wherein,
Between described partial layer, via hole is formed by using the silk screen printing of conductive paste.
7. printing distributing board according to any one of claim 1 to 6, wherein,
Between described partial layer, via hole is formed at the via hole blind hole having bottom outlet,
Described via hole is more than or equal to 40 μm with there being the internal diameter of bottom outlet and being less than or equal to 100 μm,
Described via hole is more than or equal to 10 μm with there being the degree of depth of bottom outlet and being less than or equal to 100 μm.
8. the manufacture method of a printing distributing board, wherein, this printing distributing board has via hole between partial layer, via hole electrical connection the 1st conductive layer and the 2nd conductive layer between this partial layer, 1st conductive layer is formed at described 1st of the base material with the 1st and the 2nd respect to one another, 2nd conductive layer is formed at the 2nd of described base material
The manufacture method of this printing distributing board has:
Form the via hole operation having bottom outlet;
Conductive paste containing conducting particles and adhesive is filled to the described via hole operation having bottom outlet; And
Make the operation that described conductive paste solidifies,
The viscosity of described conductive paste is more than or equal to 20Pas and is less than or equal to 95Pas, and thixotropic index is more than or equal to-0.05 and is less than or equal to 0.50,
The average grain diameter of described conducting particles is more than or equal to 0.5 μm and is less than or equal to 5.0 μm, and draw ratio is more than or equal to 2 and is less than or equal to 20, and,
The mass ratio of described conducting particles and described adhesive is more than or equal to 80:20 and is less than or equal to 96:4.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013244432A JP5945262B2 (en) | 2013-11-26 | 2013-11-26 | Printed wiring board and manufacturing method thereof |
| JP2013-244432 | 2013-11-26 |
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| Publication Number | Publication Date |
|---|---|
| CN104684249A true CN104684249A (en) | 2015-06-03 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410697006.9A Pending CN104684249A (en) | 2013-11-26 | 2014-11-26 | Printed wiring board and method of manufacturing same |
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| Country | Link |
|---|---|
| JP (1) | JP5945262B2 (en) |
| CN (1) | CN104684249A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108550977A (en) * | 2018-03-30 | 2018-09-18 | 深圳市振华微电子有限公司 | RFID antenna, RFID tag and RFID antenna production method |
| CN111050496A (en) * | 2019-03-28 | 2020-04-21 | 苏州经纬通电子科技有限公司 | Circuit board preparation process |
| CN111627824A (en) * | 2020-06-09 | 2020-09-04 | 山东新恒汇电子科技有限公司 | Reverse-pasted packaging carrier tape for realizing CSP chip roll-to-roll production and manufacturing method thereof |
-
2013
- 2013-11-26 JP JP2013244432A patent/JP5945262B2/en active Active
-
2014
- 2014-11-26 CN CN201410697006.9A patent/CN104684249A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108550977A (en) * | 2018-03-30 | 2018-09-18 | 深圳市振华微电子有限公司 | RFID antenna, RFID tag and RFID antenna production method |
| CN111050496A (en) * | 2019-03-28 | 2020-04-21 | 苏州经纬通电子科技有限公司 | Circuit board preparation process |
| CN111627824A (en) * | 2020-06-09 | 2020-09-04 | 山东新恒汇电子科技有限公司 | Reverse-pasted packaging carrier tape for realizing CSP chip roll-to-roll production and manufacturing method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JP5945262B2 (en) | 2016-07-05 |
| JP2015103720A (en) | 2015-06-04 |
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Application publication date: 20150603 |